Battery control system and battery control method

Abstract

A battery control system (1) for controlling a solid-state battery provided with a battery cell (21) having a solid electrolyte and a negative electrode containing lithium, the battery control system (1) being provided with: a measurement means for measuring a surface pressure distribution on the basis of a measured value or an estimated value of the surface pressure distribution on the main surface of the battery cell (21); and a control means for controlling a charge / discharge current, which is a charge current and / or discharge current of the solid-state battery, the control means determining the charge / discharge current on the basis of the upper limit surface pressure difference and the lower limit surface pressure difference. The upper limit surface pressure difference is the difference between the measured value of the surface pressure distribution measured by the measuring unit and the upper limit surface pressure of the battery cell (21), and the lower limit surface pressure difference is the difference between the measured value of the surface pressure distribution measured by the measuring unit and the lower limit surface pressure of the battery cell (21).

Description

Technical Field

[0001] This invention relates to a battery control system and a battery control method. Background Technology

[0002] A known battery system determines whether a lithium secondary battery is likely to experience high-rate degradation due to charging or discharging based on the surface pressure at the center and the surface pressure at the ends of the electrode body housed within it (see Patent Document 1). The battery system described in Patent Document 1 limits the input or output current to the secondary battery when it determines, based on a first pressure at the center of the electrode body and a second pressure at the ends of the electrode body, that a resistance increase due to charging and / or discharging of the secondary battery has occurred.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-61749 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] In solid-state batteries using lithium-containing negative electrodes, there is a need to control the charge and discharge current of the solid-state battery in a way that ensures the surface pressure of the individual cells included in the solid-state battery does not fall below a lower limit. However, the systems of the prior art described above do not perform current limiting to ensure that the pressure of the electrode body does not fall below a lower limit, thus presenting a problem that they cannot be applied to systems controlling the charge and discharge current of solid-state batteries.

[0008] The problem to be solved by the present invention is to provide a battery control system and a battery control method that can control the charging and discharging current of a solid-state battery in a manner that ensures that the surface pressure of the individual cells included in the solid-state battery is not lower than a lower limit.

[0009] Solution for solving the problem

[0010] This invention solves the above-mentioned problem by determining either the charging current or the discharging current of a solid-state battery based on the upper limit surface pressure difference and the lower limit side difference. The upper limit surface pressure difference is the difference between the measured value of the surface pressure distribution on the main surface of the battery cell and the upper limit surface pressure of the battery cell, and the lower limit side difference is the difference between the measured value of the surface pressure distribution and the lower limit surface pressure of the battery cell.

[0011] Invention Effects

[0012] According to the present invention, the charging and discharging current of a solid-state battery can be controlled in such a way that the surface pressure of the individual cells included in the solid-state battery is not lower than a lower limit. Attached Figure Description

[0013] Figure 1 This is a block diagram illustrating a battery control system according to an embodiment of the present invention.

[0014] Figure 2 This is a top view of a single battery cell.

[0015] Figure 3 It is a graph showing the characteristics of lithium creep in a single battery cell relative to surface pressure and the characteristics of cell resistance.

[0016] Figure 4 It is a graph showing the SOC characteristics, surface pressure characteristics, and charging current characteristics of a single battery cell.

[0017] Figure 5 It is a graph showing the temperature distribution characteristics, charging current characteristics, thickness difference / lithium migration characteristics, and surface pressure characteristics of a single battery cell.

[0018] Figure 6 This is a flowchart illustrating the process of a battery control method according to an embodiment of the present invention.

[0019] Figure 7 It is a graph showing the characteristics of the upper and lower limit surface pressures of a battery cell relative to the state of charge (SOC) and the characteristics of the upper and lower limit surface pressures relative to the cell temperature.

[0020] Figure 8 This is a flowchart illustrating a modified embodiment of the battery control method according to the present invention.

[0021] Figure 9 This is a flowchart illustrating a modified embodiment of the battery control method according to the present invention. Detailed Implementation

[0022] like Figure 1 As shown, the battery control system 1 includes a controller 10, a voltage sensor 11, a current sensor 12, a temperature sensor 13, a DC-DC converter 14, a surface pressure distribution measuring device 15, a pressure application mechanism 16, and a busbar 17. Furthermore, in this embodiment, the controller 10 corresponds to an example of a "control unit" in this invention, the surface pressure distribution measuring device 15 corresponds to an example of a "measuring unit" in this invention, and the pressure application mechanism 16 corresponds to an example of a "pressure application unit" in this invention.

[0023] The controller 10 is a battery control unit (BCU). The controller 10 consists of a memory such as ROM or RAM and a processor such as a CPU. The controller 10 manages the state of the battery module 2 based on the detected voltage detected by the voltage sensor 11, the detected current detected by the current sensor 12, the detected temperature detected by the temperature sensor 13, and the measured value measured by the surface pressure distribution measuring device 15. Furthermore, the controller 10 controls the charging and discharging current used to charge or discharge the battery module 2. The charging and discharging current is either the charging current or the discharging current of the battery module 2.

[0024] Voltage sensor 11 is used to detect the voltage between the terminals of battery module 2. Voltage sensor 11 is connected between the wiring connected to the positive and negative terminals of battery module 2. Current sensor 12 is used to detect the input and output current of battery module 2. Current sensor 12 is connected to the wiring connected to either the positive or negative terminal of battery module 2. Temperature sensor 13 is disposed on battery module 2. Temperature sensor 13 is used to detect the temperature of battery module 2.

[0025] DC-DC converter 14 is a power conversion device that converts the voltage input from battery module 2 to a specified voltage and outputs power to loads such as motors. Additionally, DC-DC converter 14 also converts the voltage input from a charging device to a specified voltage and outputs power to battery module 2. This DC-DC converter 14 is controlled by controller 10. Battery module 2 is connected to the input side of DC-DC converter 14, and a load is connected to the output side of DC-DC converter 14. The load may include a power grid such as a motor inverter. A charging device can also be connected to the output side of DC-DC converter 14.

[0026] The surface pressure distribution measuring device 15 measures the surface pressure distribution on the main surface of the battery cells 21 included in the battery module 2. The measured values ​​of the surface pressure distribution measuring device 15 are the actual measured values ​​of the surface pressure distribution. The surface pressure distribution measuring device 15 is arranged along the main surface of the battery cells 21. The surface pressure distribution measuring device 15 may also include a pressure sensor, etc. The surface pressure distribution measuring device 15 can also separately measure the maximum surface pressure (maximum pressure) and the minimum surface pressure (minimum pressure) on the main surface of the battery cells 21.

[0027] Furthermore, the surface pressure distribution measuring device 15 can measure the pressure on the entire surface of the main surface of the battery cell 21, or it can measure the pressure at at least one measuring point on the main surface of the battery cell 21. Moreover, the maximum and minimum surface pressure values ​​of the surface pressure distribution can be calculated by the controller 10 based on the measured values ​​from the surface pressure distribution measuring device 15. For example, the controller 10, which models the surface pressure distribution on the main surface of the battery cell 21 using a mathematical formula, only needs to obtain the measured values ​​at the measuring points from the surface pressure distribution measuring device 15 and use the mathematical formula for the surface pressure distribution obtained through modeling to calculate the maximum and minimum surface pressure values.

[0028] The pressure application mechanism 16 applies pressure to the battery module 2 by pressing it against the stacking direction of the battery cells 21 included in the battery module 2. The pressure application mechanism has multiple cell pressure plates. These cell pressure plates are disposed on the top and bottom surfaces of the battery module 2, and also inside the battery module 2. The cell pressure plates disposed on the top and bottom surfaces of the battery module 2 are end plates that clamp the stack of battery cells 21 from the stacking direction to apply pressure to the battery cells 21. The cell pressure plates disposed inside the battery module 2 are disposed between the multiple battery cells 21, and these cell pressure plates are components capable of absorbing displacement caused by the charging and discharging of the battery module 2, for example, made of an elastic body. The pressure application mechanism 16 has cell fixing plates for fixing the multiple battery cells 21 to a pack structure. Furthermore, the pressure application mechanism 16 has a mechanism for varying the distance between the cell fixing plates and the pressure plates. The pressure application mechanism 16, based on the control command of the controller 10, causes the distance between the cell fixing plate and the pressure plate to change, thereby changing the pressure applied to the battery cell 21.

[0029] Battery module 2 is a solid-state battery and is electrically connected to a charging device. The charging device connected to the individual battery cells 21 is, for example, a device used to charge battery module 2 installed in an electric vehicle or hybrid vehicle. Charging the on-board battery module 2 is performed by removing the charging cable from the charging device, attaching the charging gun at the end of the charging cable to the connector of the vehicle's charging port, and then operating the charging start switch. Controller 10 controls DC-DC converter 14 and charging device respectively to manage the state of charge (SOC) of the individual battery cells 21 included in battery module 2 and to make the state of charge of battery module 2 the target state of charge.

[0030] As described above, battery module 2 is electrically connected to a load such as a motor. The load is a device that operates using the power from battery module 2, and includes auxiliary equipment such as a motor, air conditioner, and lights, which serve as the vehicle's drive source. Discharging of battery module 2 is performed under the control of controller 10 based on system requests or external power requests. System requests are equivalent to instructions from an onboard computer such as the ECU during vehicle operation. Regarding external power requests, for example, if the air conditioner is activated before vehicle operation based on instructions from an external device such as a portable terminal, set via a timer to ensure a comfortable temperature inside the passenger compartment at the start of vehicle operation, the instructions from the external device are equivalent to external power requests.

[0031] In addition, the battery module 2 installed in electric vehicles and hybrid vehicles can also be used for vehicle grid integration (VGI). VGI is a technology that connects electric vehicles and hybrid vehicles equipped with battery module 2 to the system so that the power stored in battery module 2 can be supplied to the system (load) via the power grid.

[0032] The battery module 2 includes a battery cell 21 having at least a positive electrode, a solid electrolyte, and a negative electrode. The positive electrode contains at least a positive electrode active material capable of releasing and absorbing alkali metals such as lithium (Li), sodium (Na), or potassium (K), although not particularly limited, it contains a positive electrode active material containing sulfur. As the solid electrolyte, for example, a sulfide solid electrolyte or an oxide solid electrolyte can be used. The negative electrode only needs to contain lithium, for example, lithium metal or a lithium alloy. The battery cell 21 is sealed by the casing member while the tabs are connected to the stack having the positive electrode, solid electrolyte, and negative electrode. The battery cell 21 is formed in a flat shape. Furthermore, multiple stacked battery cells 21 are interconnected via a busbar 17. Figure 2 This is a top view of a single battery cell 21. Multiple battery cells 21 are stacked along the y-direction, and the surface along the xz plane is the main surface of the battery cell 21 and corresponds to the stacking surface. Figure 2 In the battery cell 21 shown, the tabs extend from both sides, but it is also possible for the tabs to extend from only one side. Furthermore, the tabs can be configured as follows: Figure 2 It can extend from the short side of the main surface of the battery cell 21 as shown, or it can extend from the long side.

[0033] Next, refer to Figure 3 This is to illustrate the surface pressure of the battery cell 21. Figure 3These are graphs showing the creep characteristics of lithium relative to surface pressure when the thickness of the battery cell 21 is constant (graph a) and graphs showing the cell resistance relative to surface pressure (graph b). As shown in graph a, the higher the surface pressure, the greater the creep. For example, during the charging of battery module 2, when the surface pressure of the battery cell 21 increases and the creep increases excessively, the possibility of dendrite formation and short circuit increases. Therefore, a predetermined surface pressure limit (upper limit surface pressure: P) is determined. th_H Lower limit surface pressure: P th_L The reference value (criteria: C) is used, and the surface pressure corresponding to the intersection of the surface pressure-creep characteristic (curve a) and the reference value (C) is preset as the upper limit surface pressure (P). th_H When the surface pressure of a single battery cell 21 exceeds the upper limit surface pressure, the likelihood of a short circuit increases. That is, the upper limit surface pressure (P) th_H This refers to the upper limit of the permissible surface pressure for a single battery cell (P21). th_H The threshold value is set based on the performance of the battery cell 21 to keep the short-circuit probability, which varies with surface pressure, below a specified value.

[0034] Furthermore, in solid-state batteries using lithium as the negative electrode, both an upper and lower limit surface pressure must be observed. As shown in curve b, the lower the surface pressure, the higher the individual cell resistance (DCR: DC resistance). For example, during the charging of battery module 2, when the surface pressure of battery cell 21 decreases while the individual cell resistance increases, the charging current decreases relative to the charging voltage applied to battery cell 21, thus increasing the charging time. Additionally, during the discharging of battery module 2, when the individual cell resistance increases, the current supplied to the load decreases, potentially failing to ensure the current required to operate the load. Therefore, the surface pressure corresponding to the intersection of the surface pressure-individual cell resistance (DCR) characteristic (curve b) and the reference value (C) is preset as the lower limit surface pressure (P). th_L That is, the lower limit surface pressure (P). th_L This refers to the lower limit of the permissible surface pressure for a single battery cell (P21). th_L The threshold value is the threshold value that makes the resistance of a single cell, which varies according to surface pressure, below a specified value. This threshold value is determined based on external factors of the battery cell 21, such as the allowable charging time during the charging of the battery module 2 and the operating current of the connected load.

[0035] Next, the current control during charging and discharging performed by the controller 10 will be explained. Furthermore, the following explanation mainly focuses on the control during charging of the battery module 2, but the discharge control of the battery module 2 is also the same as the charging control. The controller 10 determines the discharge current of the battery module 2 using the same method as the method for determining the charging current, and controls the discharge of the battery module 2.

[0036] Upon receiving a command to start charging of the battery module 2, the controller 10 acquires the measured value of the surface pressure distribution obtained by the surface pressure distribution measuring device 15. The surface pressure distribution measuring device 15 measures the measured value (actual value) of the surface pressure distribution of the battery module 2 at a predetermined period, and the controller 10 acquires the measured value of the surface pressure distribution from the surface pressure distribution measuring device 15 during the charging of the battery module 2.

[0037] The controller 10 obtains the measured value of the surface pressure distribution and the upper limit surface pressure (P) of the battery cell. th_H The upper limit surface pressure difference is calculated by taking the measured value of the surface pressure distribution and the lower limit surface pressure (P) of the battery cell. th_L The lower limit surface pressure difference is calculated by the difference between the two values.

[0038] Furthermore, when the maximum and minimum surface pressure values ​​of the surface pressure distribution are measured, the controller 10 can also take the maximum surface pressure value of the surface pressure distribution and the upper limit surface pressure of the battery cell (P). th_H The upper limit surface pressure difference is calculated by taking the difference between the minimum surface pressure of the surface pressure distribution and the lower limit surface pressure of the blue monomer (P). th_L The lower limit surface pressure difference is calculated by the difference between the two values.

[0039] Then, the controller 10 determines the charging and discharging current based on the upper limit surface pressure difference and the lower limit surface pressure difference. Specifically, the controller 10 determines the charging and discharging current in a manner that keeps the upper limit surface pressure difference and the lower limit surface pressure difference below a differential threshold. As described above, the battery module 2 in this embodiment needs to comply with the upper limit surface pressure and the lower limit surface pressure during charging. For example, during the charging of the battery module 2, if the measured value of the surface pressure distribution of the battery cell 21 reaches the upper limit surface pressure, the controller 10 reduces the charging current. When charging continues in a reduced charging current state and the pressure difference of the surface pressure distribution is mitigated, the maximum surface pressure decreases, and therefore the upper limit surface pressure difference is greater than the differential threshold. The controller 10 increases the charging current when the upper limit surface pressure difference exceeds the differential threshold. As the charging current increases, the charging reaction in the battery cell 21 is promoted, the surface pressure on the main surface of the battery cell 21 increases, and the upper limit surface pressure difference becomes below the differential threshold. The controller 10 determines the charging current by repeatedly increasing the current corresponding to such an upper limit surface pressure difference during the charging of the battery module 2, so as to keep the upper limit surface pressure difference below the differential threshold.

[0040] During the charging of battery module 2, controller 10 only needs to reduce the charging current when the measured value of the surface pressure distribution of battery cell 21 is lower than the lower limit surface pressure, and increase the charging current when the lower limit surface pressure difference becomes greater than the difference threshold. Furthermore, if the upper and lower limit surface pressure differences differ depending on the surface pressure distribution of battery cell 21 during the charging of battery module 2, controller 10 only needs to reduce the charging current when the smaller of the upper and lower limit surface pressure differences reaches the difference threshold. Then, controller 10 only needs to increase the charging and discharging current when the smaller surface pressure difference becomes greater than the difference threshold after reducing the charging current. The difference threshold only needs to be a value greater than or equal to 0. For example, when the difference threshold is set to zero or close to zero, controller 10 ensures that the surface pressure distribution of battery cell 21 does not exceed the surface pressure limit (upper limit surface pressure: P). th_H Lower limit surface pressure: P th_L The method determines that the maximum surface pressure of the battery cell 21 is maintained at a high level (close to the upper limit surface pressure P). th_H (state), and maintain the minimum surface pressure at a low level (close to the lower limit surface pressure P) th_L The charging current is like that (in the state of charging).

[0041] Here, refer to Figure 4 This is used to illustrate the relationship between the surface pressure distribution of battery cell 21 and the charging current. Figure 4In the graphs, (a) represents the SOC characteristic, (b) represents the surface pressure characteristic, and (c) represents the charging current (C-rate) characteristic. Furthermore, the horizontal axis of each graph represents time. Graph a shows the characteristics when the battery module 2 is charged using the charging control of this embodiment, and graph b shows the characteristics when the battery module 2 is charged using the charging control of the comparative example. In the charging control of the comparative example, when the measured surface pressure of the battery cell 21 reaches the upper limit surface pressure, the charging current decreases, and then the battery module 2 is charged while maintaining the decreased charging current.

[0042] Battery module 2 is constructed by stacking multiple battery cells 21. In the central portion of the battery cell 21, the heat insulation effect of adjacent battery cells 21 on the upper and lower surfaces plays a role. On the other hand, heat tends to escape more easily from the tabs of the battery cell 21 compared to the central portion. Therefore, during charging of the battery cell 21, high-temperature and low-temperature regions are generated on the main surface of the battery cell 21. Moreover, in the high-temperature regions, the charging reaction is promoted, the amount of lithium deposition increases, and the surface pressure rises. Additionally, as... Figure 3 As shown in curve b, when the surface pressure increases, the single-cell resistance decreases, thus further promoting the charging reaction and causing the surface pressure to rise further. Thus, due to the temperature difference on the main surface of the battery cell 21, a surface pressure difference (the difference between the maximum and minimum surface pressure) is generated in the surface pressure distribution.

[0043] When the battery module 2 is being charged and the measured surface pressure distribution of the battery cell 21 reaches the upper limit surface pressure, the controller 10 reduces the charging current. Figure 4 In the example, at time t a At a certain point in time, the measured value of the surface pressure distribution of the battery cell 21 reaches the upper limit of surface pressure, therefore the controller 10 reduces the charging current. As in the comparative example, when the charging current is reduced and charging control continues, the surface pressure difference between the high-pressure and low-pressure areas gradually decreases and converges to a certain surface pressure (refer to...). Figure 4 (b) is a graph (b). Furthermore, in the comparative example, because charging control continues while the current is reduced, the time until the SOC of battery module 2 reaches the target SOC is longer. That is, as... Figure 4 As shown in graph (b) of (a), the charging time is longer in the comparative example.

[0044] In this embodiment, at time t aAt the point in time when the measured value of the surface pressure distribution of the battery cell 21 reaches the upper limit of the surface pressure, the controller 10 temporarily reduces the charging current and performs charging control. When charging of the battery module 2 continues while the charging current is reduced, lithium deposition thickens as charging proceeds. As described above, due to the temperature difference (temperature distribution) on the main surface of the battery cell 21, a surface pressure difference is generated in the surface pressure distribution. Lithium wets and spreads along the main surface due to the pressure applied to the high surface pressure portion. That is, lithium moves from the high surface pressure portion to the low surface pressure portion. In this way, the amount of lithium movement in the surface direction that alleviates the surface pressure distribution increases.

[0045] Furthermore, when the surface pressure distribution is eased and the difference between at least one of the upper and lower surface pressure differences falls below a differential threshold, the controller 10 increases the charging current. That is, when the surface pressure distribution is partially eased and the measured value of the surface pressure distribution of the battery cell 21 is lower than the upper surface pressure, the controller 10 increases the charging current. Then, when charging control continues under the increased charging current state and the measured value of the surface pressure distribution of the battery cell 21 reaches the upper surface pressure, the controller 10 temporarily reduces the charging current to ease the surface pressure distribution and then increases the charging current again (hereinafter, this control is also referred to as high-current control). Figure 4 As shown in graph a of (c), from time t a At time t b During the charging process, the controller 10 performs high-current control. When the maximum surface pressure of the surface pressure distribution of the battery cell 21 reaches the upper limit surface pressure, the controller 10 performs high-current control; conversely, when the minimum surface pressure of the surface pressure distribution of the battery cell 21 reaches the lower limit surface pressure, the controller 10 also performs high-current control. The greater the increase in lithium thickness through charging, the greater the amount of lithium movement. Therefore, as charging continues and the SOC (State of Charge) increases, the surface pressure distribution is more easily mitigated, allowing the battery module 2 to be charged with a higher charging current.

[0046] Through high-current control by controller 10, the surface pressure on the main surface of battery cell 21 becomes... Figure 4 As shown in curve (a) of (b), the maximum surface pressure of the battery cell 21 is maintained at a high value within a range not exceeding the upper limit surface pressure, and the minimum surface pressure of the battery cell 21 is maintained at a low value within a range not lower than the lower limit surface pressure. Furthermore, the charging current becomes... Figure 4 As shown in curve a of (c), the charging current gradually increases. Furthermore, at time t... bWhen the voltage of battery module 2 reaches its upper limit voltage, the controller 10 gradually reduces the current (CV current control) while maintaining the charging voltage of battery module 2 at the upper limit voltage. In this embodiment, battery module 2 is charged by high current control, therefore the charging time is shorter than in the comparative example (see reference). Figure 4 The curve of (a) is shown in graph a). Furthermore, in Figure 4 The characteristics during charging are shown and the effect of shortening charging time is explained. However, the discharge current can also be increased by using the same control logic as high current control on the discharge side.

[0047] Next, refer to Figure 2 and Figure 5 The temperature distribution, charging current, thickness difference, lithium migration, and surface pressure distribution within the battery cell 21 are explained. Furthermore, in the following description, the central portion of the main surface of the battery cell 21 is designated A1, and the end portion is designated A2. During the charging of the battery module 2, the temperature at the central portion A1 of the battery cell 21 rises more easily than the temperature at the end portion A2; therefore, as... Figure 5 As shown in (a), as the charging time progresses, the temperature distribution of the battery cell 21 expands, and the temperature difference increases. The central portion (A1) of the main surface of the battery cell 21 has a higher temperature and a larger charging current compared to the end portion (A2). Figure 5 As shown in (b), the charging current in the central portion (A1) follows the characteristics of curve a, while the charging current in the end portion (A2) follows the characteristics of curve b. In the central portion (A1), the charging current is high, promoting the charging reaction, thus resulting in a thicker lithium deposit than in the end portion (A2). Furthermore, the difference in lithium deposit thickness between the central portion (A1) and the end portion (A2) increases with charging time (see reference). Figure 5 (c) is a curve. Furthermore, in the thicker portion of the battery cell 21 (the central portion (A1)), creep increases as lithium deforms and moves from the central portion (A1) towards the end (A2). Figure 5 As shown in curve (c)b, the amount of lithium movement increases with the passage of charging time. Furthermore, the surface pressure in the central portion (A1) increases... Figure 5 The characteristic shift shown in curve a of (d) indicates that the surface pressure at the end (A2) is... Figure 5 The characteristic shift is shown in curve (b) of (d).

[0048] Thus, during the charging of battery module 2, a temperature distribution is generated within the surface of battery cell 21, forming high-temperature and low-temperature regions. Furthermore, this temperature distribution creates a surface pressure distribution on the main surface of battery cell 21, forming thick and thin regions. In the thicker regions, due to the further application of pressure, lithium wets and spreads along the main surface of battery cell 21. As charging of battery cell 21 progresses, the amount of lithium movement increases; therefore, the higher the state of charge (SOC), the greater the amount of lithium movement, and the more the surface pressure distribution is mitigated. In this embodiment, when the surface pressure distribution is mitigated, the charging current is increased by the amount of mitigation. Therefore, during the charging of battery module 2, it is possible to comply with the upper and lower limits of surface pressure (P). th_H P th_L This shortens charging time at the same time.

[0049] The following describes the battery control method for battery module 2. Figure 6 This is a flowchart illustrating the process of the battery control method of this embodiment. The battery control method of this embodiment is repeatedly executed according to each predetermined cycle during the charging of the battery module 2.

[0050] First, in step S1, the controller 10 acquires the measured value of the surface pressure distribution on the main surface of the battery cell 21 from the surface pressure distribution measuring device 15. In step S2, the controller 10 acquires the SOC, temperature, and degradation state (degree of degradation) of the battery cell 21. The SOC of the battery cell 21 can be calculated, for example, by integrating the current of the battery cell 21. The temperature of the battery cell 21 can be acquired from the temperature sensor 13. The controller 10 can also use a calculation model of the temperature distribution of the battery cell 21 to calculate the temperature distribution on the main surface of the battery cell 21 based on the temperature detected by the temperature sensor 13. The degradation state of the battery cell 21 can be calculated, for example, based on the ratio of the current battery capacity to the initial battery capacity of the battery cell 21. Furthermore, the above-described calculation methods for the SOC and degradation state of the battery cell 21 are merely one example; other methods may also be used.

[0051] In step S3, the controller 10 obtains the measured value of the surface pressure distribution and the upper limit surface pressure (P) of the battery cell. th_H The difference between the upper limit surface pressure (P) and the upper limit surface pressure (P) th_H The upper limit of surface pressure difference is calculated by taking the measured value of surface pressure distribution and the lower limit of surface pressure (P) of the battery cell. th_L The difference between the measured surface pressure distribution and the lower limit surface pressure (P) is: th_LThe lower limit surface pressure difference is calculated using the ratio of the maximum and minimum surface pressure values ​​of the surface pressure distribution. When the maximum and minimum surface pressure values ​​of the surface pressure distribution are measured separately, the controller 10 can also calculate the lower limit surface pressure difference based on the ratio of the maximum surface pressure value to the upper limit surface pressure (P). th_H The difference between the upper limit surface pressure (P) and the upper limit surface pressure (P) th_H The upper limit surface pressure difference is calculated using the ratio of the minimum surface pressure to the lower limit surface pressure (P). th_L The difference between "minimum surface pressure" and "lower limit surface pressure (P)" is: th_L The controller 10 calculates the lower limit surface pressure difference using the upper and lower limit surface pressure differences. Based on these differences, the controller 10 determines the surface pressure request current value (I0). E Specifically, in the differential ("upper limit surface pressure (P)") th_H "" - "Measured value of surface pressure distribution") and the difference ("Measured value of surface pressure distribution" - "Lower limit surface pressure (P)") th_L When the value of the surface pressure request current (I) is greater than 0, the controller 10 increases the surface pressure request current value (I). E On the other hand, in the differential ("upper limit surface pressure (P)") th_H When the measured value of surface pressure distribution is less than 0, or when the difference (measured value of surface pressure distribution - lower limit surface pressure (P)) is less than 0, th_L When the surface pressure is less than 0, the requested current value (I) is reduced. E ). Surface pressure request current value (I) E ) is the maximum current value requested based on the surface pressure, and is the current value determined by high current control.

[0052] The controller 10 can also adjust the upper limit surface pressure (P) based on at least one of the following factors: the state of charge (SOC) of the battery cell 21, temperature, and degradation state. th_H ) and lower limit surface pressure (P) th_L ). Figure 7 (a) and (b) show the upper and lower limits of the surface pressure (P) of the battery cell 21. th_H P th_L A graph showing the characteristics relative to SOC. Figure 7 (c) shows the upper and lower limit surface pressures (P) of the battery cell 21. th_H P th_L A graph showing the characteristics relative to temperature. Furthermore, in Figure 7 In (a) to (c), the solid line represents the characteristics before degradation, and the dashed line represents the characteristics after degradation. The upper and lower limits of surface pressure (P) corresponding to the SOC of the battery cell 21 are also shown. th_H P th_L The characteristics of ) and the upper and lower limits of surface pressure (P) corresponding to temperature.th_H P th_L The characteristics of the battery cell 21 vary depending on the battery materials, etc. The controller 10 is pre-equipped with upper and lower limits for surface pressure (P) to be adjusted based on the characteristics of the battery cell 21 for SOC, temperature, and degradation state. th_H P th_L The calculation model, tables, and other correction indicators are used. For example, as a characteristic of the battery cell 21, there is a battery characteristic such as increasing the amount of lithium movement along the main surface of the battery cell 21 to improve the possibility of short circuit when the SOC is high or the temperature of the battery cell 21 is high. In this case, the controller 10 increases the upper limit of the surface pressure (P) as the SOC or temperature increases. th_H The smaller the value, the more the upper limit of surface pressure (P) is corrected based on SOC or temperature. th_H ) (reference Figure 7 (a) and (c)). Additionally, for example, a characteristic of the battery cell 21 is that, under high SOC conditions, the cell resistance increases due to the contraction of the positive electrode active material. In this case, the controller 10 sets a lower limit for the surface pressure (P) as the SOC increases. th_L The larger the value, the lower limit surface pressure (P) is corrected according to the SOC. th_L ) (reference Figure 7 (a)). Furthermore, in the case of high degradation of the battery cell 21, compared to the case of low degradation, the controller 10 increases the upper limit surface pressure (P). th_H The decrease in pressure and the reduction in the lower limit surface pressure (P) th_L The upper and lower limits of surface pressure (P) are corrected by increasing the value of the pressure. th_H P th_L ).

[0053] Furthermore, the correction direction can be appropriately changed according to the battery materials (positive and negative electrode active materials, etc.) used in the battery cell 21 and the battery structure of the battery cell 21 and battery module 2. For example, such as Figure 7 As shown in (b), controller 10 can also increase the upper limit of surface pressure (P) as the SOC increases. th_H The larger the lower limit surface pressure (P), the greater the surface pressure. th_L The smaller the value, the better the correction of the upper and lower limits of surface pressure (P). th_H P th_L Additionally, the controller 10 can also combine factors such as the SOC, temperature, and degradation state of the battery cell 21 to correct the upper and lower limits of surface pressure (P). th_H P th_L Alternatively, all factors can be used to correct for the upper and lower limits of surface pressure (P). th_H P th_L ).

[0054] In step S4, the controller 10 acquires other control request currents determined based on factors other than the surface pressure of the battery cell 21. These other control request currents include the system request current (I0) determined based on the system request. F ), and the protection request current (I) determined according to the protection request of battery cell 21. G I H The system request current is the maximum current of the system used to charge or discharge battery module 2. The charging system request current is equivalent to the maximum current that can be output from the charging device. The discharging system request current is equivalent to the maximum current determined by the operating state of loads such as motors connected to battery module 2. Protection request current (I...) G The maximum current (I) is determined based on the upper limit temperature of the battery cell 21 to ensure that the temperature of the battery cell 21 does not exceed the upper limit temperature. G Additionally, the protection request current (I) H ) is the maximum current (I) determined by the upper limit voltage of the battery cell to prevent the battery cell 21 from being overcharged or over-discharged. H Furthermore, when the charging voltage of battery module 2 reaches the upper limit voltage, controller 10 switches from high current control to CV current control, but the current value in CV current control only needs to be adjusted to the maximum current (I). H That's all.

[0055] In step S5, the controller 10 requests a current value (I) based on the surface pressure. E ), system current (I) F ) and protection request current (I G I H The lowest current in the parameter is determined as the actual current used for charging and discharging battery module 2, and is also determined as the command current used to set the charging current of battery module 2 as the actual current. That is, controller 10 takes the surface pressure request current value (I0). E ), system current (I) F ) and protection request current (I G I H The low selectivity of the command current is used to determine the command current.

[0056] In step S6, if the command current is zero and the measured value of the surface pressure distribution is less than the predetermined value of the surface pressure distribution, the controller 10 terminates the charging control. Conversely, if the command current is not zero, or if the measured value of the surface pressure distribution is above the predetermined value, the controller 10 sends a control command for the command current (actual current command value) to the charging device and executes charging control from step S1. Furthermore, the predetermined value of the surface pressure distribution used to determine the termination of charging control can be set simply based on the deviation of the measured value of the surface pressure distribution. In the control flow of the above battery control method, even when the command current is zero, charging control continues when the measured value of the surface pressure distribution is above the predetermined value of the surface pressure distribution to mitigate the deviation of the surface pressure and prepare for the next charge / discharge event. Furthermore, the condition for the surface pressure distribution can be omitted in the control flow of step S6.

[0057] As described above, in the battery control system and battery control method of this embodiment, the surface pressure distribution is measured based on the measured value of the surface pressure distribution on the main surface of the battery cell 21. The charging current and / or discharging current of the battery module 2 (solid-state battery) are determined based on the upper limit surface pressure difference and the lower limit difference. The upper limit surface pressure difference is the difference between the measured value of the surface pressure distribution and the upper limit surface pressure of the battery cell 21, and the lower limit difference is the difference between the measured value of the surface pressure distribution and the lower limit surface pressure of the battery cell 21. Therefore, it is possible to ensure that the surface pressure of the battery cell 21 is not lower than the lower limit surface pressure (P). th_L The charging and discharging current of battery module 2 is controlled in a manner that conforms to the upper and lower limits of surface pressure (P). Furthermore, during the charging of battery module 2, the charging and discharging current can be controlled according to the upper and lower limits of surface pressure (P). th_H P th_L This shortens charging time at the same time.

[0058] Furthermore, the battery control system of this embodiment corrects the upper limit surface pressure (P) based on at least one of the following factors: the SOC of the battery cell 21, the temperature of the battery cell 21, and the degree of degradation of the battery cell 21. th_H ) and lower limit surface pressure (P) th_L Therefore, even if the state of the battery cell 21 changes, it can still comply with the upper and lower limits of surface pressure (P). th_H P th_L This shortens charging time at the same time.

[0059] Furthermore, the battery control system in this embodiment will determine the charging and discharging current (equivalent to the surface pressure request current value I) based on the upper limit surface pressure difference and the lower limit side difference. EThe lowest current among the system request current determined by the system request and the protection request current determined by the protection request of the battery cell is set as the actual current for charging and discharging battery module 2. This satisfies the current conditions determined by requests other than surface pressure, while not exceeding the upper and lower limits of surface pressure (P). th_H P th_L This shortens charging time within the range of [missing information].

[0060] Furthermore, in this embodiment, the battery control system reduces the charging / discharging current when the surface pressure difference, which is the smaller of the upper and lower surface pressure differences, reaches a difference threshold. Conversely, if the surface pressure difference becomes greater than the difference threshold after reducing the charging / discharging current, the system increases the charging / discharging current. Therefore, during the charging of battery module 2, it is possible to comply with the upper and lower surface pressure limits (P...). th_H P th_L This shortens charging time at the same time.

[0061] Furthermore, during the charging and discharging of the battery module 2, the battery control system of this embodiment determines the charging and discharging current in such a way that the upper limit surface pressure difference (the difference between the maximum surface pressure and the upper limit surface pressure, which is a surface pressure distribution) is kept below a difference threshold, or the lower limit surface pressure difference (the difference between the minimum surface pressure and the lower limit surface pressure, which is a surface pressure distribution) is kept below a difference threshold. Therefore, during the charging of the battery module 2, it is possible to comply with the upper and lower limit surface pressures (P... th_H P th_L This shortens charging time at the same time.

[0062] Furthermore, in this embodiment, the surface pressure distribution measuring device 15 may not be provided. Instead, the controller 10 measures the surface pressure distribution based on the estimated value of the surface pressure distribution on the main surface of the battery cell 21. That is, the controller 10 may not set the actual value measured by the surface pressure distribution measuring device 15 as the measured value of the surface pressure distribution, but may estimate the surface pressure distribution through calculation processing such as a calculation model, and set the estimated value as the result of the calculation as the measured value of the surface pressure distribution. The method for estimating the surface pressure distribution will be described below.

[0063] The controller 10 calculates an estimated value for the surface pressure distribution based on measured values ​​of the current distribution on the main surface of the battery cell 21, measured values ​​of the temperature distribution on the main surface of the battery cell 21, and the state of charge (SOC) of the battery cell 21. The current distribution can be calculated solely based on the resistance distribution within the battery cell 21. The resistance distribution can be measured using a resistance distribution device such as a shunt resistor. The resistance distribution device is located on the outermost layer of the stacked battery cells 21. During charging and discharging, the controller 10 acquires the detected values ​​of the input or output voltage of the battery module 2 from the voltage sensor 11, and calculates the current distribution on the main surface of the battery cell 21 based on the voltage of the battery module 2 and the resistance distribution measured by the resistance distribution device. Furthermore, the current distribution corresponds to the distribution of lithium deposition.

[0064] The controller 10 acquires the detected temperature from the temperature sensor 13 and calculates the temperature distribution of the battery cell 21 based on a calculation model obtained by modeling the temperature distribution of the battery cell 21 and the detected temperature. Alternatively, the controller 10 can replace the temperature sensor 13 with a temperature distribution measuring device to measure the temperature distribution. The controller 10 calculates the state of charge (SOC) of the battery cell 21 based on the detected voltage from the voltage sensor 11 or the integral value of the charge / discharge current. The controller 10 can infer the surface pressure distribution by calculating the amount of lithium movement along the main surface of the battery cell 21 based on the current distribution, temperature distribution, and SOC. Figure 5 As shown, the amount of lithium migration is correlated with the temperature and current distribution on the main surface of the battery cell 21; the higher the state of charge (SOC), the greater the amount of lithium migration. Furthermore, the surface pressure distribution on the main surface of the battery cell 21 can be calculated based on the amount of lithium migration. Therefore, for example, the calculation formula used to calculate the amount of lithium migration (or surface pressure distribution) can be modeled based on the temperature distribution, current distribution, and SOC, and the controller 10 can infer the surface pressure distribution based on the mathematical formula obtained from the modeling. Thus, the controller 10 can determine the surface pressure distribution based on the inferred value of the surface pressure distribution. This eliminates the need for a surface pressure distribution measuring device 15, achieving low cost.

[0065] The controller 10 can also infer the surface pressure distribution using the following estimation method. The controller 10 can also calculate the current distribution on the main surface of the battery cell 21 based on the measured temperature distribution and the battery resistance characteristics of the battery cell 21, and calculate the estimated value of the surface pressure distribution based on the calculated current distribution, the measured temperature distribution, and the state of charge (SOC) of the battery cell 21. The battery resistance characteristics of the battery cell 21 are represented by a mapping indicating the correlation between battery temperature and resistance (DCR mapping). The controller 10 has a DCR mapping; it only needs to calculate the resistance distribution characteristics relative to the measured temperature distribution by referring to the DCR mapping. Then, the controller 10 calculates the current distribution on the main surface of the battery cell 21 based on the measured temperature distribution and the battery resistance characteristics of the battery cell 21. Furthermore, the controller 10 can infer the surface pressure distribution by calculating the amount of lithium movement along the main surface of the battery cell 21 based on the current distribution, temperature distribution, and SOC. The method for inferring the surface pressure distribution is the same as described above. Therefore, the controller 10 can determine the surface pressure distribution based on the estimated value of the surface pressure distribution. This eliminates the need for a resistance distribution measuring device, thus achieving cost reduction. Furthermore, the controller 10 in this embodiment is equivalent to an example of the "measuring unit" in this invention.

[0066] The controller 10 can also infer the surface pressure distribution using an inference method as follows. The controller 10 can also calculate the heat generation and / or heat dissipation of the battery cell 21 based on the battery resistance characteristics of the battery cell 21, the various battery characteristics determined by the shape and / or material of the battery cell 21, the internal temperature of the battery cell 21, and the ambient temperature. Based on the calculated heat generation and / or heat dissipation, and the state of charge (SOC) of the battery cell, the controller 10 calculates the inferred value of the surface pressure distribution. The various battery characteristics represent the thermal conductivity of the battery cell 21, which depends on the active material, tab material, and shape of the battery cell 21. The internal temperature of the battery cell 21 corresponds to the temperature detected by the temperature sensor 13. The ambient temperature is the temperature surrounding the battery module 2, which can be detected by the sensor. The calculation formula for calculating heat generation and / or heat dissipation is modeled based on the battery resistance characteristics, various battery characteristics, the internal temperature of the battery cell 21, and the ambient temperature. The controller 10 calculates the heat generation and / or heat dissipation based on the mathematical formula obtained from the modeling. Then, the controller 10 calculates the temperature distribution on the main surface of the battery cell 21 based on the calculated heat generation and / or heat dissipation, and calculates the estimated value of the surface pressure distribution based on the current distribution and SOC. Thus, the controller 10 can determine the surface pressure distribution based on the estimated value. This eliminates the need for a temperature distribution measurement device, achieving cost reduction.

[0067] Furthermore, as a variation of this embodiment, the battery control system 1 may also adjust the pressure applied to the battery cell 21 based on the relationship between the upper limit surface pressure difference and the lower limit surface pressure difference during the charging and discharging of the battery module 2, thereby increasing the surface pressure difference and performing high current control. Figure 8 This is a flowchart illustrating the process of the battery control method according to a modified example of this embodiment. The battery control method of the modified example is repeatedly executed according to each predetermined cycle during the charging of battery module 2. In the following description, the control during charging of battery module 2 will be explained, but the control process during charging can also be appropriately applied to the discharging control of battery module 2.

[0068] The control flow up to steps S11-S15 is the same as the control flow of steps S1-S5 described above, so the explanation is omitted. In step S16, the controller 10 calculates the upper limit surface pressure difference and the lower limit surface pressure difference respectively, and determines whether the current can be increased by pressure adjustment based on the magnitude of the difference between the upper limit surface pressure difference and the lower limit surface pressure difference. If the upper limit surface pressure difference and the lower limit surface pressure difference are different, the charging current is determined in a way that matches the one with the smaller difference. In a modified example, if there is a difference between the upper limit surface pressure difference and the lower limit surface pressure difference, the pressure is adjusted to reduce the difference between the upper limit surface pressure difference and the lower limit surface pressure difference. On the other hand, if the difference between the upper limit surface pressure difference and the lower limit surface pressure difference is small, that is, if the upper limit surface pressure difference and the lower limit surface pressure difference are approximately the same size, the increase in current caused by pressure adjustment is small. Therefore, for example, if the difference between the upper limit surface pressure difference and the lower limit surface pressure difference is above a predetermined value, the controller 10 determines that the current can be increased by pressure adjustment, and if the difference between the upper limit surface pressure difference and the lower limit surface pressure difference is less than a predetermined value, the controller 10 determines that the current cannot be increased by pressure adjustment.

[0069] If it is determined that the current can be increased through pressure adjustment, in step S17, the controller 10 determines whether the upper limit surface pressure difference is greater than the lower limit surface pressure difference. If the upper limit surface pressure difference is greater than the lower limit surface pressure difference, in step S18, the controller 10 outputs a command to the pressure application mechanism 16 to increase the pressure applied to the battery cell 21. On the other hand, if the upper limit surface pressure difference is less than the lower limit surface pressure difference, in step S19, the controller 10 outputs a command to the pressure application mechanism 16 to decrease the pressure applied to the battery cell 21. After pressure adjustment, the controller 10 performs charging control from step S11. Then, the controller 10 can further increase the charging and discharging current of the battery cell 21 by executing the control flow of step S13 after pressure adjustment.

[0070] If, in the determination process of step S16, it is determined that the current cannot be increased by adjusting the pressure, the controller 10 executes the control flow of step S20. The control flow of step S20 is the same as the control flow of step S6 described above, so its explanation is omitted.

[0071] That is, in the modified embodiment of this invention, the battery control system 1 increases the pressure applied to the battery cell 21 when the upper surface pressure difference is greater than the lower surface pressure difference, and decreases the pressure applied to the battery cell 21 when the upper surface pressure difference is less than the lower surface pressure difference. This alleviates the limitations on charging and discharging required by the upper and lower surface pressure limits and shortens the charging time.

[0072] Furthermore, as a variation of this embodiment, the battery control system 1 can also adjust the temperature of the battery cell 21 based on the temperature distribution on the main surface of the battery cell 21 during the charging and discharging of the battery module 2, and perform high current control. Figure 9 This is a flowchart illustrating the process of the battery control method according to a modified example of this embodiment. The battery control method of the modified example is repeatedly executed in each predetermined cycle during the charging of the battery module 2. Furthermore, the battery control system 1 includes a temperature regulator for cooling the battery cells 21. The temperature regulator can cool the interior of the battery cell 21 and the tabs of the battery cell 21 separately. For example, if the internal temperature of the battery cell 21 is high, the cooling amount inside the battery cell 21 (especially the central portion) can be increased, while the cooling amount of the battery cell 21's tabs can be decreased. On the other hand, if the temperature near the tabs of the battery cell 21 is high, the cooling amount inside the battery cell 21 (especially the central portion) can be decreased, while the cooling amount of the battery cell 21's tabs can be increased. In addition, the temperature regulator is equivalent to a "temperature adjustment unit" for adjusting the temperature of the battery cells 21.

[0073] Figure 9 This is a flowchart illustrating the process of the battery control method according to a modified example of this embodiment. The battery control method of the modified example is repeatedly executed according to each predetermined cycle during the charging of battery module 2. In the following description, the control during charging of battery module 2 will be explained, but the control process during charging can also be appropriately applied to the discharging control of battery module 2.

[0074] The control flow up to steps S21-S25 is the same as the control flow up to steps S1-S5 described above, so the explanation is omitted. In step S26, the controller 10 determines whether the current can be increased by temperature adjustment based on the relationship between the upper limit temperature protection current determined by the upper limit temperature of the battery cell and the charge / discharge current determined by the upper limit surface pressure difference and the lower limit side difference. The upper limit temperature protection current is equivalent to the maximum current determined by the upper limit temperature of the battery cell 21 (protection request current: I).G The charging and discharging current, determined by the upper and lower limit surface pressure differences, is equivalent to the surface pressure request current value (I). E If the upper temperature protection current, determined by the upper limit temperature of the battery cell 21, is higher than the charge / discharge current, determined by the upper surface pressure difference and the lower side difference, the controller 10 determines that the current can be increased by temperature adjustment. If the upper temperature protection current, determined by the upper limit temperature of the battery cell, is lower than the charge / discharge current, determined by the upper surface pressure difference and the lower side difference, the controller 10 determines that the current cannot be increased by temperature adjustment.

[0075] If it is determined that the current can be increased by adjusting the pressure, in step S27, the controller 10 outputs a command to the temperature controller to adjust the temperature of the battery cell 21. Specifically, when the temperature is highest in the center of the battery cell, the controller 10 outputs a control command to the temperature controller, increasing the internal cooling of the battery cell 21. Additionally, when the temperature is highest near the tabs of the battery cell, the controller 10 outputs a control command to the temperature controller, increasing the cooling near the tabs of the battery cell 21. After temperature adjustment, the controller 10 performs charging control from step S21. By adjusting the temperature of the battery cell 21, the upper limit temperature protection current, determined by the upper limit temperature of the battery cell 21, increases.

[0076] If, in the determination process of step S26, it is determined that the current cannot be increased by adjusting the temperature, the controller 10 executes the control flow of step S28. The control flow of step S28 is the same as the control flow of step S6 described above, so its explanation is omitted.

[0077] That is, in the modified embodiment of this invention, when the upper limit temperature protection current determined by the upper limit temperature of the battery cell 21 is higher than the charging and discharging current determined by the upper limit surface pressure difference and the lower limit surface pressure difference, the battery control system 1 controls the temperature regulator to reduce the temperature difference of the temperature distribution on the main surface of the battery cell 21. As a result, the charging time can be shortened.

[0078] Explanation of reference numerals in the attached figures

[0079] 1: Battery Control System

[0080] 10: Controller

[0081] 11: Voltage sensor

[0082] 12: Current sensor

[0083] 13: Temperature sensor

[0084] 14: DC-DC converter

[0085] 15: Surface pressure distribution measuring device

[0086] 16: Pressure application mechanism

[0087] 2: Battery Module

[0088] 21: Battery cell.

Claims

1. A battery control system for controlling a solid-state battery comprising a single cell, the single cell having a solid electrolyte and a lithium-containing negative electrode, the battery control system comprising: The measuring unit measures the surface pressure distribution based on measured or estimated values ​​of the surface pressure distribution on the main surface of the battery cell; and The control unit controls either the charging current or the discharging current of the solid-state battery, i.e., the charging and discharging current. in, The control unit determines the charging and discharging current based on the upper limit surface pressure difference and the lower limit surface pressure difference. The upper limit surface pressure difference is the difference between the measured value of the surface pressure distribution determined by the measuring unit and the upper limit surface pressure of the battery cell. The lower limit surface pressure difference is the difference between the measured value of the surface pressure distribution determined by the measuring unit and the lower limit surface pressure of the battery cell.

2. The battery control system according to claim 1, wherein, The measurement unit calculates the estimated value based on the measured values ​​of the current distribution on the main surface of the battery cell, the measured values ​​of the temperature distribution on the main surface of the battery cell, and the state of charge (SOC) of the battery cell.

3. The battery control system according to claim 1 or 2, wherein, The measuring unit calculates the current distribution on the main surface of the battery cell based on the measured temperature distribution and the battery resistance characteristics of the battery cell. The measurement unit calculates the estimated value based on the calculated value of the current distribution, the measured value of the temperature distribution, and the state of charge (SOC) of the battery cell.

4. The battery control system according to any one of claims 1 to 3, wherein, The measuring unit calculates the heat generation and / or heat dissipation of the battery cell based on the battery resistance characteristics, various battery characteristics determined by the shape and / or material of the battery cell, the internal temperature of the battery cell, and the ambient temperature. The measuring unit calculates the estimated value based on the calculated heat generation and / or heat dissipation, and the state of charge (SOC) of the battery cell.

5. The battery control system according to any one of claims 1 to 4, wherein, The control unit corrects the upper limit surface pressure and the lower limit surface pressure based on at least one of the following factors: the state of charge (SOC) of the battery cell, the temperature of the battery cell, and the degree of degradation of the battery cell.

6. The battery control system according to any one of claims 1 to 5, wherein, The control unit sets the lowest current among the charge / discharge current determined by the upper limit surface pressure difference and the lower limit surface pressure difference, the system request current determined by the system request, and the protection request current determined by the protection request of the battery cell as the actual current for charging and discharging the solid-state battery.

7. The battery control system according to any one of claims 1 to 6, wherein, It also includes a pressure application unit that applies pressure to the solid-state battery. The measuring unit measures the maximum and minimum surface pressure values ​​of the surface pressure distribution, respectively. If the upper limit surface pressure difference (which is the difference between the maximum surface pressure and the upper limit surface pressure of the surface pressure distribution) is greater than the lower limit surface pressure difference (which is the difference between the minimum surface pressure and the lower limit surface pressure of the surface pressure distribution), the control unit increases the pressure applied to the battery cell. When the upper limit surface pressure difference is less than the lower limit surface pressure difference, the control unit reduces the pressure applied to the battery cell.

8. The battery control system according to any one of claims 1 to 5, wherein, It also includes a temperature adjustment unit, which adjusts the temperature of the individual battery cells. When the upper limit temperature protection current, determined based on the upper limit temperature of the battery cell, is higher than the charge / discharge current, determined based on the upper limit surface pressure difference and the lower limit surface pressure difference, the control unit controls the temperature adjustment unit to reduce the temperature difference of the temperature distribution on the main surface of the battery cell.

9. The battery control system according to any one of claims 1 to 8, wherein, If the surface pressure difference, which is the smaller of the upper and lower limit surface pressure differences, reaches a difference threshold, the control unit reduces the charging and discharging current. If the surface pressure difference becomes greater than the difference threshold after the charging / discharging current is reduced, the control unit increases the charging / discharging current.

10. The battery control system according to any one of claims 1 to 9, wherein, The control unit determines the charging and discharging current in such a way that the upper limit surface pressure difference, which is the difference between the maximum surface pressure of the surface pressure distribution and the upper limit surface pressure, is kept below a difference threshold, or the lower limit surface pressure difference, which is the difference between the minimum surface pressure of the surface pressure distribution and the lower limit surface pressure, is kept below the difference threshold.

11. A battery control method for controlling a solid-state battery comprising a single battery cell, the single battery cell having a solid electrolyte and a lithium-containing negative electrode, the battery control method comprising the following processes: The surface pressure distribution is determined based on measured or estimated values ​​of the surface pressure distribution on the main surface of the battery cell; and The charging current and / or discharging current of the solid-state battery are determined based on the upper limit surface pressure difference and the lower limit side difference. The upper limit surface pressure difference is the difference between the measured value of the surface pressure distribution and the upper limit surface pressure of the battery cell. The lower limit side difference is the difference between the measured value of the surface pressure distribution and the lower limit surface pressure of the battery cell.

Images