DE102022106656A1 - Electrochemical energy storage, electrochemical round cell and method for producing an electrochemical round cell - Google Patents

Abstract

An electrochemical energy storage device (10), a method for producing an electrochemical round cell (1) and an electrochemical round cell (1) are proposed. The electrochemical round cell (1) comprises: a cell winding (2), a cell cover (3), a cell base (4), a hollow cell winding mandrel (5) and a thermostat (6), which is arranged in the cell winding mandrel (5), the Cell winding mandrel (5) forms a fluid channel (7) together with a first opening in the cell cover (3) and a second opening in the cell bottom (4), the thermostat (6) being arranged in the fluid channel (7).

Description

The present invention relates to an electrochemical energy storage device, an electrochemical round cell and a method for producing an electrochemical round cell. In particular, the present invention relates to an improved cooling of electrochemical round cells for traction batteries of electrically powered means of transportation.

The electrification of personal transport is currently progressing rapidly. One method for storing electrical energy in the means of transport is to build the traction battery, usually known as high-voltage storage, from a large number of electrochemical round cells. Here, the electrodes or layers containing the cell chemistry are wound around a common winding mandrel. This is usually removed and reused during production.

DE 20 2007 018 731 U1 discloses a portable and stackable cell based on lithium polymer cells, in which tubular winding mandrels remain in the cell core and are flushed with fluid for cooling purposes. Threads on the pole caps are used to mount them on the winding mandrel.

For heat dissipation, either normal heat conduction or fluid cooling is known in the prior art. However, cells are usually not cooled from the inside. If this is the case, global control takes place, whereby, if necessary, a pump is driven to drive the cooling fluid along or through the cells. The control is usually carried out by a large number of distributed temperature sensors. In addition, throttling and the expansion of compressed gases represent standard procedures in the field of cell cooling.

Based on the aforementioned prior art, it is an object of the present invention to improve the cooling of electrochemical cells. In particular, it is an object of the present invention to ensure needs-based cooling of individual electrochemical cells.

The aforementioned object is achieved according to the invention by an electrochemical round cell with the features according to claim 1. The subclaims show preferred developments of the invention.

The electrochemical round cell according to the invention comprises a cell coil, which comprises the cell chemistry and/or the inner cell electrodes as well as any separator contained therein. This is wrapped around a hollow cell winding mandrel. The cell winding mandrel can have the shape of a tube so that it has a hollow core as a fluid guide. At the front, the electrochemical round cell is closed off by a cell base and a cell cover. On the shell side, an optional housing surrounds the cell coil. A thermostat is also provided, which is arranged in or on the cell winding mandrel. In this way, the thermostat can open or close the channel in the cell winding mandrel depending on the temperature. The cell winding mandrel forms a fluid channel together with a first opening in the cell cover and a second opening in the cell bottom. In this way, the electrochemical round cell is able to be flushed axially by cooling fluid, which dissipates excess heat. The thermostat is therefore arranged or set up in the fluid channel to open or close the axial fluid channel through the electrochemical round cell depending on the temperature. By thermally coupling the thermostat to the cell coil, particularly rapid, low-delay and cell-specific cooling of the electrochemical round cell can be provided. The electrochemical round cell can be designed in the cell network of an electrochemical energy storage device (e.g. a traction battery, in particular for an electrically driven means of transportation).

The fluid channel can run partially or completely through the thermostat. If the cooling fluid flows through the thermostat proportionally, in the event of a malfunction or accidental blocking of the thermostat, cooling fluid running past the thermostat can dissipate excess heat or the flow resistance for the cooling fluid can be reduced even in the correct functional state. If the fluid channel runs completely through the thermostat, the fluid flow can be regulated particularly comprehensively.

The thermostat is arranged in particular at one end of the cell winding mandrel. For example, it can be welded, glued, screwed or otherwise fluid-tightly attached to the front of the cell winding mandrel. In particular, friction welding, ultrasonic welding and a screw connection are possible for sealing between the cell winding mandrel and the thermostat. For example, a thread can also be cut in the cell winding mandrel, into which the thermostat can be screwed. Such a thread can also be used during production, in particular when winding the cell roll, for temporarily fixing the cell winding mandrel in a machine tool.

For example, the thermostat can be set up to at least partially open the fluid channel in response to a temperature exceeding 30°C, in particular 35°C, preferably 40°C, particularly preferably 45°C and extremely preferably 50°C. In this way it can be avoided that the electrochemical round cell ages excessively because it is operated in a temperature range that is too high. Below the aforementioned temperature thresholds, the thermostat can close the fluid channel in order to achieve a suitable working temperature of the cell chemistry as quickly as possible and not to unnecessarily reduce performance.

If a thread is provided in the cell winding mandrel or on the cell winding mandrel, this can be designed as an internal thread and/or an external thread. Accordingly, the thermostat has a corresponding thread if it is to be brought into engagement with this thread. A seal can also be provided here.

A particularly simple production and particularly resistant, robust seal between a cell cover and a cell winding mandrel can be achieved by manufacturing the cell cover integrally with the cell winding mandrel. In other words, the cell cover is first connected to the cell winding mandrel in a cohesive and/or form-fitting manner or is manufactured directly in one piece (e.g. by deep drawing). A brazing process or a welding process can preferably also connect the cell cover and the cell winding mandrel to one another. Thus, the assembly consisting of the cell cover and cell winding mandrel can then be clamped in a machine tool and used, in particular rotated, to produce the cell winding. This design will be discussed in detail in connection with the manufacturing process described below.

The cell winding mandrel can, for example, have an inner diameter of 2 mm to 10 mm, in particular 3 mm to 5 mm. All integer millimeter inner diameters from 2 mm to 10 mm are hereby disclosed as potential range limits.

For example, the electrochemical round cell can have a housing which, for example, has an outer diameter of at least 18 mm, in particular at least 21 mm, preferably at least 40 mm. In other words, energy storage devices known as standard cells in the prior art can be manufactured and designed in accordance with the invention. The housing can, for example, be made of plastic and/or metal or comprise one of the aforementioned materials. Combinations of the aforementioned materials can also be used to manufacture the housing.

According to a second aspect of the present invention, an electrochemical energy storage device is proposed, which can have a plurality of electrochemical round cells according to the above statements. In addition, the electrochemical energy storage has a fluid guide with a large number of connections for the electrochemical cells. The fluid guide can be designed as a rigid or flexible connection in the manner of a common pressure connection (also: common rail) and the large number of connections can be connected to the connections of the electrochemical round cells for locking, in particular in the manner of a garden hose connection and/or using a bayonet lock become. Here too, a cohesive connection is possible in order to secure the plug connection more strongly against unwanted loosening.

According to a third aspect of the present invention, a method for producing a round electrochemical cell is proposed. The electrochemical round cell can preferably be designed according to the first-mentioned aspect of the invention. In a first step, cell material, which may have electrode material, electrodes, separators and other chemical substances for energy storage, is wound onto a particularly hollow cell winding mandrel to produce a cell coil. The cell winding mandrel can be designed as a solid rod or as a tube/tube. The cell winding mandrel can in particular have a thread by means of which it is temporarily connected to a machine tool while the cell material is wound onto the cell winding mandrel. In a further step, the cell winding mandrel is connected to the cell cover, whereby in particular a plug connection, screw connection, welded connection, adhesive connection or press fit can be selected. Combinations of the aforementioned assembly methods are also possible. The cell winding mandrel can be connected to the cell cover before winding up cell material or after winding cell material onto the cell winding mandrel. A thermostat is then arranged on the cell winding mandrel or in the cell winding mandrel. In any case, the thermostat is provided on the electrochemical round cell or as a component of the electrochemical round cell in such a way that it can enable or prevent fluid flow through the optionally hollow cell winding mandrel. Subsequently or beforehand, the cell winding can be introduced together with the cell winding mandrel, the cell cover and the thermostat into a housing, which is then sealed in a fluid-tight manner with the cell cover. This can be done using a flanged groove, gluing, or sealing a resin or similar. This results in an electrochemical round cell designed in particular according to the above statements in a particularly reliable and efficient manufacturing process.

Preferably, connecting the cell winding mandrel to the cell cover can include welding, in particular friction welding, ultrasonic welding and/or brazing. The cell winding mandrel can be designed to be hollow so that it can accommodate a thermostat and, alternatively or additionally, a cooling fluid can flow through it as a fluid channel for heat dissipation. The features, combinations of features and the advantages resulting from these correspond to those which have been described in detail in connection with the aforementioned aspects of the invention in such a way that reference is made to the above statements to avoid repetition.

• 1 einen Längsschnitt durch eine im Stand der Technik bekannte elektrochemische Rundzelle ohne Wickeldorn;
• 2 eine schematische Darstellung der in 1 gezeigten elektrochemischen Zelle in einer geschnittenen Seitenansicht sowie in einer geschnittenen Draufsicht;
• 3 ein Ausführungsbeispiel eines erfindungsgemäß ausgestalteten elektrochemischen Energiespeichers mit einem Ausführungsbeispiel einer erfindungsgemäß ausgestalteten elektrochemischen Rundzelle;
• 4 eine schematische Schnittdarstellung einer Deckelbaugruppe eines Ausführungsbeispiels einer erfindungsgemäßen elektrochemischen Rundzelle; und
• 5 ein Flussdiagramm veranschaulichend Schritte eines Ausführungsbeispiels eines erfindungsgemäßen Herstellungsverfahrens.

Further details, features and advantages of the invention result from the following description and the figures. Show it:

• 1 a longitudinal section through an electrochemical round cell known from the prior art without a winding mandrel;
• 2 a schematic representation of the in 1 electrochemical cell shown in a sectioned side view and in a sectioned top view;
• 3 an exemplary embodiment of an electrochemical energy storage device designed according to the invention with an exemplary embodiment of an electrochemical round cell designed according to the invention;
• 4 a schematic sectional view of a cover assembly of an exemplary embodiment of an electrochemical round cell according to the invention; and
• 5 a flowchart illustrating steps of an exemplary embodiment of a manufacturing method according to the invention.

1 shows a sectional view of an electrochemical round cell 1 known from the prior art, the cell winding 2 of which no longer has a cell winding mandrel. Rather, the removal of the cell winding mandrel after producing the cell winding 2 left a cavity 13, which cannot be used as a fluid guide in the illustration shown, since a cell cover 3 hermetically seals the round cell volume from the outside.

2 shows a sectioned side view (bottom) and a sectioned top view (top) of the in 1 shown round cell 1. The electrochemical round cell 1 is sealed at the bottom by a cell base 4, which is connected to a wall of a housing 9. An innermost layer 14 of the cell coil 2 defines the outer diameter of the clear interior of the electrochemical round cell 1.

3 shows an exemplary embodiment of an electrochemical energy storage device 10 according to the invention, in which two electrochemical round cells 1 according to an exemplary embodiment of the present invention are fluidically connected via thermostats 6 to a common fluid guide in the form of a common rail 11. For this purpose, the common rail 11 has two connections 12 into which the thermostats 6 intervene. A hollow cell winding mandrel 5 serves to fluidly seal the cell windings 2 from the cooling fluid (not shown), which seals the fluid guide 11 and the fluid channel 7. While the thermostat 6 shown on the left in the picture prevents fluid flow through the fluid channel 7, the open thermostat 6 shown on the right in the picture allows cooling fluid located in the fluid guide 11 to flow into the fluid channel 7 and thus ensures cooling of the hotter (right) electrochemical round cell 1.

4 shows a sectional view of a cover assembly in which a thermostat 6 is screwed into a hollow cell winding mandrel 5 via a thread 8. For this purpose, the upper end of the cell winding mandrel 5 has a thread 8 corresponding to the thread of the thermostat 6. At the top, the thermostat 6 has a connection for the fluidic coupling with a common rail (reference number 11 in 3 ), which has an external thread 8. The thermostat 6 has a fluid channel 7, within which a guide 60 with a bore (not shown) guides a shaft 62 of a stamp 63. Via a bimetal actuator 61, the stamp 63 strives from a rest position, in which the sealant 64 blocks the fluid channel 7, towards the fluid connection (top of the picture) when a predefined threshold temperature is reached, so that the fluid channel 7 is opened by the electrochemical round cell 1. Via a common rail (not shown), pressurized cooling fluid (a gas and/or a liquid) can now flow through the core of the electrochemical round cell 1 and dissipate process heat.

5 shows steps of an exemplary embodiment of a method for producing an electrochemical round cell. In step 100, cell material comprising electrode material and a separator is wound on a hollow cell winding mandrel to produce a cell coil. The cell winding mandrel can have a thread by means of which it is temporarily screwed onto a rotating machine tool. In step 200 the Cell winding mandrel connected to a cell cover in a fluid-tight and mechanically stable manner. In step 300, a thermostat is placed on the cell winding mandrel so that the thermostat is capable of closing or opening a hollow core of the cell winding mandrel. Depending on the dimensioning of the thermostat, fluidic cooling of the electrochemical round cell can be achieved once a predefined threshold temperature is reached. Finally, in step 400, the cell winding, the cell winding mandrel, the cell cover and the thermostat are inserted into a housing of the electrochemical round cell. Only then is there a fluid-tight connection between the cell cover and the housing (jacket) of the electrochemical round cell.

List of reference symbols:

1

electrochemical round cell

2

Cell wrap

3

Cell cap

4

cell bottom

5

Cell winding mandrel

6

thermostat

7

Fluid channel

8th

thread

9

Housing

10

electrochemical energy storage

11

Fluid guidance

12

connections

13

cavity

14

innermost layer of the cell coil

60

guide

61

Bimetallic actuator

62

Pistons

63

Rubber stamp

64

poetry

100 to 400

Procedural steps

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 202007018731 U1 [0003]

Claims (11)

Comprehensive electrochemical round cell • a cell wrap (2), • a cell cover (3), • a cell base (4), • a hollow cell winding mandrel (5) and • a thermostat (6), which is arranged in the cell winding mandrel (5), the cell winding mandrel (5) forming a fluid channel (7) together with a first opening in the cell cover (3) and a second opening in the cell base (4), whereby the Thermostat (6) is arranged in the fluid channel (7). Electrochemical round cell Claim 1 , wherein the fluid channel (7) runs through the thermostat (6). Electrochemical round cell Claim 1 or 2 , wherein the thermostat (6) is arranged at one end of the cell winding mandrel (5). Electrochemical round cell according to one of the preceding claims, wherein the thermostat (6) is set up to release the fluid channel (7) in response to a temperature of 30°C, in particular 40°C, preferably 50°C being exceeded. Electrochemical round cell according to one of the preceding claims, wherein the cell winding mandrel (5) has a thread (8) into which the thermostat (6) is screwed. Electrochemical round cell Claim 5 , whereby the thread (8) is an internal thread or an external thread. Electrochemical round cell according to one of the preceding claims, wherein the cell cover (3) is manufactured integrally with the cell winding mandrel (5) and/or is cohesively connected to it, preferably welded. Electrochemical round cell according to one of the preceding claims, wherein - the cell winding mandrel (5) has an inner diameter of 3 mm to 10 mm, in particular 3 mm to 5 mm and/or - The electrochemical round cell (1) has a housing (9) which has an outer diameter of at least 18 mm, in particular at least 21 mm, preferably at least 40 mm. Comprehensive electrochemical energy storage - a fluid guide (11) with a large number of connections (12) for electrochemical cells (1) - An electrochemical round cell (1) according to one of the above claims, the fluid channel (7) of which is fluidly connected to one of the connections (12). Method for producing an electrochemical round cell (1) comprising the steps: - winding (100) of cell material onto a cell winding mandrel (5) to produce a cell winding mandrel (2), the cell winding mandrel (5) in particular having a thread (8) by means of which it is temporarily connected to a machine tool, - Connecting (200) the cell winding mandrel (5) with a cell cover (3), and - Inserting (400) the cell winding (2), the cell winding mandrel (5), the cell cover (3) into a housing (9). Procedure according to Claim 10 , wherein - connecting the cell winding mandrel (5) to the cell cover (3) includes welding and/or - the cell winding mandrel (5) is hollow and/or designed as a fluid channel.

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