Secondary battery, secondary battery abnormal expansion detection method, and electric device

Abstract

The application provides a secondary battery, a secondary battery abnormal expansion detection method and an electric device. The secondary battery comprises a battery cell unit, the battery cell unit comprises a battery cell and a limiting frame, the limiting frame is provided with a limiting groove, the battery cell is arranged in the limiting groove, an equal force plate and an elastic limiting piece are arranged in a laminated manner between the battery cell and the groove bottom of the limiting groove, and the equal force plate is arranged between the battery cell and the elastic limiting piece. The elastic limiting piece comprises an elastic section capable of being compressed and reset and mounting roots located at two ends of the elastic section and used for being connected with the limiting frame. In the secondary battery, the elastic limiting piece can solve the problem that the battery cell is excessively pressed due to volume expansion in the charging and discharging process, prevent the battery from being damaged, automatically recover the contraction gap, solve the problem that the battery cell is loose in contact and the electrical connection reliability is reduced when the volume is contracted, and maintain stable contact pressure.

Description

Technical Field

[0001] This invention relates to the field of secondary battery technology, and more specifically, to secondary batteries, a method for detecting abnormal expansion of secondary batteries, and an electrical device for such detection. Background Technology

[0002] Power battery packs are gradually evolving from the traditional "cell to module" structure to the "cell to pack" structure to improve the volumetric energy density of power battery packs.

[0003] In CTP (Computer-to-Pack) structures, pouch cells are widely used due to their advantages such as flexible shape, light weight, and high energy density. However, pouch cells undergo significant volume changes during charging and discharging, which become even more pronounced after the electrolyte is changed from liquid to solid electrolyte. During charging, the battery expands, increasing internal pressure and causing deformation of the aluminum-plastic film, potentially leading to internal short circuits. During discharging, the battery contracts, creating gaps between cells and increasing contact resistance, resulting in localized overheating. Further thermal runaway can occur, with a sudden increase in internal pressure releasing gas, causing the battery casing to collapse. This collapse can lead to cell displacement and detachment, causing secondary short circuits. Ensuring reliable positioning and electrical connection stability of individual cells under these dynamic conditions while preventing damage from excessive clamping has become a pressing technical challenge in this field. Summary of the Invention

[0004] The present invention aims to provide a secondary battery, a method for detecting abnormal expansion of a secondary battery, and an electrical device that can reduce the pressure on the battery cell when the cell expands and suppress the increase of internal porosity and thus the increase of contact resistance when the cell discharges.

[0005] The embodiments of the present invention can be implemented as follows: In a first aspect, the present invention provides a secondary battery, including a cell unit, the cell unit including a cell and a limiting frame, the limiting frame being provided with a limiting groove, the cell being disposed in the limiting groove, and a force equalizing plate and an elastic limiting member being stacked between the cell and the bottom of the limiting groove, the force equalizing plate being disposed between the cell and the elastic limiting member; The elastic limiting member includes an elastic segment that can be compressed and reset, and mounting roots located at both ends of the elastic segment for connection with the limiting frame.

[0006] In an optional embodiment, an installation groove is provided on the side wall of the limiting groove at a position corresponding to the installation root, the installation root is inserted into the installation groove, and a gap is provided between the installation root and the bottom of the installation groove, and the thickness of the installation root is less than the width of the installation groove. And / or, the elastic segment is selected from a corrugated plate; And / or, the secondary battery is selected from at least one of solid-state batteries and liquid batteries.

[0007] In an optional embodiment, the limiting frame is provided with an exhaust hole that connects the inside of the limiting groove with the outside of the limiting frame.

[0008] In an optional embodiment, the peak on the side of the wave plate closer to the equalizing plate is taken as the wave crest, and the peak on the side of the wave plate farther from the equalizing plate is taken as the wave trough, wherein the radius of curvature of the wave crest is greater than the radius of curvature of the wave trough.

[0009] In an optional embodiment, the portion of the mounting root located within the mounting groove is provided with an anti-detachment limiting part.

[0010] In an optional embodiment, there are two or more battery cell units, which are stacked sequentially to form a battery cell module; And / or, the secondary battery further includes two end plates and a driving device capable of adjusting the distance between the two end plates, the two end plates being respectively disposed on both sides of the cell module.

[0011] In an optional embodiment, the battery cell module is provided with a controller, an alarm, a pressure sensor for detecting the pressure on the battery cell and / or a hydrogen sulfide gas sensor for detecting the hydrogen sulfide concentration in the battery cell module, and a controller capable of collecting and analyzing the data from the pressure sensor and / or the hydrogen sulfide gas sensor, wherein the controller is signal-connected to the alarm.

[0012] In an optional embodiment, the pressure sensor is selected from pressure film sensors; And / or, the sensor is disposed between the bottom of the limiting groove and the force equalizing plate.

[0013] Secondly, the present invention provides a method for detecting abnormal expansion of a secondary battery as described in the foregoing embodiments, comprising: Step S1: Set pressure threshold N1 and hydrogen sulfide gas concentration thresholds C1 and C2, where threshold C2 > threshold C1; Step S2: Read the pressure P from the pressure sensor and the concentration C from the hydrogen sulfide gas sensor; Step S3: If P < threshold N1 and C > threshold C1, then the alarm will issue an alarm for aluminum-plastic film breakage. If P ≥ threshold N1, the drive device is activated to increase the distance between the two end plates until P < threshold N1, and an abnormal expansion alarm is issued. If P ≥ threshold N1, the distance between the two end plates has reached its maximum value and cannot be increased further, and C ≥ threshold C2, then a pressure burst warning is issued and the gas is vented. If P ≥ threshold N1, the distance between the two end plates has reached its maximum value and cannot be increased further, and threshold C2 ≥ C ≥ threshold C1, then a mechanical abnormality alarm will be issued. If P ≥ threshold N1, the distance between the two end plates has reached its maximum value and cannot be increased further, and C < threshold C1, then an alarm for abnormal expansion of non-hydrogen sulfide gas will be issued.

[0014] Thirdly, the present invention provides an electrical device comprising a secondary battery as described in any of the foregoing embodiments.

[0015] The beneficial effects of the secondary battery, the method for detecting abnormal expansion of the secondary battery, and the electrical device provided in the embodiments of the present invention include: The secondary battery of this application incorporates an elastic limiting component. The elastic segment of this component can be compressed under external force and recovers or partially recovers its deformation after the force is removed or reduced. This allows the elastic limiting component to initially position the battery cell while also adapting to changes in cell volume. Even after the cell's volume shrinks due to gas dissipation, it still functions as a limiting element. This addresses the problem of excessive compression of the cell during charging and discharging due to volume expansion, preventing battery damage. It also automatically fills the shrinkage gap, resolving issues of loose contact and decreased electrical connection reliability during cell volume contraction, maintaining stable contact pressure. Furthermore, a force-equalizing plate is placed between the battery cell and the elastic limiting component, which helps to distribute the force of the elastic limiting component relatively evenly to the battery cell. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is an exploded view of a solid-state battery provided in this application; Figure 2 This is a front view of a flexible limiting member provided in this application; Figure 3 This is a top view of an elastic limiting member provided in this application; Figure 4 This is a schematic diagram of an installation groove within a limiting frame provided in this application; Figure 5 This is a schematic diagram of a battery cell module provided in this application; Figure 6 This is a flowchart of a process for detecting abnormal expansion of a secondary battery provided in this application; Figure 7 This is a flowchart of a process for detecting abnormal expansion of a secondary battery provided in this application; Figure 8 This is a schematic diagram of the structure of an electrical device.

[0018] Diagram: 10-Battery cell; 20-Elastic limiting component; 30-Limiting frame; 40-Force equalizing plate; 50-Thin film pressure sensor; 11-Drive device; 12-End plate; 201-Mounting root; 202-Elastic section; 203-Crest; 204-Trough; 301-Left tank wall; 302-Right tank wall; 303-Upper tank wall; 304-Lower tank wall; 305-Exhaust hole; 306-Limiting groove; 307-Mounting groove. Detailed Implementation

[0019] Research has found that lithium-ion cells undergo periodic volume deformation during charge-discharge cycles, an inherent physical change resulting from lithium insertion / extraction in the electrode materials. When the battery is charging, a large number of lithium ions are inserted into the lattice of the negative electrode material, causing the electrode to expand as a whole. This compresses the internal space of the cell, leading to a continuous increase in internal pressure. When the outer aluminum-plastic film packaging of a pouch cell is subjected to pressure, it bulges outward and deforms locally, stretching and thinning the film. This causes the internal structures, such as the electrodes and separator, to shift under stress. Sharp tabs or coating debris can easily puncture the separator, leading to internal short circuits within the cell and posing a risk of leakage and fire.

[0020] When a battery enters the discharge phase, lithium ions are released from the negative electrode and flow back to the positive electrode, causing the electrodes to shrink and the overall volume of the cell to decrease. Gaps appear between the previously tightly fitted cells, reducing the adhesion between the electrodes and the current collector and active materials, and significantly increasing the interfacial contact resistance. When current passes through the high-resistance region, Joule heating is generated, forming localized hot spots. Over long-term cycling, these hot spots accumulate and can easily induce thermal runaway accidents.

[0021] Once thermal runaway occurs, the decomposition of the electrolyte and active materials inside the battery cell rapidly generates a large amount of high-temperature gas, causing a sudden surge in internal pressure. The gas then breaks through the sealing structure and leaks outward. After the internal pressure drops sharply, the aluminum-plastic film loses its support, causing the casing to collapse. The electrode assembly inside the battery cell loses its restraint, leading to problems such as overall displacement and delamination. The misaligned electrodes scrape against and contact each other, forming a more dangerous secondary short circuit and exacerbating the spread of thermal runaway.

[0022] During the operation of a vehicle or energy storage system, the battery cells continuously expand and contract repeatedly, operating under dynamic stress conditions for extended periods. Insufficient clamping force during assembly can cause cell movement, disrupting electrical connection stability and leading to poor contact and abnormal voltage drops. Conversely, excessive clamping force leaves no buffer space during the charging expansion phase, causing damage to the aluminum-plastic film and electrode sheets through rigid compression, accelerating failure. Achieving a balance between precise cell positioning and reliable electrical connections under dynamic deformation conditions, while simultaneously providing expansion buffer space and preventing damage from excessive clamping, is a core technical challenge that urgently needs to be overcome in the energy storage and power battery fields.

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0025] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0026] In the description of this invention, it should be noted that if terms such as "upper," "lower," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed, they are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0027] Furthermore, the terms "first" and "second" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0028] It should be noted that, where there is no conflict, the features in the embodiments of the present invention can be combined with each other.

[0029] This invention provides a secondary battery, including a cell 10 unit. The cell 10 unit includes a cell 10 and a limiting frame 30. The limiting frame 30 is provided with a limiting groove 306. The cell 10 is disposed in the limiting groove 306. A force equalizing plate 40 and an elastic limiting member 20 are stacked between the cell 10 and the bottom of the limiting groove 306. The force equalizing plate is disposed between the cell and the elastic limiting member. The elastic limiting member 20 includes an elastic segment 202 that can be compressed and reset, and mounting roots 201 located at both ends of the elastic segment 202 for connection with the limiting frame 30.

[0030] In this application, an elastic limiting member 20 is provided in the secondary battery. The elastic segment 202 of the elastic limiting member 20 can be compressed after being subjected to external force, and can recover or partially recover its deformation after the external force is removed or reduced. This allows the elastic limiting member 20 to achieve initial positioning of the battery cell 10 while also adapting to changes in the volume of the battery cell 10. Even after the volume of the battery cell 10 shrinks due to venting, it can still perform the limiting function of the battery cell 10. This solves the problem of excessive compression of the battery cell 10 due to volume expansion during charging and discharging, preventing battery damage. It can also automatically fill the shrinkage gap, solving the problem of loose contact and decreased electrical connection reliability when the volume of the battery cell 10 shrinks, and maintaining stable contact pressure. Furthermore, it can also retain its positioning function after the battery cell 10 collapses due to venting, thereby solving the problem of collapse and detachment after thermal runaway venting, and preventing secondary short circuits and the spread of thermal runaway. In the secondary battery of this application, a force equalizing plate 40 is provided between the cell 10 and the elastic limiting member 20, which is beneficial to transmit the force of the elastic limiting member 20 to the cell 10 relatively evenly.

[0031] It should be noted that in the initial state of the battery cell 10 unit, the elastic limiting member 20 can withstand a certain pressure within the bearing capacity of the battery cell 10 and be partially compressed. This allows the elastic segment 202 to be further compressed when the battery cell 10 expands, and the elastic segment 202 to recover some deformation when the battery cell 10 discharges, thus providing a positioning function for the battery cell 10. At the same time, the remaining unrecovered deformation can also act on the battery cell 10, applying pressure to the battery cell 10, causing the pores in the battery cell 10 to contract under pressure, thereby suppressing the problem of decreased electrical connection reliability caused by increased gaps, and maintaining stable contact pressure. In an optional embodiment, a mounting groove 307 is provided on the side wall of the limiting groove 306 corresponding to the mounting root 201. The mounting root 201 is inserted into the mounting groove 307, and a gap is provided between the mounting root 201 and the bottom of the mounting groove 307. The thickness of the mounting root 201 is less than the width of the mounting groove 307. The mounting root 201 is inserted into the mounting groove 307, and the mounting groove 307 is used to limit the elastic limiting member 20. At the same time, a gap is provided between the mounting root 201 and the bottom of the mounting groove 307, and the thickness of the mounting root 201 is less than the width of the mounting groove 307, so that the elastic limiting member 20 has a certain amount of movement space in the direction perpendicular to the force equalizing plate, which can adapt to the change in the volume of the battery cell 10.

[0032] It should be noted that the expansion and contraction of the battery cell 10 will cause deformation in the direction perpendicular to the force equalizing plate 40. Therefore, the elastic limiting member 20 may move in the direction perpendicular to the force equalizing plate 40. Therefore, in this application, the thickness of the mounting root 201 is set to be less than the width of the mounting groove 307. In addition, when the elastic segment 202 is subjected to an external force in the direction perpendicular to the force equalizing plate 40, the dimensions of the plane where the elastic limiting member 20 is located may also change. For example, when the external force on the elastic segment 202 in the direction perpendicular to the force equalizing plate 40 increases, the thickness of the elastic segment 202 will decrease and the area will increase, thereby causing the two mounting roots 201 to move to both ends. Therefore, a gap is provided between the mounting root 201 and the bottom of the mounting groove 307 to avoid the elastic segment 202 being squeezed by the mounting roots 201 at both ends, which would affect its thickness change and thus weaken its ability to adapt to changes in the volume of the battery cell 10.

[0033] It should be noted that, in order to disperse pressure, the force equalizing plate should at least cover the elastic section 202. In some embodiments, the force equalizing plate can refer to the elastic limiting member 20 and be set with an installation root, and be installed in the installation groove 307 together with the elastic limiting member. However, like the elastic limiting member, a gap needs to be set between it and the bottom of the installation groove, and there needs to be a certain amount of movement space in the direction perpendicular to the force equalizing plate.

[0034] In an optional embodiment, the elastic segment 202 is selected from a corrugated plate; In an optional embodiment, the secondary battery is selected from at least one of solid-state batteries and liquid batteries. In particular, for liquid batteries, the presence of the stress equalizing plate 40 is of greater significance in avoiding stress concentration.

[0035] In an optional embodiment, the limiting frame 30 is provided with an exhaust hole 305 that connects the inside of the limiting groove 306 with the outside of the limiting frame. When sulfur dioxide gas generated in the battery cell 10 leaks, sulfur dioxide can be discharged through the exhaust hole 305, which plays a role in relieving pressure and controlling risks, preventing vicious chain failures, and reducing the risk of explosion and secondary short circuit.

[0036] In an optional embodiment, the peak of the wave plate closer to the force equalizing plate 40 is designated as the wave crest 203, and the peak of the wave plate farther from the force equalizing plate 40 is designated as the wave trough 204. The radius of curvature of the wave crest 203 is larger than that of the wave trough 204. The larger radius of curvature of the wave crest 203 helps to disperse the force between the elastic limiting member 20 and the force equalizing plate 40, thereby making the force transmitted to the battery cell 10 more uniform. The smaller radius of curvature of the wave trough 204 helps to increase the deformation of the elastic limiting member 20, thereby improving its self-adaptive capability.

[0037] In an optional embodiment, the portion of the mounting root 201 located within the mounting groove 307 is provided with an anti-detachment limiting portion.

[0038] In an optional embodiment, there are two or more battery cell 10 units, and the two or more battery cell 10 units are stacked sequentially to form a battery cell 10 module; In an optional embodiment, the secondary battery further includes two end plates 12 and a driving device 11 capable of adjusting the distance between the two end plates 12. The two end plates 12 are respectively disposed on both sides of the cell 10 module. When it is necessary to reduce the pressure on the cell 10, the distance between the two end plates 12 is increased by the driving device 11; when it is necessary to increase or maintain the pressure on the cell 10, the distance between the two end plates 12 is decreased by the driving device 11.

[0039] It should be noted that the drive device 11 can be a clamping device. When it is necessary to increase the pressure on the battery cell 10, the clamping device is loosened, and when it is necessary to reduce the pressure on the battery cell 10, the clamping device is clamped.

[0040] In an optional embodiment, the battery cell 10 module is equipped with a controller, an alarm, a pressure sensor for detecting the pressure exerted on the battery cell 10, and / or a hydrogen sulfide gas sensor for detecting the hydrogen sulfide concentration within the battery cell 10 module, as well as a controller capable of collecting and analyzing data from the pressure sensor and / or the hydrogen sulfide gas sensor. The controller is signal-connected to the alarm. The controller compares the collected data with a preset threshold and activates the drive device 11 or the corresponding alarm through a pre-set program.

[0041] In an optional embodiment, the pressure sensor is selected from pressure film sensors; In an optional embodiment, the sensor is disposed between the bottom of the limiting groove 306 and the force equalizing plate 40.

[0042] This invention also provides a method for detecting abnormal expansion of a secondary battery as described in the foregoing embodiments, comprising: Step S1: Set pressure threshold N1 and hydrogen sulfide gas concentration thresholds C1 and C2, where threshold C2 > threshold C1. It should be noted that in this embodiment, threshold N1 refers to the maximum pressure the battery cell can withstand. If the pressure exceeds threshold N1, the battery cell may be damaged due to excessive pressure. Threshold C1 refers to the concentration of hydrogen sulfide exceeding the normal level. For example, if the normal concentration of hydrogen sulfide in the battery is 0, then threshold C1 is the detection line of the hydrogen sulfide sensor. Threshold C2 is the maximum concentration of hydrogen sulfide that the battery can withstand; exceeding this concentration may affect safe production. Step S2: Read the pressure P from the pressure sensor and the concentration C from the hydrogen sulfide gas sensor; Step S3: If P < threshold N1 and C > threshold C1, then the alarm will issue an alarm for aluminum-plastic film breakage. If P ≥ threshold N1, then the drive device 11 is activated to increase the distance between the two end plates 12 until P < threshold N1, and an abnormal expansion alarm is issued. If P ≥ threshold N1, the distance between the two end plates 12 has reached its maximum value and cannot be increased further, and C ≥ threshold C2, then a pressure burst warning is issued and the gas is vented. If P ≥ threshold N1, the distance between the two end plates 12 has reached its maximum value and cannot be increased further, and threshold C2 ≥ C ≥ threshold C1, then a mechanical abnormality alarm will be issued. If P ≥ threshold N1, the distance between the two end plates 12 has reached its maximum value and cannot be increased further, and C < threshold C1, then an alarm for abnormal expansion of non-hydrogen sulfide gas will be issued.

[0043] For example, one embodiment of this application provides a solid-state battery, including an elastic limiting member 20, a limiting frame 30, a force equalizing plate 40, a left groove wall 301, a right groove wall 302, an upper groove wall 303, a lower groove wall 304, an exhaust hole 305, a limiting groove 306, and a mounting groove 307, wherein the left groove wall 301, the right groove wall 302, the upper groove wall 303, and the lower groove wall 304 form the limiting groove 306.

[0044] like Figure 1 As shown, the limiting frame 30 can be made of alloy material or injection molded material, and is integrally formed into a hollow rectangular structure with a limiting groove 306. Specifically, mounting grooves 307 are formed inside the left groove wall 301 and the right groove wall 302, forming a slot shape for fixing the elastic limiting member 20. The upper groove wall 303 and the lower groove wall 304 are used to limit the position of the battery cell 10, so that the position of the battery cell 10 is fixed. Since hydrogen sulfide gas is heavier than air, at least one through hole and an exhaust hole 305 can be formed in the lower groove wall 304. The shape or number of through holes can be set as needed. In some cases, through holes can also be set in other positions of the limiting groove.

[0045] Direct contact between the battery cell 10 and the elastic segment 202 may cause uneven pressure distribution in the battery cell 10. Excessive local pressure can easily cause the aluminum-plastic film to rupture. Therefore, a force equalizing plate 40 is inserted between the elastic limiting member 20 and the large surface of the battery cell 10 to ensure that the force is evenly distributed throughout the battery cell 10. The force equalizing plate 40 needs to be able to withstand the pressure during the assembly and operation of the battery cell 10, and the material can be plastic or metal.

[0046] like Figure 2 As shown, the elastic limiting member 20 can be made of alloy material or injection molded material, and its surface can be coated with an insulating coating. It is formed into a shape with compressible resilience as the elastic segment 202. For example, the cross-section of the elastic segment 202 is wavy, and the overall shape is elongated. Alternating crests 203 and troughs 204 are formed on the elastic segment 202. The shapes of the crests 203 and troughs 204 can be arc-shaped, square, zigzag, or other shapes. For example, the crest 203 is arc-shaped, and the trough 204 is arc-shaped. The radius of the crest 203, the radius of the trough 204, and the wave height can be selected to match typical models. For example, the elastic limiting member 20 has thickened, straight flanges at both ends as mounting roots 201, facilitating the installation and fixing of the elastic limiting member 20.

[0047] like Figure 3 As shown, the radii of the crests 203 and troughs 204 in the elastic segment 202 of the elastic limiting member 20 can be different. Because the battery cell 10 directly contacts the force equalizing plate 40 and indirectly contacts the crests 203, the radius of the crests 203 is set to be larger, which is beneficial for the battery cell 10 to be evenly stressed and to protect the aluminum-plastic film. At the same time, (all crests 203 have the same radius), because the battery cell 10 does not indirectly contact the troughs 204, and the troughs 204 contact the limiting grooves 306 of the limiting frame 30, the radius of the troughs 204 is set to be smaller, which improves the local stiffness and ensures the stability of the spring sheet. For example, the shape and size of the crests 203 and the shape and size of the troughs 204 in the same elastic limiting member 20 are exactly the same.

[0048] like Figure 4As shown, the mounting grooves 307 formed in the left groove wall 301 and right groove wall 302 serve as locking slots. The elastic limiting member 20 is longitudinally engaged in the mounting grooves 307 of the left and right groove walls 302 to prevent the elastic limiting member 20 from coming out of the groove wall. The elastic segment 202 of the elastic limiting member 20 faces the side of the battery cell 10, and contracts or rebounds in response to changes in the volume of the battery cell 10. When machining the mounting root 201 of the elastic limiting member 20, the mounting groove 307 can also be machined into a T-shaped groove, dovetail groove, or other shapes, while matching the shape of the mounting root 201 with the shape of the mounting groove 307. These shapes have stronger pull-out resistance than a straight mounting groove 307, making them suitable for applications with high vibration. For example, an elastic buffer strip can be provided at one end of the mounting root 201 near the bottom of the mounting groove 307 to fill the gap between the mounting groove 307 and the mounting root 201, thereby preventing the elastic limiting member 20 from shaking under force and affecting the battery, and improving stability. This application shows that one elastic limiting member 20 limits the battery cell 10, or multiple elastic limiting members 20 arranged in an array can be used to limit the battery cell 10, that is, a whole surface elastic limiting member 20 is divided into multiple strip elastic limiting members 20, which achieves a more uniform pressure distribution for large battery cells 10.

[0049] During initial assembly, the elastic limiting member 20 is compressed to provide corresponding preload force, eliminating assembly gaps. When the cell 10 expands in volume during charging or at high temperatures, the large surface of the cell 10 presses outward against the elastic limiting member 20, flattening the wavy elastic segment 202. Simultaneously, the elastic limiting member 20 generates rebound stress to absorb the expansion force of the cell 10, inhibiting excessive expansion. When the cell 10 contracts in volume during discharging or at low temperatures, the elastic potential energy of the elastic limiting member 20 is released, generating a rebound force. The crest 203 adheres tightly to the large surface of the cell 10, filling the gaps created by the contraction. When one of the cells 10 experiences thermal runaway and generates gas, the released gas is discharged through the vent 305 at the bottom of the lower tank wall 304. Simultaneously, the cell 10's battery casing collapses, and its thickness decreases sharply. At this time, the elastic limiting member 20 can recover its deformation, filling the gaps created by the collapse and keeping the cell 10 in its original position.

[0050] Figure 5 A schematic diagram of a battery cell 10 module is provided. The battery cell 10 module adopts the structure of battery cell 10-elastic limiting member 20-limiting frame-elastic limiting member 20-battery cell 10. An end plate 12 and a driving device 11 are arranged on the outside of the stacked battery cells 10. At the same time, a pressure film sensor 50 is arranged between the stacked battery cells 10 to detect the pressure status between the battery cells 10 in real time. Figure 5Two pressure sensors are arranged between the displayed battery cells 10. The number and arrangement of the thin-film pressure sensors 50 can be changed as needed. The pressure detection values ​​of the thin-film pressure sensors 50 are used to determine whether the battery cell 10 has abnormally expanded and whether further measures should be taken. It should be noted that when multiple pressure sensors are arranged within the battery cell 10 module, the highest pressure sensor detection value P used in the abnormal expansion detection process of the secondary battery can be taken. For example, if two pressure sensors are arranged with detection values ​​P1 and P2 respectively, if P1 > P2, then the obtained detection value P is P1. In addition, this application arranges a hydrogen sulfide gas sensor (not shown in the figure) on the outside of the battery cell 10 module to monitor the concentration of hydrogen sulfide gas in the battery pack in real time. Simultaneously, two threshold values ​​C1 and C2 are set for the hydrogen sulfide gas concentration within the module, where C2 > C1.

[0051] A drive device 11 is arranged on the outside of the battery cell 10 module. The drive device 11 provides a restraining force on the battery cells 10 to ensure good interface contact between the battery cells 10. Under normal circumstances, the expansion of the battery cells 10 in the module is absorbed by the elastic element, and the drive device 11 is in a standby state. That is, when the battery cells 10 undergo normal charge and discharge cycles and their volume expands and contracts, the drive device 11 does not work and is only in a standby state. When the drive device 11 adjusts the restraining force of the module, it is generally assumed that the elastic element has reached its own compression limit and cannot cope with the continued expansion of the battery cells 10, that is, the battery cells 10 enter an abnormal expansion state. At this time, the drive device 11 moves in the opposite direction to the stacking direction of the battery cells 10, reducing the restraining force between the battery cells 10, releasing the squeezing pressure between the battery cells 10, providing more expansion space for the battery cells 10, and preventing the aluminum-plastic film of the battery cells 10 from being crushed. The distance that the drive device 11 moves is D, and the maximum distance that the module can support the movement of the drive unit is Dmax. When the drive unit 11 moves to give the battery cell 10 more room to expand, the limiting structure can ensure that the battery cell 10 maintains a stable position in directions other than the direction of movement within the module to the greatest extent.

[0052] When the pressure sensor does not detect abnormal expansion, the following methods can be used: Figure 6The process is shown below. At this time, the drive device 11 is not working, and the position of the battery cell 10 does not change. The state of the aluminum-plastic film of the battery cell 10 is determined by detecting the concentration of hydrogen sulfide gas inside the battery module. In step S61, the thin-film pressure sensor 50 collects the pressure state between the battery cells 10. In step S62, if the pressure sensor value P < N1, it indicates that the battery cell 10 has not experienced abnormal expansion. At this time, proceed to step S63 to obtain the value C of the hydrogen sulfide sensor. When C > the threshold C1, it indicates that there is hydrogen sulfide gas leakage inside the battery pack. At this time, the battery cell 10 has no abnormal expansion but there is hydrogen sulfide gas leakage, indicating that the aluminum-plastic film between the battery cells 10 is ruptured, and the sulfide solid electrolyte inside the aluminum-plastic film is exposed to the air environment. It is highly likely that it will react with water vapor in the air to generate a large amount of hydrogen sulfide gas, threatening personnel safety. At this time, proceed to step S65 to trigger a mechanical abnormality alarm and take subsequent measures.

[0053] When the pressure sensor detects abnormal expansion, it uses, for example Figure 7 The process is shown below. In step S71, the pressure sensor value P and the hydrogen sulfide gas sensor detection value C are obtained. When the pressure detection value P ≥ N1, it indicates that the battery cell 10 is abnormally expanding. At this time, the process proceeds to step S73, where it is determined whether the distance D moved by the drive device 11 has reached the maximum distance Dmax that supports the movement of the drive unit within the module.

[0054] If D is less than Dmax, it indicates that there is still space within the module to support the movement of the drive unit 11. At this point, step S74 is initiated, where the drive unit moves in the opposite direction to the stacking of the battery cells 10. This actively relaxes the elastic element, increasing the expansion space of the battery cells 10 and triggering an alarm for any abnormal expansion of the battery cells 10. This step alleviates the stress on the battery cells 10, preventing excessive pressure during abnormal expansion and increasing the risk of aluminum-plastic film rupture. Simultaneously, because the battery cells 10 are in an abnormally expanded state, an abnormal expansion alarm is implemented to protect vehicle safety.

[0055] If the drive device 11 has moved to its maximum distance and there is no space within the module to support its movement, it indicates that the cell 10 is still under excessive pressure even after being relaxed to its limit. At this point, proceed to step S75 to determine the hydrogen sulfide gas concentration within the module. If the hydrogen sulfide gas sensor detects a value C ≥ threshold C2, it indicates that the hydrogen sulfide concentration within the battery module is severely excessive, potentially threatening personnel safety. Proceed to step S76 to determine that a large amount of hydrogen sulfide gas has been generated inside the cell 10, causing the aluminum-plastic film to expand until it ruptures. At this point, open the vent 305 to release the hydrogen sulfide gas from the battery module, reducing its concentration. If the hydrogen sulfide gas sensor detection value C is less than the threshold C2, the process proceeds to step S77 to determine if the hydrogen sulfide gas sensor detection value C is greater than the threshold C1. If it is greater than C1, the battery cell 10 has abnormally expanded and a certain concentration of hydrogen sulfide gas has been detected inside the module. This indicates that hydrogen sulfide gas has been generated inside the aluminum-plastic film and may burst later, releasing a large amount of hydrogen sulfide gas. The process proceeds to step S78 to trigger a mechanical abnormality alarm and take subsequent measures. If C is less than C1, it indicates that the battery cell 10 has abnormally expanded, but the concentration of hydrogen sulfide gas inside the module has not exceeded the standard. In this case, the cause of the abnormal expansion of the battery cell 10 due to the generation of hydrogen sulfide gas can be ruled out. However, the process still needs to proceed to step S79 to trigger a non-hydrogen sulfide gas abnormal expansion alarm.

[0056] This invention does not impose any particular limitation on the shape of the secondary battery; it can be cylindrical, square, or any other arbitrary shape. It is understood that the terminals (or electrode posts) can be arranged on the same side of the battery or on two opposite ends of the battery; this invention does not impose any limitation on this.

[0057] In some embodiments, the battery includes a casing, within which electrode assemblies are encapsulated. The battery may contain one or more electrode assemblies, which can be selected by those skilled in the art according to specific practical needs.

[0058] The present invention also provides an electrical device, including the secondary battery described in any of the foregoing embodiments.

[0059] The electrical device includes the aforementioned secondary battery. The secondary battery can be used as a power source for the electrical device or as an energy storage unit for it. The electrical device may include mobile devices (typically mobile phones, laptops, etc.), electric vehicles (typically pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, or energy storage systems.

[0060] Figure 8This is an example of an electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the secondary battery for this device, a battery pack or battery module can be used.

[0061] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A secondary battery, characterized in that, The device includes a battery cell unit, which includes a battery cell and a limiting frame. The limiting frame is provided with a limiting groove, and the battery cell is disposed in the limiting groove. A force equalizing plate and an elastic limiting member are stacked between the battery cell and the bottom of the limiting groove, and the force equalizing plate is disposed between the battery cell and the elastic limiting member. The elastic limiting member includes an elastic segment that can be compressed and reset, and mounting roots located at both ends of the elastic segment for connection with the limiting frame.

2. The secondary battery according to claim 1, characterized in that, The limiting groove has an installation groove on its side wall corresponding to the installation root. The installation root is inserted into the installation groove, and there is a gap between the installation root and the bottom of the installation groove. The thickness of the installation root is less than the width of the installation groove. And / or, the elastic segment is selected from a corrugated plate; And / or, the secondary battery is selected from at least one of solid-state batteries and liquid batteries.

3. The secondary battery according to claim 1, characterized in that, The limiting frame is provided with an exhaust hole that connects the inside of the limiting groove with the outside of the limiting frame.

4. The secondary battery according to claim 2, characterized in that, The peak on the side of the wave plate closer to the equalizing plate is taken as the wave crest, and the peak on the side of the wave plate farther from the equalizing plate is taken as the wave trough. The radius of curvature of the wave crest is greater than the radius of curvature of the wave trough.

5. The secondary battery according to claim 2, characterized in that, The portion of the mounting root located within the mounting groove is provided with an anti-detachment limiting part.

6. The secondary battery according to claim 1, characterized in that, The battery cell unit has two or more units, and the two or more battery cell units are stacked in sequence to form a battery cell module; And / or, the secondary battery further includes two end plates and a driving device capable of adjusting the distance between the two end plates, the two end plates being respectively disposed on both sides of the cell module.

7. The secondary battery according to claim 1, characterized in that, The battery cell module is equipped with a controller, an alarm, a pressure sensor for detecting the pressure on the battery cell and / or a hydrogen sulfide gas sensor for detecting the hydrogen sulfide concentration in the battery cell module, and a controller capable of collecting and analyzing data from the pressure sensor and / or the hydrogen sulfide gas sensor. The controller is connected to the alarm.

8. The secondary battery according to claim 7, characterized in that, The pressure sensor is selected from a pressure thin-film sensor. And / or, the sensor is disposed between the bottom of the limiting groove and the force equalizing plate.

9. A method for detecting abnormal expansion of a secondary battery according to any one of claims 1-8, characterized in that, include: Step S1: Set pressure threshold N1 and hydrogen sulfide gas concentration thresholds C1 and C2, where threshold C2 > threshold C1; Step S2: Read the pressure P from the pressure sensor and the concentration C from the hydrogen sulfide gas sensor; Step S3: If P < threshold N1 and C > threshold C1, then the alarm will issue an alarm for aluminum-plastic film rupture. If P ≥ threshold N1, the drive device is activated to increase the distance between the two end plates until P < threshold N1, and an abnormal expansion alarm is issued. If P ≥ threshold N1, the distance between the two end plates has reached its maximum value and cannot be increased further, and C ≥ threshold C2, then a pressure burst warning is issued and the gas is vented. If P ≥ threshold N1, the distance between the two end plates has reached its maximum value and cannot be increased further, and threshold C2 ≥ C ≥ threshold C1, then a mechanical abnormality alarm will be issued. If P ≥ threshold N1, the distance between the two endplates has reached its maximum value and cannot be increased further, and C < threshold C1, then an alarm for abnormal expansion of non-hydrogen sulfide gas will be issued.

10. An electrical appliance, characterized in that, Includes the secondary battery as described in any one of claims 1-8.

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