WO2024062053A1

WO2024062053A1 - Detecting battery failure through pressure sensing

Info

Publication number: WO2024062053A1
Application number: PCT/EP2023/076108
Authority: WO
Inventors: Niklas ROOS; Robert Wassmur; Jongseok Moon; Cheng Liu
Original assignee: Polestar Performance AB
Current assignee: Polestar Performance AB
Priority date: 2022-09-21
Filing date: 2023-09-21
Publication date: 2024-03-28
Anticipated expiration: 2025-03-21

Abstract

Battery systems such as those used to power electric vehicles include series of cells that are interconnected to provide sufficient voltage and current. In some circumstances, individual ones of these cells can fail in a so-called thermal event, which causes heating, expansion, and then rupture of the affected cell. Using sensors arranged between the cells (or blocks of cells), the failure point can be detected early to provide ameliorative cooling, electrical disconnection, and warning to occupants of the vehicle to get to a place of safety.

Description

DETECTING BATTERY FAILURE THROUGH PRESSURE SENSING

TECHNICAL FIELD

Embodiments described herein relate to arrangements for monitoring or controlling batteries, including those adapted for electric vehicles. Particularly, systems and methods described herein may be used to prevent thermal propagation within a multi-cell battery system. More particularly, battery failure prior to thermal propagation may be detected through pressure sensing.

BACKGROUND

Safety features of electric vehicles have been a topic of heightened discussion. In many countries, laws and regulations dictate safety requirements for electric vehicles. In the European Union, China, and many other countries, safety requirements dictate that an electric vehicle should give vehicle occupants a 5-minute warning at minimum to help avoid a dangerous situation. Currently, most BMSs (battery management systems) generate alerts based on abnormalities in key parameters, such as temperature, state-of-charge, or voltage at the pack level.

As is well known, there is a desire to preserve unaffected parts of a battery module in the event of a thermal runaway (or thermal propagation), which requires notice of the thermal event, and time to remedy or stop the event. This warning is crucial to the preservation of the battery module, and to the safety of the occupants within the vehicle. However, implemented methods detect pressure build up at too late of a stage, i.e. , once the cell has already begun to rupture or leak. Using pressure sensors to detect the internal pressure of a battery cell, only allows for a change in pressure to be detected once the cell’s pressure has progressed nearly to the point of rupturing. Not only is this problematic in terms of battery cell preservation and recycling, but it is also a concern from a safety standpoint.

Systems and methods recognize pressure buildup in batteries as an indicator of failure, specifically measured by the internal battery pressure, rather than external pressure measurements. Then when the cell ruptures or leaks, this system notices it is due to pressure drop. These methods do not help with proactive detection of battery failure, because it will only sense once the rupture has already occurred. In an electric vehicle, this would likely occur very close in sequence to the time that the car starts to combust.

Although various systems have been developed over the years to regulate the temperature of the battery pack, further improvements in the ability detect and warn passengers of the possibility of a thermal event are needed. Warning passengers once battery cells have progressed beyond swelling/expanding using only temperature sensors, limits the amount of time passengers have to exit the vehicle. Further, it is likely that fewer battery cells within the module will be able to be preserved, as more cells begin to become unhealthy or damaged.

It would therefore be desirable to provide a system of sensing battery failure before thermal propagation occurs, including giving adequate notice to passengers, and allowing preservation of unaffected battery cells.

SUMMARY

The herein disclosed technology seeks to mitigate, alleviate or eliminate one or more of the aboveidentified deficiencies and disadvantages in the prior art to address various problems relating to detecting battery failures at an early stage.

Embodiments described herein provide systems and methods for detecting battery failure via pressure sensing. As a battery degrades, there are four stages of change: the battery cell will get hot/increase in temperature, the cells will begin to vent gasses as the temperature increases, the accumulation of gasses forces the cells to swell/expand, and finally, the cell will rupture, resulting in a thermal event. The disclosed system can monitor pressure levels within the battery tray itself, providing an opportunity to warn passengers in an adequate amount of time, of potential battery failure. More specifically, the presently disclosed technology facilitates detection of potential battery failures before thermal propagation or rupture occurs in the battery. Thus, it provides a proactive detection of battery failures which allows for actions to be put in place to stop, or handle the thermal event. Various aspects and embodiments of the disclosed technology are defined below and in the accompanying independent and dependent claims.

According to a first aspect, there is provided a battery pressure sensing system for detecting potential failure in a battery assembly. The battery assembly comprises a battery tray and several battery modules housed within the battery tray. Each battery module comprises a string of battery cells. The battery pressure sensing system comprises a pressure sensor arranged on a battery module of the several battery modules, or on a battery cell of said battery module. The pressure sensor is configured to detect an expansion of walls of any battery cell of said battery module such that a potential failure can be detected prior to a thermal propagation within the battery assembly. In other words, a thermal event can be detected prior to said battery cell reaching a gas venting state or rupture.

As stated above, a possible associated advantage is that potential failures in the battery assembly can be detected at an early stage. This may be advantageous from a safety perspective in that any occupants can be informed prior to a thermal propagation happening. Further, it may allow for other ameliorative actions to be performed such as stopping the potential failure from progressing further, or limiting possible damages within the battery assembly.

The pressure sensor may be arranged between any two adjacent battery modules of the several battery modules. Alternatively, the pressure sensor may be arranged between any two adjacent battery cells of a string of battery cells.

Arranging the pressure sensor between battery modules, or between battery cells may facilitate an early detection of the potential battery failure by detecting swelling of the battery cells.

The battery pressure sensing system may further comprise a further pressure sensor. The pressure sensor may be arranged on a first battery cell of a battery module, and the further pressure sensor may be arranged on a second battery cell of said battery module.

Having at least two pressure sensors within the same battery module may be advantageous in that detection of expanding walls of any battery cell within the module can be done more reliably. It may further be utilized in determining which battery cell(s) within the module that has expanded. This can e.g. be done by comparing a detected pressure of the pressure sensor and a detected pressure of the further pressure sensor, as well as taking into account the placement of the two pressure sensors within the battery module.

The pressure sensor may be a first pressure sensor. The battery pressure sensing system may further comprise a second pressure sensor. The first pressure sensor may be arranged on a first battery module or on a battery cell of said first battery module, and the second pressure sensor may be arranged on a second battery module or on a battery cell of said second battery module.

Having pressure sensors provided in more than one module of the battery assembly may be advantageous in that potential failures can be detected over a larger part of the battery assembly. It may further be used in determining in which battery module of the battery assembly, an expanding battery cell is present. Thereby, a targeted approach for handling the potential failure can be achieved. For example, if it is found that only one battery module of the battery assembly is affected, said battery module can be dealt with without having to affect the rest of the battery modules. For instance, the failing battery module can be disconnected, while the rest of the battery assembly can continue to work as normal. The battery pressure sensing system may further comprise a strap wrapped around a battery module of the several battery modules. The strap may comprise a strain gauge configured to measure a strain in the strap.

The strap comprising the strain gauge may be used as further indication of expanding battery cells. In particular, using a combination of the strap comprising the strain gauge, and pressure sensor(s) within the module may be advantageous in that the strain gauge may give an early indication of expansion within the module, whereas the pressure sensor(s) can be used to determine which battery cell(s) within the module are expanding, and/or to what degree they have expanded.

The strap may be formed of a steel or aluminum band.

The pressure sensor may be a directional pressure sensor configured to determine a direction of the pressure caused by an expanding cell.

Directional pressure sensor(s) can be utilized in determining which battery cell within a battery module are expanding, based on the measured direction of the pressure.

The pressure sensor may be a piezoelectric pressure sensor or a resistive pressure sensor. The pressure sensor may be one of a gauge pressure sensor, a relative pressure sensor, a compression sensor, a tension sensor and a mechanical deformation sensor.

The battery assembly may be configured to provide power to operate an electric vehicle.

In some embodiments, the pressure sensors work to detect pressure building in or around the battery cell. This pressure sensing may allow for earlier detecting of potential battery failure or a thermal event. By placing a pressure sensor within the battery tray, but outside of the battery cell, the sensor can detect a multitude of changes, including those that happen to surrounding or neighboring cells.

In some embodiments, the pressure sensors may be piezoelectric pressure sensors. The sensors may be placed outside of the battery module. This placement may detect the expansion of the walls of a battery cell at any point in the string of cells. The sensor may be placed on the top side of the battery module, with fixations at the end points of the sensor. During the second stage of battery cell changes when the module begins to expand or swell due to gassing, force may be exerted on the sensor, thus detecting the gassing event.

In some embodiments, the sensor may be placed between the individual battery cells within the tray. Placing a piezoelectric pressure sensor, or another type of pressure sensor between two of the battery cells may allow the sensors to detect the cells expanding within the module. For example, in a string of multiple battery cells within a module, if one cell expands on the end of the pack, there may still be enough force to push the rest of the cells as a chain, even if the sensor is placed in the middle of the sequence of cells. The expansion of any of the battery cells in the chain will induce pressure from the expansion in a chain reaction down the string of battery cells, triggering the pressure sensor.

In some embodiments, the battery cells may be rectangular in shape, providing a plurality of surfaces to attach the pressure sensor to. Alternatively, the battery cells within the module may be cylindrical in shape, allowing for different placements of the pressure sensors within the battery tray. The shape of cylindrical battery cells may allow for the battery to distribute the internal pressure from side reactions over the cell circumference more evenly than a cell of a different shape. This also may allow the cell to tolerate a higher level of internal pressure without deformation or rupture.

In some embodiments, the sensors may be gauge pressure sensors, providing a pressure measurement relative to the local atmospheric pressure. The sensors may also be relative pressure sensors. The sensors used may also be a tension or compression sensor that acts by using plates that move closer together as a battery cell expands. Finally, a mechanical deformation sensor may be used. Selection of the type of sensor to be used may vary based on how many sensors are being used, where they are being placed in the battery tray, and perhaps the type of safety event the sensor is primed to detect. If potential deformation is a concern (i.e. , in the case of a side impact or crash), a mechanical deformation pressure sensor may be the most sensible choice. In another embodiment, a piezoelectric sensor may be the fitting choice, to detect a change in dynamic pressure due to their high sensitivity, high stability and low-pressure consumption.

In some embodiments, the pressure sensors may sense real-time changes in pressures. The pressure sensors may also be configured such that they may detect and monitor pressure changes on any pre-determined schedule or interval. The pressure sensor completed over-time may allow for more accurate detection of recurring problems related to battery function and health. Further, on-going sensing may enable data collection that may inform future battery development, pressure sensor placement, and overall safety metrics related to the electric vehicle.

Early detection of unhealthy battery cells not only provides adequate notice to passengers, but it also makes it far more possible to recycle and repurpose the unharmed battery cells. When potential thermal events are discovered beyond stage 2, damage has likely begun to spread down the string of battery cells, making it unlikely that those cells will be able to be used again. According to a second aspect, there is provided a battery assembly comprising the battery pressure sensing system for detecting potential failure in the battery assembly according to the first aspect.

The battery assembly may further comprise a cooling system configured to cool the battery assembly.

The battery cells of the battery assembly may be rectangular or cylindrical in shape.

The above-mentioned features of the first aspect, when applicable, apply to this second aspect as well. In order to avoid undue repetition, reference is made to the above.

According to a third aspect, there is provided an electric vehicle comprising the battery assembly according to the second aspect. The above-mentioned features of the first and second aspect, when applicable, apply to this third aspect as well. In order to avoid undue repetition, reference is made to the above.

According to a fourth aspect, there is provided a method for detecting potential failure in a battery assembly using a battery pressure sensing system. The battery assembly comprises a battery tray and several battery modules housed within the battery tray. Each battery module comprises a string of battery cells. The battery pressure sensing system comprises a pressure sensor arranged on a battery module of the several battery modules, or on a battery cell of said battery module. The pressure sensor is configured to detect an expansion of walls of any battery cell of said battery module such that a potential failure can be detected prior to a thermal propagation within the battery assembly. The method comprises obtaining, via the pressure sensor, sensor data relating to a pressure caused by an expansion of walls of an expanding battery cell of said battery module. The method further comprises, in response to the obtained sensor data being indicative of a pressure exceeding a threshold value, performing an ameliorative action of the battery assembly. The method provides for early detection and mitigation of potential battery failures. As mentioned above, this may provide for improved safety as well as reducing potential damages which may be caused by the failure.

Performing the ameliorative action may comprise providing a notification to an occupant of the vehicle.

The ameliorative action may be performed for a battery cell, a set of battery cells, or a string of battery cells of a battery module. In other words, a targeted approach of performing the ameliorative action can be achieved, which may improve the results of the ameliorative action, as well as having limited effect on the operation of the other battery modules or battery cells. The method may further comprise determining, based on the obtained sensor data, the battery cell, the set of battery cells, or the string of battery cells of the battery module for which the ameliorative action is to be performed.

Determining the battery cell, the set of battery cells, or the string of battery cells of the battery module for which the ameliorative action is to be performed may be further based on sensor data obtained via at least a further pressure sensor of the battery pressure sensing system. The further pressure sensor may be arranged within the same battery module, or within another battery module. Using sensor data of a further pressure sensor may be advantageous in that the battery cell(s) for which the ameliorative action is to be performed can be determined with higher certainty.

Performing the ameliorative action may comprise disconnecting the battery cell, the set of battery cells, or the string of battery cells of the battery module, for which the ameliorative action is to be performed, from the battery assembly. By disconnecting only those battery cell(s) which experiences expansion, the remaining parts of the battery assembly can continue to operate.

Performing the ameliorative action may comprise adjusting a cooling, provided by a cooling system of the battery assembly, of the battery cell, the set of battery cells, or the string of battery cells of the battery module for which the ameliorative action is to be performed. By e.g. increasing cooling of the battery cell(s) which experiences expansion, the thermal event can be prevented from progressing further.

Obtaining the sensor data may be repeated at a pre-determined interval. This may provide for continuous monitoring of the battery assembly.

The method may further comprise determining a degree of expansion of the expanding battery cell based on the obtained sensor data relating to the pressure caused by the expansion of walls of the expanding battery cell.

The above-mentioned features of the first through third aspect, when applicable, apply to this fourth aspect as well. In order to avoid undue repetition, reference is made to the above.

According to a fifth aspect, there is provided a computer program product comprising instructions which, when the program is executed by a computing device, causes the computing device to carry out the method according to the fourth aspect. The above-mentioned features of the first through fourth aspect, when applicable, apply to this fifth aspect as well. In order to avoid undue repetition, reference is made to the above. According to a sixth aspect, there is provided a (non-transitory) computer-readable storage medium. The non-transitory computer-readable storage medium stores one or more programs configured to be executed by one or more processors of a processing system, the one or more programs comprising instructions for performing the method according to the fourth aspect. The above-mentioned features of the first through fifth aspect, when applicable, apply to this sixth aspect as well. In order to avoid undue repetition, reference is made to the above.

The term “non-transitory,” as used herein, is intended to describe a computer-readable storage medium (or “memory”) excluding propagating electromagnetic signals, but are not intended to otherwise limit the type of physical computer-readable storage device that is encompassed by the phrase computer-readable medium or memory. For instance, the terms “non-transitory computer readable medium” or “tangible memory” are intended to encompass types of storage devices that do not necessarily store information permanently, including for example, random access memory (RAM). Program instructions and data stored on a tangible computer-accessible storage medium in non-transitory form may further be transmitted by transmission media or signals such as electrical, electromagnetic, or digital signals, which may be conveyed via a communication medium such as a network and/or a wireless link. Thus, the term “non-transitory”, as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM).

The above summary is not intended to describe each illustrated embodiment or every implementation of the subject matter hereof. The figures and the detailed description that follow more particularly exemplify various embodiments.

The disclosed aspects and preferred embodiments may be suitably combined with each other in any manner apparent to anyone of ordinary skill in the art, such that one or more features or embodiments disclosed in relation to one aspect may also be considered to be disclosed in relation to another aspect or embodiment of another aspect.

Further embodiments are defined in the dependent claims. These and other features and advantages of the disclosed technology will in the following be further clarified with reference to the embodiments and variants described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

Subject matter hereof may be more completely understood in consideration of the following detailed description of various embodiments in connection with the accompanying figures, in which: FIG. 1 is a flow chart showing a sequence of the stages of battery degradation.

FIG. 2A is a perspective view of a battery tray according to some embodiments.

FIG. 2B is a perspective view of a battery assembly according to some embodiments.

FIG. 3A is a perspective view of a rectangular battery module according to some embodiments.

Fig. 3B is a cross-sectional view of the rectangular battery module housing an expanded battery cell.

FIG. 4A is a perspective view of a battery module with rectangular battery cells illustrating sensor placement between the individual rectangular battery cells.

FIG. 4B is a side view of the battery module, showing sensor placement between the individual rectangular battery cells.

Fig. 4C is a perspective view of a battery module having a strap wrapped around.

FIGS. 5A-5D are perspective views of examples of multi-sensor arrangements according to some embodiments.

Fig. 6 is a schematic flowchart representation of a method for detecting potential failure in a battery assembly according to some embodiments.

Fig. 7 is a schematic illustration of an electric vehicle according to some embodiments.

While various embodiments are amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the claimed inventions to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the subject matter as defined by the claims.

DETAILED DESCRIPTION OF THE DRAWINGS

The present disclosure will now be described in detail with reference to the accompanying drawings, in which some example embodiments of the disclosed technology are shown. The disclosed technology may, however, be embodied in other forms and should not be construed as limited to the disclosed example embodiments. The disclosed example embodiments are provided to fully convey the scope of the disclosed technology to the skilled person. Those skilled in the art will appreciate that the steps, services and functions explained herein may be implemented using individual hardware circuitry, using software functioning in conjunction with a programmed microprocessor or general purpose computer, using one or more Application Specific Integrated Circuits (ASICs), using one or more Field Programmable Gate Arrays (FPGA) and/or using one or more Digital Signal Processors (DSPs).

It will also be appreciated that when the present disclosure is described in terms of a method, it may also be embodied in apparatus or device comprising one or more processors, one or more memories coupled to the one or more processors, where computer code is loaded to implement the method. For example, the one or more memories may store one or more computer programs that causes the apparatus to perform the steps, services and functions disclosed herein when executed by the one or more processors in some embodiments.

It is also to be understood that the terminology used herein is for purpose of describing particular embodiments only, and is not intended to be limiting. It should be noted that, as used in the specification and the appended claim, the articles "a", "an", "the", and "said" are intended to mean that there are one or more of the elements unless the context clearly dictates otherwise. Thus, for example, reference to "a unit" or "the unit" may refer to more than one unit in some contexts, and the like. Furthermore, the words "comprising", "including", "containing" do not exclude other elements or steps. It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps, or components. It does not preclude the presence or addition of one or more other features, integers, steps, components, or groups thereof. The term “and/or” is to be interpreted as meaning “both” as well and each as an alternative. More specifically, the wording “one or more” of a set of elements (as in “one or more of A, B and C” or “at least one of A, B and C”) is to be interpreted as either a conjunctive or disjunctive logic. Put differently, it may refer either to all elements, one element or combination of two or more elements of a set of elements. For example, the wording “A, B and C” may be interpreted as A or B or C, A and B and C, A and B, B and C, or A and C.

It will also be understood that, although the term first, second, etc. may be used herein to describe various elements or features, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the embodiments. The first element and the second element are both elements, but they are not the same element.

As described herein, embodiments of the present disclosure provide systems and methods of detecting battery failure using pressure senses. Further, embodiments of the present disclosure use pressure sensing to detect early signs of battery failure, providing adequate notice to occupants of an electric vehicle in the event of a thermal event. Providing notice in the early stages of potential battery failure, also allows for the possibility of preserving any unaffected battery cells within the module.

In addition to regulatory requirements, embodiments described herein provide an array of possible ameliorative actions. As used herein, “ameliorative” can refer to a number of actions that prevent injury or damage that would otherwise follow a thermal event in one of the cells.

One category of ameliorative actions is the disconnection of a cell from the remainder of a battery. Typically, when a thermal event occurs in a cell, providing more charge to the cell or drawing power out of the cell exacerbates the problem. Therefore, removing the cell from the remainder of the battery’s cells lets the cell be isolated and either prevent current in and out of the cell, or in some circumstances provide for safe discharge of the energy in the cell. See, e.g., US Patent Application No. 17/534,079 by the Applicant, the contents of which are incorporated herein by reference in their entirety.

Another category of ameliorative actions is provision of cooling. Typically, an electric vehicle includes a cooler (or cooling system) that routes cooling fluid to various locations throughout the vehicle, including the battery. In some vehicles, there is a cooler designated just for the battery. By use of valves or similar structures, a battery cell undergoing a thermal event can be preferentially cooled. It has been shown that by providing sufficient cooling, a thermal event within a cell can be arrested before it spreads to adjacent cells in most circumstances. Even where the spread does occur, cooling helps slow the propagation of a thermal event.

Another category of ameliorative action is a warning. Upon detection of a thermal event within a cell, a user should cease to operate the vehicle as soon as possible until the vehicle can be taken for maintenance and repair and verified as stable. Otherwise, there is a significant risk of loss of power, vehicle damage, and vehicle fire. An occupant of a vehicle with a cell undergoing a thermal event therefore benefits significantly from an early warning that lets them stop the vehicle, call for assistance, and get to an area of safety.

The presently disclosed technology will in the following be described in relation to electrically powered vehicles, also referred to as electric vehicles. By electric vehicle, it is herein meant to encompass both fully electric vehicles and partly electric vehicles (such as hybrid vehicles). It is however to be noted that the presently disclosed technology is not limited to the application of electric vehicles as it may be applicable also to other forms of units or devices comprising a battery assembly.

An embodiment of the present disclosure provides a method of detecting battery failure using a pressure sensor, as will be further described below in connection with Fig. 6. The pressure sensor may be a piezoelectric sensor, a compression sensor, a gauge pressure sensor, a relative pressure sensor, or any pressure sensor capable of detecting a change in pressure within the battery tray. More specifically, the pressure sensor may be any pressure sensor configured to detect expansion of an area, or pressure between two surfaces (i.e. caused by an expanding cell). The pressure sensor may be fixated on a battery module, in a plurality of different locations. The battery modules are housed within the battery tray. Pressure sensors may be placed on the battery module 300, or on or between individual battery cells. Placement of the pressure sensors may be dependent on the shape of the battery cells, the organization of the battery modules within the battery tray, or any number of relevant factors. The pressure sensors may be placed in any way such that they can detect pressure caused by swelling on a battery cell. Placement of the pressure sensor(s) will be further described below.

Referring to FIG. 1 , a flowchart 100 illustrates the sequence of events as a battery degrades. An electrolyte is converted into gas due to chemical reactions at S102 such as a runaway thermal event or an internal short, which leads to pressure beginning to rise inside the battery cell causing further heat to releaser and the battery cell to swell S104. As the battery cell swells S104, a pressure sensor (see, e.g., 304 of FIG. 3A or 404 of Fig. 4A) may detect the change, providing a warning more than 5 minutes before a thermal event S106. If the pressure sensor is not present at the second stage, the battery cell begins to vent gasses, if violation stops at this point, the chemical reaction may stop S106. However, if the violation proceeds, pressure may exceed the valve capacity, causing cracking and/or melting of the separator S108. Finally, the battery cell ruptures, referred to throughout this application as a thermal event S110. This may in turn result in a thermal propagation during which a thermal event starts in other battery cells as well.

There are four generally recognized phases during a thermal event in a battery. The first phase involves chemical reaction causing heat to build up (also referred to herein as “stage 1” herein), corresponding to S102 of FIG. 1. The second phase involves pressure buildup that causes swelling (also referred to as “stage 2” herein), corresponding to S104 of FIG. 1. The third phase involves venting of the pressure buildup, which often occurs through a one-way valve (“stage 3” herein). Notably, it is only at stage 3 that a cell is irreparably damaged to the point where an entire module may need to be scrapped, as the venting can lead to deposition of toxic or flammable materials throughout the module and the one-way valve is often released in a destructive fashion. A full thermal event (also referred to herein as “stage 4”) is one in which the internal pressure of the battery or a cell or module thereof causes a rupture or a fire, can be hazardous to occupants of the vehicle. At stage 4, it becomes highly likely that all of the cells in a module will be unrecoverable as well as the one that began the thermal event.

As described above, for passenger safety (and to comply with various regulations) it can be necessary to provide a certain amount of time in which the vehicle can be safely stopped and the passengers can leave to safety. Additionally, it can be beneficial to arrest the progression of the battery failure prior to a full thermal event, such as at stages 1 or 2 (i.e., elements S102 or S104). For that reason, it can be helpful to detect heat or swelling in individual battery cells prior to venting, cracking, or melting (S106, S108).

Referring again to FIG. 1 , the sequence of events as a battery degrades 100 illustrates the need of placing a pressure sensor in a proper position to detect changes before stages 3 and 4 are take place. Once stages 3 and 4 of battery degradation begin, damage may have reached a point of no return, wherein any affected battery cells may not be able to be saved. Further, the instability of the entire battery module may be at risk once the thermal propagation progresses. If thermal propagation progresses, other cells of the battery assembly will start to swell. Thus, the process described in Fig. 1 will spread to other cells. Detection after stage 2 may allow for preservation of the entire battery module, or at the very least, any unaffected battery cells.

Referring to FIG. 2A and 2B, a perspective view of a battery assembly 200, and a battery tray 202 of the battery assembly 200 according to some embodiments is shown, by way of example. More specifically, Fig. 2A illustrates the battery tray 202 of the battery assembly 200, and Fig. 2B illustrates the battery assembly 200 comprising the battery tray 202. The battery assembly 200 may be configured to provide power to operate an electric vehicle 700. The battery assembly 200 comprises the battery tray 202. The battery tray 200 houses individual battery modules 300. More specifically, the battery assembly 200 further comprises several battery modules 300 housed within the battery tray 202. Each battery module 300 comprises a string of battery cells, further shown e.g. in Fig. 4A to 4C.

The battery modules 300 may be arranged in any manner selected, often packed together in a space-efficient manner within the battery tray 200. Fig. 2B shows an example of how the battery modules 300 may be arranged. As shown herein, the battery tray 202 may be divided into a plurality of sections 206a-e, formed by dividing walls 204a-d within the battery tray 202. The battery modules 300 may be arranged in one or more of the sections as shown herein. In any remaining sections of the battery tray 300, other components of the battery assembly 200 may be provided, such as a cooling system, or control circuitry. As is readily understood, the battery modules 300 may be provided in different sizes and shapes and be arranged in the battery tray 202 in any suitable way.

The battery assembly 200 further comprises a battery pressure sensing system 704 as will be further explained in the following. The battery pressure sensing system 704 comprises at least one pressure sensor. Within the battery tray 202, the battery modules 300 may be provided with the at least one pressure sensors. The pressure sensor is configured to obtain sensor data indicative of a pressure. The pressure sensor is configured to detect an expansion (also referred to as swelling) of battery cells within the battery modules 300. More specifically, the pressure sensor is configured to detect an expansion of walls of the battery cell(s). Detecting the expansion may thus be done based on the obtained sensor data. As described in the foregoing, expansion of a battery cell may be an indication of a potential failure of the cell. If the battery cell continues to expand, it may eventually rupture and generate a complete thermal event. The thermal event may lead to thermal propagation within the battery assembly at which further battery cells start to expand. Any number of battery modules 300 of the several battery modules housed within the battery tray 202 may be provided with one or more pressure sensors. In some embodiments, each battery module 300 of the battery assembly 200 are provided with one or more pressure sensors. The pressure sensors may be arranged on top of the battery modules 300, between the battery modules 300, within the battery modules 300 (e.g. on or between the battery cells, or inside of a module housing (further described below) of the battery module), or in another position to detect changes in pressure within the modules 300 of the battery tray 202. Rather than being placed within individual battery cells of the battery modules 300, placing pressure sensors outside of the cells or between cells allows for earlier detection of changes, resulting in the ability to notify occupants more quickly. The pressure sensors of the battery assembly 200 form part of the battery pressure sensing system 704. Thus, the pressure sensor(s) may be arranged on a battery module, or on a battery cell of a battery module. The pressure sensor(s) being configured to detect an expansion of walls (also referred to as swelling) of any battery cell of said battery module, i.e. through a sensed pressure. Thereby, a potential failure in the battery assembly can be detected. The potential failure can be detected at an early stage. More specifically, the potential failure can be detected prior to a thermal propagation (e.g. before any battery cell starts to leak gases) within the battery assembly 200. Put differently, the potential failure can be detected at an early state during a thermal event such that the thermal event can be prevented from progressing further.

The battery assembly 200 may further comprise a cooling system (not shown). The cooling system is configured to cool the battery assembly 200. More specifically, the cooling system may be configured to cool the battery cells of the battery assembly 200. Referring now to FIG. 3A and 3B, different views of a rectangular battery module 300 is shown. The battery module 300 is an example of a battery module being part of the battery assembly 200 as described in the foregoing.

More specifically, Fig. 3A shows the battery module 300 in a perspective view, as well as in a cross-sectional view in a plane denoted A-A’. The battery module 300 as illustrated herein comprises a module housing 306. The module housing 306 is configured to house a string (or series) of battery cells (not shown). In other words, the module housing 306 is configured to enclose a number of battery cells. The module housing 306 comprises a cavity 308 in which the string of battery cells can be housed. The module housing 306 is herein illustrated as a rectangular box, having a top, a bottom, and four sides. It is however to be noted that the module housing 306 (and thus also the battery module 300) may have different shapes and sizes, depending on a specific realization.

Moreover, the battery module 300 as show herein, is provided with a battery pressure sensing system 704. The battery pressure sensing system 704 herein comprises a pressure sensor 304. It is to be appreciated that the battery pressure sensing system 704 may further comprise additional pressure sensors, within the same battery module 300 and/or in additional battery modules of the battery assemble 200.

Fig. 3A shows a placement of the pressure sensor 304 on the top of the battery module 300. Placing the pressure sensor 304 outside of the battery module 300, may allow for the detection an unhealthy module as the walls of the battery module 300 begin to expand (as shown in Fig. 3B below). Further, placement of the pressure sensor 304 on the top, either side, or bottom of the battery module 300, may allow for detection of the swelling or expansion of any single battery cell within the battery module 300. In other words, the pressure sensor may be arranged on any side of the battery module 300. Even though illustrated on an outside of the battery module 300, the pressure sensor 304 may, in some embodiments, be arranged on an inside of the module housing 306.

As shown in the example of Fig. 3A, the pressure sensor 304 is provided as a plate with fixations at end points of the plate (e.g. at locations indicated by the arrows in the cross-sectional view in Fig. 3A). The pressure sensor 304 may be any type of pressure sensor configured to detect an expanding area. For example, the pressure sensor 304 may e.g. be a piezo electric sensor plate. In another example, the pressure sensor 304 may be resistance sensing pressure film. It is to be appreciated that the shape and size of the pressure sensor 304 may not be representative of an actual pressure sensor 304, but rather serves an illustrative purpose. The same holds for any other illustrated parts or components throughout the present disclosure.

The pressure sensor 304 may be configured to detect bending (or expansion) of the sensor plate. Fig. 3B shows a cross-sectional view of the battery module 300 as show previously. In this case, the module housing 306 houses a battery cell 302. The battery cell 302 has, as shown herein (and indicated by the arrows), expanded due to gassing event within the cell. This expansion may in turn cause expansion of the module housing 306, which in turn results in the sensor plate bending (or expanding). Thereby, the pressure sensor 304 can detect the expansion of any battery cell within the battery module 300.

Moreover, in case of the battery assembly 200 comprising several battery modules 300 adjacent to each other, as illustrated in Fig. 2B, providing the pressure sensor 304 at a side of the battery module 300 may allow for detecting an increase in pressure among two or more battery modules adjacent to each other, due to expansion of one or more battery cells in any of the battery modules. This arrangement of pressure sensors relies on the same principles as utilized in arrangement of pressure sensors within the battery module (between adjacent battery cells, or between a battery cell and the module housing 406), as will be further described in the following.

Referring now to FIG. 4A to 4C, a battery module 400 is shown that includes a set (or series) of rectangular battery cells 402. More specifically, the battery module 400 comprises a string 406 of battery cells 402. The battery cells 402 of the string 406 of battery cells are arranged in a row adjacent to each other. The battery module 400 as shown herein may further comprise a module housing 306, e.g. as described in the foregoing with reference to Fig. 3A and 3B. Alternatively, the battery module 400 may be provided without a formal housing. In some embodiments, the string 406 of battery cells 402 of the battery module 400 may be arranged in a module housing 306 only partly enclosing the battery cells 402. In some embodiments, the battery module 400 may be enclosed by a strap wrapped around the string 406 of battery cells 402, e.g. as shown in Fig. 4C.

Fig. 4A shows the battery module 300 in perspective view. Fig. 4A also shows a pressure sensor 404 (herein represented by a crossed circle) placement on a battery cell 402 of the string 406 of battery cells. The pressure sensor 402 may be arranged on the battery cell 402 in any way in a closed environment such that swelling of the battery cell 402 generates a pressure. The illustrated pressure sensor 404 placement is between two adjacent battery cells 402. The pressure sensor 404 may be placed between individual battery cells 402, rather than on the surface of the battery module 300 (as shown in Fig. 3A and 3B). In some embodiments, the pressure sensor 404 may be placed in the middle of the string 406 of individual battery cells 402, or on either end of the string of individual battery cells 402. However, the pressure sensor 404 may as well be arranged between any pair of adjacent battery cells of the string 406 of battery cells. Moreover, two or more pressure sensors may be arranged within the same string 406 of battery cells. As an example, a pressure sensor may be arranged on every other, every third, or every fourth battery cell, etc. Placement of the sensor between the battery cells 402 may allow for detection of an unhealthy battery cell 304 in any position on the string of battery cells 402. As a single battery cell 402 expands or swells, the pressure sensor 402 may sense the change as it moves down the string of battery cells 402.

Referring now to FIG. 4B, a side view of the battery module 400 comprising the string 406 of battery cells, as described above is shown. For the purpose of this illustrative example, a single pressure sensor 404 is placed between the individual battery cells 402 at a middle of the string 406. Fig. 4B further shows an expanded rectangular battery cell 402 (indicated by brackets). As shown illustrated by the arrows herein, as the battery cell 402 expands the pressure exerted may begin to push on the surrounding battery cells 402, reaching the pressure sensor 404 and detecting the potential failure (e.g. a thermal event) in the neighboring battery cell 402.

As the battery cell 402 expands, the battery cell 402 begins to push on the surrounding cells, increasing the overall pressure within the battery module 400. Placement of the pressure sensor 404 between the individual battery cells 402 may be advantageous, because the increase in pressure will be sensed as soon as the individual unhealthy battery cell 402 begins to expand. The early detection may allow for more battery cells 402 to be preserved or saved, removing only the unhealthy or damaged battery cells 402. When the pressure sensor is placed within the battery cell 402 itself (i.e. as done today), the likelihood of detecting a potential thermal event before it has impacted other cells is unlikely. Internal placement of pressure sensors 404 may not detect a potential thermal event until the battery cell 402 has progressed to stage 3 or 4 of the diagram in FIG. 1.

By providing one or more pressure sensors 404 within the string 406 of cells may further allow for determining a degree of expansion of the expanding battery cell(s) 402, based on the measured pressure. In addition, a position of the expanding battery cell 402 within the string 406 of battery cells can be determined.

In the battery assembly 200, the battery tray 202 may house several battery modules 400. The battery modules 400 may be arranged in the battery tray 202 in various ways. The arrangement of the battery modules 400 within the battery tray 202 may be determined by the placement of other electric vehicle components, where the passengers will be seated in relation to the battery modules, and any other relevant factors and considerations. Within each battery module 400 is a string of individual battery cells 402. The battery cells 402 may be rectangular, cylindrical, or any other shape that is suitable.

Within each battery module 400, the battery cells 402 may be arranged in close proximity as seen e.g. in Figs. 4A to 4C. Placement of pressure sensors 404, may vary based on the arrangement of the battery cells 402, or even the shape of the battery cells 402. In the case of rectangular battery cells 402, the pressure sensors 404 may be placed on the top of the battery cell 402, the bottom of the battery cell 402, or either side of the battery cell 402. Whereas, in some embodiments, there may only be one pressure sensor 404 placed on the surface of a battery module 400. In another embodiment, there may be two or more pressure sensors 404 arranged on the surface of a battery module 400.

The pressure sensors 404 may also be arranged between or on individual battery cells 402. In one embodiment, a single pressure sensor 404 may be placed between two battery cells 402 as seen in Fig. 4A and 4B. The placement of the pressure sensor 404 may vary based on a variety of factors, including but not limited to, how many battery cells 402 are included in the string 406 of cells, the shape of the battery cells 402, how many battery modules 400 are within the battery tray 202, and any other relevant factors and considerations. In one embodiment, the placement of the pressure sensors 404 on cylindrical battery cells 402 may vary from the placement of pressure sensors 404 on rectangular cells. The arrangement of the pressure sensors 404 may be based on the distribution of pressure within an individual battery cell 402 as it swells or expands, which will change with battery cells 402 of different shapes.

Pressure sensors 404 may be placed on any critical locations of the battery cell 402, battery module 400, or battery tray 202, where crash or side impacts of the electric vehicle may cause deformation and a safety concern. Placement of pressure sensors 404 in these critical locations may allow earlier detection of potential thermal events, otherwise unhealthy battery cells 402, or any relevant safety concerns. The placement of the pressure sensors 404 may vary, for example in electric vehicles with different designs, seat placements, or different shaped battery trays 202.

In operation, the pressure sensors 404 may act to detect instability in individual battery cells 402. If left undetected, the instability may lead to thermal runaway or propagation, which results from the temperature within the battery cell 304 rising uncontrollably. As pressure increases due to the increase in temperature, damage, or any other reason, the battery cell may begin to expand and release toxic and flammable gasses. Ignition of the battery cell 402 may result when the temperature reaches a sufficient level and interacts with the flammable gasses being released from the battery cell 402.

The pressure sensors 404 may help reduce the likelihood of a thermal runaway or event, by discovering the malfunctioning battery modules 400 through pressure sensing. Pressure sensing may allow for earlier detection as seen in FIG. 1 , because at stage 2 as the battery cell 402 begins to expand or swell, the external pressure sensor 404 will detect the change and provide a warning or notice to the occupants. Further, pressure sensing can detect a change in battery health largely before damage begins to occur. Placing the pressure sensor 404 on the battery module 400, or between or on individual battery cells 402 may provide earlier detection of said thermal events and increases in pressure, than placing the pressure sensor 404 inside of the individual battery cell 402.

Moving on, Fig. 4C shows a perspective view of the battery module 400. In addition to what is shown in Fig. 4A, the battery module 400 of Fig. 4C further comprises a strap 408 wrapped around the string of cells 406. In the illustrated example, the strap 408 wraps around the top, the bottom, and the two connecting sides at the ends of the battery module 400. Alternatively, the strap 408 may wrap around the four sides of the battery module 400. In case the battery module 400 comprises a module housing 306, the strap 408 also be wrapped around the top, the bottom and the two connecting sides along a longitudinal direction of the battery module 400.

The strap 408 may comprise a strain gauge (not shown) configured to measure a strain in the strap. The strap 408 may thus form part of the battery pressure sensing system 704. By measuring the strain in the strap 408 wrapped around the string 406 of battery cells 402 of the battery module 400, an early indication of an expanding cell within the module 400 can be detected. The pressure sensor(s) 402 provided within the string 406 of cells may then be used to determine which cell or cells of the string 406 are expanding. Thus, the use of both the strap 408 and pressure sensor(s) 404 within the battery module 400 may provide for improved detection of potential battery failures.

Figs. 5A-5D depict simplified examples of multi-sensor arrangements that can be used for early detection of a thermal event. FIG. 5A depicts a series (or string) 506 of cells 502 with pressure sensors 504 arranged there between. As depicted in FIG. 5B, when a single cell 502A begins to expand due to pressure buildup, the adjacent sensors 504A are compressed earlier and potentially more than those arranged further away from the expanded cell 502A.

Based on the amount of pressure detected at each sensor 504 in FIG. 5B, a particular cell can be identified that is the expanding. Similarly, directional sensors may be able to determine movement caused by the expansion of cell 502A, as shown by the arrows of FIG. 5B, which can pinpoint the individual cell 502A. Even further, the measured pressure of one or more of the pressure sensors 502 may be used to determine a degree of expansion of the expanded battery cell 502A. For example, based on a measured pressure, a certain percentage of swelling can be determined.

In embodiments, sensors 504 may not be positioned between every individual cell in the manner shown in FIGS. 5A and 5B, but rather can be arranged between blocks or segments of cells. Pressure sensors can be positioned selectively to identify blocks or segments of cells that are electrically decoupleable from the remainder of the cells in the module, for example. In such circumstances, the pressure sensor can determine that the cells within the particular block or segment contains a cell having a failure and that block or segment can be electrically disconnected, providing two advantages: the remaining cells can continue to provide power to drive the vehicle to safety, and additional ameliorative measures can also be powered by the remaining cells such as running a cooler to prevent the thermal event from spreading further.

FIGS. 5C and 5D show top views of a set of cells 502 arranged in a 2-dimensional layout that is typical within a battery tray (e.g., tray 202), though in other embodiments it should be understood that cylindrical cells or other geometries can be used. Depending upon the shape of the cells and also possibly the surrounding tray, different packing arrangements can be used. For example, cylindrical cells may be positioned in a hexagonal closest packing arrangement. The sensors 504 are positioned between any two adjacent cells 502 where it is desirable to measure a pressure or a directional force (as indicated by the arrows). This could be between all of the individual cells as shown in FIG. 5D, or it could alternatively be between blocks or segments of cells as described previously.

Additionally, pressure or tension sensors can be used to determine the existence of a swelled cell (e.g., 502A) by positioning such sensors on a strap wrapped around a block, module, or segment of cells. An expanding or pressurized cell within the strap will cause tension on the band. Sensors could also be placed on the battery tray itself, at one or more locations.

These pressure sensing features can be used alone or in combination with one another. In the Clauses section below, various examples are given that include one or more such sensors working together.

CLAUSE 1 : Interleaved sensors between cells

In a first example, a set of rectilinear cells are arranged together in a grid pattern. Between each of the cells is a pressure sensor, as shown in FIG. 5C. The entire grid of cells and sensors is arranged within a battery tray as shown in FIG. 2A. The cells are all wired together to provide power to operate an electric vehicle, and are all cooled by a cooling system that routes cooled fluid to the battery tray wherein the cells are housed.

CLAUSE 2: Use of a strap

In embodiments it can be beneficial to include a plurality of cells that are removable from the overall battery tray. Such a group of cells can be positioned in a device referred to as a module, which has walls to contain the cells. The cells within a module can be held together around an outside perimeter with a strap, such as a steel or aluminum band. The strap can include a strain gauge such that expansion of the cells therein cause a detectable change in strain that indicates a thermal event occurring within at least one cell within the module.

While modules are a common way to arrange battery cells, it should also be understood that formal module walls are not required in all embodiments.

CLAUSE 3: Use of a strap with interleaved sensors

The features of Clauses 1 and 2 can be used together. That is, a strain gauge can provide an indication of a failure within the module, while the pressure sensors provide more detailed information about the location of the failure. This can be useful to provide an early warning of a battery failure, because the strap may indicate the existence of an expanding cell before the pressure sensors can accurately detect an exact position of the failing cell. That is, even while cells may shift within the strap due to expansion of one cell, the strap overall will still pick up on the failure early on, providing valuable time to arrest further failure by disconnecting the module and apply cooling or warn the occupants of the vehicle to get to a place of safety.

CLAUSE 4: Use of blocks for disconnection

In some embodiments, such as those where conventional modules with rigid dividing walls are not used within the battery tray, multiple sets of cells can be blocked together for purposes of detecting thermal failure events. As described above, these blocks can be surrounded by a strap, or can be separated from other blocks by pressure sensors. The blocks are disconnectable, as a group, from the rest of the battery system that is used to operate the vehicle. As such, when pressure sensors ora strap detect failure within the block, that block can be removed from service.

CLAUSE 5: Use of blocks for cooling

Like Clause 4, the block can be separated from surrounding blocks by a strap or a set of pressure sensors. Unlike Clause 4, in this example the block is not separately disconnectable from the remainder of the batteries for purposes of powering the vehicle. Rather, the block can be cooled separately from the other blocks, or differently. That is, upon detecting the existence of a thermal event within a cell of the block, additional cooling fluid can be routed adjacent to the block to increase thermal transfer out of that block. Increasing thermal transfer out of the block has been shown to decrease the chances of propagation of the thermal event, and therefore can increase passenger safety.

CLAUSE 6: Use of blocks for both cooling and disconnection

It should be understood that blocks of cells can be both electrically disconnected, and also separately cooled, relative to the other blocks of cells that power a vehicle. Likewise, the blocks can be separated from other blocks either by one or more pressure sensors arranged therebetween, or by a surrounding strap. In one example, the block is both electrically disconnectable and also separately coolable such that upon detection of a thermal event within the block it is no longer used to power the vehicle nor its functions, and also the block is cooled more than other cells or blocks.

Fig. 6 is a schematic flowchart representation of a method 600 for detecting potential failure in a battery assembly 200 according to some embodiments. The method 600 involves using a battery pressure sensing system 704 as described in the foregoing. For details regarding the battery assembly 200 or the battery pressure sensing system 704, reference is made to the above.

The method 600 may be a computer-implemented method. The method 600 may for instance be performed by a control system of a vehicle. The control system may for example comprise one or more processors and one or more memories coupled to the one or more processors, wherein the one or more memories store one or more programs that perform the steps, services and functions of the method 600 disclosed herein when executed by the one or more processors.

Below, the different steps of the method 600 are described in more detail. Even though illustrated in a specific order, the steps of the method 600 may be performed in any suitable order as well as multiple times. Thus, although Fig. 6 shows a specific order of method steps, the order of the steps may differ from what is depicted. In addition, two or more steps may be performed concurrently or with partial concurrence. For example, the steps denoted S610 to S614 may be performed irrespectively of each other at any point in time. Such variation will depend on the software and hardware systems chosen and on designer choice. All such variations are within the scope of the invention. Likewise, software implementations could be accomplished with standard programming techniques with rule-based logic and other logic to accomplish the various steps. The above mentioned and described embodiments are only given as examples and should not be limiting to the present invention. Other solutions, uses, objectives, and functions within the scope of the invention as claimed in the below described patent claims should be apparent for the person skilled in the art.

The method 600 comprises obtaining S602, via the pressure sensor, sensor data relating to a pressure caused by an expansion of walls of an expanding battery cell of said battery module.

The method 600 further comprises, in response to the obtained sensor data being indicative of a pressure exceeding a threshold value, performing S608 an ameliorative action of the battery assembly 200.

Performing S608 the ameliorative action may comprise providing S610 a notification to an occupant of the vehicle. The notification may e.g. serve as a warning signal to the occupant to stop and/or leave the vehicle. In another example, the notification may be to tell the occupant to take the vehicle to a service mechanic or the like to have a look at the battery assembly 200.

The ameliorative action may be performed S608 for a battery cell, a set of battery cells, or a string of battery cells of a battery module. In other words, the ameliorative action may be performed for one or more battery cells of the battery assembly 200.

The method may further comprise determining S606, based on the obtained sensor data, the battery cell, the set of battery cells, or the string of battery cells of the battery module for which the ameliorative action is to be performed.

Determining S606 the battery cell, the set of battery cells, or the string of battery cells of the battery module for which the ameliorative action is to be performed may be further based on sensor data obtained via at least a further pressure sensor of the battery pressure sensing system 704.

Performing S608 the ameliorative action may comprise disconnecting S612 the battery cell, the set of battery cells, or the string of battery cells of the battery module, for which the ameliorative action is to be performed S608, from the battery assembly. Disconnection said cells may be done by a control system of the vehicle. Put differently, the battery cell, the set of battery cells, or the string of battery cells of the battery module may be removed from service.

Performing S608 the ameliorative action may comprise adjusting S614 a cooling, provided by a cooling system of the battery assembly, of the battery cell, the set of battery cells, or the string of battery cells of the battery module for which the ameliorative action is to be performed. For example, additional cooling may be routed to the battery cell(s) for which the ameliorative action is to be performed (i.e. to those cells that has expanded or are expanding). Obtaining S602 the sensor data may be repeated at a pre-determined interval. Thus, the battery assembly 200 can be continuously monitored for any potential failures.

The method 600 may further comprise determining S604 a degree of expansion of the expanding battery cell based on the obtained sensor data relating to the pressure caused by the expansion of walls of the expanding battery cell. The ameliorative action may be performed in response to the degree of expansion exceeding a threshold value. Moreover, the type of ameliorative action to be performed may be selected based on the obtained sensor data, and/or based on the determined degree of expansion.

Executable instructions for performing these functions are, optionally, included in a non- transitory computer-readable storage medium or other computer program product configured for execution by one or more processors.

Fig. 7 is a schematic illustration of an electric vehicle 700 according to some embodiments. As used herein, a “vehicle” is any form of motorized transport. For example, the vehicle 700 may be any road vehicle such as a car (as illustrated herein), a motorcycle, a (cargo) truck, a bus, a smart bicycle, etc. Alternatively, the vehicle may be any vehicle travelling on water, or in the air. Moreover, by electric, it is herein meant that the vehicle 700 is either fully electric, i.e. powered by electric power only, or partly electric, i.e. a hybrid vehicle.

The vehicle 700 comprises the battery assembly 200 as described above. The vehicle 700 further comprises a control system 702. The control system is configured to perform the overall control of functions and operations of the vehicle 700. In particular, the control system 702 may control the battery assembly 200. The control system 702 may be configured to perform the method 600 as described above in connection with Fig. 6.

The battery assembly 200 comprises the battery pressure sensing system 704 as described in the forgoing. The battery assembly 200 may further comprise a cooling system 706. The cooling system 706 may be configured to cool the battery assembly 200. More specifically, the cooling system 706 may be configured to cool the battery cells of the battery assembly. The cooling system 706 may route cooling liquid throughout the battery tray 202.

Various embodiments of systems, devices, and methods have been described herein. These embodiments are given only by way of example and are not intended to limit the scope of the claimed inventions. It should be appreciated, moreover, that the various features of the embodiments that have been described may be combined in various ways to produce numerous additional embodiments. Moreover, while various materials, dimensions, shapes, configurations and locations, etc. have been described for use with disclosed embodiments, others besides those disclosed may be utilized without exceeding the scope of the claimed inventions.

Persons of ordinary skill in the relevant arts will recognize that the subject matter hereof may comprise fewer features than illustrated in any individual embodiment described above. The embodiments described herein are not meant to be an exhaustive presentation of the ways in which the various features of the subject matter hereof may be combined. Accordingly, the embodiments are not mutually exclusive combinations of features; rather, the various embodiments can comprise a combination of different individual features selected from different individual embodiments, as understood by persons of ordinary skill in the art. Moreover, elements described with respect to one embodiment can be implemented in other embodiments even when not described in such embodiments unless otherwise noted.

Although a dependent claim may refer in the claims to a specific combination with one or more other claims, other embodiments can also include a combination of the dependent claim with the subject matter of each other dependent claim or a combination of one or more features with other dependent or independent claims. Such combinations are proposed herein unless it is stated that a specific combination is not intended.

Any incorporation by reference of documents above is limited such that no subject matter is incorporated that is contrary to the explicit disclosure herein. Any incorporation by reference of documents above is further limited such that no claims included in the documents are incorporated by reference herein. Any incorporation by reference of documents above is yet further limited such that any definitions provided in the documents are not incorporated by reference herein unless expressly included herein.

Claims

1 . A battery pressure sensing system (704) for detecting potential failure in a battery assembly (200), wherein the battery assembly (200) comprises a battery tray (202) and several battery modules (300, 400) housed within the battery tray (202), wherein each battery module (300, 400) comprises a string (406) of battery cells (302, 402, 502), the battery pressure sensing system (704) comprising: a pressure sensor (304, 404, 504) arranged on a battery module (300, 400) of the several battery modules (300, 400), or on a battery cell (302, 402, 502) of said battery module (300, 400), wherein the pressure sensor (304, 404, 504) is configured to detect an expansion of walls of any battery cell (302, 402, 502) of said battery module (300, 400) such that a potential failure can be detected prior to a thermal propagation within the battery assembly (200).

2. The battery pressure sensing system (704) according to claim 1 , wherein the pressure sensor (304, 404, 504) is arranged between any two adjacent battery modules of the several battery modules (300, 400), or between any two adjacent battery cells of a string (406) of battery cells (302, 402, 502).

3. The battery pressure sensing system (704) according to claim 1 or 2, wherein the battery pressure sensing system (704) further comprises a further pressure sensor, wherein the pressure sensor is arranged on a first battery cell of a battery module (300, 400), and the further pressure sensor is arranged on a second battery cell of said battery module (300, 400).

4. The battery pressure sensing system (704) according to any one of the claims 1 to 3, wherein the pressure sensor (304, 404, 504) is a first pressure sensor and wherein the battery pressure sensing system (704) further comprises a second pressure sensor, wherein the first pressure sensor is arranged on a first battery module or on a battery cell of said first battery module, and the second pressure sensor is arranged on a second battery module or on a battery cell of said second battery module.

5. The battery pressure sensing system (704) according to any one of the claims 1 to 4, wherein the battery pressure sensing system (704) further comprises a strap (408) wrapped around a battery module of the several battery modules, wherein the strap (408) comprises a strain gauge configured to measure a strain in the strap.

6. The battery pressure sensing system (704) according to claim 5, wherein the strap (408) is formed of a steel or aluminum band.

7. The battery pressure sensing system (704) according to any one of the claims 1 to 6, wherein the pressure sensor (304, 404, 504) is a directional pressure sensor configured to determine a direction of the pressure caused by an expanding cell.

8. The battery pressure sensing system (704) according to any one of the claims 1 to 7, wherein the pressure sensor (304, 404, 504) is a piezoelectric pressure sensor or a resistive pressure sensor.

9. The battery pressure sensing system (704) according to any one of the claims 1 to 8, wherein the battery assembly (200) is configured to provide power to operate an electric vehicle (700).

10. A battery assembly (200) comprising the battery pressure sensing system (704) for detecting potential failure in the battery assembly (200) according to any one of the claims 1 to 9.

11 . The battery assembly (200) according to claim 10, further comprising a cooling system (706) configured to cool the battery assembly (200).

12. The battery assembly (200) according to claim 10 or 11 , wherein the battery cells (302, 402, 502) are rectangular or cylindrical in shape.

13. An electric vehicle (700) comprising the battery assembly (200) according to any one of the claims 10 to 12.

14. A method (600) for detecting potential failure in a battery assembly (200) using a battery pressure sensing system (704), wherein the battery assembly (200) comprises a battery tray (202) and several battery modules (300) housed within the battery tray (202), wherein each battery module (300, 400) comprises a string (406) of battery cells (302, 402, 502), and wherein the battery pressure sensing system (704) comprises a pressure sensor (304, 404, 504) arranged on a battery module (300, 400) of the several battery modules (300, 400), or on a battery cell (302, 402, 502) of said battery module (300, 400), wherein the pressure sensor (304, 404, 504) is configured to detect an expansion of walls of any battery cell (302, 402, 502) of said battery module (300, 400) such that a potential failure can be detected prior to a thermal propagation within the battery assembly (200), the method (600) comprising: obtaining (S602), via the pressure sensor, sensor data relating to a pressure caused by an expansion of walls of an expanding battery cell of said battery module; in response to the obtained sensor data being indicative of a pressure exceeding a threshold value, performing (S608) an ameliorative action of the battery assembly.

15. The method (600) according to claim 14, wherein performing (S608) the ameliorative action comprises providing (S610) a notification to an occupant of the vehicle.

16. The method (600) according to claim 14 or 15, wherein the ameliorative action is performed (S608) for a battery cell, a set of battery cells, or a string of battery cells of a battery module.

17. The method (600) according to claim 16, wherein the method further comprises determining (S606), based on the obtained sensor data, the battery cell, the set of battery cells, or the string of battery cells of the battery module for which the ameliorative action is to be performed.

18. The method (600) according to claim 16 or 17, wherein determining (S606) the battery cell, the set of battery cells, or the string of battery cells of the battery module for which the ameliorative action is to be performed is further based on sensor data obtained via at least a further pressure sensor of the battery pressure sensing system (704).

19. The method (600) according to any one of the claims 16 to 18, wherein performing (S608) the ameliorative action comprises disconnecting (S612) the battery cell, the set of battery cells, or the string of battery cells of the battery module, for which the ameliorative action is to be performed (S608), from the battery assembly.

20. The method (600) according to any one of the claims 16 to 19, wherein performing (S608) the ameliorative action comprises adjusting (S614) a cooling, provided by a cooling system of the battery assembly, of the battery cell, the set of battery cells, or the string of battery cells of the battery module for which the ameliorative action is to be performed.

21 . The method (600) according to any one of the claims 14 to 20, wherein obtaining (S602) the sensor data is repeated at a pre-determined interval.

22. The method (600) according to any one of the claims 14 to 21 , further comprising determining (S604) a degree of expansion of the expanding battery cell based on the obtained sensor data relating to the pressure caused by the expansion of walls of the expanding battery cell.

23. A computer program product comprising instructions which, when the program is executed by a computing device, causes the computing device to carry out the method (600) according to any one of claims 14 to 22.