JP2016091613A - Battery system and capacity recovery method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery system capable of being more safely operated for a long period of time.SOLUTION: A battery system comprises a battery pack configured by connecting a plurality of lithium-ion batteries. The lithium-ion battery comprises: a positive electrode; a negative electrode; a third electrode for adjusting a lithium-ion amount of at least either of the positive and negative electrodes; and a fourth electrode that is to have reference electric potential.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a battery system and a capacity recovery method.

  At present, in order to prevent global warming, the replacement of gasoline engine vehicles, which are a major source of carbon dioxide, with hybrid electric vehicles and electric vehicles has begun. Large secondary batteries represented by power sources for hybrid electric vehicles and electric vehicles need to have high output and large capacity, so the storage battery modules that make up them are connected in series and parallel. Configured.

  In recent years, attention has been focused on using power other than that generated by natural energy or generated by an electric power company. However, the amount of power generated by natural energy generation varies greatly. This can cause voltage fluctuations in the power system. In order to supply stable quality power, it is necessary to mitigate fluctuations in the voltage of the power system, and a storage battery system is used to mitigate the fluctuations.

  Lithium ion batteries used as secondary batteries in these storage battery systems need to be properly used from the standpoints of preventing high-voltage charging and preventing performance degradation due to overdischarge. For this reason, the storage battery module mounted in the storage battery system has a function of detecting voltage, current, temperature, and the like, which are battery states. FIG. 15 shows a configuration of a storage battery module mounted on a typical hybrid electric vehicle or electric vehicle. As shown in FIG. 15, the plurality of battery cells are connected to the cell controller, and the cell controller detects the state of the plurality of battery cells. The plurality of cell controllers are connected to the battery controller, and the battery controller acquires the states of the plurality of battery cells from the plurality of cell controllers. Furthermore, the battery controller calculates a battery capacity (SOC: State of Charge) and a battery deterioration state (SOH: State of Health) from the acquired states of the plurality of battery cells, and notifies the host controller of the calculation results. Become. In a large-capacity battery system, the number of man-hours for connection and the amount of wiring at the time of manufacture are enormous, and there is a risk of incorrect wiring and an increase in cost.

  A large-capacity battery system used for mitigating fluctuations in an electric power system, etc., is multi-series and multi-parallel, and is continuously operated for several days or more unlike a vehicle application. In a multi-series battery system, if the remaining capacity varies among the series batteries, a difference occurs in the maximum voltage and the minimum voltage during operation. Lithium ion batteries can be overcharged due to a maximum voltage shift and overdischarge due to a minimum voltage shift. When these events occur, there is a concern that the battery system becomes unsafe and a stable operation cannot be ensured.

  In a large-capacity battery system, when replacing batteries individually to balance them, the amount of wiring is enormous, which increases the number of man-hours and the risk of miswiring, etc., and the cell itself contains internal information for control. There is a concern that the stability of the control after replacement is lacking because it is not sufficient. Therefore, since it must be exchanged in units of modules or series connection units, the maintenance cost at the time of cell failure becomes high. Therefore, in a multi-series battery system, it is important to monitor each cell voltage individually and balance the capacity when energized in order to suppress capacity variation and ensure stable operation of the battery system. .

  In general, as a method of balancing cells, surplus power is consumed by a parallel bypass circuit for a single cell that has reached a specified voltage, as used in a commercially available small lithium secondary battery pack. There are known methods for equalizing. Patent Documents 1 and 2 disclose a method of matching internal voltages of only high voltage cells by turning on and off a switch in a bypass discharge circuit. Patent Document 3 discloses a technique for replenishing a capacity using a cell having a third electrode having a lithium source.

JP 2003-282159 A JP 2005-328603 A JP 2013-45507 A

  As described above, as a method of balancing cells, surplus power is consumed by a parallel bypass circuit for single cells that have reached a specified voltage, such as those used in commercially available small lithium secondary battery packs. A method for equalizing the state of charge is known. However, this method needs to align the state of charge to a state close to full charge, and this method is difficult to apply when applied to power fluctuation mitigation. When applying to power fluctuation mitigation, the input / output to the battery constantly fluctuates because there is no usage method such as continuous energization at a constant charging voltage to achieve full charge, so only the charging state is aligned. This is because there is no opportunity.

  The relationship between the remaining battery level (SOC) and the voltage is not clear, and in the case of a battery in which the voltage is almost constant even when the SOC changes, as shown in Patent Documents 1 and 2, the voltage is high. In the method of matching the internal voltage by turning on and off the switch in the bypass discharge circuit only for the cell, there is a problem that the capacity is unbalanced because the remaining amount cannot be determined by the voltage. Discharging in the bypass discharge circuit consumes the discharge amount of the battery in parallel with the load line that is normally used, so there is a demerit that the period in which the cell can be used repeatedly is shortened.

  Patent Document 3 discloses a technique for performing capacity recovery control in a cell having a third electrode having a lithium source. As in Patent Document 3, when a lithium metal foil is used as a lithium source, it is necessary to consider the stability in air and the legal handling. Patent Document 3 is intended to extend the battery life by replenishing lithium ions through an external power source only when deterioration has progressed, and does not necessarily match the voltages between cells.

  Therefore, an object of the present invention is to provide a battery system that can balance the voltage between cells and can be operated safely for a long time.

  In order to solve the problems described above, a battery system according to the present invention is a battery system including an assembled battery configured by connecting a plurality of lithium ion batteries, and the lithium ion battery includes a positive electrode, a negative electrode, and a positive electrode. And a third electrode for adjusting a lithium ion amount of at least one of the negative electrode and a fourth electrode serving as a reference potential.

  The present invention can provide a battery system that can be used for a long time. Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

1 is a diagram showing a battery system according to Example 1. FIG. 6 is a diagram showing a battery system according to Example 2. FIG. 6 is a diagram showing a battery system according to Example 3. FIG. It is a figure which shows the battery system in the case of serving as a 3rd electrode and a reference electrode. It is a figure which shows the difference in operation | movement by the capacity | capacitance of a battery. It is a figure which shows the structural example of battery assembly. It is explanatory drawing which shows operation | movement of a cell. The capacity | capacitance adjustment system of the 4-pole cell of an Example is shown. It is a figure which shows the capacity | capacitance adjustment principle at the time of charge. It is a figure which shows the capacity | capacitance adjustment principle at the time of discharge. 6 is a diagram showing a lithium ion battery according to Example 5. FIG. 6 is a diagram showing a lithium ion battery according to Example 5. FIG. It is an example of the flowchart of the capacity | capacitance adjustment of this invention. It is a figure which shows the structure of a large capacity battery system. This is an example in which information between the battery management device and the battery management device is implemented by wireless communication. It is a figure which shows the conventional battery system for motor vehicles.

  In a multi-series battery system, the operating voltage varies due to cell capacity variation. FIG. 5 shows voltage fluctuations when a new cell and a cell that has deteriorated and has a reduced capacity are charged and discharged with the same current. It can be seen that the degraded product having a reduced capacity has a lower voltage at the end of discharge than the new product.

FIG. 7 shows the fluctuation of each cell voltage when charging / discharging with the cell capacity varying in a system in which a plurality of cells are connected in series. In each graph of FIG. 7, the vertical axis represents voltage, and the horizontal axis represents time t. FIG. 7A shows operating voltages of batteries a1 and a2 that are connected in series with each other and have different start voltages V _OCV at the time of no load. Since the currents energized in series are the same, the amount of electricity used in the battery is the same depending on the energization time. For this reason, the battery a1 having a high V _OCV operates in the normal operating voltage range, whereas the battery a2 having a low V _OCV has a voltage at the time of discharging outside the range of the operating lower limit voltage. As a result, the voltage of the battery a2 is out of the safe range. A high voltage means that the battery capacity stored at that time is large. Since the available capacity differs between the upper limit voltage and the lower limit voltage in each cell, a2 having a smaller capacity has a larger voltage fluctuation width in a1 and a2.

FIG. 7B is a diagram showing operating voltages of batteries b1 and b2 having the same voltage V _OCV at no load but different capacities. Even if the voltage V _OCV at the time of no load is the same, the battery b1 having a small capacity has a higher voltage than the voltage V _H that is safely allowed when charging with a large current, and is overcharged. End up. As a result, safety is reduced.

FIG. 7C schematically shows a case where the battery C1 having a small capacity reaches both the upper limit voltage V _H and the lower limit voltage V _L for safety, and there is a risk of both overcharge and overdischarge. Show.

  Thus, balancing and equalizing the capacities is important for ensuring stable operation of the battery system. Capacity imbalance is not only the initial cell performance variation in the series battery, but also current concentration based on the difference in environmental temperature during energization due to the assembled battery structure, capacity decrease due to side reaction in a high temperature cell, resistance increase, etc. It also occurs due to performance changes.

  In order to eliminate the capacity imbalance and extend the life of the battery system by capacity recovery, the battery system according to the present invention includes a positive electrode, a negative electrode, a third electrode that adjusts the amount of lithium ions in the positive electrode or the negative electrode, It has an assembled battery in which a plurality of lithium secondary batteries including a fourth electrode serving as a reference potential are connected. The third electrode is connected to at least one of the positive electrode and the negative electrode via a switch, and the switch is switched based on information obtained by the fourth electrode.

  The third electrode includes a material capable of supplying lithium ions, and plays a role of adjusting the amount of lithium ions in at least one of the positive electrode and the negative electrode. The fourth electrode is a reference electrode for measuring the internal potential of the positive electrode, the negative electrode, and the third electrode. Based on the information obtained by the fourth electrode, the internal potential or internal information of the positive electrode and the negative electrode is calculated by a host controller that is a control circuit, and the switch is opened and closed based on this information. The switch is switched when the voltage of each lithium ion battery is non-uniform when not energized and the variation in the remaining capacity of the battery exceeds a threshold value, and the positive electrode or the negative electrode and the third electrode are connected. The Further, by controlling the energization time based on the internal potential difference between the third electrode and the positive electrode or the negative electrode, the amount of Li ions in the positive electrode or the negative electrode can be increased or decreased, and the battery capacity can be adjusted. As a result, the capacity variation of each battery can be eliminated. Here, the threshold value of the variation in the remaining capacity of the battery capacity is an allowable range determined by battery performance, safety, and the like.

  Specifically, it is desirable that the third electrode includes a material in which both the positive electrode and the negative electrode are insulated during normal use and lithium ions are sufficiently occluded. Examples of the material used for the third electrode include lithium-containing metal oxides and lithium-containing graphite. Unlike metal lithium conventionally used as a capacity recovery electrode, the lithium-containing metal oxide has advantages that it is easy to produce an electrode and that dendrite is difficult to deposit. Further, the manufacturing cost can be reduced by using the same material as that used for the positive electrode for the third electrode.

  Specific examples of the material used for the fourth electrode include lithium-containing graphite and lithium-containing oxide. Furthermore, the material used for the third electrode can also be used for the fourth electrode. As a result, the manufacturing cost can be reduced.

  In the battery system of the present invention, after measuring the open circuit voltage of each of the plurality of lithium ion batteries, the SOC of the lithium ion battery is calculated from the measured open circuit voltage, and the lithium ion battery that adjusts the amount of lithium ions from the calculated SOC select. Then, the lithium ion adjustment amount is calculated based on the information obtained by the fourth electrode, the switch opening time is determined based on the lithium ion adjustment amount, and the switch capacity is controlled based on the opening time. Can be recovered.

ADVANTAGE OF THE INVENTION According to this invention, the voltage between cells can be balanced in the battery system comprised by the battery cell of multi-series multi-parallel. In addition, the adjustment of the unit cell capacity in the series battery system can be performed without reducing the discharge amount of the battery, and a storage battery system with little variation in battery capacity can be provided. Furthermore, since the state of the internal electrode can be estimated for the unit cell having the internal reference electrode, it is possible to select whether the capacity adjustment of the electrode based on the reason for deterioration of the battery is performed with the positive electrode or the negative electrode. As a result, an appropriate amount of Li ion can be easily adjusted without using an external power source. Therefore, it is possible to replace the single cells individually without replacing the entire assembled battery. Further, the dischargeable capacity Q of the replacement battery can be appropriately adjusted according to the discharge capacity of the series battery before replacement. In addition, the battery can be easily replaced, and a highly versatile battery system applicable to various applications can be realized. The present invention balances the voltage between the batteries while using the third electrode that does not cause deterioration inside the battery. Thus, the capacity of the lithium ion secondary battery can be recovered. As a result, a long-life power storage system can be realized. Embodiments will be described below with reference to the drawings.

  A basic configuration of the battery system of Example 1 is shown in FIG. The assembled battery 10 is a battery in which unit cells 5 including a positive electrode, a negative electrode, a third electrode, and a fourth electrode are connected in series. The assembled battery 10 has a positive electrode E1 and a negative electrode E2 connected to an external load (not shown). The fourth electrode is a reference electrode potential, and this potential and the three potentials of the positive electrode, the negative electrode, and the third electrode are collected as voltage values by the battery management device (cell controller). An upper assembled battery management device 8 (battery controller) receives a wired or wireless signal 9 from the battery management device (not shown) and information on each cell. The positive electrode, the negative electrode, the third electrode, and the fourth electrode include a positive electrode terminal 1, a negative electrode terminal 2, a third electrode terminal 3, and a fourth electrode terminal 4, respectively. A switch 6 is connected via a resistor 7 between the positive terminal and the terminal of the third electrode. In this embodiment, the switch is disposed between the positive electrode terminal and the third electrode terminal, but may be disposed between the negative electrode terminal and the third electrode terminal. The third electrode may be connected to the positive electrode or the negative electrode by switching the switch based on the information obtained from the fourth electrode. The battery management device may be arranged directly in the cell and may be inside the assembled battery 10 or may be collectively outside the assembled battery 10.

  For example, the remaining battery capacity is such that the positive electrode active material is a lithium-containing oxide, the negative electrode active material is a non-graphitizable carbon material, and an organic electrolyte containing lithium hexafluorophosphate as an electrolyte is used. (SOC) is a battery that correlates with voltage.

With respect to the plurality of single cells 5a to 5n, the open circuit voltage of each battery before energizing the power storage system is measured in order to measure the voltage variation of each battery. The OCV of each battery is measured by a voltage sensor or the like provided in each cell. The SOC of each cell is calculated by converting the measured OCV into SOC, and the median or average SOC _av and its OCV _av are calculated. For example, the SOC of each cell can be calculated by storing the relationship between the OCV and SOC of the battery in advance in the battery management device and calculating the SOC corresponding to the measured OCV. The SOC of each of these cells and the measured OCV of each cell are compared with a predetermined value, the SOC difference ΔSOC or the comparison voltage difference ΔV is calculated, and a cell having a larger deviation than the predetermined value is specified. For this specified cell, the positive electrode potential V _cath and the negative electrode potential V _ano are confirmed from the potential of the fourth reference electrode, and the required amount of electricity is calculated. When the positive electrode potential V _cath is higher than the third electrode potential V _LiS , the storage battery system is opened, the switch 6 of the specified cell is closed, and the positive electrode and the third electrode are short-circuited. Lithium ions can be replenished by opening and closing the switch 6 based on a predetermined time during which the amount of electricity calculated by the assembled battery management device 8 can be supplemented. Since lithium ions are replenished by utilizing the potential difference between the positive electrode potential V _cath and the third electrode V _LiS , the external power supply required in Patent Document 3 is not necessary. Furthermore, by monitoring the positive electrode potential V _cath and the third electrode V _LiS from the reference potential V _ref obtained by the fourth electrode, there is an advantage that the lithium ion movement amount can also be confirmed. When the comparison voltage difference ΔV is set to a value that requires maintenance after normal operation is stopped, maintenance such as battery replacement and failure analysis must be performed. However, it is possible to avoid battery replacement due to maintenance in the battery system according to the first embodiment.

  Also, depending on the resistance value of the connected resistor, even if the threshold value for energization adjustment in order to balance the batteries in the series is ΔV, it is short when the connected resistance value is small and the energizable current value is large. The capacity can be adjusted over time. The resistor 7 does not necessarily have to be configured as a resistance component. If the internal resistance of the third electrode is high, the internal resistance alone can be substituted.

  Further, when it is desired to reduce the amount of lithium ions from the electrode, when the positive electrode potential is lower than the potential of the third electrode, the same switching is performed while the SOC is discharged to some extent and the SOC is lowered. Thus, it is possible to remove a desired amount of lithium ions from the positive electrode.

FIG. 2 is a diagram illustrating a configuration of the battery system according to the second embodiment. In FIG. 2, the switch is a three-point switch that can be connected to the third electrode terminal 3 by selecting the positive terminal 1 or the negative terminal 2. A capacity adjustment method for the battery system according to the second embodiment will be described. As in the first embodiment, the assembled battery management device 8 confirms the measured OCV and SOC of each cell and determines the target SOC for capacity adjustment. Thereafter, not only the positive electrode potential V _cath but also the negative electrode potential V _ano is calculated from the potential of the fourth electrode. The third electrode is connected to either the positive electrode or the negative electrode, and the battery capacity is adjusted by moving lithium ions. When the positive electrode potential V _cath is higher than the third electrode potential V _LiS , the battery pack system is opened, the switch 6 is closed to the positive electrode side, the positive electrode and the third electrode are short-circuited, and the assembled battery management device 8 calculates The amount of electricity can be supplemented. Based on the time corresponding to the amount of lithium ions that move, the switch 6 is opened and closed to replenish lithium ions. When reducing the lithium ion amount of the negative electrode, it is confirmed that the negative electrode potential _Vano is lower than the potential _VLiS, and the energization time is calculated from the necessary amount of electricity. The switch of the negative electrode terminal and the third electrode terminal is closed for the calculated energization time to move lithium ions. The lithium ions that have moved to the third electrode can be replenished to the positive electrode again. As described above, since it is possible to appropriately determine and execute the adjustment in accordance with the internal state of the electrode, it is possible to adjust the capacity in a short time.

FIG. 3 is a diagram illustrating a configuration of the battery system according to the third embodiment. In FIG. 3, the switch can be connected by selecting either the positive electrode, the third electrode or the battery external load. That is, in the electronic system of Example 3, when the positive electrode terminal 1 and the third electrode terminal 3 are connected, the positive electrode terminal is disconnected for each battery from the battery system including the assembled battery connected in series. The terminal 1 and the third electrode terminal 3 can be connected. By adjusting the amount of lithium ion of the positive electrode or the negative electrode by cutting off the power line, the assembled battery 10 is not charged / discharged, and the change in the positive electrode voltage V _cath of the target cell can be confirmed with higher accuracy. The possibility of leakage current other than the balancing operation performed can be further reduced. In Example 3, a switch was provided between the positive electrode terminal and the third electrode terminal, and the amount of lithium ions was adjusted between the positive electrode and the third electrode. However, the negative electrode and the third electrode or the battery external load A switch that can be selected and connected may be used. In this case, the battery capacity can be adjusted by transferring lithium ions between the negative electrode and the third electrode.

  FIG. 4 is a diagram illustrating the configuration of the battery system according to the fourth embodiment. In the battery system of FIG. 4, the battery 5 has three terminals, a positive electrode terminal 1, a negative electrode terminal 2, and a third electrode 3, and the third electrode also serves as a fourth electrode that is a reference potential electrode. That is, the third electrode and the fourth electrode are one electrode. The voltage of the positive electrode, the negative electrode, and the third electrode is input to the assembled battery management device 8 (battery controller) as a voltage signal 9 (not shown).

For the third electrode, an electrode material having a constant potential in a certain structural range is used regardless of the amount of lithium ions. For example, spinel-structured lithium-containing ion oxide (LiMn ₂ O ₄ ), olivic acid iron (LiFePO ₄ ), lithium titanate (Li ₄ Ti ₅ O ₁₂ ), Li ₃ V ₂ (PO ₄ ) ₃ , LixV ₂ O Transition metal oxide such as ₅ or a material obtained by pre-doping graphite with lithium ions. An electrode containing these materials has a region where the potential is almost constant even when lithium ions are taken in and out, and can be used stably as a reference potential electrode. At this time, if the capacity of the third electrode is designed to be sufficiently large in accordance with the characteristics of the lithium-containing ion material so that the potential of the reference electrode is stabilized, the reference electrode potential can be measured with the third electrode, and the number of parts at the time of manufacture Can be reduced.

  FIG. 6 shows an example of a module in which a plurality of cells are connected in series with a prismatic battery. FIG. 6A shows a case where the cell includes a third electrode and a fourth electrode which is a reference potential electrode, and FIG. 6B shows that the third electrode and the fourth electrode which is a reference potential electrode are combined. This is a case where a cell of a possible type is used. The positive terminal of the module is connected to the load at E1 and negative terminal E2. A switch 6 is provided between the positive electrode and the third electrode via a resistor 7 and can be opened and closed by a signal from the assembled battery management device 8. When the switch 6 is closed, lithium ions are exchanged between the positive electrode and the third electrode. Each battery is arranged in a staggered manner, the positive electrode and the negative electrode are connected by a bus bar, and only the uppermost circuit is shown in the drawing, but a resistor 7 and a switch 6 are arranged between the positive electrode and the third electrode of each battery. Thus, the assembled battery management device 8 can select cells and adjust the capacity.

  FIG. 8 is a diagram showing a configuration of a battery system including a three-point switch 6 that connects either the positive electrode terminal 1 or the negative electrode terminal 2 of the lithium battery 1100 and the third electrode terminal 3. Using the signal of the fourth electrode 4, the assembled battery management device 8 determines the opening / closing direction and opening / closing time of the switch and connects to the third electrode. In addition to equalizing the capacity of the assembled battery, the internal potential of the positive electrode and the negative electrode can be adjusted by the exchange of lithium ions even when the battery deteriorates and the capacity decreases. As a result, the capacity can be recovered, and the battery usage period can be extended.

FIG. 9A is a diagram schematically showing internal potentials of the positive electrode 1, the negative electrode 2, and the third electrode 3 of the lithium ion battery during charging. The positive electrode potential V _cath is noble and the negative electrode potential V _ano is base, and the battery voltage V _cell is determined by this potential difference. In a lithium ion battery, during charging, the positive electrode is noble and the negative electrode is base, and the potential difference increases. When the third electrode is between the positive electrode potential and the negative electrode potential, by connecting the positive electrode 1 and the third electrode 3, the voltage between the positive electrode potential V _cath and the third electrode potential V _LiS (V _cath −V _LiS ) Lithium ions are exchanged to reach an equilibrium potential. When the lithium ion battery uses a lithium ion material as the positive electrode material and the lithium ions are released from the positive electrode during charging, in order to replenish the lithium ion to the positive electrode, V _cath > V _LiS Need to connect.

FIG. 9B schematically shows the internal potentials of the positive electrode, the negative electrode, and the third electrode of the lithium ion battery during discharge. At the time of discharging, the potential difference between V _cath and V _ano becomes small, and the positive electrode potential V _cath decreases. Therefore, when the potential V _Lis of the third electrode is higher than V _cath , lithium ions are not replenished, and lithium is not _supplied to the third electrode. Ions move. When the negative electrode is lower than the potential of the third electrode, lithium ions always move to the third electrode. When the potential of the third electrode is lower than the negative electrode potential, lithium ions can be supplied to the positive electrode. However, when the positive electrode potential is as high as possible, the lithium-containing positive electrode material functions more effectively.

On the other hand, when the positive electrode active material is not a lithium-containing material and the negative electrode is a lithium-containing material, lithium ions move to the positive electrode material during discharging and return to the negative electrode during charging. Since the amount of lithium ions is smaller when the positive electrode potential V _ano is higher, it is more preferable to switch the adjustment switch 6 when V _cath > V _LiS at the third electrode potential V _LiS in order to increase the positive electrode capacity.

  FIG. 10 is a schematic diagram of the inside of the unit cell. A positive electrode plate 301 coated on both sides of an aluminum current collector and a negative electrode plate 302 coated on both sides of a copper current collector are stacked facing each other through a separator 600. In this configuration, the capacity recovery electrode 303 is disposed on the exterior body side through the separator 600 so as to face the negative electrode on the surface side of the battery exterior body 500. In the fourth reference electrode, a reference electrode 304 covered with a bag-like separator is disposed in the vicinity of the separator in the substantially central portion of the laminate of the positive electrode and the negative electrode so as not to short-circuit the positive electrode, the negative electrode, and the third electrode ( Not shown). In order to maintain the stability of the potential, the exterior body is impregnated and encapsulated with an electrolyte solution having an appropriate concentration that sufficiently fills the gap of the separator and the gap of the electrode. Here, the exterior body is made of aluminum laminate, metal can, or other chemical-resistant material, and any material can be used as long as it is sufficiently isolated from the atmosphere. A cylindrical can can also be constructed by winding the negative electrode with the positive electrode and the separator facing each other and winding the third electrode around the outermost periphery.

  In FIG. 10, a switch S1 is provided between the positive electrode terminal E1 and the third electrode terminal E3, and by closing this switch, lithium ions can be exchanged between the positive electrode plate and the third electrode. Further, by providing a switch S2 between the negative electrode terminal E2 and the third electrode terminal E3 and closing this switch, lithium ions can be exchanged between the negative electrode plate and the third electrode. When the third electrode inside the outer package is connected to the terminal E3 together with the positive electrode and the negative electrode, the amount of lithium ions capable of adjusting the capacity can be increased. Further, the switches S1 and S2 can be combined on some surface of the exterior body so that it can be selected whether to connect to the positive electrode or the negative electrode, or downsizing is possible by using a three-point switch.

  In FIG. 10, the third electrode is an example that can be connected to the positive electrode and the negative electrode independently, but in this case, the voltage at the third electrode when supplying lithium ions to the positive electrode plate The voltage of the third electrode when lithium ions are transferred to the negative electrode can be set separately, and there is an advantage that it can be carried out in a short time especially when it is desired to adjust both the positive electrode and the negative electrode.

  FIG. 11 is an example schematically showing the inside from a surface that is not on the side of the laminated section when the structure of the unit cell of the present invention is applied to a rectangular cell. The positive electrode terminal E1, the negative electrode terminal E2, and the third electrode terminal E3 are arranged from the laminate 300 of the positive electrode, the negative electrode, the separator, and the third electrode, and the reference electrode terminal E4 from the reference electrode 304 is concentrated on the end face of the cell. Is. The reference electrode 304 has a configuration in which a separator is sandwiched and is not in contact with the electrode group 300 so as not to be short-circuited with other electrodes. The reference electrode 304 is disposed as close as possible and has a large area, so that the stability of the reference electrode is improved.

  In Example 6, a battery system control method according to an embodiment of the present invention will be described. In the battery system, in order to evaluate the voltage variation of the plurality of single cells 5, the open circuit voltage (OCV) before energizing the power storage system is evaluated and balancing is performed. The battery system according to the present embodiment includes an assembled battery including a plurality of lithium ion secondary batteries and an assembled battery management device that manages the assembled battery. The assembled battery management device includes a battery management device that detects a voltage value and a current value of each lithium ion battery, and a charge state calculation that calculates a battery state such as an SOC of each lithium ion battery based on the detected voltage value and current value. A battery selection unit that selects a lithium ion battery that adjusts the lithium ion amount from the assembled battery based on the SOC calculated by the charge state calculation unit, and a switch control unit that controls opening and closing of the switch Prepare. The battery selection unit calculates, for example, the median value of the SOC from the SOC of each lithium ion secondary battery calculated by the charge state calculation unit, and the amount of lithium ions from the difference between the median value and the SOC of each lithium ion secondary battery Select the lithium-ion battery to adjust. The switch control unit determines the state of the positive electrode and the negative electrode based on the information obtained from the fourth electrode for the lithium ion battery selected by the battery selection unit, calculates the lithium ion adjustment amount, and calculates the calculated lithium The opening / closing time of the switch is determined from the amount of ions.

  FIG. 12 shows the procedure of the balancing method. First, the battery management device acquires voltage and temperature information of each electrode of each battery 5 according to a command from the assembled battery management device 8 when the device is activated or in a no-load state (S501).

Next, this potential and the three potentials of the positive electrode, the negative electrode, and the third electrode are collected as voltage values by the assembled battery management device (cell controller) 8 to calculate the open circuit voltage (OCV) of the battery. After the OCV is converted to SOC and the SOC of each cell is calculated, the median (median value) SOC _m is calculated (S502). The deviation ΔSOC of those values and the SOC of each cell is calculated.

If the deviation is larger than the threshold value SOC _th1 in step S504 (ΔSOC> SOC _th1 ), it is assumed that there is a variation incapacitance adjustment, a warning display of a cell voltage abnormality notification is displayed, and the process is terminated.

If ΔSOC ≦ SOC _{th1 in} step S504, the deviation is compared with the threshold SOC2 in the next step S505, and if ΔSOC> SOC _th2 , the process proceeds to the next step S508. In the case of ΔSOC ≦ SOC _th2 , it is within a range where the operation can be safely performed without adjusting the capacity. Therefore, the process ends without adjusting the capacity, and the charge / discharge preparation is completed.

The cell of SOC _th1 >ΔSOC> SOC _th2 is identified as a cell whose capacity is to be adjusted, and the capacity required for adjustment is calculated from ΔSOC (S508). Based on the reference electrode potential of the specified target cell, the positive electrode potential, the negative electrode potential, and the third electrode potential are calculated, and the lithium ion amount that can be replenished to the positive electrode and the lithium ion amount are replenished from the difference between the positive electrode potential and the third electrode potential. Calculate the time required for At this time, the calculation is performed including the total energization time and the time during which the energization is stopped to suppress the heat generation of the components (S509). The switch between the third electrode and the positive electrode is opened / closed for a predetermined time calculated in step S509 (S510). After the switch is opened (S511), each potential of the battery is measured again, and a deviation ΔSOC _r between the adjusted SOC and the previously calculated SOC _m is calculated (S513). If the deviation is larger than SOC _th2 , the process returns to step S508 and the process is repeated again. In the case of ΔSOC _r ≦ SOC _th2, the process is terminated as the completion of balancing, and the charge / discharge preparation is completed.

  If the relationship between the SOC and the OCV can be approximated by a linear expression, the threshold value can also be determined by the voltage without using the SOC conversion in step 502 and using the voltage value as it is. In this example, the median value of the SOC of each lithium ion battery was used as a reference value, and the lithium ion battery for capacity adjustment was selected by comparing the SOC reference value and the SOC of each lithium ion battery. Is not limited to the median value or the median value, and can be set as appropriate.

  FIG. 13 shows an example of a battery system to which the present invention is applied. The battery management device 11 includes one or more measuring devices (sensors) 20 that measure the state of the battery, a processing unit 30 that acquires and processes battery state information, a radio circuit 40, and an antenna 50 that inputs and outputs radio waves. Then, the processing unit 30 detects the state of the battery cell or the plurality of battery cells from the power supply circuit 31 that receives power from the plurality of battery cell groups 10 and generates an operating voltage and the information measured by the measuring instrument 20. A circuit (A / D converter) 32, a processing circuit (CPU) 33 for diagnosing the state of a battery cell or a plurality of battery cells based on detection information detected by the detection circuit 32, individual identification information and detection information Or it is comprised from the memory | storage device (memory) 34 which memorize | stores diagnostic information or both.

  The assembled battery management device 8 includes a wireless circuit 210, a processing circuit (CPU) 220, a power supply circuit 230 including a battery, a storage device (memory) 240, and an antenna 250. The power supply circuit 230 includes a battery in FIG. 13, but may be supplied from the outside.

  The assembled battery management device 8 communicates with one or more battery management devices 11 and acquires a battery state detected by the battery management device 11. In the wireless communication between the battery management device 11 and the assembled battery management device 8 at this time, the assembled battery management device 8 performs a master operation and the battery management device 11 performs a slave operation. The battery management device 11 performs an operation in accordance with a request from the assembled battery management device 8 and then returns a result to the assembled battery management device 8 as necessary.

  Here, the plurality of sensors 20 that measure the state of the battery measure the voltages of the positive electrode 1, the negative electrode 2, the third electrode 3, and the fourth electrode 4, and the assembled battery management device 8 processes these detection information. In accordance with the above calculation flow, calculation of balancing necessity / unnecessity determination, selection of execution method, balancing switch 6 open / close time, etc. is performed to balance the voltage and capacity of each battery in each assembled battery group 10. Balancing is performed through the battery management device 11. At this time, the sensor 20 can acquire additional information such as the temperature of the individual cell to increase the accuracy of the balancing current and the balancing time that match the temperature characteristics of the battery.

  FIG. 14 is a diagram illustrating an example of communication operation in the battery system including the assembled battery management device 8 and the plurality of battery management devices 11.

  Sensing information such as the battery voltage, current, battery surface temperature, and battery internal temperature of the cell 1 at the time of activation is requested from the assembled battery management device 8 and transmitted from the battery management device 11. As for the sensing information, the information is transmitted according to the received instruction at regular intervals of 10 ms to 60 s in accordance with the reading designated time of each information. Before the start of charging / discharging, individual information on the initial state of the plurality of battery management devices 11 is read, and when there is SOC imbalance in the entire battery, a command is transmitted to the target battery management device 9 and the received battery management device 11 is received. Connects the positive or negative electrode and the third electrode to the cell 10 with a switch, and opens and closes the switch 6 (not shown) until the battery cell 1 reaches a desired voltage.

  Communicates that the capacity has increased or decreased to the assembled battery management device 8 for each cell, and changes the calculation parameters so that the calculation error of SOC, SOH (SOHR, SOCQ) during charging / discharging does not increase, Stabilize the control.

  As described above, the battery system using the battery including the reference electrode and the third lithium supply electrode can easily perform equalization of the capacity and cell voltage in the cell, ensure stable operation, and maintain. Costs can be reduced and the operating life of the storage battery system can be extended.

DESCRIPTION OF SYMBOLS 1 ... Positive electrode terminal, 2 ... Negative electrode terminal, 3 ... 3rd lithium ion supply electrode, 4 ... Reference potential electrode, 5 ... Cell, 6 ... Switch, 7 ... Resistance, 8 ... Assembly battery management apparatus, 9 ... Wireless or wired Voltage signal, 10... Assembled battery composed of one or more battery cell groups, 11... Battery management device (cell controller), 20... One or more measuring instruments (sensors) for measuring the state of the battery, 30 ... Processing unit (battery control unit) for acquiring and processing battery status information, 31 ... Power supply circuit, 32 ... Detection circuit (A / D converter) for detecting battery cell status, 33 ... Battery cell status Processing circuit (CPU) for diagnosis, 34... Storage device (memory), 40 .. wireless circuit, 50 .. antenna, 60... Processing unit for acquiring and processing battery state information, 61. Detection circuit (A / D converter), 6 3 ... processing circuit (CPU) for diagnosing the state of the battery cell, 64 ... storage device (memory), 100 ... battery system, 200 ... inverter, 201 ... motor, 202 ... host controller, 210 ... wireless circuit, 220 ... processing circuit (CPU), 230 ... power supply circuit including battery, 240 ... storage device (memory), 250 ... antenna, S2 ... negative electrode-third electrode switching part, S1 ... positive electrode-third electrode switching part, 300 ... electrode group, 301 ... Positive electrode plate, 302 ... Negative electrode plate, 303 ... Third electrode, 304 ... Fourth electrode reference potential electrode, E1 ... Positive electrode terminal, E2 ... Negative electrode terminal, E3 ... Third electrode terminal, E4 ... Fourth electrode terminal, R1 ... Resistance, R2 ... Resistance, 500 ... Exterior body (can, laminate), 600 ... Separator, 110 ... Lithium ion secondary battery

Claims (18)

A battery system comprising an assembled battery configured by connecting a plurality of lithium ion batteries,
The lithium ion battery includes a positive electrode, a negative electrode, a third electrode for adjusting a lithium ion amount of at least one of the positive electrode and the negative electrode, and a fourth electrode serving as a reference potential. . The battery system according to claim 1,
The third electrode is connected to at least one of the positive electrode and the negative electrode via a switch,
The battery system, wherein the switch is switched based on information obtained by the fourth electrode. The battery system according to claim 2,
The plurality of lithium ion batteries are connected in series. The battery system according to claim 2,
When the battery pack is non-energized and the voltages of the plurality of lithium ion batteries are non-uniform and the variation in the remaining capacity of the battery exceeds a threshold, the positive electrode or the A battery system, wherein a negative electrode and the third electrode are connected. The battery system according to any one of claims 1 to 4,
The battery system is characterized in that the switch is a three-point switch that can be connected to the third electrode by selecting either the positive electrode or the negative electrode. The battery system according to any one of claims 1 to 4,
The battery system is characterized in that the switch can be connected to the positive electrode by selecting either the third electrode or an external load. The battery system according to any one of claims 1 to 4,
The battery system is characterized in that the switch can be connected to the negative electrode by selecting either the third electrode or an external load. The battery system according to any one of claims 1 to 4,
It has an assembled battery management device,
The assembled battery management device selects a battery management device that detects a voltage value of each of the plurality of lithium ion batteries, and a lithium ion battery that adjusts a lithium ion amount from the assembled battery based on the detected voltage value. A battery system comprising: a battery selection unit; and a switch control unit that controls opening and closing of the switch. The battery system according to any one of claims 1 to 4,
The assembled battery management device includes: a battery management device that detects a voltage value and a current value of each of the plurality of lithium ion batteries; and a lithium ion battery that adjusts a lithium ion amount from the assembled battery based on the detected voltage value A battery state selection unit that calculates the SOC of each of the plurality of lithium ion batteries based on the detected voltage value and current value, and the SOC based on the SOC calculated by the state of charge calculation unit. A battery system comprising: a battery selection unit that selects a lithium ion battery that adjusts the lithium ion amount from the assembled battery; and a switch control unit that controls opening and closing of the switch. The battery system according to claim 9,
The battery selection unit calculates an SOC reference value from the SOC of the plurality of lithium ion secondary batteries calculated by the charge state calculation unit, and a difference between the reference value and the SOC of the plurality of lithium ion secondary batteries. The battery system characterized by selecting a lithium ion battery that adjusts the amount of lithium ions from. The battery system according to claim 9 or 10,
The battery selection unit calculates an SOC median value from the SOCs of the plurality of lithium ion secondary batteries calculated by the charge state calculation unit, and a difference between the median value and the SOCs of the plurality of lithium ion secondary batteries. The battery system characterized by selecting a lithium ion battery that adjusts the amount of lithium ions from. The battery system according to any one of claims 8 to 10,
The switch control unit calculates an adjustment amount of lithium ions based on the information obtained by the fourth electrode for the lithium ion battery selected by the battery selection unit, and calculates the amount of the switch from the calculated lithium ion amount. A battery system characterized by determining an opening and closing time. The battery system according to any one of claims 1 to 4,
The battery system, wherein the third electrode includes at least one of lithium-containing graphite and lithium-containing metal oxide. The battery system according to claim 9,
The battery system, wherein the lithium-containing metal oxide is a material used for the positive electrode or the negative electrode. The battery system according to any one of claims 1 to 4,
The battery system according to claim 4, wherein the fourth electrode includes at least one of lithium-containing graphite and lithium-containing oxide. The battery system according to any one of claims 1 to 4,
The lithium-containing oxide of the fourth electrode is any one of lithium manganate, lithium iron olivine, lithium titanate, Li ₃ V ₂ (PO ₄ ) ₃ , and LixV ₂ O ₅ . system. The battery system according to any one of claims 1 to 4,
The battery system, wherein the third electrode and the fourth electrode are one electrode. The battery system capacity recovery method according to claim 1,
Measuring an open circuit voltage of each of the plurality of lithium ion batteries;
Calculate the SOC of the lithium ion battery from the open circuit voltage,
Select a lithium ion battery that adjusts the amount of lithium ions from the SOC of the lithium ion battery,
Calculate the lithium ion adjustment amount based on the information obtained by the fourth electrode,
Determine the opening time of the switch based on the lithium ion adjustment amount,
A method for recovering the capacity of a battery system, wherein opening and closing of the switch is controlled based on the opening time.