Battery cell, battery, and electric device

Abstract

A battery cell, a battery, and an electric device. The battery cell comprises: a casing, a pressure relief mechanism and an electrode assembly, wherein the casing is provided with a first wall and a second wall, which are adjacent to and connected to each other; the pressure relief mechanism is arranged on the first wall; and the electrode assembly is arranged in the casing and is provided with a first portion and a second portion, which are arranged in sequence in a first direction, the first portion and the second portion each comprising a plurality of anode electrode sheet layers and a plurality of cathode electrode sheet layers, the plurality of anode electrode sheet layers and the plurality of cathode electrode sheet layers being alternately stacked one by one in the first direction, the second portion being arranged between the first portion and the second wall, the distance between the cathode electrode sheet layers of the second portion and the first wall being greater than the distance between the cathode electrode sheet layers of the first portion and the first wall, and the first direction being perpendicular to the second wall.

Description

Battery cells, batteries and electrical devices Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a battery cell, a battery, and an electrical device. Background Art

[0002] In recent years, new energy vehicles have experienced rapid development. In the electric vehicle sector, batteries, as the power source of electric vehicles, play an irreplaceable and important role. As core components of new energy vehicles, batteries have high requirements in terms of both energy density and reliability.

[0003] In related technologies, a battery includes multiple battery cells. The battery cells generate a large amount of heat during continuous charging and discharging. Generally, a pressure relief mechanism is provided in the battery cells to relieve pressure when the battery cells experience thermal runaway. However, in some technologies, the pressure relief mechanism is easily pulled and cracked, affecting the reliability of the battery cells.

[0004] Summary of the Invention

[0005] The present application proposes a battery cell, a battery, and an electrical device, which can improve the reliability of the battery cell while taking into account the energy density of the battery cell to a certain extent.

[0006] In the first aspect, an embodiment of the present application provides a battery cell, which includes: a shell, the shell having a first wall and a second wall that are adjacent and connected; a pressure relief mechanism, the pressure relief mechanism is arranged on the first wall; an electrode assembly, the electrode assembly is arranged in the shell, the electrode assembly has a first part and a second part arranged in sequence along a first direction, the first part and the second part both include a multi-layer anode electrode layer and a multi-layer cathode electrode layer, the multi-layer anode electrode layer and the multi-layer cathode electrode layer are alternately stacked one by one along the first direction, a second part is provided between the first part and the second wall, the distance x2 between the cathode electrode layer of the second part and the first wall is greater than the distance x1 between the cathode electrode layer of the first part and the first wall, and the first direction is perpendicular to the second wall.

[0007] In the above technical solution, by arranging the second part between the first part and the second wall, and the distance between the cathode electrode layer of the second part and the first wall is greater than the distance between the cathode electrode layer of the first part and the first wall, when the electrode assembly expands and deforms, it is beneficial to weaken the effect of the part of the second wall close to the first wall on the first wall, and weaken the pulling effect of the second wall on the pressure relief mechanism through the first wall, which can reduce the probability of damage to the pressure relief mechanism such as cracking on the first wall, improve the reliability of the battery cell, and at the same time, to a certain extent, take into account the energy density of the battery cell.

[0008] In some embodiments, the distance between the multi-layer cathode plate layer of the second portion and the first wall is equal; or, the distance between the multi-layer cathode plate layer of the second portion and the first wall increases from the inside of the battery cell to the outside of the battery cell along the first direction.

[0009] In the above technical solution, by setting the distance between the multi-layer cathode electrode layer of the second part and the first wall to be equal, the regular stacking of the multi-layer cathode electrode layer is facilitated, and when the electrode assembly expands and deforms, it is beneficial to further increase the distance between the position where the main force exerted by the second part on the second wall and the first wall, thereby helping to further reduce the risk of the pressure relief mechanism being pulled, damaged or failed; by setting the distance between the multi-layer cathode electrode layer of the second part and the first wall to increase along the first direction from the inside of the battery cell to the outside of the battery cell, when the electrode assembly expands and deforms, it is beneficial to further take into account the energy density of the battery cell while reducing the force exerted by the second part on the part of the second wall adjacent to the first wall.

[0010] In some embodiments, the distance x4 between the anode plate layer of the second portion and the first wall is greater than or equal to the distance x3 between the anode plate layer of the first portion and the first wall.

[0011] In the above technical solution, by setting the distance between the anode electrode layer of the second part and the first wall to be greater than or equal to the distance between the anode electrode layer of the first part and the first wall, it is convenient to make the height of the anode electrode layer of the second part in the third direction (i.e., the direction perpendicular to the plane where the first wall is located) and the height of the cathode electrode layer of the second part in the third direction well matched, and the height of the anode electrode layer of the first part in the third direction and the height of the cathode electrode layer of the first part in the third direction well matched. When the battery cell is a lithium battery, the lithium ion accommodation capacity of the electrode assembly can be better taken into account, which is conducive to realizing the design requirement that the corresponding size of the anode electrode layer in the battery cell is larger than the corresponding size of the cathode electrode layer, so as to maintain the good electrochemical performance of the battery cell.

[0012] In some embodiments, the distances between the multi-layer anode plate layers in the second portion and the first wall are equal; or, the distances between the multi-layer anode plate layers in the second portion and the first wall increase along the first direction from the inside of the battery cell to the outside of the battery cell.

[0013] In the above technical solution, by setting the distance between the multi-layer anode electrode layer of the second part and the first wall to be equal, the regular stacking of the multi-layer anode electrode layer of the second part is facilitated, and when the electrode assembly expands and deforms, it is beneficial to further increase the distance between the position where the main force exerted by the second part on the second wall and the first wall, thereby helping to further reduce the risk of the pressure relief mechanism being pulled, damaged or failed; by setting the distance between the multi-layer cathode electrode layer of the second part and the first wall to increase along the first direction from the inside of the battery cell to the outside of the battery cell, when the electrode assembly expands and deforms, it is beneficial to further take into account the energy density of the battery cell while reducing the force exerted by the second part on the part of the second wall adjacent to the first wall.

[0014] In some embodiments, the first part and the second part respectively include an isolation membrane, and when the distance between the anode electrode layer of the second part and the first wall is greater than the distance between the anode electrode layer of the first part and the first wall, the distance between the isolation membrane of the second part and the first wall is greater than the distance between the isolation membrane of the first part and the first wall; when the distance between the anode electrode layer of the second part and the first wall is equal to the distance between the anode electrode layer of the first part and the first wall, the distance between the isolation membrane of the second part and the first wall is equal to the distance between the isolation membrane of the first part and the first wall.

[0015] In the above technical solution, the distance between the isolation membrane of the second part and the first wall is set to be greater than or equal to the distance between the isolation membrane of the first part and the first wall, so as to achieve a good match with the arrangement of the anode electrode layer of the second part relative to the anode electrode layer of the first part, that is, the height of the isolation membrane of the second part in the direction perpendicular to the first wall is well matched with the height of the anode electrode layer of the second part and the cathode electrode layer in the direction perpendicular to the first wall, and the height of the isolation membrane of the first part in the direction perpendicular to the first wall is well matched with the height of the anode electrode layer of the first part and the cathode electrode layer in the direction perpendicular to the first wall, so as to facilitate the maximum utilization of the isolation membrane material under the premise that the isolation membrane realizes effective isolation of the anode electrode layer and the cathode electrode layer.

[0016] In some embodiments, the number of second parts is n, where n is a positive integer, and when the distance between the anode electrode layer of the second part and the first wall is greater than the distance between the anode electrode layer of the first part and the first wall, the sum of the thicknesses of the anode electrode layer and the cathode electrode layer of the second part accounts for 25% / n to 30% / n of the thickness of the electrode assembly in the first direction; and / or, the sum of the number of layers of the anode electrode layer and the cathode electrode layer of the second part accounts for 10% / n to 20% / n of the sum of the number of layers of the anode electrode layer and the cathode electrode layer of the electrode assembly.

[0017] In the above technical solution, when the distance between the anode electrode layer of the second part and the first wall is greater than the distance between the anode electrode layer of the first part and the first wall, by setting the sum of the thicknesses of the anode electrode layer and the cathode electrode layer of the second part to a proportion of the thickness of the electrode assembly in the first direction, and / or the sum of the number of layers of the anode electrode layer and the cathode electrode layer of the second part to a proportion of the sum of the number of layers of the anode electrode layer and the cathode electrode layer of the electrode assembly, it is convenient to make the thickness and / or the number of layers of the second part reasonably set, which is conducive to achieving both the reliability of the battery cell and the energy density of the battery cell.

[0018] In some embodiments, there are n second parts, where n is a positive integer, and when the distance between the anode electrode layer of the second part and the first wall is equal to the distance between the anode electrode layer of the first part and the first wall, the sum of the thicknesses of the cathode electrode layers of the second part accounts for 25% / n to 30% / n of the thickness of the electrode assembly in the first direction; and / or, the number of cathode electrode layers of the second part accounts for 10% / n to 20% / n of the number of cathode electrode layers of the electrode assembly.

[0019] In the above technical solution, when the distance between the anode electrode layer of the second part and the first wall is equal to the distance between the anode electrode layer of the first part and the first wall, by setting the sum of the thicknesses of the cathode electrode layers of the second part to a proportion of the thickness of the electrode assembly in the first direction, and / or the number of layers of the cathode electrode layers of the second part to a proportion of the sum of the number of layers of the cathode electrode layers of the electrode assembly, it is convenient to reasonably set the thickness and / or the number of layers of the cathode electrode layers of the second part, which is conducive to achieving a simultaneous consideration of both the reliability of the battery cell and the energy density of the battery cell.

[0020] In some embodiments, on the plane where the first wall is located, the orthographic projection of the second portion is located outside the orthographic projection outer contour of the pressure relief mechanism.

[0021] In the above technical solution, by being arranged on the plane where the first wall is located, the orthographic projection of the second part is located outside the outer contour of the orthographic projection of the pressure relief mechanism, so that the orthographic projection of the second part and the orthographic projection of the pressure relief mechanism are spaced apart along the first direction, so as to reduce the pulling effect on the pressure relief mechanism due to the expansion and deformation of the electrode assembly, and at the same time, further appropriately increase the thickness of the second part in the first direction, so as to further take into account the volume energy density of the battery cell.

[0022] In some embodiments, the maximum distance between the multi-layer cathode electrode layer of the second portion and the first wall is h, and h≥2 mm.

[0023] In the above technical solution, the maximum distance h between the multi-layer cathode electrode layer of the second part and the first wall is set to ≥ 2 mm, so as to effectively reduce the pulling of the pressure relief mechanism when the electrode assembly expands and deforms, and facilitate the cooperation between the second part and the first wall.

[0024] In some embodiments, h≤15 mm.

[0025] In the above technical solution, by setting h≤15 mm, the pulling of the pressure relief mechanism when the electrode assembly expands and deforms can be reduced while taking into account the volume energy density of the battery cell to a certain extent.

[0026] In some embodiments, 3 mm ≤ h ≤ 10 mm.

[0027] In the above technical solution, by setting 3mm≤h≤10mm, both the reliability and energy density of the battery cell can be taken into consideration.

[0028] In some embodiments, the electrode assembly is a laminated electrode assembly, and the stacking direction of the anode electrode layer and the cathode electrode layer in the electrode assembly is a first direction; or, the electrode assembly is a wound electrode assembly, and the axial direction of the electrode assembly is perpendicular to the first direction.

[0029] In the above technical solution, by setting the electrode assembly to a laminated structure or a wound structure, the battery cell can be provided with electrode assemblies of different structures according to actual needs, which is beneficial to improving the applicability of the battery cell.

[0030] In some embodiments, the electrode assembly is a wound electrode assembly, and the second portion is provided on two opposite sides of the first portion in the first direction.

[0031] In the above technical solution, by setting the electrode assembly as a wound electrode assembly, the second part is provided on two opposite sides of the first part in the first direction, which is conducive to simplifying the unfolding structure of the wound electrode assembly and facilitating the processing of the electrode assembly 3.

[0032] In some embodiments, the distances between the cathode electrode layers of the two second portions and the first wall are equal, and the distances between the anode electrode layers of the two second portions and the first wall are equal.

[0033] In the above technical solution, by setting the distance between the cathode electrode layer of the two second parts and the first wall to be equal, and the distance between the anode electrode layer of the two second parts and the first wall to be equal, it is convenient to further simplify the structure of the cathode electrode sheet and the anode electrode sheet of the wound electrode assembly and simplify the processing process.

[0034] In some embodiments, the sum of the lengths of the multi-layer cathode electrode sheets of the two second portions in the circumferential direction of the electrode assembly accounts for 30% to 50% of the circumferential length of the electrode assembly.

[0035] In the above technical solution, by setting the sum of the lengths of the multi-layer cathode electrode layers of the two second parts in the circumferential direction of the electrode assembly to account for 30% to 50% of the circumferential length of the electrode assembly, it is convenient to set the thickness and / or number of layers of the second part reasonably, which is conducive to achieving both the reliability of the battery cell and the energy density of the battery cell.

[0036] In some embodiments, the housing has two second walls arranged opposite to each other along a first direction, the first wall connects the two second walls, and a second portion is provided between the first portion and each second wall.

[0037] In the above technical solution, a first wall is provided to be connected between two second walls, and a second part is provided between the first part and each second wall, so that when the electrode assembly expands and deforms, the effect of each second wall on the first wall is weakened, thereby facilitating the weakening of the overall pulling on both ends of the pressure relief mechanism in the first direction, thereby further reducing the risk of the pressure relief mechanism being damaged by pulling.

[0038] In some embodiments, the second wall is the wall with the largest area in the housing.

[0039] In the above technical solution, by arranging the pressure relief mechanism on the first wall, which is not the wall with the largest area of ​​the shell, the pressure relief mechanism can be arranged on the smaller stress surface of the shell. Compared with arranging the pressure relief mechanism on the second wall, when the electrode assembly expands and deforms, the stress on the pressure relief mechanism can be reduced, which is conducive to further reducing the risk of the pressure relief mechanism being pulled, damaged or failing.

[0040] In some embodiments, the pressure relief mechanism and the poles of the battery cells are disposed on walls on different sides of the housing.

[0041] In the above technical solution, the pole is connected to the pole ear of the electrode assembly, and there is a certain gap between the wall where the pole is located and the main body of the electrode assembly. By placing the pressure relief mechanism and the pole on the walls on different sides of the shell, the distance between the pressure relief mechanism and the main body of the electrode assembly can be appropriately shortened to a certain extent, so that the distance between the pressure relief mechanism and the main body of the electrode assembly is not easily restricted by the pole. When the battery cell thermally runs away, most of the discharge medium in the shell can flow directly from the edge of the main body of the electrode assembly to the pressure relief mechanism, thereby shortening the path of the discharge medium flowing to the pressure relief mechanism, allowing the discharge medium to flow quickly to the pressure relief mechanism, shortening the time for the discharge medium to reach the pressure relief mechanism, and improving the timeliness of the pressure relief of the battery cell.

[0042] In some embodiments, the shell further has a third wall, the pole is arranged on the third wall, and the third wall is adjacent to and connected to the first wall and the second wall respectively; or, the third wall is adjacent to and connected to the second wall, and the third wall is arranged opposite to the first wall.

[0043] In the above technical solution, by arranging the pole on the third wall, and the third wall being adjacent to or opposite to the first wall, it is easy to meet the differentiated arrangement requirements of the battery cells, which is beneficial to improving the applicability of the battery cells.

[0044] In some embodiments, the shell includes a shell body and a shell cover, at least one of the two ends of the shell body in the second direction is open, the shell cover is arranged at the open end of the shell body, the first wall and the second wall are both formed on the shell body, and the second direction is perpendicular to the first direction.

[0045] In the above technical solution, by setting the first wall and the second wall to be formed on the shell body, the structure of the shell cover can be simplified, and at the same time, it is convenient to shorten the distance between the pressure relief mechanism and the main body of the electrode assembly, thereby shortening the path of the discharge medium flowing to the pressure relief mechanism during pressure relief, shortening the time for the discharge medium to reach the pressure relief mechanism, and improving the timeliness of pressure relief of the battery cell.

[0046] In some embodiments, one end of the shell body in the second direction is open, and the first wall is connected to the end of the second wall away from the open end; or, both ends of the shell body in the second direction are open, and the first wall and the second wall extend to the open ends on both sides.

[0047] The above technical solution facilitates the improvement of the processing convenience of the shell body and the shell cover, and improves the assembly convenience of the shell.

[0048] In some embodiments, the pressure relief mechanism is integrally formed with the first wall.

[0049] In the above technical solution, by integrally forming the pressure relief mechanism and the first wall, the pressure relief mechanism is formed in a simple manner, which can reduce the number of components constituting the battery cell, simplify the structure of the battery cell, and reduce costs.

[0050] In some embodiments, the inner surface and / or outer surface of the first wall is provided with a groove, and the bottom wall of the groove forms a pressure relief mechanism.

[0051] In the above technical solution, a groove is provided on the inner surface and / or outer surface of the first wall, and the bottom wall of the groove forms a pressure relief mechanism, so as to facilitate the processing and forming of the pressure relief mechanism.

[0052] In some embodiments, a score groove is formed on the first wall, and a region of the first wall corresponding to the score groove is configured as a weakened area of ​​the pressure relief mechanism, and the weakened area is configured to rupture when the battery cell is depressurized.

[0053] In the above technical solution, the first wall is provided with a notched groove, and the area of ​​the first wall corresponding to the notched groove is configured as a weak area of ​​the pressure relief mechanism, which facilitates the processing and forming of the pressure relief mechanism.

[0054] In some embodiments, the pressure relief mechanism is provided separately from the first wall, and the pressure relief mechanism is installed on the first wall.

[0055] In the above technical solution, the pressure relief mechanism and the first wall are constructed as separate parts, which facilitates the installation of the pressure relief mechanism on the shell. This has low production difficulty and high efficiency, and can improve the production efficiency of battery cells.

[0056] In the second aspect, an embodiment of the present application provides a battery cell, which includes: a shell having a first wall and a second wall that are adjacent and connected; a pressure relief mechanism, which is arranged on the first wall; an electrode assembly, which is arranged in the shell, and the electrode assembly includes an anode electrode layer and a cathode electrode layer stacked along a first direction, and the distance between the electrode assembly and the first wall is 2mm≤h≤15mm, and the first direction is parallel to the plane where the first wall is located.

[0057] In the above technical solution, by setting the distance between the electrode assembly and the first wall to 2mm≤h≤15mm, when the electrode assembly expands and deforms, it is beneficial to increase the distance between the position of the main force exerted by the electrode assembly on the two walls of the shell that are relatively arranged along the first direction and the first wall, thereby helping to reduce the risk of the pressure relief mechanism being pulled on the first wall, damaged or failing, and improving the reliability of the battery cell. At the same time, it can take into account the volume energy density of the battery cell to a certain extent and will not excessively reduce the energy density of the battery cell.

[0058] In a third aspect, an embodiment of the present application provides a battery comprising the above-mentioned battery cell.

[0059] In the above technical solution, since the battery adopts the above battery monomer, it is beneficial to improve the reliability and energy density of the battery.

[0060] In a fourth aspect, an embodiment of the present application provides an electrical device comprising the above-mentioned battery, which is used to provide electrical energy.

[0061] In the above technical solution, since the electrical device adopts the above battery, and the battery has good reliability and energy density, it is beneficial to improve the reliability and endurance of the electrical device. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0063] FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0064] FIG2 is an exploded view of a battery provided in some embodiments of the present application;

[0065] FIG3 is a schematic structural diagram of a battery cell provided in some embodiments of the present application, wherein the motor assembly is a wound electrode assembly;

[0066] FIG4 is a schematic structural diagram of a battery cell provided in some embodiments of the present application;

[0067] FIG5 is a schematic diagram of a battery cell provided in some embodiments of the present application, wherein the electrode assembly is a laminated electrode assembly;

[0068] FIG6 is a partial cross-sectional view of a battery cell provided in some embodiments of the present application, wherein the electrode assembly is a wound electrode assembly or a laminated electrode assembly;

[0069] FIG7 is a partial cross-sectional view of a battery cell provided in some embodiments of the present application, wherein the electrode assembly is a wound electrode assembly or a laminated electrode assembly;

[0070] FIG8 is a partial cross-sectional view of a battery cell provided in some embodiments of the present application, wherein the electrode assembly is a wound electrode assembly or a laminated electrode assembly;

[0071] FIG9 is a partial cross-sectional view of a battery cell provided in some embodiments of the present application, wherein the electrode assembly is a wound electrode assembly or a laminated electrode assembly;

[0072] FIG10 is a schematic diagram of the unfolding of the cathode electrode sheet of the wound electrode assembly provided in some embodiments of the present application.

[0073] Figure numerals: electrical device 1000, controller 300, motor 400, battery 200, battery cell 100, box 101, first box 101a, second box 101b, shell 1, first wall 11, groove 11a, notched groove 11b, second wall 12, third wall 13, shell body 1a, shell cover 1b, pressure relief mechanism 2, electrode assembly 3, flat area 30, first part 3a, second part 3b, cathode electrode layer 31, anode electrode layer 32, isolation membrane 33, pole ear 34, first section 35, second section 36, pole 4. DETAILED DESCRIPTION

[0074] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0075] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0076] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments.

[0077] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0078] In the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the dimensions and other sizes of the various components in the embodiments of the present application shown in the drawings are for illustrative purposes only and should not constitute any limitation on the present application.

[0079] The term "plurality" used in this application refers to two or more (including two).

[0080] In this application, battery cells may include lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries, magnesium-ion batteries, nickel-metal hydride batteries, nickel-cadmium batteries, or lead-acid batteries, etc., and the embodiments of this application do not limit this. Battery cells may be cylindrical, flat, rectangular, or other shapes, etc., and the embodiments of this application do not limit this. Battery cells are generally divided into three types based on the packaging method: cylindrical battery cells, prismatic battery cells, and soft-pack battery cells, and the embodiments of this application do not limit this.

[0081] The battery referred to in the embodiments of this application refers to a single physical module that includes one or more battery cells to provide higher voltage and capacity. For example, the battery referred to in this application may be a battery module or battery pack. A battery module generally includes multiple battery cells. A battery generally includes a casing for enclosing multiple battery cells or multiple battery modules. The casing can, to a certain extent, prevent liquids or other foreign matter from affecting the charging or discharging of the battery cells. Of course, the battery may also not include a casing.

[0082] For example, a battery cell may generally include a housing, a cell assembly, and an electrolyte. The housing is used to accommodate the cell assembly and the electrolyte, and is provided with at least one positive electrode post and at least one negative electrode post. The cell assembly includes one or more electrode assemblies, which are formed by stacking or winding a positive electrode sheet, a negative electrode sheet, and a separator. The housing may be a steel shell, an aluminum shell, a plastic shell (such as a polypropylene shell), a composite metal shell (such as a copper-aluminum composite shell), or an aluminum-plastic film.

[0083] Among them, the positive electrode sheet generally includes a positive electrode sheet body and a positive electrode active material layer. The positive electrode active material layer is directly or indirectly coated on the positive electrode sheet body. The positive electrode sheet body not coated with the positive electrode active material layer serves as a positive electrode tab. Multiple positive electrode tabs are stacked together and electrically connected to the positive electrode column. For example, the multiple stacked positive electrode tabs can be directly welded to the positive electrode column to form an electrical connection; alternatively, the battery cell assembly may further include a positive electrode adapter. The multiple stacked positive electrode tabs are welded to one end of the positive electrode adapter, and the other end of the positive electrode adapter is welded to the positive electrode column to form an electrical connection between the positive electrode tab and the positive electrode column.

[0084] The negative electrode sheet can generally include a negative electrode sheet body and a negative electrode active material layer. The negative electrode active material layer is directly or indirectly coated on the negative electrode sheet body. The negative electrode sheet body not coated with the negative electrode active material layer serves as a negative electrode tab sheet. Multiple negative electrode tab sheets are stacked together and electrically connected to the negative electrode column. For example, the multiple stacked negative electrode tab sheets can be directly welded to the negative electrode column to form an electrical connection; alternatively, the battery cell assembly can further include a negative electrode adapter sheet. The multiple stacked negative electrode tab sheets are welded to one end of the negative electrode adapter sheet, and the other end of the negative electrode adapter sheet is welded to the negative electrode column to form an electrical connection between the negative electrode tab sheet and the negative electrode column. The material of the separator is not limited, for example, it can be polypropylene or polyethylene.

[0085] The pressure relief mechanism on the battery cell mentioned in this application is used to release gas from the battery cell when the internal pressure of the battery cell is too high (for example, due to overcharging), thereby reducing the internal pressure of the battery cell, preventing the battery cell from exploding due to excessive internal pressure, and improving the reliability of the battery cell. For example, the pressure relief mechanism can be an explosion-proof valve, explosion-proof disk, etc.

[0086] In recent years, new energy vehicles have experienced rapid development. In the electric vehicle sector, batteries, as the power source of electric vehicles, play an irreplaceable and important role. As core components of new energy vehicles, batteries have high requirements in terms of both energy density and reliability.

[0087] In related technologies, a battery includes multiple battery cells. A battery cell generates a large amount of heat during continuous charging and discharging. Generally, a pressure relief mechanism is provided in the battery cell to relieve pressure when the battery cell experiences thermal runaway.

[0088] When designing a battery cell, considering the battery's energy density, the battery cell's electrode assembly occupies as much space within the casing as possible. Therefore, the distance between the electrode assembly and the casing wall where the pressure relief mechanism is located is relatively close to the distance between the electrode assembly and the casing wall opposite the pressure relief mechanism. However, when the battery cell's electrode assembly expands and deforms, the battery cell casing also deforms, causing the casing to bulge. The pressure relief mechanism is usually located on the casing, which causes the casing wall where the pressure relief mechanism is located to be pulled. When the pulling force reaches a certain level, it can easily cause the pressure relief mechanism to crack, resulting in damage and failure of the pressure relief mechanism, and thus reduce the reliability of the battery cell. Therefore, developing more reliable battery systems that do not cause heat spread has become the goal of battery manufacturers and vehicle manufacturers.

[0089] Based on the above considerations, in order to improve the reliability of battery cells, a battery cell is proposed, including a shell, a pressure relief mechanism and an electrode assembly, the shell having a first wall and a second wall that are adjacent and connected, the pressure relief mechanism is arranged on the first wall, the electrode assembly is arranged in the shell, the electrode assembly has a first part and a second part arranged in sequence along a first direction, the first part and the second part both include a multi-layer anode electrode layer and a multi-layer cathode electrode layer, the multi-layer anode electrode layer and the multi-layer cathode electrode layer are alternately stacked one by one along the first direction, a second part is provided between the first part and the second wall, the distance x2 between the cathode electrode layer of the second part and the first wall is greater than the distance x1 between the cathode electrode layer of the first part and the first wall, and the first direction is perpendicular to the second wall.

[0090] In the above technical solution, by arranging the second part between the first part and the second wall, and the distance between the cathode electrode layer of the second part and the first wall is greater than the distance between the cathode electrode layer of the first part and the first wall, when the electrode assembly expands and deforms, it is beneficial to weaken the effect of the part of the second wall close to the first wall on the first wall, and weaken the pulling effect of the second wall on the pressure relief mechanism through the first wall, which can reduce the probability of damage to the pressure relief mechanism such as cracking on the first wall, improve the reliability of the battery cell, and at the same time, to a certain extent, take into account the energy density of the battery cell.

[0091] The present application provides an electrical device using the battery of the present disclosure as a power source. The electrical device may be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, a battery-powered vehicle, an electric car, a ship, a spacecraft, and the like. The electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, and the like. The spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, and the like.

[0092] For the convenience of description, the following embodiments take the electric device 1000 as a vehicle as an example, and describe in detail the structures of the electric device 1000, the battery 200 and the battery cell 100 of the present application.

[0093] Please refer to Figure 1, which is a schematic structural diagram of a vehicle in which the power-consuming device 1000 provided in some embodiments of the present application is a vehicle. The vehicle can be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. The vehicle is provided with a battery 200, and the battery 200 can be arranged at the bottom, head or tail of the vehicle. The battery 200 can be used to power the vehicle, for example, the battery 200 can be used as an operating power source for the vehicle. The vehicle may also include a controller 300 and a motor 400, and the controller 300 is used to control the battery 200 to power the motor 400, for example, for the starting, navigation and working power requirements of the vehicle during driving. In some embodiments of the present application, the battery 200 can not only serve as the operating power source of the vehicle, but also as the driving power source of the vehicle, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle.

[0094] Please refer to Figure 2, which is an exploded view of the structure of a battery 200 provided in some embodiments of the present application. The battery 200 includes a housing 101 and a plurality of battery cells 100, and the battery cells 100 are accommodated in the housing 101. The housing 101 is used to provide an assembly space for the battery cells 100, and the housing 101 can adopt a variety of structures. In some embodiments, the housing 101 can include a first housing 101a and a second housing 101b, and the first housing 101a and the second housing 101b cover each other, and the first housing 101a and the second housing 101b jointly define a housing cavity for accommodating the battery cells. The second box 101b can be a hollow structure with one end open, and the first box 101a can be a plate-like structure. The first box 101a covers the open side of the second box 101b, so that the first box 101a and the second box 101b together define a storage cavity; alternatively, the first box 101a and the second box 101b can both be hollow structures with one end open (for example, as shown in FIG. 2 ), with the open side of the first box 101a covering the open side of the second box 101b. Of course, the box 101 formed by the first box 101a and the second box 101b can be of various shapes, such as a cylinder or a rectangular parallelepiped.

[0095] In the battery 200, multiple battery cells 100 can be connected in series, in parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections among the multiple battery cells 100. Multiple battery cells 100 can be directly connected in series, in parallel, or in a hybrid connection, and then the entire battery cell 100 can be housed within the housing 101. Alternatively, the battery 200 can be constructed by first connecting multiple battery cells 100 in series, in parallel, or in a hybrid connection to form a battery module. The multiple battery modules are then connected in series, in parallel, or in a hybrid connection to form a single unit, which is then housed within the housing 101. The battery 200 may also include other structures. For example, the battery 200 may also include a busbar to electrically connect the multiple battery cells 100.

[0096] In some embodiments, the box 101 may serve as part of a chassis structure of a vehicle. For example, the box 101 may serve as at least a portion of a floor of the vehicle, or the box 101 may serve as at least a portion of a cross member and a longitudinal member of the vehicle.

[0097] Please refer to Figures 3 and 4. Figure 3 is a schematic diagram of the structure of a battery cell 100 provided in some embodiments of the present application, and Figure 4 is a schematic diagram of the structure of a battery cell 100 provided in some embodiments of the present application. The battery cell 100 is a rectangular parallelepiped, with the height direction of the battery cell 100 being the third direction Z, the length direction of the battery cell 100 being the second direction Y, and the thickness direction of the battery cell 100 being the first direction X. The first direction X, the second direction Y, and the third direction Z are mutually perpendicular; however, this is not limiting. In other embodiments of the present application, the battery cell 100 may also be a polygonal prism, a flat body, or other shapes.

[0098] Please refer to Figures 3 to 5. In an embodiment of the present application, the battery cell 100 includes a shell 1 and a pressure relief mechanism 2. The shell 1 has a first wall 11 and a second wall 12. The second wall 12 is adjacent to and connected to the first wall 11. The pressure relief mechanism 2 is provided on the first wall 11, and the pressure relief mechanism 2 is configured to release the pressure inside the battery cell 100.

[0099] The battery cell 100 also includes an electrode assembly 3, which is disposed within the housing 1. The electrode assembly 3 includes a first portion 3a and a second portion 3b arranged sequentially along a first direction. The first portion 3a and the second portion 3b each include multiple anode electrode layers 32 and multiple cathode electrode layers 31. The multiple anode electrode layers 32 and multiple cathode electrode layers 31 of the first portion 3a are alternately stacked one by one along the first direction, while the multiple anode electrode layers 32 and multiple cathode electrode layers 31 of the second portion 3b are alternately stacked one by one along the first direction. Thus, for the electrode assembly 3, the multiple anode electrode layers 32 and multiple cathode electrode layers 31 of the electrode assembly 3 are alternately stacked one by one along the first direction, with one cathode electrode layer 31 disposed between two adjacent anode electrode layers 32, and one anode electrode layer 32 disposed between two adjacent cathode electrode layers 31. The first direction is perpendicular to the second wall 12.

[0100] It is understandable that one electrode assembly 3 or multiple electrode assemblies 3 may be provided in the housing 1 , and each electrode assembly 3 includes multiple anode electrode layers 32 and multiple cathode electrode layers 31 stacked along a first direction. Exemplarily, the electrode assembly 3 can be a laminated structure, that is, the multiple electrode layers of the electrode assembly 3 are stacked, and the multiple electrode layers are stacked to form a straight area 30. In the straight area 30, at least a portion of the cathode electrode layer 31 and the anode electrode layer 32 are stacked along the first direction, or at least a portion of the anode electrode layer 32 and the cathode electrode layer 31 are stacked along the first direction. At this time, the expansion deformation of the electrode assembly 3 is particularly obvious in the first direction; the electrode assembly 3 can also be a wound structure, that is, the multiple electrode layers of the electrode assembly 3 are stacked and wound into shape, and a straight area 30 is formed. In the straight area 30, a portion of the anode electrode layer, namely the anode electrode layer 32, and a portion of the cathode electrode layer, namely the cathode electrode layer 31, are stacked along the first direction. For example, after winding, the cathode electrode layer 31 and the anode electrode layer 32 can both be pierced by an axis extending along the first direction. At this time, the expansion deformation of the electrode assembly 3 is particularly obvious in the first direction.

[0101] Obviously, when the electrode assembly 3 expands, most of the expansion of the electrode assembly 3 will act on the second wall 12, so the first wall 11 is affected less by the expansion of the electrode assembly 3 than the second wall 12. Therefore, the pressure relief mechanism 2 is arranged on the first wall 11, which is beneficial to reducing the risk of obstruction or damage to the pressure relief mechanism 2 due to the expansion of the electrode assembly 3.

[0102] Please refer to Figures 6 to 9. A second part 3b is provided between the first part 3a and the second wall 12. The distance x2 between the cathode electrode layer 31 of the second part 3b and the first wall 11 is greater than the distance x1 between the cathode electrode layer 31 of the first part 3a and the first wall 11, so that the cathode electrode layer 31 of the second part 3b close to the second wall 12 in the first direction is relatively far away from the first wall 11 in the direction perpendicular to the first wall 11, which facilitates the shortening design of the cathode electrode layer 31 of the second part 3b in the direction perpendicular to the first wall 11, so that the end of the cathode electrode layer 31 of the second part 3b close to the first wall 11 is hollowed out relative to the end of the cathode electrode layer 31 of the first part 3a close to the first wall 11.

[0103] Therefore, when the electrode assembly 3 expands and deforms, the expansion and deformation of the electrode assembly 3 is particularly obvious in the first direction, and the electrode assembly 3 applies a force to the second wall 12, that is, the second part 3b applies a force to the second wall 12. The above-mentioned arrangement of the present application facilitates increasing the distance between the position where the main force applied by the second part 3b on the second wall 12 is applied and the first wall 11, and / or facilitates reducing the force applied by the second part 3b on the portion of the second wall 12 adjacent to the first wall 11, thereby facilitating reducing the force applied by the second wall 12 to the first wall 11, so that the first wall 11 is basically not subjected to force or the first wall 11 is subjected to less force, thereby weakening the pulling effect of the second wall 12 on the pressure relief mechanism 2 through the first wall 11 due to the expansion of the electrode assembly 3, thereby reducing the probability of damage to the pressure relief mechanism 2 such as cracking on the first wall 11, and improving the reliability of the battery cell 100.

[0104] In addition, the above-mentioned setting of the embodiment of the present application can realize the height differentiation setting of the cathode electrode layer 31 of the first part 3a and the cathode electrode layer 31 of the second part 3b in the direction perpendicular to the first wall 11, so as to reduce the risk of the pressure relief mechanism 2 being pulled and damaged, while also reducing the probability of leakage to a certain extent, and can take into account the volume energy density of the battery cell 100 at the same time, without excessively reducing the volume energy density of the battery cell 100.

[0105] Exemplarily, the height direction of the battery cell 100 is the third direction Z, the length direction of the battery cell 100 is the second direction Y, and the thickness direction of the battery cell 100 is the first direction X. In the third direction Z, the distance between the cathode electrode layer 31 of the second part 3b and the first wall 11 is greater than the distance between the cathode electrode layer 31 of the first part 3a and the first wall 11. Taking the third direction Z as the vertical direction as an example, the first wall 11 is the bottom wall of the housing 1. By differentiating the heights of the cathode electrode layer 31 of the first portion 3a and the cathode electrode layer 31 of the second portion 3b in the vertical direction, the force on the lower portion of the housing 1 due to the expansion and deformation of the electrode assembly 3 is reduced, thereby reducing the pulling effect on the pressure relief mechanism 2 on the bottom wall of the housing 1 and reducing the risk of the pressure relief mechanism 2 being pulled and cracked. In addition, the pressure relief mechanism 2 is arranged on the bottom wall of the housing 1, so that the battery cell 100 realizes a bottom-spraying design, which helps to improve the heat spread of the battery 200. For example, the battery 200 is generally placed at the bottom of an electrical device, with electrical components or personnel above it. When the battery 200 experiences thermal runaway, the battery cell 100 can exhaust and release pressure downward, thereby reducing the fire in the area above the battery 200. Especially when the number of battery cells 100 is large, that is, reducing the loss of electrical components and reducing personal injury. The use of this structure can reduce the impact of the battery 200 on the electrical device under thermal runaway and improve the reliability of the battery 200.

[0106] In the above technical solution, by arranging the second part 3b between the first part 3a and the second wall 12, and the distance between the cathode electrode layer 31 of the second part 3b and the first wall 11 is greater than the distance between the cathode electrode layer 31 of the first part 3a and the first wall 11, when the electrode assembly 3 expands and deforms, it is beneficial to weaken the effect of the part of the second wall 12 close to the first wall 11 on the first wall 11, and weaken the pulling effect of the second wall 12 on the pressure relief mechanism 2 through the first wall 11, which can reduce the probability of damage such as cracking of the pressure relief mechanism 2 on the first wall 11, thereby improving the reliability of the battery cell 100 and, to a certain extent, taking into account the energy density of the battery cell 100.

[0107] It can be understood that only the distance between all the cathode electrode layers 31 and the first wall 11 in the second part 3b is greater than the distance between the cathode electrode layer 31 and the first wall 11 in the first part 3a; or, not only the distance between all the cathode electrode layers 31 and the first wall 11 in the second part 3b is greater than the distance between the cathode electrode layer 31 and the first wall 11 in the first part 3a, but also the distance between at least one anode electrode layer 32 in the second part 3b and the first wall 11 is greater than the distance between the cathode electrode layer 31 and the first wall 11 in the first part 3a.

[0108] Please refer to Figures 6 and 8. In some embodiments, the distance between the multilayer cathode electrode layer 31 of the second part 3b and the first wall 11 is equal; alternatively, please refer to Figures 7 and 9. The distance between the multilayer cathode electrode layer 31 of the second part 3b and the first wall 11 increases along the first direction from the inside of the battery cell 100 to the outside of the battery cell 100.

[0109] It can be seen that in the above scheme, among any two adjacent cathode electrode layers 31 of the multi-layer cathode electrode layer 31 of the second part 3b, the distance between the cathode electrode layer 31 close to the second wall 12 and the first wall 11 is greater than or equal to the distance between the cathode electrode layer 31 farther away from the second wall 12 and the first wall 11.

[0110] In the above technical solution, by setting the distance between the multi-layer cathode electrode layer 31 of the second part 3b and the first wall 11 to be equal, the regular stacking of the multi-layer cathode electrode layer 31 of the second part 3b is facilitated, and when the electrode assembly 3 expands and deforms, it is beneficial to further increase the distance between the position where the main force exerted by the second part 3b on the second wall 12 and the first wall 11, thereby helping to further reduce the risk of the pressure relief mechanism 2 being pulled, damaged or failed; by setting the distance between the multi-layer cathode electrode layer 31 of the second part 3b and the first wall 11 to increase along the first direction from the inside of the battery cell 100 to the outside of the battery cell 100, when the electrode assembly 3 expands and deforms, it is beneficial to further achieve a balance between the energy density of the battery cell 100 while reducing the force exerted by the second part 3b on the part of the second wall 12 adjacent to the first wall 11.

[0111] It can be understood that the distance between the multi-layer cathode electrode layer 31 of the second part 3b and the first wall 11 increases along the first direction from the inside of the battery cell 100 to the outside of the battery cell 100, which may mean that the distance between at least two layers of the multi-layer cathode electrode layer 31 of the second part 3b and the first wall 11 is not equal, and the distance between the above-mentioned at least two layers of the cathode electrode layer 31 of the second part 3b and the first wall 11 increases along the first direction from the inside of the battery cell 100 to the outside of the battery cell 100.

[0112] Exemplarily, the distance between the multi-layer cathode electrode layer 31 of the second part 3b and the first wall 11 gradually increases in a step-by-step manner from the inside of the battery cell 100 to the outside of the battery cell 100 along the first direction. Then, among any two adjacent cathode electrode layers 31 of the multi-layer cathode electrode layer 31 of the second part 3b, the distance between the cathode electrode layer 31 close to the second wall 12 and the first wall 11 is greater than the distance between the cathode electrode layer 31 farther away from the second wall 12 and the first wall 11.

[0113] 6-9 , in some embodiments, the distance x4 between the anode plate layer 32 of the second portion 3 b and the first wall 11 is greater than or equal to the distance x3 between the anode plate layer 32 of the first portion 3 a and the first wall 11 .

[0114] In the above technical solution, by setting the distance x4 between the anode electrode layer 32 of the second part 3b and the first wall 11 to be greater than or equal to the distance x3 between the anode electrode layer 32 of the first part 3a and the first wall 11, it is convenient to make the height of the anode electrode layer 32 of the second part 3b in the third direction (i.e., the direction perpendicular to the first wall 11) and the cathode electrode layer 31 of the second part 3b in the third direction well matched, and the height of the anode electrode layer 32 of the first part 3a in the third direction and the cathode electrode layer 31 of the first part 3a in the third direction well matched. When the battery cell 100 is a lithium battery, the lithium ion accommodation capacity of the electrode assembly 3 can be better taken into account, which is conducive to realizing the design requirement that the corresponding size of the anode electrode layer 32 in the battery cell 100 is larger than the corresponding size of the cathode electrode layer 31, so as to maintain the good electrochemical performance of the battery cell 100.

[0115] If the distance x4 between the anode electrode layer 32 of the second part 3b and the first wall 11 is greater than the distance x3 between the anode electrode layer 32 of the first part 3a and the first wall 11, the anode electrode layer 32 of the second part 3b close to the second wall 12 in the first direction is relatively far away from the first wall 11 in the direction perpendicular to the first wall 11, which facilitates the shortening design of the anode electrode layer 32 of the second part 3b in the direction perpendicular to the first wall 11, so that the end of the anode electrode layer 32 of the second part 3b close to the first wall 11 is closer to the end of the anode electrode layer 32 of the first part 3a. The end near the first wall 11 is hollowed out, which further increases the distance between the position where the second part 3b exerts the main force on the second wall 12 and the first wall 11 when the electrode assembly 3 expands and deforms, and / or further reduces the force exerted by the second part 3b on the part of the second wall 12 adjacent to the first wall 11, thereby further reducing the probability of the pressure relief mechanism 2 being pulled and cracked; and the anode electrode layer 32 of the second part 3b and the cathode electrode layer 31 of the second part 3b can be further well matched, which is beneficial to saving the material used for the anode electrode layer 32 and reducing costs.

[0116] If the distance x4 between the anode electrode layer 32 of the second part 3b and the first wall 11 is equal to the distance x3 between the anode electrode layer 32 of the first part 3a and the first wall 11, it is convenient to achieve that the anode electrode layer 32 of the second part 3b and the anode electrode layer 32 of the first part 3a adopt the same specifications and dimensions, thereby reducing the processing difficulty of the electrode assembly 3 and improving the processing efficiency.

[0117] Please refer to Figures 6 to 8. In some embodiments, the distance between the multi-layer anode electrode layer 32 of the second part 3b and the first wall 11 is equal; or, please refer to Figure 9, the distance between the multi-layer anode electrode layer 32 of the second part 3b and the first wall 11 increases along the first direction from the inside of the battery cell 100 to the outside of the battery cell 100.

[0118] It can be seen that in the above scheme, among any two adjacent anode electrode layers 32 of the multi-layer anode electrode layer 32 of the second part 3b, the distance between the anode electrode layer 32 close to the second wall 12 and the first wall 11 is greater than or equal to the distance between the anode electrode layer 32 farther away from the second wall 12 and the first wall 11.

[0119] In the above technical solution, by setting the distance between the multi-layer anode electrode layer 32 of the second part 3b and the first wall 11 to be equal, the regular stacking of the multi-layer anode electrode layer 32 of the second part 3b is facilitated, and when the electrode assembly 3 expands and deforms, it is beneficial to further increase the distance between the position where the main force exerted by the second part 3b on the second wall 12 and the first wall 11, thereby helping to further reduce the risk of the pressure relief mechanism 2 being pulled, damaged or failed; by setting the distance between the multi-layer cathode electrode layer 31 of the second part 3b and the first wall 11 to increase along the first direction from the inside of the battery cell 100 to the outside of the battery cell 100, when the electrode assembly 3 expands and deforms, it is beneficial to further achieve a balance between the energy density of the battery cell 100 while reducing the force exerted by the second part 3b on the part of the second wall 12 adjacent to the first wall 11.

[0120] It can be understood that the distance between the multi-layer anode electrode layer 32 of the second part 3b and the first wall 11 increases along the first direction from the inside of the battery cell 100 to the outside of the battery cell 100, which may mean that the distance between at least two layers of the multi-layer anode electrode layer 32 of the second part 3b and the first wall 11 is not equal, and the distance between the above-mentioned at least two layers of the anode electrode layer 32 of the second part 3b and the first wall 11 increases along the first direction from the inside of the battery cell 100 to the outside of the battery cell 100.

[0121] Exemplarily, the distance between the multi-layer anode electrode layer 32 of the second part 3b and the first wall 11 gradually increases in a step-by-step manner from the inside of the battery cell 100 to the outside of the battery cell 100 along the first direction. Then, among any two adjacent anode electrode layers 32 of the multi-layer anode electrode layer 32 of the second part 3b, the distance between the anode electrode layer 32 close to the second wall 12 and the first wall 11 is greater than the distance between the anode electrode layer 32 farther away from the second wall 12 and the first wall 11.

[0122] For example, the distance between the multi-layer cathode electrode layer 31 of the second part 3b and the first wall 11 is equal, and the distance between the multi-layer anode electrode layer 32 of the second part 3b and the first wall 11 is equal. At this time, the distance between the cathode electrode layer 31 of the second part 3b and the first wall 11 is equal to or different from the distance between the anode electrode layer 32 of the second part 3b and the second wall 11; or, the distance between the multi-layer cathode electrode layer 31 of the second part 3b and the first wall 11 is equal, and the distance between the multi-layer anode electrode layer 32 of the second part 3b and the first wall 11 increases along the first direction from the inside of the battery cell 100 to the outside of the battery cell 100. Increase; or, the distance between the multilayer cathode electrode layer 31 of the second part 3b and the first wall 11 increases along the first direction from the inside of the battery cell 100 to the outside of the battery cell 100, and the distance between the multilayer anode electrode layer 32 of the second part 3b and the first wall 11 is equal; or, the distance between the multilayer cathode electrode layer 31 of the second part 3b and the first wall 11 increases along the first direction from the inside of the battery cell 100 to the outside of the battery cell 100, and the distance between the multilayer anode electrode layer 32 of the second part 3b and the first wall 11 increases along the first direction from the inside of the battery cell 100 to the outside of the battery cell 100.

[0123] Referring to Figures 8 and 9 , in some embodiments, the first portion 3a and the second portion 3b each include a separator 33. When the distance between the anode electrode layer 32 of the second portion 3b and the first wall 11 is greater than the distance between the anode electrode layer 32 of the first portion 3a and the first wall 11, the distance between the separator 33 of the second portion 3b and the first wall 11 is greater than the distance between the separator 33 of the first portion 3a and the first wall 11. Referring to Figures 6 and 7 , when the distance between the anode electrode layer 32 of the second portion 3b and the first wall 11 is equal to the distance between the anode electrode layer 32 of the first portion 3a and the first wall 11, the distance between the separator 33 of the second portion 3b and the first wall 11 is equal to the distance between the separator 33 of the first portion 3a and the first wall 11.

[0124] In the above technical solution, the distance between the isolation membrane 33 of the second part 3b and the first wall 11 is set to be greater than or equal to the distance between the isolation membrane 33 of the first part 3a and the first wall 11, so as to achieve a good match with the arrangement of the anode electrode layer 32 of the second part 3b relative to the anode electrode layer 32 of the first part 3a, that is, the height of the isolation membrane 33 of the second part 3b in the direction perpendicular to the first wall 11 is well matched with the height of the anode electrode layer 32 of the second part 3b and the cathode electrode layer 31 in the direction perpendicular to the first wall 11, and the height of the isolation membrane 33 of the first part 3a in the direction perpendicular to the first wall 11 is well matched with the height of the anode electrode layer 32 of the first part 3a and the cathode electrode layer 31 in the direction perpendicular to the first wall 11, so as to maximize the utilization of the material used for the isolation membrane 33 under the premise that the isolation membrane 33 realizes effective isolation of the anode electrode layer 32 and the cathode electrode layer 31.

[0125] In some embodiments, the number of the second portion 3b is n, where n is a positive integer. When the distance between the anode electrode layer 32 of the second portion 3b and the first wall 11 is greater than the distance between the anode electrode layer 32 of the first portion 3a and the first wall 11:

[0126] The sum of the thicknesses of the anode electrode layer 32 and the cathode electrode layer 31 of the second part 3b accounts for 25% / n to 30% / n of the thickness of the electrode assembly 3 in the first direction; and / or, the sum of the number of layers of the anode electrode layer 32 and the cathode electrode layer 31 of the second part 3b accounts for 10% / n to 20% / n of the sum of the number of layers of the anode electrode layer 32 and the cathode electrode layer 31 of the electrode assembly 3.

[0127] For example, when the second part 3b is one and the distance between the anode electrode layer 32 of the second part 3b and the first wall 11 is greater than the distance between the anode electrode layer 32 of the first part 3a and the first wall 11: the sum of the thicknesses of all anode electrode layers 32 and all cathode electrode layers 31 of the second part 3b accounts for 25% to 30% of the thickness of the electrode assembly 3 in the first direction; and / or the sum of the number of layers of all anode electrode layers 32 and all cathode electrode layers 31 of the second part 3b accounts for 25% to 30% of the thickness of the electrode assembly 3 in the first direction. 1; for example, the ratio of the sum of the thickness of all anode electrode layers 32 and all cathode electrode layers 31 of the second part 3b to the thickness of the electrode assembly 3 in the first direction is 25%, 26%, 27%, 28%, 29%, or 30%, etc., and the sum of the number of anode electrode layers 32 and all cathode electrode layers 31 of the second part 3b accounts for 10%, 13%, 15%, 18%, or 20%, etc. of the sum of the number of anode electrode layers 32 and cathode electrode layers 31 of the electrode assembly 3.

[0128] Alternatively, when there are two second parts 3b, and the distance between the anode electrode layer 32 of the second part 3b and the first wall 11 is greater than the distance between the anode electrode layer 32 of the first part 3a and the first wall 11: the sum of the thickness of all anode electrode layers 32 and all cathode electrode layers 31 of the second part 3b accounts for 12.5% ​​to 15% of the thickness of the electrode assembly 3 in the first direction; and / or, the sum of the number of layers of all anode electrode layers 32 and all cathode electrode layers 31 of the second part 3b accounts for 12.5% ​​to 15% of the thickness of all anode electrode layers 32 and all cathode electrode layers 31 of the electrode assembly 3. 5% to 10% of the sum of the number of layers; for example, the ratio of the sum of the thickness of all anode electrode layers 32 and all cathode electrode layers 31 of the second part 3b to the thickness of the electrode assembly 3 in the first direction is 12.5%, 13%, 13.5%, 14%, 14.5%, or 15%, etc., and the sum of the number of layers of all anode electrode layers 32 and all cathode electrode layers 31 of the second part 3b accounts for 5%, 6%, 7.5%, 9%, or 10%, etc. of the sum of the number of layers of all anode electrode layers 32 and all cathode electrode layers 31 of the electrode assembly 3.

[0129] In the above technical solution, when the distance between the anode electrode layer 32 of the second portion 3b and the first wall 11 is greater than the distance between the anode electrode layer 32 of the first portion 3a and the first wall 11, by setting the ratio of the sum of the thickness of the anode electrode layer 32 and the cathode electrode layer 31 of the second portion 3b to the thickness of the electrode assembly 3 in the first direction, and / or the ratio of the sum of the number of layers of the anode electrode layer 32 and the cathode electrode layer 31 of the second portion 3b to the sum of the number of layers of the anode electrode layer 32 and the cathode electrode layer 31 of the electrode assembly 3, the thickness and / or the number of layers of the second portion 3b can be reasonably set, thereby facilitating achieving a balance between the reliability and energy density of the battery cell 100. It is understood that in this solution, the distance between the multiple anode electrode layers 32 of the second portion 3b and the first wall 11 is equal; alternatively, the distance between the multiple anode electrode layers 32 of the second portion 3b and the first wall 11 increases along the first direction from the interior of the battery cell 100 to the exterior of the battery cell 100.

[0130] In some embodiments, the number of second portions 3b is n, where n is a positive integer. When the distance between the anode electrode layer 32 of the second portion 3b and the first wall 11 is equal to the distance between the anode electrode layer 32 of the first portion 3a and the first wall 11, the sum of the thicknesses of the cathode electrode layers 31 of the second portion 3b accounts for 25% / n to 30% / n of the thickness of the electrode assembly 3 in the first direction; and / or the number of cathode electrode layers 31 of the second portion 3b accounts for 10% / n to 20% / n of the number of cathode electrode layers 31 of the electrode assembly 3.

[0131] Exemplarily, when there is one second part 3b and the distance between the anode electrode layer 32 of the second part 3b and the first wall 11 is equal to the distance between the anode electrode layer 32 of the first part 3a and the first wall 11: the sum of the thicknesses of all the cathode electrode layers 31 of the second part 3b accounts for 25% to 30% of the thickness of the electrode assembly 3 in the first direction; and / or, the number of all the cathode electrode layers 31 of the second part 3b accounts for 10% to 20% of the number of all the cathode electrode layers 31 of the electrode assembly 3; for example, the ratio of the sum of the thicknesses of all the cathode electrode layers 31 of the second part 3b to the thickness of the electrode assembly 3 in the first direction is 25%, 26%, 27%, 28%, 29%, or 30%, etc., and the number of all the cathode electrode layers 31 of the second part 3b accounts for 10%, 13%, 15%, 17%, or 20%, etc.

[0132] Alternatively, when there are two second parts 3b and the distance between the anode electrode layer 32 of the second part 3b and the first wall 11 is equal to the distance between the anode electrode layer 32 of the first part 3a and the first wall 11: the sum of the thicknesses of all the cathode electrode layers 31 of the second part 3b accounts for 12.5% ​​to 15% of the thickness of the electrode assembly 3 in the first direction; and / or, the number of all the cathode electrode layers 31 of the second part 3b accounts for 5% to 10% of the number of all the cathode electrode layers 31 of the electrode assembly 3; for example, the ratio of the sum of the thicknesses of all the cathode electrode layers 31 of the second part 3b to the thickness of the electrode assembly 3 in the first direction is 12.5%, 13%, 13.5%, 14%, 14.5%, or 15%, etc., and the number of all the cathode electrode layers 31 of the second part 3b accounts for 5%, 6%, 7.5%, 8%, or 10%, etc.

[0133] In the above technical solution, when the distance between the anode electrode layer 32 of the second part 3b and the first wall 11 is equal to the distance between the anode electrode layer 32 of the first part 3a and the first wall 11, by setting the sum of the thicknesses of the cathode electrode layer 31 of the second part 3b to a ratio of the thickness of the electrode assembly 3 in the first direction, and / or the number of layers of the cathode electrode layer 31 of the second part 3b to a ratio of the sum of the number of layers of the cathode electrode layer 31 of the electrode assembly 3, it is convenient to reasonably set the thickness and / or the number of layers of the cathode electrode layer 31 of the second part 3b, which is conducive to achieving a simultaneous consideration of the reliability of the battery cell 100 and the energy density of the battery cell 100.

[0134] Referring to Figures 6-9 , in some embodiments, the orthographic projection of the second portion 3b is located outside the outer contour of the orthographic projection of the pressure relief mechanism 2 on the plane of the first wall 11. Thus, the orthographic projection of the second portion 3b is spaced apart from the orthographic projection of the pressure relief mechanism 2 along the first direction on the plane of the first wall 11. For example, in the first direction, the distance between the end of the second portion 3b distal to the second wall 12 and the second wall 12 is less than the minimum spacing between the pressure relief mechanism 2 and the second wall 12.

[0135] In the above technical solution, by being arranged on the plane where the first wall 11 is located, the orthographic projection of the second part 3b is located outside the outer contour of the orthographic projection of the pressure relief mechanism 2, so that the orthographic projection of the second part 3b and the orthographic projection of the pressure relief mechanism 2 are spaced apart along the first direction, so as to reduce the pulling effect on the pressure relief mechanism 2 due to the expansion and deformation of the electrode assembly 3, and at the same time, further appropriately increase the thickness of the second part 3b in the first direction, so as to further take into account the volume energy density of the battery cell 100.

[0136] Referring to Figures 6-10, in some embodiments, the maximum distance between the multi-layer cathode electrode layer 31 of the second portion 3b and the first wall 11 is h, where h ≥ 2 mm. It is understood that when the distances between the multi-layer cathode electrode layer 31 of the second portion 3b and the first wall 11 are equal, the distance between any cathode electrode layer 31 of the second portion 3b and the first wall 11 is h; alternatively, when the distances between the multi-layer cathode electrode layer 31 of the second portion 3b and the first wall 11 increase along the first direction from the interior of the battery cell 100 to the exterior of the battery cell 100, the distance between the cathode electrode layer 31 of the second portion 3b closest to the second wall 12 and the first wall 11 is h.

[0137] In the above technical solution, the maximum distance h between the multi-layer cathode electrode layer 31 of the second part 3b and the first wall 11 is set to ≥ 2 mm, so as to effectively reduce the pulling of the pressure relief mechanism 2 when the electrode assembly 3 expands and deforms, and at the same time facilitate the cooperation between the second part 3b and the first wall 11.

[0138] For example, h is 2 mm, 3 mm, 5 mm, 8 mm, 9 mm, 13 mm, 15 mm, or 16 mm.

[0139] Furthermore, h≤15 mm. Thus, while reducing the pulling force on the pressure relief mechanism 2 when the electrode assembly 3 expands and deforms, the volume energy density of the battery cell 100 can be taken into consideration to a certain extent.

[0140] For example, h is 2.5 mm, 3.5 mm, 6 mm, 10 mm, 14 mm, or 14.5 mm.

[0141] Furthermore, 3 mm ≤ h ≤ 10 mm, so as to achieve a balance between reliability and energy density of the battery cell 100 .

[0142] For example, h is 4 mm, 5.5 mm, 6.5 mm, 7 mm, 8.5 mm, or 9.5 mm.

[0143] In some embodiments, the electrode assembly 3 is a laminated electrode assembly, and the stacking direction of the anode electrode layer 32 and the cathode electrode layer 31 in the electrode assembly 3 is the first direction; or, the electrode assembly 3 is a wound electrode assembly, and the axial direction of the electrode assembly 3 is perpendicular to the first direction.

[0144] In the above technical solution, by setting the electrode assembly 3 to a laminated structure or a wound structure, the battery cell 100 can be provided with electrode assemblies 3 of different structures according to actual needs, which is beneficial to improving the applicability of the battery cell 100.

[0145] As an example, the anode electrode layer 32 and the cathode electrode layer 31 are respectively multi-layered, and the multi-layer anode electrode layer 32 and the multi-layer cathode electrode layer 31 are alternately stacked. As an example, the cathode electrode layer 31 is multi-layered, and the anode electrode sheet is folded to form a plurality of stacked anode electrode layers 32, and a cathode electrode layer 31 is sandwiched between adjacent anode electrode layers 32. As an example, the anode electrode sheet is folded to form a plurality of stacked anode electrode layers 32, and the cathode electrode sheet is folded to form a plurality of stacked cathode electrode layers 31. As an example, a plurality of separators 33 can be provided, and each separator 33 is respectively provided between any adjacent anode electrode layer 32 and cathode electrode layer 31. As an example, the separator 33 can be provided continuously, and can be provided between any adjacent anode electrode layer 32 and cathode electrode layer 31 by folding or winding. For example, for a laminated electrode assembly, the separator 33 can extend roughly in a serpentine shape.

[0146] It can be understood that, for a laminated electrode assembly, the difference between the cathode electrode layer 31 of the second part 3b and the cathode electrode layer 31 of the first part 3a in the embodiment of the present application can be completed by cutting when cutting a single layer of electrode; similarly, for a laminated electrode assembly, the difference between the anode electrode layer 32 of the second part 3b and the anode electrode layer 32 of the first part 3a in the embodiment of the present application can also be completed by cutting when cutting a single layer of electrode.

[0147] In some embodiments, as shown in FIG10 , the electrode assembly 3 is a wound electrode assembly, and the first portion 3a is provided with a second portion 3b on opposite sides of the first portion 3a in the first direction. In this case, the two second portions 3b may correspond to the outer winding layers of the wound electrode assembly, and the first portion 3a may correspond to the inner winding layer of the wound electrode assembly.

[0148] In the above technical solution, by setting the electrode assembly 3 as a wound electrode assembly, the first part 3a is provided with a second part 3b on two opposite sides in the first direction, which is conducive to simplifying the unfolding structure of the wound electrode assembly and facilitating the processing of the electrode assembly 3.

[0149] For example, taking the cathode electrode of the electrode assembly 3 as an example, the unfolded cathode electrode may include a first section 35 and a second section 36 arranged in sequence along the length direction, the first section 35 corresponds to the inner winding layer and can form a first part 3a, the second section 36 corresponds to the outer winding layer and can form two second parts 3b; if the multi-layer cathode electrode layer 31 of the second part 3b is at the same distance from the first wall 11, it is convenient to make the edge of the second section 36 corresponding to the second part 3b adjacent to the first wall 11 a straight line; further, if the cathode electrode layer 31 of the two second parts 3b is at the same distance from the first wall 11, it is convenient to make the edge of the entire second section 36 adjacent to the first wall 11 a straight line, which is conducive to simplifying the processing of the cathode electrode.

[0150] 6-9 , in some embodiments, the cathode electrode layers 31 of the two second portions 3 b are equidistant from the first wall 11 , and the anode electrode layers 32 of the two second portions 3 b are equidistant from the first wall 11 .

[0151] Optionally, in the above solution, the distance between the cathode electrode layer 31 of the two second parts 3b and the first wall 11 can be understood as the minimum distance, the maximum distance, or the average distance. For example, the two second parts 3b can be symmetrically arranged with respect to the first part 3a.

[0152] In the above technical solution, by setting the cathode electrode layer 31 of the two second parts 3b to be at an equal distance from the first wall 11, and the anode electrode layer 32 of the two second parts 3b to be at an equal distance from the first wall 11, it is convenient to further simplify the structure of the cathode electrode sheet and the anode electrode sheet of the wound electrode assembly and simplify the processing process.

[0153] Of course, in other embodiments, the distances between the cathode electrode layer 31 of the two second parts 3b and the first wall 11 are different; and / or the distances between the anode electrode layer 32 of the two second parts 3b and the first wall 11 are different.

[0154] In some embodiments, the sum of the lengths of the multi-layer cathode electrode sheet layers 31 of the two second portions 3b in the circumferential direction of the electrode assembly 3 accounts for 30% to 50% of the circumferential length of the electrode assembly 3. The circumferential direction of the electrode assembly 3 can be understood as the winding direction of the electrode assembly 3, which is perpendicular to the axial direction of the electrode assembly 3. Therefore, for the unfolded cathode electrode sheet of the electrode assembly 3, the length of the second segment 36 accounts for 30% to 50% of the sum of the lengths of the first segment 35 and the second segment 36, for example, 30%, 35%, 40%, 45%, or 50%.

[0155] In the above technical solution, by setting the sum of the lengths of the multi-layer cathode electrode layer 31 of the two second parts 3b in the circumferential direction of the electrode assembly 3 to account for 30% to 50% of the circumferential length of the electrode assembly 3, it is convenient to set the thickness and / or number of layers of the second part 3b reasonably, which is conducive to achieving both the reliability of the battery cell 100 and the energy density of the battery cell 100.

[0156] Referring to Figures 6-9 , in some embodiments, the housing 1 has two second walls 12 disposed opposite each other along a first direction, the first wall 11 connecting the two second walls 12, and a second portion 3b disposed between the first portion 3a and each second wall 12. It can be seen that there are two second portions 3b, with the first portion 3a disposed between the two second portions 3b.

[0157] In the above technical solution, a first wall 11 is provided to be connected between the two second walls 12, and a second part 3b is provided between the first part 3a and each second wall 12, so that when the electrode assembly 3 expands and deforms, the effect of each second wall 12 on the first wall 11 is weakened, thereby facilitating weakening the overall pulling on both ends of the pressure relief mechanism 2 in the first direction, thereby further reducing the risk of the pressure relief mechanism 2 being damaged by pulling.

[0158] In some embodiments, the second wall 12 is the wall with the largest area in the shell 1 , and the second wall 12 can be understood as the “large surface” of the shell 1 .

[0159] It can be seen that the first wall 11 is a narrow shell wall connected between the two second walls 12. After the electrode assembly 3 is installed in the shell 1, the second wall 12 is opposite to the straight area 30 of the electrode assembly 3. When the internal pressure of the shell 1 reaches a certain value, the pressure relief mechanism 2 realizes pressure relief.

[0160] When the electrode assembly 3 expands, the electrode assembly 3 pushes against the second wall 12 and pushes the shell 1 outward in the first direction, causing the shell 1 to deform. The second wall 12 is the main stress-bearing surface and deforms significantly, and the force on the first wall 11 is smaller than that on the second wall 12. Therefore, by arranging the pressure relief mechanism 2 on the first wall 11, the pressure relief mechanism 2 is arranged on the less stress-bearing surface of the shell 1. Compared with arranging the pressure relief mechanism 2 on the second wall 12, the force on the pressure relief mechanism 2 can be reduced, thereby further reducing the risk of the pressure relief mechanism 2 being damaged or failing due to pulling.

[0161] In the above technical solution, by arranging the pressure relief mechanism 2 on the first wall 11, the first wall 11 is not the wall with the largest area of ​​the shell 1, and the pressure relief mechanism 2 can be arranged on the smaller stress surface of the shell 1. Compared with arranging the pressure relief mechanism 2 on the second wall 12, when the electrode assembly 3 expands and deforms, the force on the pressure relief mechanism 2 can be reduced, which is conducive to further reducing the risk of the pressure relief mechanism 2 being pulled, damaged or failed.

[0162] 3 and 4 , in some embodiments, the pressure relief mechanism 2 and the pole 4 of the battery cell 100 are disposed on different sides of the housing 1 , that is, the pole 4 is disposed on other walls of the housing 1 except the first wall 11 .

[0163] In the above technical solution, the terminal post 4 is connected to the tab of the electrode assembly 3, and a certain gap exists between the wall where the terminal post 4 is located and the main body of the electrode assembly 3. By placing the pressure relief mechanism 2 and the terminal post 4 on different sides of the wall of the housing 1, the distance between the pressure relief mechanism 2 and the main body of the electrode assembly 3 can be appropriately shortened to a certain extent, making the distance between the pressure relief mechanism 2 and the main body of the electrode assembly 3 less restricted by the terminal post 4. In the event of thermal runaway of the battery cell 100, most of the exhaust medium in the housing 1 can flow directly from the edge of the main body of the electrode assembly 3 to the pressure relief mechanism 2, thereby shortening the path for the exhaust medium to flow to the pressure relief mechanism 2, allowing the exhaust medium to flow quickly to the pressure relief mechanism 2, shortening the time it takes for the exhaust medium to reach the pressure relief mechanism 2, and improving the timely pressure relief of the battery cell 100. The tab includes multiple tab sheets 34.

[0164] In some embodiments, the housing 1 further has a third wall 13, and the pole 4 is disposed on the third wall 13. The third wall 13 is disposed adjacent to and connected to the first wall 11 and the second wall 12, respectively; or the third wall 13 is disposed adjacent to and connected to the second wall 12, and the third wall 13 is disposed opposite to the first wall 11.

[0165] It can be seen that the wall where the pressure relief mechanism 2 is provided is adjacent to or opposite to the wall where the pole 4 is provided.

[0166] In the above technical solution, by arranging the pole 4 on the third wall 13 , and the third wall 13 being adjacent to or opposite to the first wall 11 , it is easy to meet the differentiated arrangement requirements of the battery cell 100 , which is beneficial to improving the applicability of the battery cell 100 .

[0167] Exemplarily, the shell 1 includes a shell body 1a and a shell cover 1b, the shell body 1a is open at both ends in the second direction, the shell cover 1b is arranged at the open end of the shell body 1a, the first wall 11 and the second wall 12 are both formed on the shell body 1a, and at least one of the two shell covers 1b is formed as a third wall 13. At this time, the third wall 13 is adjacent to and connected to the first wall 11 and the second wall 12 respectively; one of the two ends of the shell body 1a in the second direction is open, the shell cover 1b is arranged at the open end of the shell body 1a, the shell cover 1b is formed as the third wall 13, and the shell cover 1b is opposite to the first wall 11 along the second direction.

[0168] Please refer to Figures 3 and 4. In some embodiments, the shell 1 includes a shell body 1a and a shell cover 1b. At least one of the two ends of the shell body 1a in the second direction is open. The shell cover 1b is arranged at the open end of the shell body 1a. The first wall 11 and the second wall 12 are both formed on the shell body 1a. The second direction is perpendicular to the first direction.

[0169] Exemplarily, the shell body 1a can be a hollow structure with an opening formed at one end, or the shell body 1a can be a hollow structure with openings formed at two opposite ends. The shell body 1a can be of various shapes, such as a prismatic shape. The shell cover 1b is a component that closes the opening of the shell body 1a to isolate the internal environment of the battery cell 100 from the external environment. The shell cover 1b and the shell body 1a together define a mounting cavity for accommodating the electrode assembly 3, electrolyte, and other components. The shape of the shell cover 1b can be compatible with the shape of the shell body 1a. For example, if the shell body 1a is a rectangular parallelepiped structure, the shell cover 1b can be a rectangular plate structure that is compatible with the shell body 1a. For another example, if the shell body 1a is a cylindrical structure, the shell cover 1b can be a circular plate structure that is compatible with the shell body 1a. The material of the shell cover 1b can also be various, such as copper, iron, aluminum, steel, aluminum alloy, plastic, etc. The material of the shell cover 1b and the shell body 1a can be the same or different.

[0170] In embodiments where the housing 1a is open at one end, one housing cover 1b may be provided. In embodiments where the housing 1a is open at two opposite ends, two housing covers 1b may be provided, each of which closes the two openings of the housing 1a, and the two housing covers 1b and the housing 1a together define a mounting cavity.

[0171] The shell body 1a has a first wall 11. The pressure relief mechanism 2 can be integrally formed with the first wall 11 or can be separately arranged from the first wall 11. By arranging the pressure relief mechanism 2 on the shell body 1a, the structure of the shell cover 1b can be simplified, and at the same time, it is convenient to shorten the distance between the pressure relief mechanism 2 and the main body of the electrode assembly 3, thereby shortening the path of the discharge medium flowing to the pressure relief mechanism 2 during pressure relief, shortening the time for the discharge medium to reach the pressure relief mechanism 2, and improving the timeliness of the pressure relief of the battery cell 100, which is conducive to further improving the reliability of the battery cell 100.

[0172] In the above technical solution, by setting the first wall 11 and the second wall 12 to be formed on the shell body 1a, the structure of the shell cover 1b can be simplified, and at the same time, it is convenient to shorten the distance between the pressure relief mechanism 2 and the main body of the electrode assembly 3, thereby shortening the path of the discharge medium flowing to the pressure relief mechanism 2 during pressure relief, shortening the time for the discharge medium to reach the pressure relief mechanism 2, and improving the timeliness of pressure relief of the battery cell 100.

[0173] For example, one end of the shell body 1a in the second direction is open, and the first wall 11 is provided at the end of the shell body 1a away from the open end; or both ends of the shell body 1a in the second direction are open, and the first wall 11 extends to the open ends on both sides, and the opposite ends of the first wall 11 are connected to the two end caps. This facilitates the processing convenience of the shell body 1a and the shell cap 1b, and improves the assembly convenience of the housing 1.

[0174] Please refer to Figures 6 to 9. In some embodiments, the pressure relief mechanism 2 is integrally formed with the first wall 11; or, as shown in Figure 3, the pressure relief mechanism 2 and the first wall 11 are separately provided, and the pressure relief mechanism 2 is installed on the first wall 11. For example, the first wall 11 is provided with a through hole, and the pressure relief mechanism 2 is installed in the through hole.

[0175] When the pressure relief mechanism 2 is integrally formed with the first wall 11, a notched groove 11b can be provided on the first wall 11. The area of ​​the first wall 11 corresponding to the notched groove 11b forms a weak area of ​​the pressure relief mechanism 2. The weak area is configured to crack when the battery cell 100 is depressurized. The molding method of the pressure relief mechanism 2 is simple and the production cost is low. It can be understood that the notched groove 11b is formed on the inner surface of the first wall 11 and / or the outer surface of the first wall 11.

[0176] It can be seen that in the above technical solution, by integrally forming the pressure relief mechanism 2 and the first wall 11, the pressure relief mechanism 2 is formed in a simple manner, which can reduce the number of components constituting the battery cell 100, simplify the structure of the battery cell 100, and reduce costs.

[0177] In the embodiment of the present application, there is no specific restriction on the shape of the notched groove 11b; for example, the notched groove 11b includes a first straight groove segment and four second straight groove segments, and the two ends of the first straight groove segment are respectively connected to two second straight groove segments set at a preset angle, so that the two ends of the notched groove 41 can roughly form a Y shape.

[0178] When the pressure relief mechanism 2 is separately provided from the first wall 11, the pressure relief mechanism 2 and the shell 1 are two separate components, which are separately formed and then installed together; the pressure relief mechanism 2 can be a component such as an explosion-proof plate, an explosion-proof valve, a safety valve, etc., and the pressure relief mechanism 2 can be installed on the first wall 11 by bonding, welding, etc. The first wall 11 is provided with a through hole, and the pressure relief mechanism 2 is installed in the through hole. When the internal pressure of the battery cell 100 reaches a threshold value or the temperature reaches a threshold value, the pressure relief mechanism 2 opens at least part of the through hole, and the discharge medium inside the battery cell 100 is discharged through the through hole to release the pressure inside the battery cell 100.

[0179] It can be seen that in the above technical solution, the pressure relief mechanism 2 and the first wall 11 are constructed as separate parts, which facilitates the installation of the pressure relief mechanism 2 on the housing 1 , reduces production difficulty and increases efficiency, and can improve the production efficiency of the battery cell 100 .

[0180] For example, if the pressure relief mechanism 2 is a bursting disc, the bursting disc is a sheet having at least a portion of its strength less than that of the first wall 11. The bursting disc covers the through-hole and is welded to the first wall 11. When the internal pressure or temperature of the battery cell 100 reaches a threshold, the bursting disc is at least partially destroyed, thereby opening at least a portion of the through-hole to release the pressure within the battery cell 100.

[0181] In some embodiments, when the pressure relief mechanism 2 is integrally formed with the first wall 11 , a groove 11 a is provided on the inner surface and / or outer surface of the first wall 11 , and the bottom wall of the groove 11 a forms the pressure relief mechanism 2 .

[0182] In the above technical solution, the inner surface and / or outer surface of the first wall 11 is provided with a groove 11 a , and the bottom wall of the groove 11 a forms the pressure relief mechanism 2 , so as to facilitate the processing and forming of the pressure relief mechanism 2 .

[0183] Taking the first wall 11 as the bottom wall of the shell 1 as an example, the inner surface of the first wall 11 is provided with a groove 11a, then a portion of the upper surface of the first wall 11 is recessed downward to form the groove 11a, and the lower groove wall of the groove 11a is the groove bottom wall; the outer surface of the first wall 11 is provided with a groove 11a, then a portion of the lower surface of the first wall 11 is recessed upward to form the groove 11a, and the upper groove wall of the groove 11a is the groove bottom wall.

[0184] In some embodiments, when the pressure relief mechanism 2 is integrally formed with the first wall 11 , a notch is formed on the first wall 11 , and the area of ​​the first wall 11 corresponding to the notch is configured as a weak area of ​​the pressure relief mechanism 2 , and the weak area is configured to rupture when the battery cell 100 releases pressure.

[0185] In the above technical solution, the first wall 11 is provided with a notched groove, and the area of ​​the first wall 11 corresponding to the notched groove is configured as a weak area of ​​the pressure relief mechanism 2, which facilitates the processing and forming of the pressure relief mechanism 2.

[0186] In a second aspect, an embodiment of the present application provides a battery cell 100, comprising a housing 1, a pressure relief mechanism 2, and an electrode assembly 3. The housing 1 has an adjacent and connected first wall 11, the pressure relief mechanism 2 is disposed on the first wall 11, and the electrode assembly 3 is disposed within the housing 1. The electrode assembly 3 comprises an anode electrode layer 32 and a cathode electrode layer 31 stacked along a first direction, and a distance between the electrode assembly 3 and the first wall 11 is 2 mm ≤ h ≤ 15 mm. The first direction is parallel to the plane of the first wall 11.

[0187] In the above technical solution, by setting the distance between the electrode assembly 3 and the first wall 11 to 2mm≤h≤15mm, when the electrode assembly expands and deforms, it is beneficial to increase the distance between the position of the main force exerted by the electrode assembly on the two walls of the shell 1 arranged opposite to each other along the first direction and the first wall, thereby helping to reduce the risk of the pressure relief mechanism 2 being pulled on the first wall 11, being damaged or failing, and improving the reliability of the battery cell. At the same time, it can take into account the volume energy density of the battery cell to a certain extent and will not excessively reduce the energy density of the battery cell.

[0188] In a third aspect, an embodiment of the present application provides a battery 200 including the above-mentioned battery cell 100 .

[0189] In the above technical solution, since the battery 200 adopts the above-mentioned battery cell 100 , it is beneficial to improve the reliability and energy density of the battery 200 .

[0190] In a third aspect, an embodiment of the present application provides an electrical device 1000 , comprising the above-mentioned battery 200 , wherein the battery 200 is used to provide electrical energy.

[0191] In the above technical solution, since the power-consuming device 1000 adopts the above-mentioned battery 200 and the battery 200 has good reliability and energy density, it is beneficial to improve the reliability and endurance of the power-consuming device 1000.

[0192] Please refer to FIG. 3 to FIG. 9 again to describe the battery cell 100 according to a specific embodiment of the present application.

[0193] In an embodiment of the present application, a battery cell 100 includes a shell 1, a pressure relief structure 2 and an electrode assembly 3, the shell 1 has a first wall 11 and two second walls 12, each second wall 12 is adjacent to and connected to the first wall 11, the pressure relief mechanism 2 is provided on the first wall 11, the electrode assembly 3 is provided in the shell 1, the electrode assembly 3 has a first part 3a and a second part 3b arranged in sequence along a first direction, the first part 3a and the second part 3b both include a multi-layer anode electrode layer 32 and a multi-layer cathode electrode layer 31, the multi-layer anode electrode layer 32 and the multi-layer cathode electrode layer 31 are alternately stacked one by one along the first direction, a second part 3b is provided between the first part 3a and each second wall 12, the distance x2 between the cathode electrode layer 31 of the second part 3b and the first wall 11 is greater than the distance x1 between the cathode electrode layer 31 of the first part 3a and the first wall 11, and the first direction is perpendicular to the second wall 12

[0194] As shown in Figure 6, the distances x4 between the multi-layer cathode electrode layer 31 of the second portion 3b and the first wall 11 are equal, and the distance x4 between the anode electrode layer 32 of the second portion 3b and the first wall 11 is equal to the distance x3 between the anode electrode layer 32 of the first portion 3a and the first wall 11. As shown in Figure 7, the distances x4 between the multi-layer cathode electrode layer 31 of the second portion 3b and the first wall 11 increase from the interior of the battery cell 100 to the exterior of the battery cell 100 along the first direction, and the distance x4 between the anode electrode layer 32 of the second portion 3b and the first wall 11 is equal to the distance x3 between the anode electrode layer 32 of the first portion 3a and the first wall 11. As shown in Figure 8, the distances x4 between the multi-layer cathode electrode layer 31 of the second portion 3b and the first wall 11 are equal, and the distance x4 between the anode electrode layer 32 of the second portion 3b and the first wall 11 is greater than the distance x3 between the anode electrode layer 32 of the first portion 3a and the first wall 11. Furthermore, the distances x4 between the multi-layer anode electrode layer 32 of the second portion 3b and the first wall 11 are equal. As shown in Figure 9, the distance between the multi-layer cathode electrode layer 31 of the second part 3b and the first wall 11 increases along the first direction from the inside of the battery cell 100 to the outside of the battery cell 100, the distance x4 between the anode electrode layer 32 of the second part 3b and the first wall 11 is greater than the distance x3 between the anode electrode layer 32 of the first part 3a and the first wall 11, and the distance between the multi-layer anode electrode layer 32 of the second part 3b and the first wall 11 increases along the first direction from the inside of the battery cell 100 to the outside of the battery cell 100.

[0195] In the above technical solution, when the electrode assembly 3 expands and deforms, the pulling effect on the pressure relief mechanism 2 on the first wall 11 can be weakened, reducing the probability of the pressure relief structure 2 being damaged or failing due to pulling, while taking into account the volume energy density of the battery cell 100.

[0196] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0197] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A battery cell, wherein, comprising: a housing having adjacent and connected first and second walls; a pressure relief mechanism provided on the first wall; an electrode assembly provided inside the housing, the electrode assembly having a first portion and a second portion arranged in sequence along a first direction, both the first portion and the second portion including multiple anode electrode sheet layers and multiple cathode electrode sheet layers, the multiple anode electrode sheet layers and the multiple cathode electrode sheet layers being alternately stacked one by one along the first direction, the second portion being provided between the first portion and the second wall, the distance x2 between the cathode electrode sheet layer of the second portion and the first wall being greater than the distance x1 between the cathode electrode sheet layer of the first portion and the first wall, the first direction being perpendicular to the second wall.

2. The battery cell according to claim 1, wherein, the distances between the multiple cathode electrode sheet layers of the second portion and the first wall are equal; or, the distances between the multiple cathode electrode sheet layers of the second portion and the first wall increase from the inside of the battery cell to the outside of the battery cell along the first direction.

3. The battery cell according to claim 1 or 2, wherein, the distance x4 between the anode electrode sheet layer of the second portion and the first wall is greater than or equal to the distance x3 between the anode electrode sheet layer of the first portion and the first wall.

4. The battery cell according to claim 3, wherein, the distances between the multiple anode electrode sheet layers of the second portion and the first wall are equal; or, the distances between the multiple anode electrode sheet layers of the second portion and the first wall increase from the inside of the battery cell to the outside of the battery cell along the first direction.

5. The battery cell according to claim 3 or 4, wherein, the first portion and the second portion respectively include a separator, when the distance between the anode electrode sheet layer of the second portion and the first wall is greater than the distance between the anode electrode sheet layer of the first portion and the first wall, the distance between the separator of the second portion and the first wall is greater than the distance between the separator of the first portion and the first wall; when the distance between the anode electrode sheet layer of the second portion and the first wall is equal to the distance between the anode electrode sheet layer of the first portion and the first wall, the distance between the separator of the second portion and the first wall is equal to the distance between the separator of the first portion and the first wall.

6. The battery cell according to any one of claims 3-5, wherein, the second portion is n, n being a positive integer, when the distance between the anode electrode sheet layer of the second portion and the first wall is greater than the distance between the anode electrode sheet layer of the first portion and the first wall, the sum of the thicknesses of the anode electrode sheet layer and the cathode electrode sheet layer of the second portion accounts for 25% / n to 30% / n of the thickness of the electrode assembly in the first direction; and / or, The sum of the number of layers of the anode electrode sheet layer and the cathode electrode sheet layer of the second part accounts for 10% / n - 20% / n of the sum of the number of layers of the anode electrode sheet layer and the cathode electrode sheet layer of the electrode assembly.

7. The battery cell according to any one of claims 3-5, wherein, when there are n second parts, n being a positive integer, and the distance between the anode electrode sheet layer of the second part and the first wall is equal to the distance between the anode electrode sheet layer of the first part and the first wall, the sum of the thicknesses of the cathode electrode sheet layers of the second part accounts for 25% / n - 30% / n of the thickness of the electrode assembly in the first direction; and / or, the number of layers of the cathode electrode sheet layer of the second part accounts for 10% / n - 20% / n of the number of layers of the cathode electrode sheet layer of the electrode assembly.

8. The battery cell according to any one of claims 1-7, wherein, on the plane where the first wall is located, the orthographic projection of the second part is located outside the outer contour of the orthographic projection of the pressure relief mechanism.

9. The battery cell according to any one of claims 1-8, wherein, the maximum distance between the multiple cathode electrode sheet layers of the second part and the first wall is h, h≥2mm.

10. The battery cell according to claim 9, wherein, h≤15mm.

11. The battery cell according to claim 9 or 10, wherein, 3mm≤h≤10mm.

12. The battery cell according to any one of claims 1-11, wherein, the electrode assembly is a stacked electrode assembly, and the stacking direction of the anode electrode sheet layer and the cathode electrode sheet layer in the electrode assembly is the first direction; or, the electrode assembly is a wound electrode assembly, and the axial direction of the electrode assembly is perpendicular to the first direction.

13. The battery cell according to claim 12, wherein, the electrode assembly is a wound electrode assembly, and the second part is provided on both opposite sides of the first part in the first direction.

14. The battery cell according to claim 13, wherein, the distances between the cathode electrode sheet layers of the two second parts and the first wall are equal, and the distances between the anode electrode sheet layers of the two second parts and the first wall are equal.

15. The battery cell according to claim 13 or 14, wherein, the sum of the circumferential lengths of the multiple cathode electrode sheet layers of the two second parts accounts for 30% - 50% of the circumferential length of the electrode assembly.

16. The battery cell according to any one of claims 1-15, wherein, the housing has two second walls oppositely arranged along the first direction, the first wall connects the two second walls, and the second part is provided between the first part and each second wall respectively.

17. The battery cell according to claim 16, wherein, the second wall is the wall with the largest area in the housing.

18. The battery cell according to any one of claims 1-17, wherein, the pressure relief mechanism and the pole post of the battery cell are disposed on the walls of different sides of the housing.

19. The battery cell according to claim 18, wherein, the housing further has a third wall, and the pole is provided on the third wall, the third wall is adjacent to and connected with the first wall and the second wall respectively; or, the third wall is adjacent to and connected with the second wall, and the third wall is disposed opposite to the first wall.

20. The battery cell according to any one of claims 1-19, wherein, the housing includes a housing body and a housing cover, at least one end of the two ends of the housing body in the second direction is open, the housing cover is disposed at the open end of the housing body, and the first wall and the second wall are both formed on the housing body, and the second direction is perpendicular to the first direction.

21. The battery cell according to claim 20, wherein, one end of the housing body in the second direction is open, and the first wall is connected to one end of the second wall away from the open end; or, both ends of the housing body in the second direction are respectively open, and the first wall and the second wall both extend to the open ends on both sides.

22. The battery cell according to any one of claims 1-21, wherein, the pressure relief mechanism is integrally formed with the first wall.

23. The battery cell according to claim 22, wherein, grooves are provided on the inner surface and / or the outer surface of the first wall, and the bottom wall of the groove forms the pressure relief mechanism.

24. The battery cell according to claim 22 or 23, wherein, a scoring groove is formed on the first wall, and the area of the first wall corresponding to the scoring groove is configured as a weak area of the pressure relief mechanism, and the weak area is configured to crack when the battery cell relieves pressure.

25. The battery cell according to any one of claims 1-21, wherein, the pressure relief mechanism is separately provided from the first wall, and the pressure relief mechanism is installed on the first wall.

26. A battery cell, wherein, comprises: a housing having a first wall and a second wall that are adjacent to and connected with each other; a pressure relief mechanism provided on the first wall; an electrode assembly provided in the housing, the electrode assembly includes an anode electrode sheet layer and a cathode electrode sheet layer stacked along a first direction, and the distance between the electrode assembly and the first wall is 2mm ≤ h ≤ 15mm, and the first direction is parallel to the plane where the first wall is located.

27. A battery, wherein, comprises the battery cell according to any one of claims 1-26.

28. An electrical device, wherein, comprises the battery according to claim 27, and the battery is used to provide electrical energy.

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