Lithium-ion battery assembly and battery status detection method based on expansion pressure

Abstract

The present application provides a lithium-ion battery assembly and a battery status detection method based on expansion pressure, which belongs to the field of lithium-ion battery technology. The battery assembly includes: at least two battery cells; a rigid support plate and an ion capacitive thin film sensor sandwiched between each two battery cells, the ion capacitive thin film sensor includes at least one sensing unit formed by an ion membrane layer and an electrode array layer arranged under the ion membrane layer, and the sensing unit is used to measure the expansion pressure of the battery cell; at least one locking column, the edge of the rigid support plate is convexly provided with a first guide docking portion, and the locking column passes through the first guide docking portion of the rigid support plate, so that each battery cell and each rigid support plate remain parallel and aligned, and have a consistent pre-tightening force after being locked by the locking column. The present application can improve the consistency and uniformity of force of each battery cell in the module, and extend the service life and safety of the battery assembly.

Description

Technical Field

[0001] The present application relates to the technical field of lithium-ion batteries, and in particular to a lithium-ion battery assembly and a battery status detection method based on expansion pressure. Background Art

[0002] New energy vehicles and electrochemical energy storage are key supporting industries for the major development of my country's renewable energy transformation. Battery safety issues are an important obstacle to the large-scale development of electrochemical energy storage systems. The secondary battery components used in new energy vehicles and other equipment are formed by stacking multiple cells in series or parallel. A pressure sensor is sandwiched between two adjacent cells. The pressure sensor measures the expansion pressure of the corresponding cell, and detects whether the working state of the cell is normal based on the expansion pressure.

[0003] In order to enable the pressure sensor to measure the expansion pressure of the battery cell, a baffle assembly is arranged between adjacent battery cells, and the pressure sensor is fixed on the baffle assembly to realize pressure monitoring of the battery cell. The detailed structure refers to the content disclosed in patent CN116247353A. The baffle assembly is usually composed of two hollow U-shaped frames, and the pressure sensor is clamped in the two hollow U-shaped frames to monitor the pressure of two adjacent battery cells.

[0004] Although this approach can save the number of sensors required, the expansion of one cell in the stacked battery assembly will affect the adjacent cells, resulting in the inability to determine which one or both of the two adjacent cells the pressure data measured by the sensor belongs to. In particular, when two or more adjacent cells expand differently, the sandwiched sensor cannot determine which cell has expanded, and its expansion will affect the adjacent batteries or even all cells, thereby affecting the pressure measurement of other cells.

[0005] In addition, the overall performance and life of a battery pack formed by connecting multiple single cells in series or in parallel depends on a cell with poor performance, which requires that the performance of each cell in the battery pack be highly consistent. However, the existing structure also makes it difficult to keep the cells parallel and aligned, resulting in uneven local forces on different cells and poor consistency in cell performance, which not only leads to inaccurate data collected by the sensor, but also seriously affects the life of the battery pack. Summary of the invention

[0006] The object of the present invention is to provide a lithium-ion battery assembly and a battery status detection method based on expansion pressure to solve at least one of the above technical problems.

[0007] In a first aspect of the present application, a lithium-ion battery assembly is provided, the battery assembly comprising:

[0008] At least two battery cells stacked in sequence along a first direction;

[0009] A rigid support plate and an ion capacitive thin film sensor sandwiched between every two battery cells, the ion capacitive thin film sensor comprising an ion membrane layer and an electrode array layer arranged under the ion membrane layer, at least one electrode unit in the electrode array layer and the ion membrane layer forming at least one sensing unit, the sensing unit being used to measure the expansion pressure of the battery cell;

[0010] At least one locking column, at least one first guiding docking portion is protruding from the edge of each rigid support plate, and the locking column passes through the first guiding docking portion of each rigid support plate, so that each battery cell and each rigid support plate remain parallel and aligned, and have a consistent pre-tightening force after being locked by the locking column.

[0011] Optionally, the rigid support plate is a non-hollow planar support plate, and the first surface of each of the rigid support plates is in contact with the first battery cell among every two battery cells, and the second surface is in contact with the back side of the ion capacitive film sensor, so as to isolate the force influence between the first battery cell and the second battery cell among every two battery cells; the top surface of the ion capacitive film sensor is in contact with the second battery cell among every two battery cells, and is only used to measure the expansion pressure of the second battery cell among every two battery cells.

[0012] Optionally, the battery assembly further includes:

[0013] Locking baffles located at both ends of the battery assembly, a collection plate arranged at the edge of the rigid support plate, and a fixing frame for fixing the collection plate;

[0014] The locking baffle is used to fix the battery cells at both ends of the battery, and at least one second guide docking portion is convexly provided on the edge of the locking baffle, and the locking column also passes through the second guide docking portion of each locking baffle;

[0015] The acquisition board and the fixing frame are parallel to the locking column, and a connection terminal is provided at a position corresponding to each ion capacitive film sensor on the acquisition board. A collection module electrically connected to the ion capacitive film sensor is provided on one side of the acquisition board close to the battery cell, and the number of the connection terminals and the number of the acquisition modules are the same as the number of the ion capacitive film sensors;

[0016] The first guide docking portion and the second guide docking portion are both through holes.

[0017] Optionally, at least one first electrode unit in the electrode array layer is pressed together with the ion membrane layer to form at least one temperature sensing unit, and at least one second electrode unit is not pressed together with the ion membrane layer to form at least one pressure sensing unit;

[0018] The temperature sensing unit and the pressure sensing unit have the same temperature influence factor representing the influence weight of temperature on the output capacitance value.

[0019] Optionally, each of the temperature sensing units and each of the pressure sensing units is circular or square;

[0020] The at least one temperature sensing unit and the at least one pressure sensing unit together form a sensing unit array of m rows and n columns, where m and n are both positive integers greater than 1;

[0021] In the ion capacitive thin film sensor, a first spacing between adjacent sensing units in the middle region is smaller than a second spacing between adjacent sensing units in the edge region;

[0022] At least one temperature sensing unit and at least one pressure sensing unit are distributed in each array sub-area of ​​the ion capacitive thin film sensor. The number of the temperature sensing units in the ion capacitive thin film sensor is less than the number of the pressure sensing units.

[0023] In a second aspect of the present application, a battery status detection method based on expansion pressure is provided, and the method is applied to the lithium-ion battery assembly described in any one of the embodiments of the present application, comprising:

[0024] Acquire capacitance values ​​collected by multiple sensing units on multiple ion capacitive thin film sensors in real time;

[0025] The expansion pressure value at the corresponding position on the battery cell is calculated based on the capacitance value to form an expansion pressure matrix P of the battery assembly at each time. The element p in the expansion pressure matrix P is ij represents the expansion pressure value at the jth position on the i-th battery cell;

[0026] Based on the expansion pressure matrix P at each moment, a curve of the expansion pressure at each position in each battery cell changing with time is formed;

[0027] It is analyzed whether the change trends of the change curves at different positions in the same battery cell are consistent. When the change trends are inconsistent, it is determined that the battery cell is abnormal.

[0028] Optionally, the analysis of whether the change trends of the change curves at different positions in the same battery cell are consistent includes: performing oblique line fitting on each change curve to obtain the slope of the fitted oblique line; comparing the differences between the slopes corresponding to the change curves at different positions in the same battery cell, and when each difference is within a preset difference range, determining that the change trends are consistent, otherwise, determining that the change trends are inconsistent.

[0029] Optionally, the analyzing whether the changing trends of the changing curves at different positions in the same battery cell are consistent includes: identifying the number of charge and discharge times of the corresponding positions based on the changing curves at different positions in the same battery cell; and analyzing whether the number of charge and discharge times at different positions in the same battery cell are consistent.

[0030] Optionally, identifying the number of charge and discharge times of corresponding positions based on the change curves at different positions in the same battery cell includes: identifying the number of curve segments in which the expansion pressure values ​​first increase and then decrease in the change curve, and using the number of curve segments as the number of charge and discharge times.

[0031] Optionally, the method further includes: analyzing whether the change trends of the change curves of different battery cells at the same position are consistent, and when the change trends are inconsistent, determining that the battery cell is abnormal.

[0032] Optionally, analyzing whether the change trends of the change curves of different battery cells at the same position are consistent includes: identifying the charge and discharge times of the corresponding position based on the change curves of different battery cells at the same position, and analyzing whether the charge and discharge times of different battery cells at the same position are consistent.

[0033] Optionally, the method further includes: calculating a total expansion pressure value of the battery cell at the same time according to the expansion pressure values ​​corresponding to multiple positions of the same battery cell at the same time, performing a first consistency comparison on the total expansion pressure values ​​of different battery cells at the same time, and determining whether the battery cell is in an abnormal state; and / or

[0034] A second consistency comparison is performed on the expansion pressure values ​​of different battery cells at the same time and the same position to determine whether the corresponding battery cell is in an abnormal state.

[0035] The lithium-ion battery assembly and the battery status detection method based on expansion pressure in the present application adopt a solid rigid support plate and a locking column. Since the rigid support plate has a high enough rigidity, it can ensure that the battery will not be squeezed and deformed during expansion, and provide sufficient support for the thin film sensor. By setting a guide locking column, when applying a pre-tightening force, a torque wrench can be used to apply a constant torque to the four locking nuts to ensure that each battery cell, the rigid support plate and the ion capacitive thin film sensor in the battery assembly are firmly fixed together, and these components are kept in a parallel and aligned state, so that the pre-tightening force applied to each battery cell is basically the same, ensuring the consistency and uniformity of force of each battery cell, and extending the service life and safety of the battery assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope of the present application.

[0037] Figure 1 is a schematic diagram of the overall structure of a battery assembly in one embodiment;

[0038] Figure 2 for Figure 1 A schematic diagram of the exploded structure of the battery assembly shown;

[0039] Figure 3 A schematic diagram of a stacking structure between battery cells in one embodiment;

[0040] Figure 4 is a schematic diagram of the structure of a thin film sensor in one embodiment;

[0041] Figure 5 is a schematic diagram of the structure of a thin film sensor in another embodiment;

[0042] Figure 6 A schematic diagram of the positional relationship between the rigid support plate and the thin film sensor in one embodiment;

[0043] Figure 7 is a schematic structural diagram of a rigid support plate in one embodiment;

[0044] Figure 8 This is a schematic diagram of the structure of a collection board in one embodiment;

[0045] Fig. 9 is a flow chart of a battery status detection method based on expansion pressure in one embodiment;

[0046] Fig.10 It is a schematic diagram of a curve showing the change of expansion pressure over time in one embodiment.

[0047] Explanation of the accompanying drawings: 10, thin film sensor; 20, battery cell; 30, rigid support plate; 40, locking baffle; 50, locking column; 60, acquisition board; 70, fixing frame; 80, fastener; 11, pressure sensing unit; 12, temperature sensing unit; 13, sensing unit wiring group; 15, array sub-area; 31, first guide docking part; 41, second guide docking part; 61, connecting terminal; 62, acquisition module; 63, screw hole. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0049] All terms (including technical and scientific terms) used in this application have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used here should be interpreted as having a meaning consistent with the context of this specification, and should not be interpreted in an idealized or overly rigid manner.

[0050] For example, the terms "first", "second", etc. used in this application are only used to distinguish similar objects and to differentiate the first object from another object, rather than to describe a specific order or sequence, and cannot be understood as indicating or implying relative importance.

[0051] The present application proposes a lithium-ion battery assembly, combined with Figure 1 and Figure 2 As shown, the battery assembly includes: a battery cell 20, a rigid support plate 30, a thin film sensor 10, and a locking column 50. The number of the battery cell 20, the rigid support plate 30, the thin film sensor 10, and the locking column 50 can include multiple.

[0052] At least two battery cells (or "battery cells") are stacked in sequence along a first direction, where the first direction is the stacking direction of the battery. Figure 3 As shown, it shows a schematic diagram of a structure in which N battery cells are stacked in series and in parallel to form a battery pack with a parallel structure or a battery pack with a series structure. N can be any positive integer greater than or equal to 2.

[0053] A rigid support plate and a thin film sensor are sandwiched between each two adjacent battery cells. That is, the rigid support plate and the thin film sensor are sandwiched between two opposite surfaces of the two battery cells that are perpendicular to the first direction. The thin film sensor can be an ion capacitive thin film sensor that has the ability to measure pressure. A corresponding ion capacitive thin film sensor and / or a rigid support plate are additionally provided on one side of one or two battery cells at both ends of the battery assembly that is close to the end of the battery assembly, so that the pressure and temperature of the end surface can be measured.

[0054] The ion capacitive thin film sensor includes an ion membrane layer and an electrode array layer arranged under the ion membrane layer. At least one electrode unit in the electrode array layer and the ion membrane layer form at least one sensing unit, and the sensing unit is used to measure the expansion pressure of the battery cell.

[0055] The ionic capacitive thin film sensor may be a sensor array formed by a plurality of sensing units, each of which may be a pressure sensing unit or a temperature sensing unit. Figure 4 As shown, each sensing unit is a pressure sensing unit 11; Figure 5 As shown, some of the sensing units are pressure sensing units 11 , and another part of the sensing units are temperature sensing units 12 .

[0056] The ion capacitive thin film sensor consists of an ion membrane layer located on the upper layer and an electrode array layer located on the lower layer. The electrode array layer includes a plurality of electrode units arranged in an array below the ion membrane layer. The ion membrane layer is made of a polymer material with ion conductivity (such as polymer electrolyte, ion exchange membrane, etc.). This material can allow ions to migrate inside the membrane layer under the action of an electric field, thereby achieving a capacitive effect. The electrode array layer is arranged below the ion membrane layer to form a capacitive structure with the ion membrane layer.

[0057] The electrode array layer includes multiple electrode units, which are distributed in a specific arrangement. The electrode array layer is usually made of conductive materials, such as metals with good conductivity and chemical stability (such as copper, silver, gold, etc.), conductive polymers or carbon materials, etc., to adapt to the harsh working environment of the battery assembly. The electrode array layer and the ion membrane layer together form a capacitor structure for monitoring the temperature and pressure changes of the battery assembly. The ion membrane layer is an ionizing thin film layer with a microstructure; the electrode array layer is a planar interdigitated electrode layer.

[0058] In one embodiment, all electrode units (referred to as second electrode units) in the ion capacitive thin film sensor are not in pressure-fit contact with the ion membrane layer region above them, and the sensing units formed by all electrode units are pressure sensing units.

[0059] In another embodiment, part of the electrode units (referred to as the first electrode units) in the ion capacitive thin film sensor are pressed together with the ion membrane layer area covered above them and contacted together; the other part of the electrode units (referred to as the second electrode units) are not pressed together with the ion membrane layer area above them. The pressed electrode units and the corresponding ion membrane layer area, the corresponding ion membrane layer area no longer have microstructure features, forming a corresponding temperature sensing unit; while the unpressed electrode units and the corresponding ion membrane layer area, the corresponding ion membrane layer area still retains the original microstructure features, forming a corresponding pressure sensing unit.

[0060] The pressing method may be a combination of one or more pressing methods such as hot pressing, ultrasonic welding, solution casting, etc. The temperature sensing unit and the pressure sensing unit have the same temperature influence factor that characterizes the weight of the influence of temperature on the output capacitance value. This means that when the temperature changes, the capacitance value changes of the two sensing units will be affected to the same extent, which is convenient for subsequent data processing and calibration, and can more easily eliminate the influence of temperature on the measurement results, thereby obtaining more accurate temperature and pressure values.

[0061] The first electrode unit and the ion membrane layer are pressed together to form a temperature sensing unit, so that the electrode unit and the ion membrane layer form good contact, which is not affected by pressure but only by temperature, so that the temperature change of the battery assembly can be monitored by the capacitance effect. When the temperature of the battery assembly rises, the capacitance value between the ion membrane layer and the electrode unit will change, and by measuring this change, real-time monitoring of the temperature can be achieved.

[0062] The second electrode unit and the ion membrane layer are not pressed into contact to form a pressure sensing unit. This non-pressed structure allows a certain gap between the electrode unit and the ion membrane layer, so that the capacitive effect can be used to monitor the pressure change of the battery assembly. When the expansion pressure is generated on the surface of the battery assembly, the gap and contact area between the electrode unit and the ion membrane layer will change, and the flexible ion film dielectric layer will deform, causing the capacitance of the electrode unit to change, thereby converting the expansion pressure inside the electronic component into a sensing capacitance value. However, since the sensing capacitance value of the pressure sensing unit is also affected by temperature at the same time, there will be a certain error in measuring pressure only by the sensing capacitance value of the pressure sensing unit. Since the sensing capacitance values ​​of the isomorphic pressure sensing unit and the temperature sensing unit are affected by the same temperature, the present application corrects the sensing capacitance value of the pressure sensing unit by the sensing capacitance value of the temperature sensor, so that the expansion pressure distribution of the battery assembly can be measured more accurately.

[0063] The shape and arrangement of the sensing units formed by the pressure sensing unit and the temperature sensing unit in the ion capacitive thin film sensor can be flexibly adjusted according to actual needs and designs (for example, according to the shape, size and monitoring needs of the battery components, etc.), and the arrangement can be linear arrangement, matrix arrangement (or grid arrangement), ring arrangement or other arbitrary irregular arrangement.

[0064] For example, each temperature sensing unit and each pressure sensing unit is circular or square; at least one temperature sensing unit and at least one pressure sensing unit together form a sensing unit array of m rows and n columns, where m and n are both positive integers greater than 1.

[0065] The first spacing between adjacent sensing units in the middle area of ​​the ion capacitive thin film sensor is smaller than the second spacing between adjacent sensing units in the edge area. The ion capacitive thin film sensor is configured such that the sensing units in the middle area are densely distributed overall, while the sensing units in the edge area are sparsely distributed overall. This distribution design helps to provide more intensive monitoring in areas where the temperature and pressure changes more drastically inside the battery assembly.

[0066] At least one temperature sensing unit and at least one pressure sensing unit are distributed in each array sub-area of ​​the ion capacitive thin film sensor. The sensing unit array formed by the ion capacitive thin film sensor is divided into regions to form a plurality of array sub-areas 15. The region size of each array sub-area can be the same or different. There is no intersection between the array sub-areas, and the union formed by all array sub-areas is all the regions of the sensing unit array. For each divided array sub-area, a certain number of temperature sensing units and pressure sensing units are contained therein.

[0067] In one embodiment, the rigid support plate is used to provide rigid support for the thin film sensor, and each battery cell is fixed at a corresponding position on the same set of rigid support plates to ensure the relative position stability between the battery cells, and prevent the battery cells from moving relative to each other when expanding or subjected to external forces, thereby affecting the overall performance and safety of the battery assembly. At the same time, the rigid support plate can also keep the battery and the sensor parallel during use, avoiding local force differences caused by non-parallelism, which affects the effectiveness of data collection.

[0068] Furthermore, at least one first guide docking portion 31 is protruded from the edge of each rigid support plate 30. Figure 6 and Figure 7 As shown, the first guide docking portion 31 may be multiple and protruded from the edge of the rigid support plate. For example, one or more first guide docking portions 31 may be protruded from the edges of multiple sides of the rigid support plate 30 .

[0069] The first guide docking portion is used to provide precise guidance and positioning functions for the locking column, ensuring that the locking column can smoothly pass through each rigid support plate. The locking column passes through the first guide docking portion of each rigid support plate, so that each battery cell remains parallel and aligned, and has a consistent pre-tightening force after being locked by the locking column.

[0070] like Figure 1 , Figure 2 and Figure 7 As shown, two first guide docking parts 31 are respectively provided on two opposite sides of the rigid support plate 30. The first guide docking part can be a through hole suitable for the locking column to pass through, or can also be other structures suitable for the locking column to pass through and fix. There are also four locking columns 50, and each locking column 50 passes through the first guide docking part 31 of each rigid support plate 30 at the same position, so that each battery cell, rigid support plate and ion capacitive film sensor are firmly fixed together, and these components are kept parallel and aligned. In this way, each battery cell can maintain a high degree of consistency and a uniform stress state after being subjected to the pre-tightening force of the locking column, thereby improving the overall performance of the battery assembly and extending the service life and safety of the battery assembly.

[0071] In one embodiment, the rigid support plate is a non-hollow planar support plate, the first surface of each rigid support plate is bonded to the first battery cell among every two battery cells, and the second surface is bonded to the back side of the ion capacitive film sensor; the top surface of the ion capacitive film sensor is bonded to the second battery cell among every two battery cells, and is only used to measure the expansion pressure of the second battery cell among every two battery cells.

[0072] The non-hollow planar support plate structure means that there are no cavities or gaps inside the rigid support plate, thereby isolating the force influence between two adjacent battery cells. Figure 6 , Figure 7 As shown, the two surfaces (the first surface and the second surface) of the rigid support plate are precisely processed to ensure a close fit with the battery cell and the ion capacitive thin film sensor.

[0073] The first surface of each rigid support plate is designed to be attached to the surface of the first battery cell of every two adjacent battery cells; the second surface of the rigid support plate is attached to the back side of the ion capacitive thin film sensor (i.e., the surface relative to the sensing unit), so that the ion capacitive thin film sensor can be stably fixed on the rigid support plate while maintaining the accuracy of its measurement function. The back side of the thin film sensor and / or the second surface of the rigid support plate can be coated with glue, and the thin film sensor is attached and fixed to the second side of the rigid support plate by the glue.

[0074] The rigid support plate isolates the force influence between the first battery cell and the second battery cell in every two battery cells, and each thin film sensor only monitors the second battery cell in every two corresponding battery cells, which can improve the accuracy of monitoring the battery cell status.

[0075] In one embodiment, the battery assembly further comprises: locking baffles located at both ends of the battery assembly, a collection plate arranged at the edge of the rigid support plate, and a fixing frame for fixing the collection plate.

[0076] Combination Figure 1 and Figure 2 As shown, the locking baffle 40 is used to fix the battery cells at both ends of the battery. At least one second guide docking portion 41 is protruded from the edge of the locking baffle 40 , and the locking column 50 also passes through the second guide docking portion 41 of each locking baffle 40 .

[0077] The rigid support plate is made of rigid materials such as metal, carbon fiber, ceramic, etc., and the first guide docking portion and the second guide docking portion are both through holes.

[0078] The second guide docking portion on the locking baffle is located at a position corresponding to the first guide docking portion, and these docking portions can be designed as through holes. The locking column passes through the first guide docking portion of each rigid support plate and the second guide docking portion of the locking baffle, and is locked by a fastener 80, which can be a locking nut.

[0079] The collection plate 60 and the fixing frame 70 are parallel to the locking column 50. The collection plate 60 is provided with a plurality of screw holes 63, and the collection plate 60 is fixed to the fixing frame 70 by screws. The collection plate and the fixing frame are both arranged on one side of the battery cell.

[0080] like Figure 8 As shown, a connection terminal 61 is provided at a position corresponding to each ion capacitive thin film sensor on the acquisition board 60, and an acquisition module 62 electrically connected to the ion capacitive thin film sensor is provided on one side of the acquisition board close to the battery cell. Each thin film sensor is electrically connected to the corresponding acquisition module 62 through the sensor unit wiring group 13 thereon.

[0081] The number of connection terminals and acquisition modules is the same as that of the ion capacitive thin film sensor. Figure 1 and Figure 2 The number of connection terminals, acquisition modules, thin-film sensors, and battery cells shown in the figure is 8 each.

[0082] The lithium-ion battery assembly in the present application adopts a solid rigid support plate and a locking column. Since the rigid support plate is sufficiently rigid, it can ensure that the battery will not be squeezed and deformed during expansion, and provide sufficient support for the thin film sensor. By setting a guide locking column, when applying a pre-tightening force, a torque wrench can be used to apply a constant torque to the four locking nuts to ensure that each battery cell, the rigid support plate and the ion capacitive thin film sensor in the battery assembly are firmly fixed together, and these components are kept in a parallel and aligned state, so that the pre-tightening force applied to each battery cell is basically the same.

[0083] For example, the preload force on the jth position area on the i-th battery cell is F ij , the sum of the preload forces at each location on the i-th battery cell is: Where M is the total number of position areas divided by the ith battery cell. During the assembly process, the sum of the preload forces on each battery cell can be made substantially the same, and the preload forces on different battery cells in the same position area can also be substantially the same. ; . N is the total number of battery cells.

[0084] In this way, each battery cell is subjected to the pre-tightening force of the locking column. After the action, it can maintain a high degree of consistency and uniform stress state, thereby improving the overall performance of the battery assembly and extending the service life and safety of the battery assembly.

[0085] In one embodiment, Fig. 9 As shown, a battery status detection method based on expansion pressure is provided, the method comprising:

[0086] Step 110 , acquiring capacitance values ​​collected by a plurality of sensing units on a plurality of ionic capacitive thin film sensors in real time.

[0087] Step 120, based on the capacitance value, calculate the expansion pressure value at the corresponding position on the battery cell to form an expansion pressure matrix P of the battery assembly at each time. The element p in the expansion pressure matrix P is ij It represents the expansion pressure value at the j-th position on the i-th battery cell.

[0088] The battery status detection method based on expansion pressure in the present application can be applied to the lithium-ion battery assembly in any of the above embodiments.

[0089] The signals output by the sensing units (such as the pressure sensing unit and / or the temperature sensing unit) on the ion capacitive film sensor are all capacitance values. For the capacitance value (recorded as the first capacitance value) output by the pressure sensing unit, the corresponding pressure can be calculated based on the relationship between the capacitance value and the pressure, and the calculated pressure is used as the expansion pressure value at the corresponding position of the pressure sensing unit and the battery cell.

[0090] Furthermore, the first capacitance value can be corrected based on the capacitance value (recorded as the second capacitance value) measured by the temperature sensing unit on the ion capacitance film sensor, and the expansion pressure value at the corresponding position can be obtained according to the corrected first capacitance value. Alternatively, the first capacitance value can be corrected in combination with the temperature in the battery assembly measured by other suitable temperature sensors, and the corresponding expansion pressure value can be obtained according to the corrected first capacitance value.

[0091] For example, the sensing unit on the ion capacitive thin film sensor includes both a pressure sensing unit and a temperature sensing unit. Step 110 includes: acquiring in real time a first capacitance value collected by each pressure sensing unit on a plurality of ion capacitive thin film sensors; acquiring in real time a second capacitance value collected by at least one temperature sensing unit on the plurality of ion capacitive thin film sensors whose interval distance from the pressure sensing unit is within a first distance range.

[0092] The expansion pressure value at the corresponding position on the battery cell is calculated based on the capacitance value, including: obtaining the contact area percentage between the second electrode unit of the pressure sensing unit and the ion membrane layer based on the ratio between the first capacitance value and the second capacitance value collected by at least one temperature sensing unit in the first distance range; calculating the calibration value of the expansion pressure of the battery cell at the first position based on the contact area percentage and the proportional factor between the contact area percentage between the second electrode unit and the ion membrane layer and the applied pressure related to the ion capacitive film sensor; calculating the calibration value of the expansion pressure of the battery cell at the second position based on the calibration value of the expansion pressure at at least one first position adjacent to the second position. Wherein, the first position is the position in the battery cell corresponding to the pressure sensing unit; the second position is the position in the battery cell corresponding to the temperature sensing unit.

[0093] In this embodiment, the pressure sensing units and temperature sensing units are distributed at different positions of the battery cells, and each pressure sensing unit and temperature sensing unit can reflect the expansion pressure and temperature of the corresponding battery cell at the corresponding position.

[0094] The first distance range can be any suitable distance range, and by pre-setting the position distribution of the sensing units in the ion capacitive thin film sensor, it can be ensured that any pressure sensing unit has at least one temperature sensing unit within its first distance range. Specifically, the selected temperature sensing unit can be the temperature sensing unit closest to the pressure sensing unit.

[0095] Similarly, the battery cells can be divided into position areas according to the position distribution of the sensing units in the corresponding ion capacitive thin film sensors. The battery cells can be divided into multiple position areas, each of which corresponds to one or more sensing units, and there is no intersection between the areas. The corresponding sensing units can be temperature sensing units and / or pressure sensing units. For example, the number of divided areas is the same as the number of sensing units, and each area corresponds to a sensing unit. Taking the above-mentioned m×n sensing unit array as an example, the battery cells can be divided into m×n position areas, with S ab represents the area at the position of row a and column b on the battery cell, then area S ab The corresponding sensing unit is sensing unit T ab , T ab represents the sensor unit at the ath row and bth column in the m×n sensor unit array. The first position is the region (or position within the region) corresponding to the pressure sensor unit x; the second position is the region (or position within the region) corresponding to the temperature sensor unit y.

[0096] The first capacitance value is recorded as the first capacitance value C p , the second capacitance value is the second capacitance value C t , the output value of the pressure sensing unit (the first capacitance value C p ) is proportional to the contact area between the microstructured ionized membrane (ion membrane) and the electrode unit multiplied by the capacitance per unit area. Using mathematical expressions, the first capacitance value C p It can be expressed as the following formula 1:

[0097] (Formula 1).

[0098] in, represents the output capacitance value of the pressure sensing unit, that is, the first capacitance value; is the contact area between the electrode unit of the pressure sensing unit and the ion membrane; represents the contact area correlation coefficient, which is a fixed value; Indicates the capacitance per unit area; The temperature influence factor is an empirical value that represents the weight of the influence of temperature on the output capacitance value of the pressure sensing unit.

[0099] The capacitance per unit area is affected by temperature. When the surface temperature of the battery cell to which the sensor unit contacts changes, the capacitance per unit area changes as follows: Then the above formula 1 can be changed into the following formula 2:

[0100] (Formula 2).

[0101] When the ionizing film is pressed onto the electrode surface by hot pressing / ultrasonic welding and other technologies, it loses its microstructure and becomes a temperature sensing unit. The contact area between the film and the electrode unit is the maximum contact area. And no longer changes, the output capacitance value is only affected by temperature. The second capacitance value C output by the temperature sensing unit t It can be expressed as:

[0102] (Formula 3).

[0103] in, represents the output capacitance value of the temperature sensing unit, that is, the second capacitance value; is the maximum contact area between the ionizing membrane and the electrode unit (total electrode surface area); represents the correlation coefficient of the contact area, which is a fixed value; Indicates the capacitance per unit area affected by temperature changes.

[0104] Divide Formula 2 by Formula 3 to get the output capacitance of the pressure sensing unit. Divide by the output capacitance of the temperature sensing unit (i.e. the ratio between the first capacitance value and the second capacitance value ), and the contact area between the ionized film and the electrode of the pressure sensing unit is obtained. Total electrode surface area Percentage / (i.e. the contact area percentage between the second electrode unit of the pressure sensing unit and the ion membrane layer). That is, the following formula 4 is obtained:

[0105] (Formula 4).

[0106] This percentage is affected by the external pressure, the stiffness coefficient of the ionizing film and the electrode material, and the surface microstructure. Among them, since the stiffness coefficient of the ionizing film and the electrode material, and the surface microstructure can be measured and calibrated in advance and are almost unchanged (approximately linear), it can be concluded that the above percentage is approximately proportional to the external pressure borne by the pressure sensing unit. The linear relationship is shown in the following formula 5:

[0107] (Formula 5).

[0108] It represents the proportionality factor between the contact area percentage and the applied pressure, which can be obtained through calibration; Indicating the applied pressure of the pressure sensing unit, that is, the calibration value of the expansion pressure at the position (that is, the first position) corresponding to the pressure sensing unit. In one embodiment, before step 430, it can also include: obtaining a proportional factor between the contact area percentage between the second electrode unit and the ion membrane layer and the applied pressure related to the ion capacitive thin film sensor.

[0109] As shown in Formula 5 above, the proportional factor of the ion capacitive thin film sensor is obtained by calibration. Under the premise of , then the value of the external pressure (i.e. the calibration value of the expansion pressure) can be calculated, that is .

[0110] In one embodiment, the calibration value of the expansion pressure of the battery cell at the first position is calculated based on the contact area percentage and the proportionality factor between the contact area percentage between the second electrode unit and the ion membrane layer and the applied pressure related to the ion capacitive thin film sensor, including: according to the above formula A calibrated value P of the expansion pressure at the first position is calculated.

[0111] For the expansion pressure at the second position, after the calibration values ​​corresponding to each pressure sensing unit are calculated according to the above formula 5, the calibration value of the expansion pressure at the second position is calculated based on the calibration values ​​of one or more adjacent pressure sensing units of the temperature sensing unit corresponding to the second position. For example, the multiple calibration values ​​can be weighted and summed to obtain a value as the calibration value of the expansion pressure at the second position.

[0112] By forming an isomorphic temperature sensing and pressure sensing array using an ionized thin film, the capacitance value of the pressure sensing array is calibrated using the capacitance value sensed by the temperature sensing array, thereby obtaining a more accurate pressure value on the surface of the battery cell and realizing multi-point temperature and pressure measurement and detection of the battery.

[0113] Step 130 : Based on the expansion pressure matrix P at each moment, a curve of the expansion pressure at different positions in each battery cell changing with time is formed.

[0114] The expansion pressure value p at each position on each battery cell measured ij , we can form the expansion pressure matrix P. The element p in the expansion pressure matrix P is ijIndicates the expansion pressure value at the jth position on the i-th battery cell. Where i=1,2,3...N; j=1,2,3...M. N is the total number of battery cells, and M is the number of position areas divided for each battery cell. For example, it can be divided into m×n areas according to the above sensor unit array.

[0115] By continuously recording the expansion pressure matrix P at different times, we can generate curves showing the expansion pressure at different locations in each battery cell over time. These curves intuitively show the dynamic behavior of the battery at different locations during the charge and discharge process, including the trend, rate, and possible abnormal fluctuations of expansion and contraction.

[0116] like Fig.10 , which is a curve showing the change of expansion pressure at one position on a battery cell over time in one embodiment. 0 Previously, the battery cell had not been charged or discharged, and the expansion pressure it was subjected to was manifested as the preload applied during the assembly process. 0 Afterwards, as the battery is charged and discharged, its expansion pressure shows a step-by-step cyclic fluctuation state of rising, falling, rising, and falling (refer to the solid line in the figure), and the overall trend is rising (refer to the fitting curve shown by the dotted line). For example, the corresponding pressure change slope F=KX can be fitted according to its actual measurement value. Among them, F is the pressure value obtained by fitting, X represents time, and K is the slope of the slope.

[0117] Step 140 , analyzing whether the change trends of the change curves at different positions in the same battery cell are consistent. When the change trends are inconsistent, it is determined that the battery cell is abnormal.

[0118] For the variation curves of each battery cell at each position, whether the corresponding battery cell represented by the variation curve is normal at the corresponding position can be determined according to the numerical values ​​and numerical variation trends of the corresponding expansion pressure values ​​at different times in the variation curve.

[0119] The difference between the change curves at different positions in the same battery cell can be analyzed. When the difference exceeds a preset difference threshold, the battery assembly is judged to be abnormal, and the position of which battery cell has the abnormality can be located. The difference can be the difference between the expansion pressure values ​​at the same time, or one or more parameters such as the difference in the above slope.

[0120] When the change curves of each identical battery cell at different positions are consistent, it can be determined that the battery assembly is normal, or it can be further identified whether the battery assembly is abnormal based on information from other dimensions.

[0121] In one embodiment, the time periods corresponding to the rising and falling sections of these change curves can be compared to see whether they are consistent, and the slopes of the oblique lines obtained by fitting each curve can be compared to see whether they are consistent, based on which it can be determined whether the change trends of each change curve are consistent.

[0122] When the expansion pressure value in one or more of the change curves is significantly greater than / less than the standard value presented under the normal state at the corresponding position at one or more moments, it can be determined that the value at that moment is abnormal, and then the position where the abnormality exists can be further located. The abnormal position is the position corresponding to the battery cell represented by the curve.

[0123] According to the characteristics of the change curve, the change curve is divided into multiple curve segments, and the curve segments in the same time period in each change curve are compared to analyze whether they are all in an upward trend or a downward trend, so as to determine whether they meet the standard trend. The standard trend is the numerical change trend presented by a normal battery cell.

[0124] For example, the first moment corresponding to the maximum value and the second moment corresponding to the minimum value of the change curve of the same battery cell at different positions in the same time period can be identified; the first time interval between each first moment and the second time interval between each second moment in the same time period can be detected; when one or more first time intervals and second time intervals exceed the preset time threshold, it is determined that the change trend is inconsistent. The time threshold is a set appropriate value.

[0125] The battery status detection method based on expansion pressure in this application obtains the capacitance value on the ion capacitive film sensor in real time and converts it into an expansion pressure value, thereby constructing an expansion pressure matrix of each battery cell of the battery assembly at different positions and at different times. By further analyzing whether the change trends of the change curves formed by the expansion pressure values ​​at different positions in the same battery cell over time are consistent, it is possible to accurately determine whether the battery assembly is in an abnormal state and locate the abnormal battery cell, providing strong support for the safe use and performance optimization of the battery.

[0126] In one embodiment, analyzing whether the change trends of the change curves at different positions in the same battery cell are consistent includes: performing oblique line fitting on each change curve to obtain the slope of the fitted oblique line; comparing the differences between the slopes corresponding to the change curves at different positions in the same battery cell, and when each difference is within a preset difference range, determining that the change trends are consistent, otherwise, determining that the change trends are inconsistent.

[0127] The change curve at each position can be fitted to form the corresponding pressure change slope F=KX. Compare whether the pressure change slopes at different positions in the same battery cell are the same. For example, the difference between the slopes K of the slopes of the same battery cell can be compared. When the difference is within the preset difference range, the battery cell is judged to be abnormal, or further combined with analysis of other dimensions to determine whether it is abnormal; when the difference is outside the preset difference range, the battery cell is judged to be abnormal. The difference range is a set appropriate range, for example, the appropriate difference range can be set according to the accuracy of the sensor.

[0128] In one embodiment, analyzing whether the change trends of the change curves at different positions in the same battery cell are consistent includes: identifying the number of charge and discharge times of the corresponding positions based on the change curves at different positions in the same battery cell; and analyzing whether the number of charge and discharge times at different positions in the same battery cell are consistent.

[0129] In this embodiment, the charge and discharge times of each battery cell in a normal battery assembly should be consistent. Based on the expansion pressure value presented in the change curve, the charge and discharge state of the battery cell in different time periods can be identified, and the corresponding charge and discharge times can be counted. Compare whether the charge and discharge times of different positions in the same battery cell are the same. If they are not the same, it is determined that the change trends of the change curves at different positions in the same battery cell are inconsistent, identify that the battery cell is abnormal, and further locate the abnormal position with different charge and discharge times.

[0130] Specifically, the number of curve segments in which the expansion pressure value first rises and then falls in the change curve is identified, and the number of curve segments is used as the number of charge and discharge times. When the battery cell is in a charging state, its expansion pressure value shows a trend of continuous increase, and when it is in a discharging state, it shows a trend of continuous decrease. Based on this feature, a curve segment in the change curve that first rises and then falls can be regarded as one charge and discharge, and the number of charge and discharge times reflected in each change curve can be counted.

[0131] In one embodiment, the method further comprises: analyzing whether the change trends of the change curves of different battery cells at the same position are consistent, and when the change trends are inconsistent, determining that the battery cell is abnormal.

[0132] In the present application, in addition to the consistency analysis of the change curves at different positions in the same battery cell, the consistency analysis is also performed on the change curves at the same position of different battery cells. The two consistency analyses can be performed in parallel or in a sequential order, such as first performing the above step 140. Similar to the consistency analysis of the change curves at different positions in the same battery cell, one or more analyses such as maximum value, minimum value, maximum value moment, minimum value moment, slope analysis, charge and discharge times, etc. can be performed on the change curves at the same position of different battery cells.

[0133] For example, for the fitted slope corresponding to the obtained change curve, the difference between the slopes corresponding to the change curves of different battery cells at the same position can be compared. When each difference is within the preset difference range, it is determined that the change trend is consistent, otherwise, it is determined that the change trend is inconsistent.

[0134] In one embodiment, analyzing whether the change trends of the change curves of different battery cells at the same position are consistent includes: analyzing whether the change trends of the change curves of different battery cells at the same position are consistent, and when the change trends are inconsistent, determining that the battery cell is abnormal.

[0135] In addition to comparing the charge and discharge times at different positions in the same battery cell, the charge and discharge times at the same position of different battery cells are also compared. When the charge and discharge times at the same position of different battery cells are different, it is determined that there is an abnormality in the battery cell, and the abnormal battery cell is further located. For example, for the same position on N battery cells, if the charge and discharge times of the kth battery cell identified at this position are different from the charge and discharge times of other battery cells at the same position, then the kth battery cell is determined to be an abnormal battery cell.

[0136] In one embodiment, the above method also includes: calculating the total expansion pressure value of the battery cell at the same time based on the expansion pressure values ​​corresponding to multiple positions of the same battery cell at the same time; performing a first consistency comparison on the total expansion pressure values ​​of different battery cells at the same time to determine whether the battery cell is in an abnormal state.

[0137] This step may be performed before the above step 140 , or may be performed in parallel with step 140 , or may be performed after it is identified in step 140 that the change trends of the change curves at different positions in the same battery cell are consistent.

[0138] After obtaining the expansion pressure values ​​of each battery cell at different positions, the expansion pressure values ​​of the same battery cell at all positions may be superimposed and summed, and the obtained value is the total expansion pressure value.

[0139] For the calculated total expansion pressure values ​​of each battery cell, the third absolute value of the difference between the total expansion pressure values ​​at the same time can be calculated. When the absolute value of the third difference is less than the preset second difference threshold, it is determined that the total expansion pressure values ​​of each battery cell are consistent; when the absolute value of the difference is greater than the preset second difference threshold, it is determined that there is an abnormality in the corresponding battery cell in the battery assembly.

[0140] In one embodiment, the method further includes: performing a second consistency comparison on the expansion pressure values ​​of different battery cells at the same time and the same position to determine whether the corresponding battery cell is in an abnormal state.

[0141] Likewise, the execution order between this step and the above-mentioned step 140 is not limited, for example, it can be executed before step 140, and when it is identified that the expansion pressure values ​​of different battery cells at the same time and the same position are consistent, step 140 is executed.

[0142] Similar to the total expansion pressure value, the expansion pressure values ​​of different battery cells at the same position of a battery assembly in a normal state are basically the same. Based on this, the fourth absolute difference between the expansion pressure values ​​of different battery cells at the same position at the same time can be calculated. When the fourth absolute difference is less than the preset third difference threshold, it is determined that the expansion pressure values ​​of the battery cells at the same position are consistent; when the absolute difference is greater than the preset third difference threshold, it is determined that the corresponding battery cell in the battery assembly is abnormal, and the abnormal position in the abnormal battery cell can be further located.

[0143] In the present application, it is possible to determine whether there is an abnormality in the battery assembly by analyzing one or more of the consistency between the various change curves, the consistency of the number of charge and discharge times, the consistency between the expansion pressure values ​​at the same position of different battery cells, and the consistency between the total expansion pressure values ​​of different battery cells. Through the above analysis method, the accuracy of abnormal identification of the battery assembly and the timeliness of abnormal identification can be improved. For example, the expansion pressure values ​​of different battery cells at the same time and the same position can be first compared for a second consistency. When the result of the second consistency comparison is normal, the total expansion pressure values ​​of different battery cells at the same time can be compared for a first consistency. When the result of the first consistency comparison is normal, it is analyzed whether the change trends of the change curves at different positions in the same battery cell are consistent. When the change trends are consistent, the number of charge and discharge times at different positions in the same battery cell are compared. When any comparison result or analysis result is inconsistent, it is determined that the battery assembly is abnormal, and the abnormal battery cell is located.

[0144] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

[0145] In addition, those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, all of the above embodiments may be used in any combination. The information disclosed in this background technology section is intended only to deepen the understanding of the overall background technology of the present application and should not be regarded as an admission or in any form to imply that the information constitutes prior art known to those skilled in the art.

Claims

1. A lithium-ion battery assembly, characterized in that: The battery assembly comprises: At least two battery cells stacked in sequence along a first direction; A rigid support plate and an ion capacitive thin film sensor sandwiched between every two battery cells, the ion capacitive thin film sensor comprising an ion membrane layer and an electrode array layer arranged under the ion membrane layer, at least one electrode unit in the electrode array layer and the ion membrane layer forming at least one sensing unit, the sensing unit being used to measure the expansion pressure of the battery cell; At least one locking column, at least one first guide docking portion is convexly provided on the edge of each rigid support plate, and the locking column passes through the first guide docking portion of each rigid support plate, so that each battery cell is kept parallel and aligned with each rigid support plate, and has a consistent pre-tightening force after being locked by the locking column; At least one first electrode unit in the electrode array layer is pressed together with the ion membrane layer to form at least one temperature sensing unit, and at least one second electrode unit is not pressed together with the ion membrane layer to form at least one pressure sensing unit; The temperature sensing unit and the pressure sensing unit have the same temperature influence factor representing the influence weight of temperature on the output capacitance value.

2. The battery assembly according to claim 1, characterized in that: The rigid support plate is a non-hollow flat support plate, and the first surface of each rigid support plate is in contact with the first battery cell among every two battery cells, and the second surface is in contact with the back surface of the ion capacitive film sensor, so as to isolate the force influence between the first battery cell and the second battery cell among every two battery cells; the top surface of the ion capacitive film sensor is in contact with the second battery cell, and is only used to measure the expansion pressure of the second battery cell.

3. The battery assembly according to claim 1, characterized in that: The battery assembly also includes: Locking baffles located at both ends of the battery assembly, a collection plate arranged at the edge of the rigid support plate, and a fixing frame for fixing the collection plate; The locking baffle is used to fix the battery cells at the head and tail ends of the battery assembly, and at least one second guide docking portion is protruding from the edge of the locking baffle, and the locking column also passes through the second guide docking portion of each locking baffle; The acquisition board and the fixing frame are parallel to the locking column, and a connection terminal is provided at a position corresponding to each ion capacitive film sensor on the acquisition board. A collection module electrically connected to the ion capacitive film sensor is provided on one side of the acquisition board close to the battery cell, and the number of the connection terminals and the number of the acquisition modules are the same as the number of the ion capacitive film sensors; The first guide docking portion and the second guide docking portion are both through holes.

4. The battery assembly according to claim 1, characterized in that: In the ion capacitive thin film sensor, a first spacing between adjacent sensing units in a middle area is smaller than a second spacing between adjacent sensing units in an edge area; at least one temperature sensing unit and at least one pressure sensing unit are distributed in each array sub-area of ​​the ion capacitive thin film sensor.

5. A battery status detection method based on expansion pressure, characterized in that: The method is applied to the lithium-ion battery assembly according to any one of claims 1 to 4, comprising: Acquire capacitance values ​​collected by multiple sensing units on multiple ion capacitive thin film sensors in real time; The expansion pressure value at the corresponding position on the battery cell is calculated based on the capacitance value to form an expansion pressure matrix P of the battery assembly at each time. The element p in the expansion pressure matrix P is ij represents the expansion pressure value at the jth position on the i-th battery cell; Based on the expansion pressure matrix P at each moment, a curve of the expansion pressure at each position in each battery cell changing with time is formed; It is analyzed whether the change trends of the change curves at different positions in the same battery cell are consistent. When the change trends are inconsistent, it is determined that the battery cell is abnormal.

6. The method according to claim 5, characterized in that The analyzing whether the change trends of the change curves at different positions in the same battery cell are consistent includes: Perform a slope line fitting on each change curve to obtain the slope of the fitted slope line; The differences between the slopes corresponding to the change curves at different positions in the same battery cell are compared. When each difference is within a preset difference range, it is determined that the change trends are consistent; otherwise, it is determined that the change trends are inconsistent.

7. The method according to claim 5, characterized in that The analyzing whether the change trends of the change curves at different positions in the same battery cell are consistent includes: Based on the change curves of different positions in the same battery cell, the charge and discharge times of the corresponding positions are identified; Analyze whether the charge and discharge times at different locations in the same battery cell are consistent.

8. The method according to claim 7, characterized in that The method of identifying the charge and discharge times of corresponding positions based on the change curves of different positions in the same battery cell includes: The number of curve segments in which the expansion pressure value first increases and then decreases in the variation curve is identified, and the number of curve segments is used as the number of charge and discharge times.

9. The method according to claim 5, characterized in that The method further comprises: It is analyzed whether the change trends of the change curves of different battery cells at the same position are consistent. When the change trends are inconsistent, it is determined that the battery cell is abnormal.

10. The method according to claim 9, characterized in that The analyzing whether the change trends of the change curves of different battery cells at the same position are consistent includes: Based on the change curves of different battery cells at the same position, the charge and discharge times of the corresponding position are identified, and whether the charge and discharge times of different battery cells at the same position are consistent is analyzed.

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