Battery cell module, battery cell restraining method, battery pack and vehicle

Abstract

The invention provides a battery cell module, a battery cell restraining method, a battery pack and a vehicle, the battery cell module comprises a restraining battery cell unit and a driving unit, when a battery cell in the restraining battery cell unit is in a charging state, the driving unit applies a first restraining force to the restraining battery cell unit, and when the battery cell in the restraining battery cell unit is in a discharging state, the driving unit applies a second restraining force to the restraining battery cell unit. And the driving unit applies a second restraining force to the battery cell restraining unit, so that different requirements of the battery cell on the restraining force in the charging process and the discharging process are met, the upsetting-tearing problem caused by too large restraining force in the charging process of the battery cell is avoided, the capacity retention ratio and coulombic efficiency in the charging and discharging process are improved, and short circuit is avoided.

Description

Technical Field

[0001] This application relates to the field of batteries, and more particularly to a cell module, a cell restraint method, a battery pack, and a vehicle. Background Technology

[0002] All-solid-state batteries require a certain amount of restraint force to be applied to both sides of the cell to maintain physical contact between the solids.

[0003] Currently, the constraint method used for all-solid-state battery cells is a fixed-gap method, which fixes the battery cell within a certain gap throughout its entire life cycle in order to apply a target constraint force to the battery cell.

[0004] However, during its lifespan, the battery cell is prone to "upsetting-tearing" at the edges due to repeated expansion and contraction, which ultimately leads to low capacity retention, low coulombic efficiency, and micro-short circuits. Summary of the Invention

[0005] This application provides a cell module, a cell restraint method, a battery pack, and a vehicle to solve the problems of low capacity retention, low coulombic efficiency, and micro-short circuits.

[0006] In a first aspect, this application provides a battery cell module, the battery cell module comprising:

[0007] The battery cell unit and drive unit are constrained;

[0008] The drive unit is configured to apply a first restraining force to the restrained battery cell unit when the battery cell in the restrained battery cell unit is in a charging state, and to apply a second restraining force to the restrained battery cell unit when the battery cell in the restrained battery cell unit is in a discharging state.

[0009] In some embodiments, the number of the restrained battery cells is multiple, and the multiple restrained battery cells are stacked in a first direction.

[0010] In some embodiments, the battery cell module further includes:

[0011] Multiple elastic units, each of which is disposed between two adjacent restraint cell units.

[0012] In some embodiments, the restrained cell unit includes a cell and two restraint plates disposed on both sides of the cell in a first direction.

[0013] In some embodiments, the elastic element includes at least one spring.

[0014] In some embodiments, the drive unit is configured to,

[0015] When the battery cell is in a charging state, the driving unit applies a first restraining force to the restraining plate to drive the restraining plate to squeeze the battery cell;

[0016] When the battery cell is in a discharging state, the driving unit applies a second restraining force to the restraining plate to drive the restraining plate to squeeze the battery cell.

[0017] In some embodiments, the drive unit is configured to,

[0018] When the battery cell in the restraint cell unit is in a charging state, the first restraint force is reduced linearly.

[0019] In some embodiments, the reduction is less than or equal to 10% to 20% of the first restraint force.

[0020] In some embodiments, when the battery cell in the restraint cell unit is in a discharged state, the second restraint force is increased linearly.

[0021] In some embodiments, the increase is less than or equal to 2% to 5% of the second restraining force.

[0022] In some embodiments, the drive unit is configured to,

[0023] The battery cell in the restraint battery cell unit is charged from zero charge to a preset charge, thereby linearly reducing the first restraint force;

[0024] The driving unit applies a reduced first restraining force to the restrained battery cell until the battery cell is fully charged.

[0025] In some embodiments, the drive unit is configured to,

[0026] The second restraint force increases linearly as the battery cell of the restraint cell unit discharges from full charge to a preset charge level.

[0027] The driving unit applies an increased second restraining force to the restrained cell unit until the cell discharges to zero charge.

[0028] In some embodiments, the drive unit is configured to,

[0029] When the constrained battery cell unit is within a first temperature range, if the battery cell in the constrained battery cell unit is in a charging state, a first constraining force is applied to the constrained battery cell unit; if the battery cell in the constrained battery cell unit is in a discharging state, a second constraining force is applied to the constrained battery cell unit.

[0030] In some embodiments, the first restraining force ranges from 0.1 MPa to 5 MPa, and the second restraining force ranges from 5 MPa to 20 MPa.

[0031] In some embodiments, when the constrained cell unit is within a second temperature range, the drive unit is configured to,

[0032] If the battery cell in the restraint battery cell unit is in a charging state, increase the first restraint force;

[0033] If the battery cell in the restraint cell unit is in a discharged state, the second restraint force is increased.

[0034] In some embodiments, the second temperature range is -30°C to 45°C.

[0035] In some embodiments, when the constrained cell unit is within a third temperature range, the drive unit is configured to,

[0036] If the battery cell in the restraint cell unit is in a charging state, reduce the first restraint force;

[0037] If the battery cell in the restraint cell unit is in a discharged state, the second restraint force is reduced.

[0038] In some embodiments, the third temperature range is 60°C to 80°C.

[0039] In some embodiments, the battery cell module further includes:

[0040] The sensor is disposed on the confined cell unit;

[0041] When the driving unit applies a restraining force to the restrained cell unit, the sensor feeds back the change in restraining force to the driving unit.

[0042] The drive unit controls the restraint force applied to the restrained cell unit based on the restraint force change.

[0043] Secondly, this application provides a cell restraint method, the method being used in the aforementioned cell module, the method comprising:

[0044] When the battery cell in the restrained battery cell unit is in a charging state, a first restraining force is applied to the restrained battery cell unit;

[0045] When the battery cell in the restrained battery cell unit is in a discharging state, a second restraining force is applied to the restrained battery cell unit.

[0046] In some embodiments, when the battery cell in the restrained battery cell unit is in a charging state, applying a first restraining force to the restrained battery cell unit includes:

[0047] When the battery cell in the restrained battery cell unit is in a charging state, the first restraining force applied to the restrained battery cell unit is linearly reduced.

[0048] In some embodiments, when the battery cell in the restrained battery cell unit is in a discharged state, applying a second restraining force to the restrained battery cell unit includes:

[0049] When the battery cell in the constrained battery cell unit is in a discharged state, the second constraining force applied to the constrained battery cell unit is increased linearly.

[0050] In some embodiments, when the battery cell in the restrained battery cell unit is in a charging state, applying a first restraining force to the restrained battery cell unit includes:

[0051] The battery cell in the restraint battery cell unit is charged from zero charge to a preset charge, thereby linearly reducing the first restraint force;

[0052] A reduced first restraint force is applied to the cell restraint unit until the cell is fully charged.

[0053] In some embodiments, when the battery cell in the restrained battery cell unit is in a discharged state, applying a second restraining force to the restrained battery cell unit includes:

[0054] The second restraint force increases linearly as the battery cell of the restraint cell unit discharges from full charge to a preset charge level.

[0055] An increased second restraint force is applied to the restrained cell unit until the cell discharges to zero charge.

[0056] In some embodiments, when the cells in the restrained battery cell unit are in a charging state, a first restraining force is applied to the restrained battery cell unit; when the cells in the restrained battery cell unit are in a discharging state, a second restraining force is applied to the restrained battery cell unit, including:

[0057] When the confined cell unit is within the first temperature range,

[0058] If the battery cell in the restrained battery cell unit is in a charging state, a first restraining force is applied to the restrained battery cell unit;

[0059] If the battery cell in the restrained battery cell unit is in a discharged state, a second restraining force is applied to the restrained battery cell unit.

[0060] In some embodiments, when the cells in the restrained battery cell unit are in a charging state, a first restraining force is applied to the restrained battery cell unit; when the cells in the restrained battery cell unit are in a discharging state, a second restraining force is applied to the restrained battery cell unit, including:

[0061] When the confined cell unit is within the second temperature range,

[0062] If the battery cell in the restraint battery cell unit is in a charging state, increase the first restraint force;

[0063] If the battery cell in the restraint cell unit is in a charging state, the second restraint force is increased.

[0064] In some embodiments, when the cells in the restrained battery cell unit are in a charging state, a first restraining force is applied to the restrained battery cell unit; when the cells in the restrained battery cell unit are in a discharging state, a second restraining force is applied to the restrained battery cell unit, including:

[0065] When the confined cell unit is within the third temperature range,

[0066] If the battery cell in the restraint cell unit is in a charging state, reduce the first restraint force;

[0067] If the battery cell in the restraint cell unit is in a discharged state, the second restraint force is reduced.

[0068] Thirdly, this application provides a battery pack including the aforementioned cell module.

[0069] Fourthly, this application provides a vehicle including the battery pack described above.

[0070] The battery cell module, battery restraint method, battery pack, and vehicle provided in this application include a restraint cell unit and a drive unit. When the battery cell in the restraint cell unit is in a charging state, the drive unit applies a first restraint force to the restraint cell unit. When the battery cell in the restraint cell unit is in a discharging state, the drive unit applies a second restraint force to the restraint cell unit. This satisfies the different restraint force requirements of the battery cell during the charging and discharging processes. During the charging process, the "upsetting-tearing" problem will not occur due to excessive restraint force, thereby improving the capacity retention rate and coulombic efficiency during the charging and discharging process and avoiding short circuits. Attached Figure Description

[0071] To more clearly illustrate the technical solutions in this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0072] Figure 1 This is a schematic diagram of the structure of a battery cell module provided in one embodiment of this application;

[0073] Figure 2This is a schematic diagram of another battery cell module provided in an embodiment of this application;

[0074] Figure 3 This is a schematic flowchart of a cell restraint method provided in an embodiment of this application. Detailed Implementation

[0075] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0076] All-solid-state batteries are a new type of battery that uses a solid electrolyte to replace the electrolyte and separator found in traditional liquid batteries. All-solid-state batteries primarily achieve the transport of active lithium ions and electrochemical reactions through the solid electrolyte and various types of solid-solid interfaces.

[0077] Compared to traditional liquid batteries, all-solid-state batteries require a certain amount of restraint force to be applied to both sides of the cell to maintain physical contact between solids and to regulate the compression state of electron clouds at the microscopic solid interface.

[0078] Currently, the commonly used restraint method for all-solid-state battery cells is the fixed-gap type. When the battery cell is in the 0SOC state (0% charge), it is fixed within a certain gap throughout the battery cell's entire life cycle by mechanical locking to apply a target restraint force to the battery cell. For example, the battery cell is fixed within a certain gap by two metal plates with a fixed distance between them.

[0079] When the battery cell expands during charging, it exerts a force on the restraint device due to the constraint. The restraint device then applies a reaction force to the battery cell to achieve the purpose of restraining the battery cell.

[0080] However, since all-solid-state cells generally use high-capacity anode materials to achieve higher energy density, high-capacity anode materials are generally accompanied by drastic volume changes during the delithiation and lithium insertion processes.

[0081] Conventional fixed-gap restraint methods are prone to significant expansion force changes during battery charging and discharging due to the expansion and contraction of the negative electrode. The force exerted on the restraint device by the cell also reacts on itself, generating a stress perpendicular to the large surface area of ​​the cell.

[0082] However, battery cells are typically unconstrained in the direction parallel to their large surface area. Therefore, during their lifespan, repeated expansion and contraction can easily lead to "upsetting-tearing" at the cell edges, ultimately resulting in low capacity retention, low coulombic efficiency, and micro-short circuits.

[0083] "Upsetting" refers to the increase in volume of the battery cell during charging due to increased internal pressure or material expansion; "tearing" refers to the cracking or breakage of the internal materials of the battery cell (such as electrodes and separators) under mechanical stress.

[0084] Capacity retention rate is the percentage of a battery's capacity retained after a certain number of charge-discharge cycles, reflecting the performance degradation of the battery over long-term use. Coulomb efficiency is the ratio of the amount of electricity released during discharge to the amount of electricity input during charging, measuring the energy conversion efficiency of the battery during charge and discharge.

[0085] To address this, this application provides a battery cell module that adapts to the expansion effect during charging and the contraction effect during discharging by changing the magnitude of the restraint force. This satisfies the different restraint force requirements of the battery cell during charging and discharging, and prevents the "upsetting-tearing" problem caused by excessive restraint force during battery cell charging. It also improves the capacity retention rate and coulombic efficiency during charging and discharging, and avoids short circuits.

[0086] The technical solutions of this application will be described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0087] Figure 1 A schematic diagram of the structure of the battery cell module provided in the embodiment of this application is shown, as follows: Figure 1 As shown, the battery cell module provided in this application embodiment includes:

[0088] The battery cell unit 10 and the drive unit 20 are constrained.

[0089] The drive unit 20 is configured to apply a first restraining force to the restraining cell unit 10 when the cell 201 in the restraining cell unit 10 is in a charging state, and to apply a second restraining force to the restraining cell unit 10 when the cell 201 in the restraining cell unit 10 is in a discharging state.

[0090] In this embodiment, the driving unit applies different restraining forces to the battery cell when the cell is in different states, thereby satisfying the different restraining force requirements of the battery cell during the charging and discharging processes. For example, the first restraining force applied when the battery cell is in the charging state is less than the second restraining force applied when the battery cell is in the discharging state.

[0091] For example, by utilizing the characteristic that the battery cell can exert a restraining force on itself during the charging expansion process, the external restraining force on the battery cell during charging can be reduced, thus preventing the "upsetting-tearing" phenomenon caused by excessive restraining force. During the battery cell discharge process, a larger restraining force is applied to the battery cell to maintain good physical contact between the negative electrode and the electrolyte layer, thereby maximizing the coulombic efficiency of the battery cell in a single charge-discharge cycle.

[0092] The first restraint force can range from 0.1 MPa to 5 MPa to meet the restraint requirements of the battery cell during the charging expansion process, and the second restraint force can range from 5 MPa to 20 MPa to meet the restraint requirements of the battery cell during the discharging contraction process.

[0093] In practical applications, battery cells include, but are not limited to, cells of one or more of the following types of batteries: sulfide all-solid-state batteries, halide all-solid-state batteries, polymer all-solid-state batteries, organic composite all-solid-state batteries, and inorganic composite all-solid-state batteries.

[0094] In some embodiments, such as Figure 2 As shown, there can be multiple confined cell units 20, and multiple confined cell units 20 are stacked in the first direction, thereby increasing the battery capacity.

[0095] Accordingly, the driving unit can apply a first restraining force to the top restraining cell unit when the cell is in a charging state, and apply a second restraining force to the top restraining cell unit when the cell is in a discharging state. It should be noted that the restraining force can be transmitted between the restraining cell units to achieve the restraining effect on the cells in each restraining cell unit. The top unit can be the first restraining cell unit in the stacking direction.

[0096] In some examples, considering the differences in State of Charge (SOC) and State of Health (SOH) among different battery cells during charging and discharging, differences in expansion or contraction may occur between the cells. In such cases, applying the same restraint force to multiple restrained battery cell units may further exacerbate the uneven distribution of remaining charge or state of health.

[0097] Therefore, as Figure 2 As shown, the battery cell module also includes multiple elastic units 203. At least one corresponding elastic unit 203 is provided between two adjacent restraint battery cell units 20. The elastic unit 203 can not only transmit restraint force between restraint battery cell units 20, but also cope with and regulate the distribution of restraint force to a certain extent, and correct the different expansion and contraction of different battery cells 201 in real time, so as to ensure that the battery cell 201 is subjected to appropriate stress within a certain range and extend the life cycle of the battery cell 201.

[0098] The elastic unit may include at least one spring, for example, it may include 4 to 12 springs. The restraining force is related to the Hooke's coefficient of the spring, so the type of spring can be determined based on the restraining force.

[0099] Specifically, F*0.01 = -k*h*n, where F is the restraint force, k is the Hooke's coefficient of the spring, h is the thickness of the battery cell expansion, and n is the number of springs. It should be noted that a negative F value indicates that the springs are in a compressed state.

[0100] For example, the adjustable expansion force range of the elastic element can be 0.01 MPa to 2 MPa, within which the difference in expansion force required by different restrained cell elements can usually be adjusted. Correspondingly, the Hooke's constant of the spring can be 150 kgN / mm to 1210 kgN / mm.

[0101] In some embodiments, such as Figure 1 and Figure 2 As shown, the confined cell unit 20 includes a cell 201 and two confining plates 202. The two confining plates 202 are disposed on both sides of the cell 201 in a first direction, thereby maintaining physical contact between the solids. For example, the first direction is perpendicular to the large surface of the cell.

[0102] Accordingly, the drive unit 20 can apply a first restraining force to the restraining plate 202 when the cell 201 is in a charging state, so as to drive the restraining plate 202 to squeeze the cell 201; the drive unit 20 can also apply a second restraining force to the restraining plate 202 when the cell 201 is in a discharging state, so as to drive the restraining plate 202 to squeeze the cell 201. In this way, the requirements of the cell for different restraining forces during the charging and discharging processes are met, thereby improving the capacity retention rate and coulombic efficiency of the cell.

[0103] For example, the drive unit can apply a first restraining force to the top restraining plate when the battery cell is in a charging state, and apply a second restraining force to the top restraining plate when the battery cell is in a discharging state. The top restraining plate can be the first restraining plate in a first direction. When there are multiple restrained battery cell units, either the first restraining force or the second restraining force can be applied to the top restraining plate of the top restrained battery cell unit.

[0104] The restraint plate may include a Young's modulus greater than or equal to 0.7*10. 11 N / m 2 The metal plate is designed to prevent excessive deformation of the battery cell when restraint force is applied and during charging and discharging, thus avoiding damage to the edges of the battery cell.

[0105] The metal sheet may include at least one of aluminum, stainless steel, copper, and brass. For example, stainless steel, where the Young's modulus is 2 × 10⁻⁶. 11 N / m2 The resistance is relatively high, ensuring that the battery cell unit does not undergo excessive deformation when restrained by a restraining force or during charging and discharging.

[0106] The metal plate may also include a shape memory alloy plate, which can automatically adjust the constraint force on the battery cell according to different states of the battery cell, further simplifying the design of the battery cell module.

[0107] In some embodiments, the drive unit includes a motor capable of applying a first restraining force or a second restraining force to the restraining cell unit. The restraining force applied by the motor can range from 0.05 MPa to 50 MPa, for example, a restraining force of 0.1 MPa to 20 MPa can be applied depending on the actual situation of the cell.

[0108] For example, the stepping adjustment range of the motor can be 10μm to 200μm to achieve precise control of the restraint force.

[0109] In some examples, sensors, such as pressure sensors, are placed on the restrained cell unit. When the drive unit applies a restraining force to the restrained cell unit, the sensor can feed back the change in restraining force to the drive unit, so that the drive unit can control the restraining force applied to the restrained cell unit based on the change in restraining force, thereby achieving the purpose of real-time regulation of the restraining force applied by the drive unit.

[0110] For example, the pressure resolution of the sensor can be 0.001 MPa to 0.01 MPa to improve the sensor's detection accuracy.

[0111] In some embodiments, the drive unit can apply a first restraining force to the battery cell unit throughout the entire charging process. For example, when the battery cell is at 0SOC (0% remaining charge), the drive unit applies a restraining force of 2.5MPa to the battery cell unit and then charges it to 100SOC (100% charge) at a current rate of 0.33C, or it can charge it to other charge levels.

[0112] The drive unit can apply a second restraining force to the battery cell throughout the entire discharge process. For example, when the battery cell is at 100% SOC, the drive unit applies a restraining force of 20 MPa to the battery cell, and then discharges under the control of the 20 MPa restraining force, which can discharge to 0% SOC or to other charges.

[0113] In other embodiments, considering that the degree of expansion of the battery cell varies at different stages of charging—for example, the expansion is greater at the initial stage of charging and less at the end of charging—the driving unit can reduce the first restraint force applied to the battery cell during charging to accommodate the cell's expansion. Specifically, the first restraint force can be linearly reduced during charging.

[0114] Accordingly, the rate of decrease of the first restraint force can be calculated using the following formula:

[0115] V1 = (F2 - F1) / (SOC2 - SOC1);

[0116] Where V1 represents the rate of decrease of the first restraint force, F2 represents the first restraint force at the end of charging, F1 represents the first restraint force at the beginning of charging, SOC1 represents the remaining charge at the beginning of charging, and SOC2 represents the remaining charge at the end of charging.

[0117] For example, during the linear reduction of the first restraint force, the reduction amount can be less than or equal to 10% to 20% of the first restraint force, thus meeting the restraint force requirements of the battery cell during the charging process.

[0118] Considering that the degree of shrinkage of the battery cell varies at different stages of discharge—for example, the shrinkage is greater at the initial stage of discharge and less at the end—the driving unit can increase the second restraint force applied to the battery cell during discharge to accommodate its shrinkage. Specifically, the second restraint force can be linearly increased during charging.

[0119] Accordingly, the rate of increase of the second restraint force can be calculated using the following formula:

[0120] V2 = (F4 - F3) / (SOC4 - SOC3);

[0121] Where V2 represents the rate of increase of the second restraint force, F4 represents the second restraint force at the end of the discharge, F3 represents the first restraint force at the beginning of the discharge, SOC4 represents the remaining charge at the beginning of the discharge, and SOC3 represents the remaining charge at the end of the discharge.

[0122] For example, during the linear increase of the second restraint force, the increase is less than or equal to 2% to 5% of the second restraint force, which meets the restraint force requirements of the cell during the discharge process.

[0123] In some examples, the expansion is considered to be large in the initial stage of charging and small in the final stage of charging. For example, the initial stage of charging may include charging from zero power to half power, and the final stage of charging may include charging from 80% power to full power.

[0124] Therefore, the drive unit can linearly reduce the first restraint force when the battery cell is charged from zero to a preset charge, and then fix the first restraint force applied to the battery cell when it continues to charge from the preset charge to full charge. That is, the reduced first restraint force is applied to the restraint battery cell unit, thereby reducing the change of restraint force during the charging stage and simplifying the operation of the drive unit.

[0125] Considering that the degree of contraction is large in the initial stage of discharge and small in the stage when the discharge is about to end, for example, the initial stage of discharge may include discharging from full charge to half charge, and the stage when the discharge is about to end may include discharging from 20% charge to zero charge.

[0126] Therefore, the drive unit can linearly increase the second restraint force as the battery cell discharges from a full charge to a preset charge level. Then, as the battery continues to discharge from the preset charge level until the charge reaches zero, the second restraint force applied to the battery cell is fixed, i.e., the increased second restraint force is applied to the restraining battery cell unit. This reduces the variation in restraint force during the discharge phase and simplifies the operation of the drive unit. The preset charge level can be, for example, 50% charge level, or any other charge level.

[0127] In some embodiments, considering that temperature affects the expansion and contraction of the battery cell, when the battery cell unit is within a first temperature range, if the battery cell in the battery cell unit is in a charging state, a first restraining force is applied to the battery cell unit; if the battery cell in the battery cell unit is in a discharging state, a second restraining force is applied to the battery cell unit. For example, the first temperature range can be 45°C to 60°C.

[0128] In some examples, when the cell temperature is too low, the electrode material inside the cell is prone to thermal contraction, causing changes in the internal pressure distribution and consequently altering the required restraint force. Therefore, when the cell is restrained within a second temperature range, the restraint force is increased upwards. If the cell is charging, the drive unit increases the first restraint force; if the cell is discharging, the drive unit increases the second restraint force. For example, the second temperature range can be -30°C to 45°C.

[0129] For example, the increased first restraint force ranges from 1 MPa to 10 MPa to meet the restraint force requirements during cell charging when the cell temperature is low. The increased second restraint force ranges from 10 MPa to 25 MPa to meet the restraint force requirements during cell discharging when the cell temperature is low.

[0130] When the cell temperature is too high, the electrode material inside the cell is prone to thermal expansion, which alters the internal pressure distribution and consequently changes the required restraint force. Therefore, when the cell is restrained within a third temperature range, the restraint force is downwardly corrected. If the cell is charging, the drive unit reduces the first restraint force; if the cell is discharging, the drive unit reduces the second restraint force. For example, the third temperature range can be 60℃ to 80℃.

[0131] For example, the reduced first restraint force can be in the range of 0.05MPa to 2.5MPa, so as to meet the restraint force requirements during the charging process of the battery cell when the cell temperature is high. The reduced second restraint force can be in the range of 2.5MPa to 15MPa, so as to meet the restraint force requirements during the discharging process of the battery cell when the cell temperature is high.

[0132] To further verify the solution of the embodiments of this application, the following test was conducted using a single battery cell:

[0133] Example 1

[0134] At 45℃, a single cell, initially at 0SOC (0% charge), is charged to 100SOC (100% charge) after being subjected to a 2.5MPa restraint force via a motor drive. During discharge, it is discharged to 0SOC at a 0.33C current rate, maintaining the 2.5MPa restraint force initially. As the SOC decreases to 0SOC, the restraint force gradually increases to 20MPa, with the rate of increase linearly increasing with decreasing SOC (0.175MPa / SOC%). Under these restraint conditions and charge / discharge scheme, the cell's charge-discharge cycle performance is tested up to 200 times, recording the capacity retention and coulombic efficiency changes for each test. The 0.33C current rating means that the current is 0.33 times the rated capacity of the battery. For example, for a battery with a capacity of 3000mAh, the current at 0.33C is 990mA.

[0135] Example 2

[0136] At 45°C, a single cell is charged at 3C current rate with a 5MPa restraint force applied by a motor at 0SOC to the cell's upper limit cutoff voltage. During charging, the motor gradually reduces the restraint force to 2.5MPa as the SOC increases, at a rate of 0.25MPa / 10SOC%. During discharge, the cell is discharged at 1C current rate to 0SOC. Initially, the restraint force remains at 2.5MPa, the same as in the fully charged state. As the SOC decreases to 50SOC (50% charge), the restraint force gradually increases to 20MPa and remains constant. The rate of increase in restraint force increases linearly with decreasing SOC, at 35MPa / SOC%. Under these restraint conditions and charge / discharge scheme, the cell's charge-discharge cycle performance is tested. The number of tests can be up to 200, and the capacity retention and coulombic efficiency changes are recorded for each test.

[0137] Example 3

[0138] The difference from Example 1 is that the cell operating temperature is 80°C. The cell operating temperature in Example 1 is 45°C. All other conditions are the same as in Example 1.

[0139] Example 4

[0140] The difference from Example 1 is that the cell operating temperature is -30°C. The cell operating temperature in Example 1 is 45°C. All other conditions are the same as in Example 1.

[0141] Example 5

[0142] The difference from Example 2 is that the cell operating temperature is 80°C. The cell operating temperature in Example 2 is 45°C. All other conditions are the same as in Example 2.

[0143] Example 6

[0144] The difference from Example 2 is that the lithium replenishing agent added was at -30°C. No lithium replenishing agent was added in Example 2. All other conditions were the same.

[0145] It should be noted that during the initial charge and discharge of a battery, some lithium ions are irreversibly consumed, forming a solid electrolyte interphase (SEI) film. This leads to an initial capacity loss in the battery. Lithium replenishment agents can compensate for these lost lithium ions, thereby increasing the battery's initial capacity. Furthermore, during battery cycling, lithium ions are gradually lost, and lithium replenishment agents can compensate for these losses to some extent, extending the battery's cycle life.

[0146] Example 7

[0147] The difference from Example 1 is that the motor applies a restraining force of 0.5 MPa to a single cell during charging, and the maximum restraining force is 5 MPa when discharged to 0 SOC. In Example 1, the motor applies a restraining force of 2.5 MPa to a single cell during charging, and the restraining force is 20 MPa when discharged to 0 SOC. All other conditions are the same as in Example 1.

[0148] Example 8

[0149] The difference from Example 1 is that the motor applies a restraining force of 5 MPa to a single cell during charging, and the maximum restraining force is 30 MPa when discharged to 0 SOC. In Example 1, the motor applies a restraining force of 2.5 MPa to a single cell during charging, and the restraining force is 20 MPa when discharged to 0 SOC. All other conditions are the same as in Example 1.

[0150] Example 9

[0151] The difference from Example 2 is that the motor applies a restraining force of 0.1 MPa to a single cell during the initial charging phase, and the restraining force becomes 15 MPa when the charging voltage reaches the cutoff voltage. During the discharge process, the restraining force reaches 30 MPa when the cell reaches 50% SOC. In Example 2, the motor applies a restraining force of 2.5 MPa to a single cell during charging, and the restraining force becomes 20 MPa when the cell reaches 0% SOC. All other conditions are the same as in Example 1.

[0152] Comparative Example 1

[0153] The difference from Example 1 is that an equal-gap restraint method is used to perform the cycle performance test at this current multiplier.

[0154] Comparative Example 2

[0155] The difference from Example 2 is that an equal-gap restraint method is used to perform the cycle performance test at this current multiplier.

[0156] Comparative Example 3

[0157] The difference from Example 2 is that a fixed restraint of 5MPa is used during the charging process.

[0158] Under the conditions of the above embodiments and comparative examples, a battery tester was used to perform constant current density charge-discharge tests on the battery cells to evaluate their cycle stability under different restraint strategies. The battery testing temperature range was -30 to 80°C, and the charge-discharge voltage range was set to 2.5V to 4.2V. The cycle performance tests employed 0.33C charge-discharge, 3C charging, and 1C discharging strategies to compare the impact of dynamic restraint forces on conventional battery cycling and high-rate charge-discharge cycling. Furthermore, the battery parameters evaluated were the capacity retention rate and coulombic efficiency after 200 cycles.

[0159] Table 1

[0160]

[0161]

[0162] As shown in Table 1, and through comparisons of Examples 1, 3, and 4, or Examples 2, 5, and 6, it can be seen that during the conventional cycle testing of the battery cell, the restraint force needs to be adjusted according to the ambient temperature of the battery cell. When the temperature rises, the required restraint force decreases. If the restraint force is not adjusted downwards, it will lead to an "upsetting-tearing" phenomenon during cycling due to excessive restraint force, resulting in battery cell cycle decay and a decrease in coulombic efficiency. When the temperature decreases, the required restraint force increases. If the restraint force is not adjusted upwards, insufficient restraint force will cause the solid-solid interface contact to deteriorate during cycling, leading to a decrease in battery cell cycle stability.

[0163] By comparing Examples 1, 7, or 8, or Examples 2, 9, and 10, it can be seen that when the initially applied restraint force is insufficient, the cell will experience excessive impedance and polarization potential due to insufficient solid-solid interface contact. This leads to current density concentration and local potential increase at the solid-solid interface, resulting in side reactions and battery capacity decay. When the initially applied restraint force is excessive, the excessive restraint force will cause a "upsetting-tearing" phenomenon during cycling, leading to cell cycle decay and a decrease in coulombic efficiency.

[0164] A comparison of Example 1 and Comparative Example 1, or Example 2 and Comparative Example 2, shows that the dynamically adjusted restraint method of this application can effectively improve battery life and cycle stability. In contrast, the equal-gap restraint method cannot actively adjust the stress changes on the cell, resulting in excessive restraint force during charging and insufficient restraint force during discharging. This leads to continuous cell degradation under the combined effect of these two effects.

[0165] A comparison of Example 2 and Comparative Example 3 shows that when the battery cell is charged and discharged at a high rate, sufficient stress needs to be applied at 0SOC to reduce polarization caused by the impedance of the interface contact. If the stress is not reduced during the subsequent electro-expansion process, the battery cell is easily subjected to large force impacts due to its rapid expansion and contraction rate, which accelerates the deterioration of the battery cell's physical structure.

[0166] In summary, by employing a drive unit to adjust the restraint force applied to the all-solid-state battery cell in real time based on the cell's charge / discharge status, remaining charge, and temperature feedback, and by using a strategy of reducing the restraint force during charging and increasing it during discharging, the cycle capacity retention and lifespan of the all-solid-state battery cell can be effectively improved. Simultaneously, by adding elastic units between the cell restraint units, uneven distribution of remaining charge or health status that may occur throughout the entire lifespan can be addressed. Finally, for high-rate charge / discharge processes, a relatively larger restraint force is required when the remaining charge is low to reduce the impact of polarization on cell capacity, while a moderate reduction in restraint force is needed when the remaining charge is high to cope with the larger impact force caused by the rapid expansion rate of the cell during lithium intercalation.

[0167] The battery cell module provided in the embodiments of this application has been described in detail above. Figure 3 A schematic flowchart of a cell restraint method provided in an embodiment of this application is shown, as follows: Figure 3 As shown, the cell restraint method provided in this application embodiment is used in the above-mentioned cell module, and the method includes:

[0168] S301. When the battery cell in the restraint cell unit is in a charging state, a first restraint force is applied to the restraint cell unit.

[0169] For example, the range of the first restraining force can be 0.1 MPa to 5 MPa.

[0170] In some embodiments, when the battery cell in the restrained battery cell unit is in a charging state, the first restraining force applied to the restrained battery cell unit is linearly reduced. For example, the reduction is less than or equal to 10% to 20% of the first restraining force to meet the restraining requirements of the battery cell during the charging process.

[0171] As one implementation method, the battery cell in the restraint cell unit is charged from zero charge to a preset charge, the first restraint force is linearly reduced, and the reduced first restraint force is applied to the battery cell restraint voltage until the battery cell is fully charged.

[0172] In some embodiments, when the restrained battery cell unit is within a first temperature range, if the battery cell in the restrained battery cell unit is in a charging state, a first restraining force is applied to the restrained battery cell unit. For example, the first temperature range is 45°C to 60°C.

[0173] In some examples, when the battery cell unit is within a second temperature range, if the battery cell in the battery cell unit is in a charging state, the first restraint force is increased. For example, the increased first restraint force can range from 1 MPa to 10 MPa to meet the restraint force requirements during battery cell charging at lower cell temperatures. The second temperature range can be from -30°C to 45°C.

[0174] In some examples, when the battery cell unit is within a third temperature range, if the battery cell in the battery cell unit is in a charging state, the first restraint force is reduced. For example, the reduced first restraint force can range from 0.05 MPa to 2.5 MPa to meet the restraint force requirements during battery cell charging at higher temperatures. The third temperature range can be from 60°C to 80°C.

[0175] S302. When the battery cell in the restraint cell unit is in a discharging state, a second restraint force is applied to the restraint cell unit.

[0176] For example, the range of the second restraint force can be 5MPa to 20MPa.

[0177] In some embodiments, when the cells in the restrained cell unit are in a discharged state, the second restraining force applied to the restrained cell unit is increased linearly. For example, the increase is less than or equal to 2% to 5% of the second restraining force.

[0178] In some examples, when the restrained cell unit is within a first temperature range, if the cell in the restrained cell unit is in a discharged state, a second restraining force is applied to the restrained cell unit. For example, the first temperature range is 45°C to 60°C.

[0179] As one implementation method, the battery cell in the restraint cell unit is discharged from full charge to a preset charge, the second restraint force is linearly increased, and the increased second restraint force is applied to the restraint cell unit until the battery cell is discharged to zero charge.

[0180] In some embodiments, when the confined cell unit is within a second temperature range, if the cell in the confined cell unit is in a discharging state, a second confining force is increased. For example, the increased second confining force can range from 10 MPa to 25 MPa to meet the confining force requirements during cell discharge when the cell temperature is high. For example, the second temperature range can be from -30°C to 45°C.

[0181] In some examples, when the confined cell unit is within the third temperature range, if the cell in the confined cell unit is in a discharging state, the second confining force is reduced. For example, the reduced second confining force can range from 2.5 MPa to 15 MPa to meet the confining force requirements during cell discharge at higher cell temperatures. For example, the third temperature range can be from 60°C to 80°C.

[0182] It should be noted that in this embodiment, steps S302 and S301 are not limited by the described order of actions, and steps S302 and S301 can be performed in other orders.

[0183] The specific implementation principle and technical effects of the cell restraint method provided in this application embodiment can be found in the above-mentioned embodiment of the cell module, and will not be repeated here.

[0184] One embodiment of this application also provides a battery pack, including the above-described cell module.

[0185] For example, it may include one or more battery cell modules.

[0186] For example, the battery pack may include, but is not limited to, one or more of the following: sulfide all-solid-state batteries, halide all-solid-state batteries, polymer all-solid-state batteries, and organic / inorganic composite all-solid-state batteries.

[0187] One embodiment of this application also provides a vehicle including the battery pack described above.

[0188] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A battery cell module, characterized in that, The battery cell module includes: The battery cell unit and drive unit are constrained; The drive unit is configured to apply a first restraining force to the restraining cell unit when the cell in the restraining cell unit is in a charging state, and to apply a second restraining force to the restraining cell unit when the cell in the restraining cell unit is in a discharging state.

2. The battery cell module according to claim 1, characterized in that, The number of the constrained battery cells is multiple, and the multiple constrained battery cells are stacked in a first direction.

3. The battery cell module according to claim 2, characterized in that, The battery cell module also includes: Multiple elastic units, each of which is disposed between two adjacent restraint cell units.

4. The battery cell module according to any one of claims 1-3, characterized in that, The restrained battery cell unit includes a battery cell and two restraint plates, which are disposed on both sides of the battery cell in a first direction.

5. The cell module according to claim 3, characterized in that, The elastic element includes at least one spring.

6. The cell module according to claim 4, characterized in that, The drive unit is configured to, When the battery cell is in a charging state, the driving unit applies a first restraining force to the restraining plate to drive the restraining plate to squeeze the battery cell; When the battery cell is in a discharging state, the driving unit applies a second restraining force to the restraining plate to drive the restraining plate to squeeze the battery cell.

7. The battery cell module according to any one of claims 1-3, characterized in that, The drive unit is configured to, When the battery cell in the restraint cell unit is in a charging state, the first restraint force is reduced linearly.

8. The cell module according to claim 7, characterized in that, The reduction is less than or equal to 10% to 20% of the first restraint force.

9. The battery cell module according to any one of claims 1-3, characterized in that, The drive unit is configured to, When the battery cell in the restraint cell unit is in a discharging state, the second restraint force increases linearly.

10. The cell module according to claim 9, characterized in that, The increase in amount is less than or equal to 2% to 5% of the second restraint force.

11. The cell module according to claim 10, characterized in that, The drive unit is configured to, The battery cell in the restraint battery cell unit is charged from zero charge to a preset charge, thereby linearly reducing the first restraint force; The driving unit applies a reduced first restraining force to the restrained battery cell until the battery cell is fully charged.

12. The cell module according to claim 10, characterized in that, The drive unit is configured to, The second restraint force increases linearly as the battery cell of the restraint cell unit discharges from full charge to a preset charge level. The driving unit applies an increased second restraining force to the restrained cell unit until the cell discharges to zero charge.

13. The battery cell module according to any one of claims 1-3, characterized in that, The drive unit is configured to, When the constrained battery cell unit is within a first temperature range, if the battery cell in the constrained battery cell unit is in a charging state, a first constraining force is applied to the constrained battery cell unit; if the battery cell in the constrained battery cell unit is in a discharging state, a second constraining force is applied to the constrained battery cell unit.

14. The cell module according to claim 13, characterized in that, The first restraint force ranges from 0.1 MPa to 5 MPa, and the second restraint force ranges from 5 MPa to 20 MPa.

15. The cell module according to claim 14, characterized in that, When the constrained cell unit is within the second temperature range, the drive unit is configured to, If the battery cell in the restraint battery cell unit is in a charging state, increase the first restraint force; If the battery cell in the restraint cell unit is in a discharged state, the second restraint force is increased.

16. The cell module according to claim 15, characterized in that, The second temperature range is -30℃ to 45℃.

17. The cell module according to claim 14, characterized in that, When the constrained cell unit is within the third temperature range, the drive unit is configured to, If the battery cell in the restraint cell unit is in a charging state, reduce the first restraint force; If the battery cell in the restraint cell unit is in a discharged state, the second restraint force is reduced.

18. The cell module according to claim 17, characterized in that, The third temperature range is 60℃~80℃.

19. The battery cell module according to any one of claims 1-3, characterized in that, The battery cell module also includes: The sensor is disposed on the confined cell unit; When the driving unit applies a restraining force to the restrained cell unit, the sensor feeds back the change in restraining force to the driving unit. The drive unit controls the restraint force applied to the restraint cell unit based on the restraint force change.

20. A method for confining battery cells, characterized in that, The method is used in the battery cell module according to any one of claims 1-19, and the method includes: When the battery cell in the restrained battery cell unit is in a charging state, a first restraining force is applied to the restrained battery cell unit; When the battery cell in the restrained battery cell unit is in a discharged state, a second restraining force is applied to the restrained battery cell unit.

21. The method according to claim 20, characterized in that, When the battery cell in the restrained battery cell unit is in a charging state, a first restraining force is applied to the restrained battery cell unit, including: When the battery cell in the restrained battery cell unit is in a charging state, the first restraining force applied to the restrained battery cell unit is linearly reduced.

22. The method according to claim 20, characterized in that, When the battery cell in the restrained battery cell unit is in a discharged state, a second restraining force is applied to the restrained battery cell unit, including: When the battery cell in the constrained battery cell unit is in a discharged state, the second constraining force applied to the constrained battery cell unit is increased linearly.

23. The method according to claim 21, characterized in that, When the battery cell in the restrained battery cell unit is in a charging state, a first restraining force is applied to the restrained battery cell unit, including: The battery cell in the restraint battery cell unit is charged from zero charge to a preset charge, thereby linearly reducing the first restraint force; A reduced first restraint force is applied to the cell restraint unit until the cell is fully charged.

24. The method according to claim 22, characterized in that, When the battery cell in the restrained battery cell unit is in a discharged state, a second restraining force is applied to the restrained battery cell unit, including: The second restraint force increases linearly as the battery cell of the restraint cell unit discharges from full charge to a preset charge level. An increased second restraint force is applied to the restrained cell unit until the cell discharges to zero charge.

25. The method according to claim 20, characterized in that, When the battery cell in the restrained battery cell unit is in a charging state, a first restraining force is applied to the restrained battery cell unit; when the battery cell in the restrained battery cell unit is in a discharging state, a second restraining force is applied to the restrained battery cell unit, including: When the confined cell unit is within the first temperature range, If the battery cell in the restrained battery cell unit is in a charging state, a first restraining force is applied to the restrained battery cell unit; If the battery cell in the restrained battery cell unit is in a discharged state, a second restraining force is applied to the restrained battery cell unit.

26. The method according to claim 25, characterized in that, When the battery cell in the restrained battery cell unit is in a charging state, a first restraining force is applied to the restrained battery cell unit; when the battery cell in the restrained battery cell unit is in a discharging state, a second restraining force is applied to the restrained battery cell unit, including: When the confined cell unit is within the second temperature range, If the battery cell in the restraint battery cell unit is in a charging state, increase the first restraint force; If the battery cell in the restraint cell unit is in a charging state, the second restraint force is increased.

27. The method according to claim 25, characterized in that, When the battery cell in the restrained battery cell unit is in a charging state, a first restraining force is applied to the restrained battery cell unit; when the battery cell in the restrained battery cell unit is in a discharging state, a second restraining force is applied to the restrained battery cell unit, including: When the confined cell unit is within the third temperature range, If the battery cell in the restraint cell unit is in a charging state, reduce the first restraint force; If the battery cell in the restraint cell unit is in a discharged state, the second restraint force is reduced.

28. A battery pack, characterized in that, Includes the battery cell module as described in any one of claims 1-19.

29. A vehicle, characterized in that, Includes the battery pack as described in claim 28.

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