Battery monomer, battery and electric device

Abstract

The invention discloses a battery monomer, a battery and a power utilization device. The battery cell includes: a case; the at least one electrode assembly is arranged in the shell; the elastic buffer pad is arranged on at least part of the surface of the electrode assembly and / or in the electrode assembly, the compression rate of the elastic buffer pad in the thickness direction of the elastic buffer pad is smaller than or equal to 30% under the pressure of 0.1 Mpa, and the compression rate of the elastic buffer pad in the thickness direction of the elastic buffer pad is larger than or equal to 50% under the pressure of 1 Mpa. Therefore, the elastic buffer pad can play a better role, the volume stability of the battery monomer in the long-term use process is improved, and meanwhile, the stress uniformity of the pole piece in the charging and discharging process is favorably maintained.

Description

Technical Field

[0001] The present application belongs to the field of battery technology, and specifically, relates to battery cells, batteries and electrical devices. Background Art

[0002] As an energy storage device, batteries are widely used in various fields. Take lithium-ion batteries as an example. They are green, environmentally friendly, high-energy, and low-carbon. They are not only used in energy storage power systems such as hydropower, thermal, wind, and solar power stations, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars, and ships, as well as military equipment and aerospace and other fields. With the development of the current society, people's requirements for batteries are getting higher and higher. Summary of the invention

[0003] In view of the technical problems existing in the background technology, the present application provides a battery cell, which aims to improve the effect of the buffer pad and improve the force uniformity of the electrode during the charging and discharging process.

[0004] In order to achieve the above-mentioned object, the first aspect of the present application provides a battery cell, which includes:

[0005] case;

[0006] at least one electrode assembly, the electrode assembly being disposed within the housing;

[0007] At least one elastic buffer pad is arranged on at least a portion of the surface of the electrode assembly and / or inside the electrode assembly, and the compression rate of the elastic buffer pad along the thickness direction under a pressure of 0.1 MPa is ≤30%, and the compression rate along the thickness direction under a pressure of 1 MPa is ≥50%.

[0008] The battery cell of the first aspect of the present application has the following beneficial effects: on the one hand, it can buffer the volume expansion force generated by the electrode assembly during charging, discharging and use, and inhibit the deformation of the battery cell; on the other hand, it can make the elastic buffer pad provide different strengths and stresses in different charging and discharging processes. In the early stage of charging or use, the elastic buffer pad is not over-compressed, and can provide a certain support strength, which is conducive to the direct bonding of the electrode assembly with the inner wall of the shell or the bonding of the elastic buffer pad with the inner wall of the shell, to achieve the interaction force and improve the force uniformity of the pole piece. In the late stage of charging or the late stage of battery cell cycle, the elastic buffer pad can be fully compressed during the expansion of the electrode assembly, and the space in the thickness direction is transferred to the electrode assembly, reducing the expansion force of the electrode assembly, and providing a larger stress, while reducing the expansion force of the electrode assembly, improving the force uniformity of the pole piece during the charging and discharging process. As a result, the elastic buffer pad can play a better effect, while improving the volume stability of the battery cell during long-term use, it is also conducive to maintaining the force uniformity of the pole piece during the charging and discharging process, thereby helping to reduce the risk of expansion deformation or performance deterioration of the battery cell and improve the long-term use performance.

[0009] In some embodiments of the present application, the elastic buffer pad is provided between the electrode assembly and the housing, and / or the elastic buffer pad is provided between two adjacent electrode assemblies. Meeting the given conditions is conducive to improving the volume stability of the battery cell during long-term use.

[0010] In some embodiments of the present application, the compression rate of the elastic buffer pad along its thickness direction under a pressure of 0.1Mpa is ≤20%, and optionally ≤10%; and / or the compression rate of the elastic buffer pad along its thickness direction under a pressure of 1Mpa is ≥60%, and optionally ≥80%. Meeting the given conditions is conducive to further improving the force uniformity of the pole piece during the charging and discharging process.

[0011] In some embodiments of the present application, the compression rate of the elastic buffer pad under a pressure of 0.5 MPa is 30% to 60%. Meeting the given conditions is conducive to improving the volume stability of the battery cell and further improving the force uniformity of the pole piece during the charging and discharging process.

[0012] In some embodiments of the present application, the electrode assembly is a wound electrode assembly and includes a straight portion and a corner portion, and the elastic buffer pad is provided on at least a portion of the surface of the straight portion and / or the corner portion.

[0013] In some embodiments of the present application, the battery cell is a prismatic battery cell.

[0014] In some embodiments of the present application, the prismatic battery cell includes: at least one first elastic buffer pad and / or at least one second elastic buffer pad, the first elastic buffer pad and the electrode assembly are stacked along the thickness direction of the battery cell, and / or the second elastic buffer pad and the electrode assembly are stacked along the length direction of the battery cell. Meeting the given conditions is conducive to reducing the expansion force generated by the electrode assembly during use.

[0015] In some embodiments of the present application, the prismatic battery cell satisfies at least one of the following conditions: in the thickness direction of the battery cell, the sum of the total thickness of the first elastic buffer pad in the free state and the total thickness of the electrode assembly in the fully discharged state is 80% to 99% of the distance between the inner walls of the shell, which can be optionally 85% to 98%, and further optionally 90% to 95%; in the thickness direction of the battery cell, the sum of the total thickness of the first elastic buffer pad in the free state and the total thickness of the electrode assembly in the fully charged state is 95% to 110% of the distance between the inner walls of the shell, which can be optionally 98% ~105%, and can be further selected as 99%~102%; in the length direction of the battery cell, the sum of the total thickness of the second elastic buffer pad in the free state and the length of the electrode assembly in the fully discharged state is 80%~99% of the distance between the inner walls of the shell, can be further selected as 85%~98%, and can be further selected as 90%~95%; in the length direction of the battery cell, the sum of the total thickness of the second elastic buffer pad in the free state and the length of the electrode assembly in the fully charged state is 95%~110% of the distance between the inner walls of the shell, can be further selected as 98%~105%, and can be further selected as 99%~102%. Meeting the given conditions is conducive to the smooth entry of the elastic buffer pad into the shell, and / or improving the volume stability of the battery cell and the force uniformity of the pole piece.

[0016] In some embodiments of the present application, the ratio of the total thickness of the first elastic buffer pad in a free state to the total thickness of the electrode assembly in a fully discharged state is 2% to 25%, optionally 5% to 20%, and further optionally 8% to 15%. Meeting the given conditions is conducive to maintaining the volume stability of the battery cell and taking into account the energy density of the battery cell.

[0017] In some embodiments of the present application, the ratio of the extension distance of the first elastic buffer in the length direction of the electrode assembly to the length of the electrode assembly in a free state is 0.8 to 1.2, optionally 0.85 to 1.1, and further optionally 0.9 to 1.05; and / or the ratio of the extension distance of the first elastic buffer in the height direction of the electrode assembly to the height of the electrode assembly in a free state is 0.8 to 1.2, optionally 0.85 to 1.1, and further optionally 0.9 to 1.05. Meeting the given conditions is conducive to enabling the elastic buffer to cover most areas of the electrode assembly, which is conducive to improving the volume stability of the battery cell and further improving the force uniformity of the pole piece.

[0018] In some embodiments of the present application, the orthographic projection of the first elastic buffer pad on the electrode assembly is located in the region where the electrode assembly is located. Meeting the given conditions is not only conducive to the smooth insertion of the elastic buffer pad into the shell during assembly, but also conducive to further taking into account the energy density of the battery.

[0019] In some embodiments of the present application, the battery cell is a cylindrical battery cell, at least one of the elastic buffer pads and the electrode assembly are stacked along the radial direction of the electrode assembly, and the distance between the inner wall surfaces of the shell is equal to the diameter of the inner cavity of the shell.

[0020] In some embodiments of the present application, in the cylindrical battery cell, the sum of the total thickness of the elastic buffer pad in the free state and the total thickness of the electrode assembly in the fully discharged state is 80% to 99% of the diameter of the inner cavity of the shell, which can be 85% to 98%, and can be 90% to 95%; and / or, the sum of the total thickness of the elastic buffer pad in the free state and the total thickness of the electrode assembly in the fully charged state is 85% to 110% of the diameter of the inner cavity of the shell, which can be 98% to 105%, and can be 99% to 102%. Meeting the given conditions is conducive to the smooth entry of the elastic buffer pad into the shell, and / or improving the volume stability of the battery cell and the force uniformity of the pole piece.

[0021] In some embodiments of the present application, in the cylindrical battery cell, the elastic buffer pad is arranged between the electrode assembly and the shell, and the ratio of the extension distance of the elastic buffer pad in the circumferential direction of the electrode assembly to the circumference of the electrode assembly in a free state is 0.8 to 1.2, optionally 0.85 to 1.1, and further optionally 0.9 to 1.05; and / or, the ratio of the extension distance of the elastic buffer pad in the height direction of the electrode assembly to the height of the electrode assembly in a free state is 0.8 to 1.2, optionally 0.85 to 1.1, and further optionally 0.9 to 1.05. Meeting the given conditions is conducive to enabling the elastic buffer pad to cover most areas of the electrode assembly, which is conducive to improving the volume stability of the battery cell and further improving the force uniformity of the pole piece.

[0022] In some embodiments of the present application, in the cylindrical battery cell, the elastic buffer pad, in a free state, extends in the circumferential direction of the electrode assembly less than or equal to the circumference of the electrode assembly; and / or, the elastic buffer pad, in a free state, extends in the height direction of the electrode assembly less than or equal to the height of the electrode assembly. Meeting the given conditions is not only conducive to the smooth insertion of the elastic buffer pad into the shell during assembly, but also conducive to further taking into account the energy density of the battery.

[0023] In some embodiments of the present application, the thickness of a single elastic buffer pad in a free state is 2% to 15%, and optionally 5% to 10%, of the thickness of a single electrode assembly in a fully discharged state. Meeting the given conditions is beneficial to maintaining the volume stability of the battery cell during the service life, especially in the later period of use, and can also take into account the energy density of the battery cell.

[0024] In some embodiments of the present application, the thickness of a single elastic buffer pad in a free state is 0.2 mm to 10.5 mm. Meeting the given conditions can not only take into account the compressible deformation of the elastic buffer pad and the energy density of the battery cell, but also make the support layer have a certain strength.

[0025] The second aspect of the present application provides a battery, which includes: the battery cell described in the first aspect of the present application.

[0026] The third aspect of the present application provides an electrical device, which includes: the battery described in the second aspect of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] 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:

[0028] Figure 1 It is a schematic diagram of the cross-sectional structure of a prismatic battery cell according to one embodiment of the present application.

[0029] Figure 2 It is a schematic cross-sectional structure diagram of a prismatic battery cell according to another embodiment of the present application.

[0030] Figure 3 It is a schematic cross-sectional structure diagram of a prismatic battery cell according to another embodiment of the present application.

[0031] Figure 4 It is a schematic cross-sectional structure diagram of a prismatic battery cell according to yet another embodiment of the present application.

[0032] Figure 5 It is a schematic cross-sectional structure diagram of a prismatic battery cell according to yet another embodiment of the present application.

[0033] Figure 6 It is a schematic cross-sectional structure diagram of a prismatic battery cell according to yet another embodiment of the present application.

[0034] Figure 7 It is a schematic cross-sectional structure diagram of a prismatic battery cell according to yet another embodiment of the present application.

[0035] Figure 8 It is a schematic cross-sectional structure diagram of a prismatic battery cell according to yet another embodiment of the present application.

[0036] Fig. 9 It is a schematic diagram of the cross-sectional structure of a cylindrical battery cell according to one embodiment of the present application.

[0037] Fig.10 It is a schematic diagram of the cross-sectional structure of a cylindrical battery cell according to another embodiment of the present application.

[0038] Fig.11 It is a schematic structural diagram of a battery cell according to an embodiment of the present application.

[0039] Fig.12 It is a schematic structural diagram of a battery module according to an embodiment of the present application.

[0040] Fig.13 It is a schematic diagram of the structure of a battery pack according to an embodiment of the present application.

[0041] Fig.14 is an exploded view of a battery pack according to an embodiment of the present application.

[0042] Fig.15 It is a schematic diagram of an implementation of an electrical device using a battery as a power source according to an embodiment of the present application.

[0043] Reference numerals:

[0044] 11: shell; 12: electrode assembly; 13: elastic buffer pad; 13a: first elastic buffer pad; 13b: second elastic buffer pad; 1: battery; 2: battery module; 3: battery pack; 4: upper box; 5: lower box. DETAILED DESCRIPTION

[0045] The present application is further described below in conjunction with specific implementations. It should be understood that these specific implementations are only used to illustrate the present application and are not used to limit the scope of the present application.

[0046] Below, the embodiments of the positive electrode active material and its preparation method, positive electrode sheet, battery and electric device of the present application are specifically disclosed with appropriate reference to the drawings. However, there are cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structure are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following descriptions are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0047] The "range" disclosed in the present application is defined in the form of a lower limit and / or an upper limit, and a given range is defined by selecting a lower limit and / or an upper limit, and the selected lower limit and / or upper limit define the boundaries of a particular range. The range defined in this way can be inclusive or exclusive of the end value, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form an unambiguous range, and any lower limit can be combined with other lower limits to form an unambiguous range, and any upper limit can be combined with any other upper limit to form an unambiguous range. In addition, each individually disclosed point or single value itself can be combined with any other point or single value as a lower limit or upper limit or with other lower limits or upper limits to form an unambiguous range. For example, if a range of 60 to 120 and 80 to 110 is listed for a specific parameter, it is understood that the range of 60 to 110 and 80 to 120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range "a-b" represents an abbreviation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0048] If not otherwise specified, all embodiments and optional embodiments of the present application may be combined with each other to form new technical solutions, and such technical solutions should be deemed to be included in the disclosure of the present application.

[0049] Unless otherwise specified, all technical features and optional technical features of the present application may be combined with each other to form new technical solutions, and such technical solutions should be deemed to be included in the disclosure of the present application.

[0050] If there is no special explanation, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps S1 and S2, which means that the method may include steps S1 and S2 performed sequentially, or may include steps S2 and S1 performed sequentially. For example, the method may also include step S3, which means that step S3 may be added to the method in any order. For example, the method may include steps S1, S2 and S3, or may include steps S1, S3 and S2, or may include steps S3, S1 and S2, etc.

[0051] If there is no special explanation, the "include" and "comprising" mentioned in this application represent open-ended or closed-ended expressions. For example, the "include" and "comprising" may represent that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0052] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0053] If there is no special explanation, in this application, the term "and / or" is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0054] In the present application, the terms "plurality" and "multiple" refer to two or more.

[0055] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used in this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions. Unless otherwise specified, the terms used in this application have the well-known meanings commonly understood by those skilled in the art. Unless otherwise specified, the numerical values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (for example, they can be tested according to the methods given in the embodiments of this application).

[0056] With the continuous advancement of the theme of green environmental protection, the application of batteries has penetrated into all aspects of life, including vehicles, electronic equipment, energy storage devices, etc. However, with the continuous promotion of battery applications, people's requirements for batteries are getting higher and higher. Taking lithium ions as an example, lithium-ion batteries will be accompanied by volume changes during charge and discharge cycles, overcharging, etc., and as the working time increases, the amount of expansion gradually increases. This not only easily causes the battery shell to deform under the extrusion force, affecting the volume stability of the battery, but also if the pole piece expands excessively during the charge and discharge cycle of the battery, it may also affect the spacing between the pole piece and the diaphragm, increase the risk of lithium plating, and affect the service life of the battery. To address this problem, there is currently a solution to set a buffer pad between or in the battery cell, but due to factors such as the type of active material of the electrode pole piece, the thickness of the active material layer, and the number of cycles, the battery will also have different expansion amounts and expansion rates during different charge and discharge processes and during the charge and discharge process at different stages of use. However, for different charging and discharging processes and charging and discharging processes in different usage stages, the stress and strain requirements of the buffer pad inside the battery cell are different. Improper matching is not conducive to the effect of the buffer pad and may even cause the deterioration of the battery cell performance.

[0057] In the present application, different restrictions are made on the stress-strain relationship of the elastic buffer pad in view of the different expansion amounts and expansion rates of the electrode assembly in the battery cell during different charging and discharging processes and different use stages, that is, an elastic buffer pad with a compression rate of ≤30% along its thickness direction under a pressure of 0.1Mpa and a compression rate of ≥50% along its thickness direction under a pressure of 1Mpa is selected, so that the elastic buffer pad can provide different strengths and stresses during the charging process. In the early stage of use or charging of the battery cell, the elastic buffer pad is not over-compressed and can provide a certain support strength, which is conducive to achieving direct bonding between the electrode assembly and the inner wall of the shell or bonding between the electrode assembly and the inner wall of the shell through the elastic buffer pad, thereby improving the uniformity of force on the electrode piece. In the later stage of charging or the later stage of use of the battery cell, the elastic buffer pad can be fully compressed during the expansion of the electrode assembly, transferring its space in the thickness direction to the electrode assembly and providing a larger stress, which is conducive to maintaining the uniformity of force on the electrode piece during the charging and discharging process while reducing the expansion force of the electrode assembly.

[0058] The battery cells and batteries disclosed in the embodiments of the present application can be used in electrical devices that use batteries as power sources or various energy storage systems that use batteries as energy storage elements. Electrical devices may include, but are not limited to, mobile phones, tablets, laptops, electric toys, electric tools, battery cars, electric cars, ships, spacecraft, and the like. Among them, electric toys may include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, and the like, and spacecraft may include airplanes, rockets, space shuttles, and spacecraft, and the like.

[0059] The first aspect of the present application provides a battery cell, which includes: a shell; at least one electrode assembly, which is placed in the shell; at least one elastic buffer pad, which is arranged on at least a portion of the surface of the electrode assembly and / or inside the electrode assembly, and the compression rate of the elastic buffer pad along the thickness direction under a pressure of 0.1 MPa is ≤30%, and the compression rate along the thickness direction under a pressure of 1 MPa is ≥50%.

[0060] refer to Figures 1 to 7 It is understood that the battery cell 1 of the first aspect of the present application includes a housing 11, at least one electrode assembly 12 and at least one elastic buffer pad 13, the electrode assembly 12 is placed in the housing 11, and the elastic buffer pad 13 can be arranged on at least a portion of the surface of the electrode assembly 12 and / or inside the electrode assembly 12. Exemplarily, the elastic buffer pad 13 can be arranged between the electrode assembly 12 and the housing 11 (refer to Figure 1 Understanding), and / or arranged between two adjacent electrode assemblies 12 (reference Figure 2 Understanding), and / or located inside the electrode assembly (reference Figure 3The elastic buffer pad 13 may be disposed between the electrode assembly 12 and the housing 11, which may be understood as being disposed in at least one of the regions between the electrode assembly 12 and the side wall of the housing 11, between the electrode assembly 12 and the bottom wall of the housing 11, and between the electrode assembly 12 and the top wall of the housing 11. Optionally, refer to Figure 4 or Figure 5 It is understood that the elastic buffer pad 13 can be provided between the electrode assembly 12 and the housing 11 and between two adjacent electrode assemblies; Figure 1 , Figure 6 , Figure 7 It is understood that the elastic buffer pad 13 can be arranged between the electrode assembly 12 and the side wall of the shell 11. In actual operation, both sides of the elastic buffer pad 13 along its thickness direction can be arranged to fit with the electrode assembly 12 (refer to Figure 2 One side may be fitted with the electrode assembly 12 and the other side may be fitted with the inner wall of the shell 11.

[0061] As some specific examples, when the battery cell 1 includes only one electrode assembly 12, the number of the elastic buffer pads 13 may be one or more, and they may be arranged between the electrode assembly 12 and the shell 11, or inside the electrode assembly, and optionally, they may be arranged between the electrode assembly 12 and the side wall of the shell 11. As some other specific examples, when the battery cell 1 includes at least two electrode assemblies 12, the number of the elastic buffer pads 13 may be one or more, and the one or more elastic buffer pads 13 may be arranged only between the battery assemblies 12, or only between the battery assembly 12 and the shell 11, or only inside the electrode assembly 12, or partially between the battery assemblies 12, partially between the battery assembly 12 and the shell 11, and so on. Optionally, the elastic buffer pad 13 arranged between the battery assembly 12 and the shell 11 may be arranged between the electrode assembly 12 and the side wall of the shell 11.

[0062] Optionally, the thickness direction of at least one elastic buffer pad 13 is the same as the thickness direction of the battery cell 1 (refer to Figures 1 to 6 and 8), optionally, the thickness direction of at least one elastic buffer pad 13 is the same as the thickness direction of the battery cell 1 and the electrode assembly 12.

[0063] In the battery cell of the present application, at least one electrode assembly 12 and at least one elastic buffer pad 13 are stacked along a first direction. Optionally, the first direction can be the thickness direction of the electrode assembly 12. When the electrode assembly 12 is a wound electrode assembly and includes a straight portion and a corner portion, the first direction can be the thickness direction of the straight portion. When the electrode assembly 12 is cylindrical, the first direction is the radial direction of the electrode assembly, and the distance between the inner wall surfaces of the shell 11 along the first direction is the inner cavity diameter of the shell.

[0064] During the charge and discharge process of the battery cell, as the remaining capacity (i.e., SOC value) increases, the deformation and expansion force generated by the electrode assembly will also increase, and as the number of cycles increases, the expansion amount and expansion force generated by the electrode assembly during the charge and discharge process usually also increase, that is, the expansion amount and expansion force generated by the electrode assembly during the charge and discharge process in the later stage of the battery's service life are usually greater than those in the early stage of the battery's service life. In the battery cell of the present application, requirements are made for the strain of the elastic buffer pad under different stress states, that is, an elastic buffer pad is selected with a compression rate along its thickness direction under a pressure of 0.1 MPa of ≤30% (such as ≤30%, ≤28%, ≤25%, ≤22%, ≤20%, ≤18%, ≤16%, ≤14%, ≤12%, ≤10%, ≤8%, ≤6%, ≤4%, etc., or it can be a range composed of any of the above values), and a compression rate along its thickness direction under a pressure of 1 MPa of ≥50% (such as ≥50%, ≥55%, ≥60%, ≥65%, ≥70%, ≥75%, ≥80%, ≥85%, etc., or it can be a range composed of any of the above values). Furthermore, the elastic buffer pad can provide different strengths and stresses in different charging and discharging processes. In the initial charging stage or the initial use of the battery cell, the elastic buffer pad is not over-compressed and can provide a certain supporting strength, which is conducive to the direct bonding of the electrode assembly to the inner wall of the shell or the bonding of the elastic buffer pad to the inner wall of the shell to achieve interaction force, improve the force uniformity of the pole piece, and reduce the risk of wrinkles in local areas of the electrode assembly and the occurrence of purple spots and lithium precipitation in the wrinkled area, which may cause a decrease in the utilization rate of active lithium. In the later stage of charging or the later stage of the battery cell cycle, the elastic buffer pad can be fully compressed during the expansion of the electrode assembly, and its space in the thickness direction can be transferred to the electrode assembly, reducing the expansion force of the electrode assembly and providing a larger stress. While reducing the expansion force of the electrode assembly, it improves the force uniformity of the pole piece during the charging and discharging process.

[0065] Among them, the compression rate of the elastic buffer pad along its thickness direction under different stresses can be carried out with reference to GB / T 1041-92. The compression rate of the elastic buffer pad along its thickness direction is the ratio of the thickness change of the elastic buffer pad in the free state and the stress state to the thickness in the free state. The free state of the elastic buffer pad refers to the state in which the elastic buffer pad is not subjected to any external force, and the stress state of the elastic buffer pad refers to the state in which the elastic buffer pad is subjected to a certain compressive stress. The thickness test of the elastic buffer pad in the free state can be tested using conventional instruments and conventional methods in the field, such as Mitutoyo ID-C112MX micrometer thickness gauge (or similar instrument), and the test can be carried out under the state where the test force is less than or equal to 1.8N, and multiple points (such as 5, 10, etc.) are randomly measured to obtain the average value. The thickness test of the elastic buffer pad under stress state can be carried out using two parallel flat plates, with the elastic buffer pad located in the middle of the flat plates, and the flat plates are used to apply a preset pressure to the elastic buffer pad and measure the distance between the flat plates. The instruments used to measure the distance between the flat plates may include but are not limited to conventional instruments such as vernier calipers.

[0066] The battery cell of the first aspect of the present application has the following beneficial effects: it can enable the elastic buffer pad to play a better effect, while improving the volume stability of the battery cell during long-term use, it is also beneficial to maintain the uniformity of force on the electrode during the charging and discharging process, thereby helping to reduce the risk of expansion and deformation or performance deterioration of the battery cell and improve long-term performance.

[0067] It can be understood that in the embodiments of the present application, battery cells include but are not limited to shells, electrode assemblies and elastic buffer pads. For example, battery cells may also include electrolytes; in the embodiments of the present application, battery cells include but are not limited to secondary battery cells, primary battery cells, etc.; in the embodiments of the present application, battery cells include but are not limited to lithium-ion battery cells, sodium-ion battery cells, magnesium-ion battery cells, etc.; in the embodiments of the present application, battery cells include but are not limited to hard battery cells, soft-pack battery cells, etc., and hard battery cells include but are not limited to metal battery shell cells, etc.

[0068] Furthermore, the battery cell of the first aspect of the present application can further improve the performance of the battery cell by further controlling the compression rate of the elastic buffer pad along its thickness direction under a specific stress, the relationship between the elastic buffer pad and the electrode assembly and / or the shell size, and the arrangement mode for different battery cell types, etc. on the basis of satisfying the above conditions. That is, on the basis of satisfying the above conditions, one or more of the following conditions can be optionally satisfied.

[0069] In some embodiments of the present application, an elastic buffer pad 13 is provided between the electrode assembly 12 and the housing 11, and / or an elastic buffer pad 13 is provided between two adjacent electrode assemblies 12. Figure 1 , Figure 2 and Figure 4 Understand. Meeting the given conditions is further conducive to improving the volume stability of the battery cell during long-term use and reducing the risk of expansion deformation or performance deterioration. Optionally, an elastic buffer pad 13 can be provided only between the electrode assembly 12 and the shell 11 and / or between two adjacent electrode assemblies 12, which is conducive to both the molding of the electrode assembly and the reduction of the expansion force generated by the electrode assembly on the shell.

[0070] In some embodiments of the present application, the compression rate of the elastic buffer pad 13 along its thickness direction under a pressure of 0.1Mpa can be ≤20%, and can be ≤10%. Selecting an elastic buffer pad that further meets the given conditions is conducive to further preventing the elastic buffer pad from being over-compressed at the initial stage of battery cell charging, can provide a certain support strength, and is conducive to achieving direct bonding of the electrode assembly with the inner wall of the shell or bonding with the inner wall of the shell through the elastic buffer pad, achieving mutual force, and improving the force uniformity of the pole piece.

[0071] In some embodiments of the present application, the compression rate of the elastic buffer pad 13 along its thickness direction under a pressure of 1Mpa can be ≥60%, and can be ≥80%. Selecting an elastic buffer pad that further meets the given conditions is beneficial in that in the late stage of charging or the late stage of battery cell cycle, the elastic buffer pad can be fully compressed during the expansion of the electrode assembly, and the space in its thickness direction is transferred to the electrode assembly, thereby reducing the expansion force of the electrode assembly and providing greater stress, which is beneficial to reducing the expansion force of the electrode assembly, improving the volume stability of the battery cell, and maintaining the force uniformity of the electrode sheet during the charging and discharging process.

[0072] In some embodiments of the present application, the compression rate of the elastic buffer pad 13 under a pressure of 0.5 MPa may be 30% to 60%.

[0073] For example, the compression rate of the elastic buffer pad 13 under a pressure of 0.5 MPa can be 30%, 35%, 40%, 45%, 50%, 55%, 60%, etc., or can be a range composed of any of the above values. Selecting an elastic buffer pad that further meets the given conditions is further conducive to the elastic buffer pad being able to provide different strengths and stresses in different charging and discharging processes, and is conducive to further improving the volume stability of the battery cell while further maintaining the force uniformity of the pole piece during the charging and discharging process.

[0074] In some embodiments of the present application, the electrode assembly 12 may be a wound electrode assembly and include a straight portion and a corner portion, and the elastic buffer pad 13 may be disposed on at least a portion of the surface of the straight portion and / or the corner portion.

[0075] In the battery cell of the present application, the electrode assembly can be a laminated electrode assembly or a wound electrode assembly; the wound electrode assembly can be used in a prismatic shell or a cylindrical shell. Among them, during the charging and discharging process of the wound electrode assembly, the risk of uneven force on the pole piece is relatively high, especially for a prismatic battery cell with a wound electrode assembly. Combining the wound electrode assembly with an elastic buffer pad is conducive to alleviating the problem of uneven force on the pole piece in the wound electrode assembly, reducing polarization differences, and improving volume stability and long-term cycle performance. Optionally, the electrode assembly 12 can be a wound electrode assembly, and includes a straight portion and a corner portion, and the elastic buffer pad 13 can be provided on at least part of the surface of the straight portion and / or the corner portion, thereby helping to further alleviate the problem of uneven force on the pole piece in the prismatic battery cell. It can be understood that prismatic battery cells include but are not limited to square battery cells. Optionally, the straight portion of the wound electrode assembly can be provided with an elastic buffer pad 13.

[0076] In some embodiments of the present application, reference Figures 1 to 8 It is understood that the battery cell 1 may be a prismatic battery cell.

[0077] In some embodiments of the present application, a prismatic battery cell may include: at least one first elastic buffer pad 13a and / or at least one second elastic buffer pad 13b, the first elastic buffer pad 13a and the electrode assembly 12 may be stacked along the thickness direction of the battery cell, and / or the second elastic buffer pad 13b and the electrode assembly 12 may be stacked along the length direction of the battery cell.

[0078] refer to Figure 8 It is understood that, taking a square battery cell as an example, in the given structural design, the thickness of the first elastic buffer pad 13a can extend along the thickness direction of the battery cell, and / or, the thickness of the second elastic buffer pad 13b can extend along the length direction of the battery cell. The first elastic buffer pad 13a and the second elastic buffer pad 13b are both helpful in reducing the expansion force generated by the electrode assembly during use. Optionally, the square battery cell may include at least one first elastic buffer pad 13a. In the shell 11 of the square battery cell, the area of ​​the two side walls arranged opposite to each other in the thickness direction of the battery cell is usually large. The first elastic buffer pad is arranged between the two side walls, which is beneficial to increase the contact area between the elastic buffer pad and the electrode assembly, thereby further reducing the expansion force that may be generated by the electrode assembly during use, and further alleviating the problem of uneven force that may exist in the pole piece of the wound electrode assembly. Optionally, the prismatic battery cell may only include the first elastic buffer pad 13a. Meeting the given conditions is beneficial to reducing the expansion force of the electrode assembly and improving the problem of uneven force that may exist in the pole piece, and omitting the second elastic buffer pad is also beneficial to simplifying the battery cell structure and improving the energy density of the battery cell.

[0079] In some embodiments of the present application, in a prismatic battery cell, in the thickness direction of the battery cell, the sum of the total thickness of the first elastic buffer pad 13a in a free state and the total thickness of the electrode assembly 12 in a fully discharged state may be 80% to 99% of the distance between the inner walls of the shell 11, optionally 85% to 98%, and further optionally 90% to 95%; and / or, the sum of the total thickness of the first elastic buffer pad 13a in a free state and the total thickness of the electrode assembly 12 in a fully charged state may be 95% to 110% of the distance between the inner walls of the shell 11, optionally 98% to 105%, and further optionally 99% to 102%.

[0080] refer to Figure 8 It is understood that, taking a square battery cell as an example, the sum of the total thickness d of the first elastic buffer pad 13a in a free state and the total thickness d2 of the electrode assembly 12 in a fully discharged state can be 80% to 99% of the distance d0 between the two inner wall surfaces of the shell 11 arranged opposite to each other along the thickness direction thereof, that is, For example, The value of can be 80%, 82%, 85%, 87%, 89%, 91%, 95%, 97%, 99%, etc., or can be a range consisting of any of the above values. In the present application, the fully discharged state refers to the state of discharging to the lower limit of the cut-off voltage at a constant current of 0.33C of the rated capacity of the battery cell at room temperature. Meeting the given conditions can allow a gap to exist between the elastic buffer pad and the electrode assembly before entering the shell, which is conducive to the smooth entry of the elastic buffer pad and the electrode assembly into the shell and facilitates the assembly of the battery cell. Optionally, Alternatively, Meeting the given conditions is further conducive to the smooth insertion of the elastic buffer pad and the electrode assembly into the shell. At the same time, it is also conducive to achieving direct or indirect contact between the electrode assembly and the inner wall of the shell after charging, thereby improving the uniformity of force on the electrode piece.

[0081] Taking a square battery cell as an example, the sum of the total thickness d of the first elastic buffer pad 13a in a free state and the total thickness d1 of the electrode assembly 12 in a fully charged state can be 95% to 110% of the distance d0 between the two inner wall surfaces of the shell 11 arranged opposite to each other along the thickness direction thereof, that is, For example, The value of can be 95%, 97%, 99%, 100%, 102%, 104%, 106%, 108%, 110%, etc., or can be a range consisting of any of the above values. In the present application, the fully charged state refers to the state of charging at room temperature with a constant current of 0.33C of the rated capacity of the battery cell to the upper limit of the cut-off voltage, and then charging at a constant voltage until the current is 0.05C, or charging under this condition until the SOC of the battery no longer changes. Meeting the given conditions is further conducive to the battery cell in the process of use, so that the electrode assembly is directly attached to the inner wall of the shell or is attached to the inner wall of the shell through an elastic buffer pad (or mylar film, i.e., insulating film) to achieve mutual force, which is conducive to further improving the force uniformity of the pole piece, reducing the risk of wrinkles in local areas of the electrode assembly and the occurrence of purple spots and lithium precipitation in the wrinkled area, which leads to a decrease in the utilization rate of active lithium, and improving the capacity retention rate of the battery cell. Optionally, Alternatively, Meeting the given conditions can improve the uniformity of force on the pole piece while further reducing the expansion force that the electrode assembly may generate on the shell.

[0082] Meeting the given conditions is not only beneficial to the assembly of battery cells, but also beneficial to improving the volume stability of the battery cells and the force uniformity of the pole pieces, thereby helping to reduce the risk of expansion and deformation or performance deterioration of the battery cells.

[0083] In some embodiments of the present application, in a prismatic battery cell, in the length direction of the battery cell, the sum of the total thickness of the second elastic buffer pad 13b in the free state and the length of the electrode assembly 12 in the fully discharged state can be 80% to 99% of the distance between the inner wall surfaces of the shell 11, optionally 85% to 98%, and further optionally 90% to 95%; and / or, the sum of the total thickness of the second elastic buffer pad 13b in the free state and the length of the electrode assembly 12 in the fully charged state can be 85% to 110% of the distance between the inner wall surfaces of the shell 11, optionally 98% to 105%, and further optionally 99% to 102%.

[0084] For example, refer to Figure 8 It is understood that, taking a square battery cell as an example, the sum of the total thickness of the second elastic buffer pad 13b in the free state and the length of the electrode assembly 12 in the fully discharged state can be 80%, 82%, 85%, 87%, 89%, 91%, 95%, 97%, 99%, etc. of the distance between the two inner wall surfaces of the shell 11 arranged opposite to each other along its length direction, or can be a range composed of any of the above values. Among them, the length direction of the electrode assembly 12 in the fully discharged state and the length direction of the shell cavity are as follows: Figure 8As shown, in the present application, the length of the electrode assembly 12 can be the maximum extension distance in the length direction of the battery cell. Meeting the given conditions can make a gap between the elastic buffer pad and the electrode assembly before entering the shell, which is conducive to the smooth entry of the elastic buffer pad and the electrode assembly into the shell, and is convenient for the assembly of the battery cell. Optionally, the sum of the total thickness of the second elastic buffer pad 13b in the free state and the length of the electrode assembly 12 in the full discharge state can be 85% to 98% of the distance between the two inner wall surfaces of the shell 11 arranged opposite to each other along its length direction, and can be further selected as 90% to 95%. Meeting the given conditions is further conducive to the smooth entry of the elastic buffer pad and the electrode assembly into the shell. At the same time, it is also conducive to achieving direct or indirect contact between the electrode assembly and the inner wall of the shell after charging, and improving the force uniformity of the pole piece.

[0085] For example, refer to Figure 8 It is understood that, taking a square battery cell as an example, the sum of the total thickness of the second elastic buffer pad 13b in a free state and the length of the electrode assembly 12 in a fully charged state can be 95%, 97%, 99%, 100%, 102%, 104%, 106%, 108%, 110% of the distance between the two inner wall surfaces of the shell 11 arranged opposite to each other along its length direction, or can be a range composed of any of the above values. Meeting the given conditions is further conducive to making the electrode assembly directly fit the inner wall of the shell or fit the inner wall of the shell through an elastic buffer pad (or mylar film) during use to achieve mutual force, which is conducive to further improving the force uniformity of the pole piece, reducing the risk of wrinkles in the local area of ​​the electrode assembly and the occurrence of purple spots and lithium precipitation in the wrinkled area, which leads to a decrease in the utilization rate of active lithium, and improving the capacity retention rate of the battery cell. Optionally, the sum of the total thickness of the second elastic buffer pad 13b in the free state and the length of the electrode assembly 12 in the fully charged state can be 98% to 105% of the distance between the two inner wall surfaces of the shell 11 arranged opposite to each other along its length direction, and can be further selected to be 99% to 102%. Meeting the given conditions can improve the uniformity of the force on the electrode piece while further reducing the expansion force that the electrode assembly may generate on the shell.

[0086] Meeting the given conditions is not only beneficial to the assembly of battery cells, but also beneficial to improving the volume stability of the battery cells and the force uniformity of the pole pieces, thereby helping to reduce the risk of expansion and deformation or performance deterioration of the battery cells.

[0087] In some embodiments of the present application, the ratio of the total thickness of the first elastic buffer pad 13a in the free state to the total thickness of the electrode assembly 12 in the fully discharged state can be 2% to 25%, optionally 5% to 20%, and further optionally 8% to 15%.

[0088] refer to Figure 8It is understood that the ratio of the total thickness d of the first elastic buffer pad 13a in the free state to the total thickness d2 of the electrode assembly 12 in the fully discharged state can be 2% to 25%, that is, 2% ≤ d / d2 ≤ 25%. For example, the value of d / d2 can be 2%, 3%, 5%, 7%, 9%, 11%, 13%, 15%, 17%, 19%, 21%, 23%, 25%, etc., or can be a range composed of any of the above values. Increasing the value of d / d2 is conducive to improving the elastic buffer pad's ability to absorb the expansion deformation and expansion force generated by the electrode assembly, and is conducive to further suppressing the expansion deformation of the battery cell. The value of d / d2 meets the given conditions, which is conducive to maintaining the volume stability of the battery cell during the service cycle, especially in the later period of use, and can also take into account the energy density of the battery cell. Optionally, the value of d / d2 can be 5% to 20%, and can be optionally 8% to 15%. Meeting the given conditions is conducive to further taking into account the volume stability and energy density of the battery cell during the service cycle, especially in the later period of use.

[0089] Meeting the given conditions is beneficial to maintaining the volume stability of the battery cell while taking into account the energy density of the battery cell.

[0090] In some embodiments of the present application, when the first elastic buffer pad 13a is in a free state, the ratio of the extension distance of the electrode assembly 12 in the length direction to the length of the electrode assembly 12 can be 0.8-1.2, optionally 0.85-1.1, and further optionally 0.9-1.05; and / or, when the first elastic buffer pad 13a is in a free state, the ratio of the extension distance of the electrode assembly 12 in the height direction to the height of the electrode assembly 12 can be 0.8-1.2, optionally 0.85-1.1, and further optionally 0.9-1.05.

[0091] refer to Figure 8 It is understood that the ratio of the extension distance of the first elastic buffer pad 13a in the length direction of the electrode assembly 12 in the free state to the length of the electrode assembly 12 can be 0.8, 0.85, 0.9, 0.95, 1, 1.05, 1.1, 1.15, 1.2, etc., or can be a range composed of any of the above values. In this ratio, the length of the electrode assembly refers to the maximum extension distance of the electrode assembly along the length direction of the battery cell in the fully charged state, and the length of the electrode assembly and the extension distance of the first elastic buffer pad in the length direction of the electrode assembly in the free state can be measured by conventional methods and conventional instruments.

[0092] refer to Figure 8It is understood that the ratio of the extension distance of the first elastic buffer pad 13a in the height direction of the electrode assembly 12 in the free state to the height of the electrode assembly 12 can be 0.8 to 1.2, 0.8, 0.85, 0.9, 0.95, 1, 1.05, 1.1, 1.15, 1.2, etc., or can be a range composed of any of the above values. In this ratio, the height of the electrode assembly refers to the maximum extension distance of the electrode assembly along the height direction of the battery cell in the fully charged state, and the height of the electrode assembly and the extension distance of the first elastic buffer pad in the height direction of the electrode assembly in the free state can be measured by conventional methods and conventional instruments.

[0093] The dimensions of the first elastic buffer pad and the electrode assembly meet the given conditions, which is conducive to the elastic buffer pad covering most areas of the electrode assembly, which is conducive to improving the volume stability of the battery cell, further improving the force uniformity of the pole piece, and reducing the risk of deterioration of battery cell performance.

[0094] In some embodiments of the present application, reference Figure 8 It is understood that the orthographic projection of the first elastic buffer 13a on the electrode assembly 12 can be located in the region where the electrode assembly 12 is located. The first elastic buffer meets the given conditions, which is not only conducive to the smooth insertion of the elastic buffer into the shell during the assembly process, but also conducive to further considering the energy density of the battery.

[0095] In some embodiments of the present application, reference Fig. 9 and Fig.10 It is understood that the battery cell 1 can be a cylindrical battery cell, at least one elastic buffer pad 13 and the electrode assembly 12 are stacked along the radial direction of the electrode assembly 12, and the distance between the inner wall surfaces of the shell 11 is equal to the inner cavity diameter of the shell 11. That is, the thickness of the electrode assembly 12 can extend along its radial direction, and the distance between the inner wall surfaces of the shell 11 can be equal to or slightly less than the inner cavity diameter of the shell 11. Exemplarily, the difference between the distance between the inner wall surfaces of the shell 11 and the inner cavity diameter of the shell 11 can be less than or equal to 2%, and optionally less than or equal to 1%. A cylindrical battery cell usually includes only one wound electrode assembly, and the elastic buffer pad can be arranged inside the wound electrode assembly so that the laminated unit of the electrode assembly begins to wind around the elastic buffer pad; and / or, the elastic buffer pad can be arranged between the wound electrode assembly and the shell. In this application, the inner cavity diameter of the shell 11 can be understood as the average diameter of the inner cavity of the shell.

[0096] In some embodiments of the present application, in a cylindrical battery cell, the sum of the total thickness of the elastic buffer pad 13 in a free state and the total thickness of the electrode assembly 12 in a fully discharged state may be 80% to 99% of the diameter of the inner cavity of the shell 11, optionally 85% to 98%, and further optionally 90% to 95%; and / or, the sum of the total thickness of the elastic buffer pad 13 in a free state and the total thickness of the electrode assembly 12 in a fully charged state may be 85% to 110% of the diameter of the inner cavity of the shell 11, optionally 98% to 105%, and further optionally 99% to 102%.

[0097] Exemplary, reference Fig. 9 It is understood that the total thickness of the elastic buffer pad 13 in the free state and the total thickness of the electrode assembly 12 in the fully discharged state (or in the fully discharged state) can be understood as the average diameter of the electrode assembly plus twice the thickness of the single-layer elastic buffer pad 13 in the free state; Fig.10 In the present application, the total thickness of the elastic cushion 13 in the free state and the total thickness of the electrode assembly 12 in the fully discharged state (or fully discharged state) can be understood as the average diameter of the elastic cushion 13 plus twice the thickness of the electrode assembly. In the present application, the inner cavity diameter of the shell 11 can be understood as the average diameter of the inner cavity of the shell, which can be measured by conventional methods and conventional instruments.

[0098] refer to Fig. 9 and Fig.10 It is understood that in a cylindrical battery cell, the sum of the total thickness of the elastic buffer pad 13 in a free state and the total thickness of the electrode assembly 12 in a fully discharged state can be 80%, 82%, 85%, 87%, 89%, 91%, 95%, 97%, 99% of the inner cavity diameter of the shell 11, or can be a range composed of any of the above values. If the given conditions are met, a gap can be provided between the elastic buffer pad and the electrode assembly before they are inserted into the shell, which is beneficial for the smooth insertion of the elastic buffer pad and the electrode assembly into the shell and facilitates the assembly of the battery cell. The sum of the total thickness of the elastic buffer pad 13 in the free state and the total thickness of the electrode assembly 12 in the fully charged state can be 95%, 97%, 99%, 100%, 102%, 104%, 106%, 108%, 110% of the inner cavity diameter of the shell 11, or can be a range composed of any of the above values. Meeting the given conditions is further beneficial to the electrode assembly being directly bonded to the inner wall of the shell or bonded to the inner wall of the shell through an elastic buffer pad (or mylar film) during the use of the battery cell to achieve interaction force, which is beneficial to further improve the force uniformity of the pole piece, reduce the risk of wrinkles in local areas of the electrode assembly and the occurrence of abnormalities such as purple spots and lithium precipitation in the wrinkled area, which leads to a decrease in the utilization rate of active lithium, and improve the capacity retention rate of the battery cell.

[0099] Meeting the given conditions is not only beneficial to the assembly of battery cells, but also beneficial to improving the volume stability of the battery cells and the force uniformity of the pole pieces, thereby helping to reduce the risk of expansion and deformation or performance deterioration of the battery cells.

[0100] In some embodiments of the present application, in a cylindrical battery cell, an elastic buffer pad 13 may be disposed between the electrode assembly 12 and the shell 11, and when the elastic buffer pad 13 is in a free state, a ratio of an extension distance in the circumferential direction of the electrode assembly 12 to the circumference of the electrode assembly 12 may be 0.8 to 1.2, optionally 0.85 to 1.1, and further optionally 0.9 to 1.05; and / or, when the elastic buffer pad 13 is in a free state, a ratio of an extension distance in the height direction of the electrode assembly 12 to the height of the electrode assembly 12 may be 0.8 to 1.2, optionally 0.85 to 1.1, and further optionally 0.9 to 1.05.

[0101] refer to Fig. 9 It is understood that the ratio of the extension distance of the elastic buffer pad 13 in the circumferential direction of the electrode assembly 12 to the circumference of the electrode assembly 12 in the free state can be 0.8, 0.85, 0.9, 0.95, 1, 1.05, 1.1, 1.15, 1.2, etc., or can be a range composed of any of the above values, in which the circumference of the electrode assembly refers to the average circumference of the electrode assembly in the fully charged state. The ratio of the extension distance of the elastic buffer pad 13 in the height direction of the electrode assembly 12 in the free state to the height of the electrode assembly 12 can be 0.8, 0.85, 0.9, 0.95, 1, 1.05, 1.1, 1.15, 1.2, etc., or can be a range composed of any of the above values, in which the height of the electrode assembly refers to the maximum extension distance of the electrode assembly along the height direction of the battery cell in the fully charged state. In the present application, the circumference and height of the electrode assembly, as well as the extension distance of the elastic buffer pad 13 in the circumferential direction or height of the electrode assembly in the free state can be measured by conventional methods and conventional instruments.

[0102] The dimensions of the first elastic buffer pad and the electrode assembly meet the given conditions, which is conducive to the elastic buffer pad covering most areas of the electrode assembly, which is conducive to improving the volume stability of the battery cell, further improving the force uniformity of the pole piece, and reducing the risk of deterioration of battery cell performance.

[0103] In some embodiments of the present application, in a cylindrical battery cell, the elastic buffer pad 13, in a free state, extends a distance in the circumferential direction of the electrode assembly 12 that is less than or equal to the circumference of the electrode assembly 12; and / or, the elastic buffer pad 13, in a free state, extends a distance in the height direction of the electrode assembly 12 that is less than or equal to the height of the electrode assembly 12. The elastic buffer pad meets the given conditions, which is not only conducive to the smooth insertion of the elastic buffer pad into the shell during the assembly process, but also conducive to further taking into account the energy density of the battery.

[0104] In some embodiments of the present application, the thickness of a single elastic buffer pad 13 in a free state may be 2% to 15% of the thickness of a single electrode assembly 12 in a fully discharged state, and may be 5% to 10%. For example, the thickness of a single elastic buffer pad 13 in a free state may be 2%, 3%, 5%, 7%, 9%, 11%, 13%, 15%, etc. of the thickness of a single electrode assembly 12 in a fully discharged state, or may be a range consisting of any of the above values. Meeting the given conditions is not only conducive to maintaining the volume stability of the battery cell during the service life, especially in the later period of use, but also takes into account the energy density of the battery cell.

[0105] In some embodiments of the present application, the thickness of a single elastic buffer pad 13 in a free state may be 0.2 mm to 10.5 mm. For example, the thickness of a single elastic buffer pad 13 in a free state may be 0.2 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 10.5 mm, etc., or may be a range consisting of any of the above values. Meeting the given conditions can not only take into account the compressible deformation of the elastic buffer pad and the energy density of the battery cell, but also make the support layer have a certain strength.

[0106] It can be understood that in the battery cell of the first aspect of the present application, the structure and material of the elastic buffer pad are not subject to special restrictions, as long as its compression rate along its thickness direction under a preset pressure can meet the given requirements. For example, at least one of the material, porosity and pore size of the elastic buffer pad can be adjusted to obtain elastic buffer pads with different stress-strain relationships, so as to achieve different compression rates of the elastic buffer pad along its thickness direction under a preset pressure.

[0107] Exemplarily, the elastic buffer pad may be a single-layer structure, and its material may include but is not limited to at least one of foamed polyethylene, polypropylene, polyurethane, silicone rubber, etc.

[0108] Exemplarily, the elastic buffer pad can be a multilayer structure, specifically including an elastic buffer layer and a support layer, the support layer can be provided on at least one of the two sides of the elastic buffer layer along the thickness direction thereof, and exemplary, in a battery cell, at least one elastic buffer pad includes an elastic buffer layer and a support layer, and / or, at least one elastic buffer pad includes an elastic buffer layer and two support layers. Optionally, the elastic modulus of the elastic buffer layer is smaller than the elastic modulus of the support layer, and / or, under the same pressure, the compression rate of the elastic buffer layer along the thickness direction thereof is greater than the compression rate of the support layer along the thickness direction thereof, and / or, the porosity of the elastic buffer layer can be greater than the porosity of the support layer, for example, the porosity of the elastic buffer layer 31 can be 40% to 95%, optionally 55% to 90%, and further optionally 70% to 85%, and the porosity of the support layer 32 can be less than or equal to 5%. Alternatively, the elastic buffer layer may include at least one of foamed polyethylene, polypropylene, polyurethane, and silicone rubber, and the support layer may include but is not limited to at least one of high-density polyethylene, polymethacrylate, polyethylene terephthalate, and polytetrafluoroethylene. Optionally, at least one of the following conditions may also be met: the thickness of the elastic buffer layer may be greater than the thickness of the support layer; in a single elastic buffer pad, the ratio of the total thickness of the support layer to the free thickness of the elastic buffer layer may be 0.005 to 0.1, such as 0.02 to 0.05; the thickness of the elastic buffer layer in a natural state may be 0.2 mm to 10 mm, and the thickness of a single support layer may be 30 μm to 200 μm; the elastic buffer layer and the support layer may be bonded together. Among them, the use of the support layer and the elastic buffer layer can provide support for the elastic buffer layer, which can not only inhibit the thermal shrinkage of the elastic buffer layer (such as thermal shrinkage during vacuum baking), but also can optionally use the support layer to inhibit the thermal shrinkage of the elastic buffer layer in a two-dimensional direction perpendicular to its thickness direction, thereby improving the problem of losing its original function due to thermal shrinkage, and at the same time, it can also improve the problem of material damage caused by mechanical stress in the later stage of battery use. Furthermore, placing the elastic buffer pad inside the battery cell is conducive to further improving the volume stability of the battery during long-term use and improving long-term performance.

[0109] In some embodiments of the present application, the electrode assembly 12 may include a positive electrode sheet, a negative electrode sheet, and a separator. The positive electrode sheet, the negative electrode sheet, and the separator may be wound to form an electrode assembly. During the battery charge and discharge process, active ions are embedded and removed back and forth between the positive electrode sheet and the negative electrode sheet. The separator is disposed between the positive electrode sheet and the negative electrode sheet to play an isolation role.

[0110] [Positive electrode]

[0111] In a battery, a positive electrode plate generally includes a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector, wherein the positive electrode active material layer includes a positive electrode active material. The positive electrode current collector may be a conventional metal foil or a composite current collector (a metal material may be disposed on a polymer substrate to form a composite current collector). As an example, the positive electrode current collector may be an aluminum foil.

[0112] In the present application, the specific type of positive electrode active material is not limited, and active materials known in the art that can be used for the positive electrode of the battery can be used, and those skilled in the art can choose according to actual needs. For example, the positive electrode active material may include but is not limited to lithium transition metal oxides and / or positive electrode active materials containing lithium phosphates of olivine structure, and the lithium transition metal oxides may include undoped and / or optionally doped and modified lithium transition metal oxides, uncoated and / or coated and modified lithium transition metal oxides, and the lithium phosphate containing olivine structure may include undoped and / or optionally doped and modified lithium phosphate containing olivine structure, uncoated and / or coated and modified lithium phosphate containing olivine structure. The positive electrode active materials within the given range can be obtained either by preparation or by commercial channels.

[0113] In some specific embodiments of the present application, the positive electrode active material layer may also optionally include a binder, a conductive agent and other optional additives. As an example, the conductive agent may include but is not limited to one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, Super P (SP), graphene and carbon nanofibers. As an example, the binder may include but is not limited to one or more of styrene-butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA) and polyvinyl butyral (PVB).

[0114] [Negative electrode]

[0115] In a battery, the negative electrode plate generally includes a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector, wherein the negative electrode active material layer includes a negative electrode active material. The negative electrode current collector may be a conventional metal foil or a composite current collector (for example, a metal material may be disposed on a polymer substrate to form a composite current collector). As an example, the negative electrode current collector may be a copper foil.

[0116] In some embodiments of the present application, the battery cell of the first aspect of the present application may be a lithium-ion battery cell. In this case, the specific type of the negative electrode active material is not limited, and active materials known in the art that can be used for the negative electrode of the battery may be used. Those skilled in the art may flexibly select according to actual needs. As an example, the negative electrode active material may include, but is not limited to, one or more of artificial graphite, natural graphite, hard carbon, soft carbon, silicon-based materials, and tin-based materials. Optionally, the silicon-based material may include one or more of elemental silicon, silicon oxide compounds (such as silicon monoxide), silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Optionally again, the tin-based material may include one or more of elemental tin, tin oxide compounds, and tin alloys. The negative electrode active material within the given range can be obtained either by preparation or by commercial channels.

[0117] In some specific embodiments of the present application, the negative electrode active material layer may also optionally include a binder, a conductive agent and other optional additives. As an example, the conductive agent may include but is not limited to one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers. As an example, the binder may include but is not limited to one or more of styrene-butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyvinyl alcohol (PVA) and polyvinyl butyral (PVB). As an example, other optional additives may include but are not limited to thickeners and dispersants (such as sodium carboxymethyl cellulose CMC-Na), PTC thermistor materials.

[0118] In some embodiments of the present application, the isolation membrane in the battery may include, but is not limited to, a polyethylene porous membrane, a polypropylene porous membrane, a polyimide porous membrane, and a porous membrane formed by a composite of multiple polymers.

[0119] The second aspect of the present application provides a battery, which includes: the battery cell described in the first aspect of the present application. Optionally, the battery may be a secondary battery, for example, the battery may be a lithium-ion secondary battery.

[0120] In some embodiments of the present application, the battery can be a battery cell 1 (refer to Fig.11 It can also be a battery module 2 composed of battery cells 1 (refer to Fig.12 Understand) or battery pack 3 (reference Fig.13 understand).

[0121] In some embodiments, the battery may be a battery module, and the number of battery cells contained in the battery module may be one or more, and the specific number may be adjusted according to the application and capacity of the battery module. Fig.122 is an example of a battery module 2. Fig.12 In the battery module 2, the plurality of battery cells 1 may be arranged in sequence along the length direction of the battery module 2. Of course, they may also be arranged in any other manner. The plurality of battery cells 1 may further be fixed by fasteners. Optionally, the battery module 2 may further include a housing having a storage space, and the plurality of battery cells 1 are stored in the storage space.

[0122] In some embodiments, the battery modules described above may also be assembled into a battery pack, and the number of battery modules contained in the battery pack may be adjusted according to the application and capacity of the battery pack. Fig.13 or Fig.14 ( Fig.13 and Fig.14 As an example, a battery pack 3 is shown, in which a battery box and a plurality of battery modules 2 disposed in the battery box may be included. The battery box may include an upper box body 4 and a lower box body 5, wherein the upper box body 4 can be covered on the lower box body 5 and form a closed space for accommodating the battery modules 2. The plurality of battery modules 2 may be arranged in the battery box in any manner.

[0123] In some embodiments, the battery may include a first battery cell assembly and at least two second battery cell assemblies, the first battery cell assembly includes at least one battery cell 1 of the first aspect of the present application, the second battery cell assembly includes at least two second battery cells, the at least two second battery cells are arranged on both sides of the first battery cell assembly along the thickness direction of the first battery cell assembly, and the thickness direction of the first battery cell assembly is consistent with the thickness direction of the battery cell 1. Optionally, the battery cell of the first aspect of the present application is a prismatic battery cell with a wound electrode assembly, and by combining a prismatic shell, a wound electrode assembly and an elastic buffer pad, the problem of uneven force on the pole piece in the prismatic wound battery can be alleviated, and the stability of the battery cell can be improved. Wherein, the battery can be either a battery module or a battery pack. Exemplarily, with the length direction of the first battery cell assembly as a row and the thickness direction of the first battery cell assembly as a column, in the battery module or the battery pack, the first battery cell assembly may include a plurality of battery cells 1 arranged in rows and / or columns, and / or, the first battery cell assembly may be independently provided with a plurality of second battery cells arranged in rows and / or columns on both sides along its thickness direction, optionally, at least two second battery cells may be symmetrically arranged on both sides of the first battery cell assembly along the thickness direction; further optionally, in the battery module or the battery pack, based on the total number of battery cells 1 and second battery cells, the number of battery cells 1 may account for 30% to 70%. A battery usually includes multiple battery cells. The stacking method of the multiple battery cells includes stacking them along the thickness direction of the battery cells. In the thickness direction of the battery cells, the battery cells located in the middle of the battery are often the parts that swell most severely and have the greatest expansion force during use. By only embedding the first elastic buffer pad in the first battery cell located in the middle, and not providing the elastic buffer pad in the second battery cells located on both sides of the thickness direction of the first battery cell assembly, it is not only beneficial to absorb the volume expansion of the battery cells with relatively more severe expansion and relatively greater expansion force in the battery, reduce the expansion force of the battery cells in the middle of the battery, and improve the volume stability of the battery, but also beneficial to alleviate the problem of stress concentration in the battery cells located in the middle of the battery due to the volume expansion of the battery cells in the later stage of battery use, thereby causing lithium precipitation in the battery cells in the middle; at the same time, it can also take into account the high energy density of the battery.

[0124] In addition, the present application also provides an electrical device, which includes: the battery of the second aspect of the present application. The battery, such as a battery cell, a battery module or a battery pack, can be used as both a power source for the electrical device and an energy storage unit for the electrical device. The electrical device may include, but is not limited to, mobile devices (such as mobile phones, laptop computers), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, and energy storage systems. Reference Fig.15 It is understood that, as a specific example, the electric device may be a vehicle. The electric device may select a specific type of battery according to its usage requirements, such as a battery cell, a battery module or a battery pack.

[0125] As an example, the electric device may be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. In order to meet the electric device's requirements for high power and high energy density of the battery, a battery pack or a battery module may be used.

[0126] As another example, the electrical device may be a mobile phone, a tablet computer, or a laptop computer. The electrical device is usually required to be thin and light, and may use a battery cell as a power source.

[0127] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If no specific techniques or conditions are indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0128] Example 1

[0129] (I) Preparation of lithium secondary batteries

[0130] (1) Preparation of positive electrode sheet

[0131] The positive electrode active material LiNi 0.6 Co 0.1 Mn 0.3 O2, conductive agent Super P, and binder PVDF were mixed in a weight ratio of 96:2:2, and solvent N-methylpyrrolidone was added. The mixture was stirred and mixed to obtain positive electrode slurry, which was then coated on both surfaces of positive electrode current collector aluminum foil with a thickness of 13 μm. The coating surface density of the positive electrode slurry on one side of the aluminum foil was 20 mg / cm 2 , then dried and cold pressed to obtain the positive electrode sheet.

[0132] (2) Negative electrode sheet preparation

[0133] The negative electrode active material artificial graphite, the conductive agent Super P, the binder styrene butadiene rubber, and the thickener sodium carboxymethyl cellulose were mixed in a weight ratio of 96:0.5:2:1.5, and the solvent deionized water was added, and the mixture was fully stirred and mixed to obtain the negative electrode slurry, which was then coated on both surfaces of the negative electrode current collector copper foil with a thickness of 6 μm. The coating thickness of the negative electrode slurry on one side of the copper foil was 100 μm, and the coating surface density of the negative electrode slurry on one side of the copper foil was 11 mg / cm 2 , then dried and cold pressed to obtain the negative electrode sheet.

[0134] (3) Preparation of electrolyte

[0135] In an argon atmosphere glove box with a water content of <10ppm, solvents EC (ethylene carbonate), PC (propylene carbonate), and DMC (dimethyl carbonate) are mixed in a ratio of 1:1:1, and then the fully dried lithium salt LiPF6 is dissolved in the above mixed organic solvents. After stirring evenly, an electrolyte is obtained in which the concentration of LiPF6 is 1 mol / L.

[0136] (4) Preparation of isolation membrane

[0137] A polyethylene porous membrane with a thickness of 7 μm was used as the separator.

[0138] (5) Preparation of elastic cushion

[0139] Polypropylene with a thickness of 3 mm in a free state is used as the elastic buffer pad.

[0140] (6) Preparation of lithium secondary batteries

[0141] The positive electrode sheet, the separator, and the negative electrode sheet are stacked in order, so that the separator is placed between the positive and negative electrode sheets to play a role of isolation, and then wound and formed to obtain an electrode assembly. The two electrode assemblies and the elastic cushion are placed in a battery casing (the distance d0 between the two inner wall surfaces oppositely arranged along the thickness direction is 60 mm), and a layer of elastic cushion is sandwiched between the two electrode assemblies, and the prepared electrolyte is injected and packaged to obtain a lithium-ion lithium secondary battery.

[0142] Examples 2 to 19 and Comparative Examples 1 to 3

[0143] The differences between Examples 2 to 19 and Comparative Examples 1 to 3 and Example 1 are detailed in Table 1. Among them, the elastic cushions in Examples 1 to 19 and Comparative Examples 1 to 3 are all porous structures, and the elastic cushions of the same material have different compression rates under the same stress due to the different porosities and pore sizes of the elastic cushions; in addition, the elastic cushions in Examples 7 to 8 are all obtained by mixing polypropylene and polyethylene in a mass ratio of 1:1 and performing melt pore formation, and the porosity and pore size of the elastic cushions in Examples 7 and 8 are different.

[0144] (II) Battery testing method

[0145] (a) Test the size of the battery and electrode assembly and the compression rate of the elastic cushion

[0146] Take two groups of secondary battery parallel samples, let the two groups of secondary batteries stand for 5 minutes at 25℃, then charge them to 4.4V at a constant current of 0.33C, then charge them to 0.05C at a constant voltage of 4.4V, and let them stand for 5 minutes. Disassemble one group of secondary batteries to obtain electrode assemblies, clean and dry the electrode assemblies, and test the thickness of the electrode assemblies, as well as the length L1 and height h1 of the electrode assemblies (the length and height of the electrode assemblies match the length and height directions of the secondary battery shell respectively; Note: The length of the cylindrical battery electrode assembly and the secondary battery is recorded in circumference); discharge the other group of secondary batteries at a constant current of 0.33C to 2.8V, let them stand for 5 minutes, then disassemble the secondary batteries to obtain electrode assemblies, clean and dry the electrode assemblies, and test the thickness of the electrode assemblies. The test method is: place the electrode assembly in the middle of two parallel plates, use the plates to apply a pressure of 0.1MPa to the electrode assembly, and measure the distance between the plates to obtain the thickness of the electrode assembly. The total thickness d1 of the electrode assembly in the secondary battery in a fully charged state and the total thickness d2 of the electrode assembly in a fully discharged state are calculated.

[0147] The thickness of the elastic buffer pad in the free state is tested using a Mitutoyo ID-C112MX micrometer thickness gauge under a test force less than or equal to 1.8 N. Multiple points (such as 5, 10, etc.) are randomly measured and the average value is taken to calculate the total thickness d of the elastic buffer pad in the secondary battery in the free state, and the length L2 and height h2 of the elastic buffer pad are tested (the length and height of the elastic buffer pad match the length direction and height direction of the electrode assembly respectively); the elastic buffer pad is placed between two parallel plates, and pressures of 0.1 MPa and 0.5 MPa are applied to the elastic buffer pad by the plates, respectively. The thickness of the electrode assembly under compressive stress is obtained by measuring the distance between the plates, and the compression rate of the elastic buffer pad along its thickness under compressive stress is the ratio of the thickness change of the elastic buffer pad in the free state and the compressive stress state to the thickness in the free state multiplied by 100%.

[0148] (b) Testing the capacity retention rate of secondary batteries

[0149] Take multiple secondary battery parallel samples, let the secondary battery stand for 5 minutes at 25°C, then charge it to 4.4V at 0.5C constant current, then charge it to 0.05C at 4.4V constant voltage, let it stand for 5 minutes, then discharge the secondary battery to 2.8V at 0.33C constant current, let it stand for 5 minutes, and record the discharge capacity C0. Repeat the above operation and calculate the battery capacity retention rate by the following formula: Capacity retention rate of secondary battery after n cycles (%) = C n / C0×100%. Record the battery capacity retention rate after n cycles.

[0150] (c) Battery cell expansion force test

[0151] After the secondary battery is left to stand at 25°C for 5 minutes, it is charged to 4.4V at 0.5C constant current, and then charged to 0.05C at 4.4V constant voltage, and left to stand for 5 minutes. Then the secondary battery is discharged to 2.8V at 0.33C constant current and left to stand for 5 minutes. Six pressure sensors are set at different positions on one side in the thickness direction, and charged to 4.4V at 0.5C constant current, and then charged to 0.05C at 4.4V constant voltage, and left to stand for 5 minutes. During this period, the expansion force displayed by the pressure sensors at different positions of the secondary battery is recorded when it is charged to 30% SOC, 50% SOC, and 100% SOC, respectively, and the average value of the expansion force under different charging states is calculated, and the range of the rate of change of each expansion force under different charging states compared to the average value is calculated based on the average value.

[0152] (d) Lithium diving test

[0153] After the secondary battery is left at 25°C for 5 minutes, it is charged to 4.4V at 0.5C constant current, and then charged to 0.05C at 4.4V constant voltage, and left to stand for 5 minutes. Then the secondary battery is discharged to 2.8V at 0.33C constant current, and left to stand for 5 minutes. Repeat the above charge and discharge cycle until the capacity of the secondary battery is significantly attenuated. After the charge and discharge cycle test is completed, the secondary battery is disassembled to observe whether there is lithium deposition on the negative electrode.

[0154] Relevant tests were carried out on Examples 1 to 19 and Comparative Examples 1 to 3, and the test results are shown in Table 2.

[0155]

[0156]

[0157] in conclusion:

[0158] It can be seen from Examples 1 to 19, Comparative Examples 1 to 3 and Tables 1 to 2 that the solution of the above embodiments of the present application is conducive to improving the volume stability and force uniformity of the battery cell and the pole piece during the charging and discharging process, and reducing the risk of expansion deformation or performance deterioration. In addition, by further regulating the sum of the total thickness d of the elastic buffer pad in the free state and the total thickness d1 (d2) of the electrode assembly in the fully charged (discharged) state and the distance d0 between the two inner wall surfaces of the shell set opposite to each other along its thickness direction, and the size of the elastic buffer pad relative to the electrode assembly, it is also conducive to further improving the volume stability and force uniformity of the battery cell during long-term use, and reducing the risk of expansion deformation or performance deterioration.

[0159] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A battery cell, characterized in that: include: case; at least one electrode assembly, the electrode assembly being disposed within the housing; At least one elastic buffer pad is arranged on at least a portion of the surface of the electrode assembly and / or inside the electrode assembly, and the compression rate of the elastic buffer pad along the thickness direction under a pressure of 0.1 MPa is ≤30%, and the compression rate along the thickness direction under a pressure of 1 MPa is ≥50%.

2. The battery cell according to claim 1, characterized in that: The elastic buffer pad is arranged between the electrode assembly and the shell, and / or the elastic buffer pad is arranged between two adjacent electrode assemblies.

3. The battery cell according to claim 1 or 2, characterized in that: The compression rate of the elastic buffer pad along its thickness direction under a pressure of 0.1 MPa is ≤20%, and can be ≤10%; and / or, The compression rate of the elastic buffer pad along its thickness direction under a pressure of 1 MPa is ≥60%, and can be optionally ≥80%.

4. The battery cell according to any one of claims 1 to 3, characterized in that: The compression rate of the elastic buffer pad under a pressure of 0.5 MPa is 30% to 60%.

5. The battery cell according to any one of claims 1 to 4, characterized in that: The electrode assembly is a wound electrode assembly and includes a straight portion and a corner portion, and the elastic buffer pad is arranged on at least a portion of the surface of the straight portion and / or the corner portion.

6. The battery cell according to any one of claims 1 to 5, characterized in that: The battery cell is a prismatic battery cell.

7. The battery cell according to claim 6, characterized in that: The battery cell includes: at least one first elastic buffer pad and / or at least one second elastic buffer pad, the first elastic buffer pad and the electrode assembly are stacked along the thickness direction of the battery cell, and / or the second elastic buffer pad and the electrode assembly are stacked along the length direction of the battery cell.

8. The battery cell according to claim 7, characterized in that: At least one of the following conditions is met: In the thickness direction of the battery cell, the sum of the total thickness of the first elastic buffer pad in a free state and the total thickness of the electrode assembly in a fully discharged state is 80% to 99% of the distance between the inner walls of the shell, optionally 85% to 98%, and further optionally 90% to 95%; In the thickness direction of the battery cell, the sum of the total thickness of the first elastic buffer pad in a free state and the total thickness of the electrode assembly in a fully charged state is 95% to 110% of the distance between the inner walls of the shell, optionally 98% to 105%, and further optionally 99% to 102%; In the length direction of the battery cell, the sum of the total thickness of the second elastic buffer pad in a free state and the length of the electrode assembly in a fully discharged state is 80% to 99% of the distance between the inner walls of the shell, optionally 85% to 98%, and further optionally 90% to 95%; In the length direction of the battery cell, the sum of the total thickness of the second elastic buffer pad in a free state and the length of the electrode assembly in a fully charged state is 95% to 110% of the distance between the inner walls of the shell, optionally 98% to 105%, and further optionally 99% to 102%.

9. The battery cell according to claim 7 or 8, characterized in that: The ratio of the total thickness of the first elastic buffer pad in a free state to the total thickness of the electrode assembly in a fully discharged state is 2% to 25%, optionally 5% to 20%, and further optionally 8% to 15%.

10. The battery cell according to any one of claims 7 to 9, characterized in that: The ratio of the extension distance of the first elastic buffer pad in the length direction of the electrode assembly to the length of the electrode assembly in a free state is 0.8 to 1.2, optionally 0.85 to 1.1, and further optionally 0.9 to 1.05; and / or, When the first elastic buffer pad is in a free state, a ratio of an extension distance of the first elastic buffer pad in a height direction of the electrode assembly to a height of the electrode assembly is 0.8 to 1.2, and may be 0.85 to 1.1, or may be 0.9 to 1.

05.

11. The battery cell according to any one of claims 7 to 10, characterized in that: The orthographic projection of the first elastic buffer pad on the electrode assembly is located in the area where the electrode assembly is located.

12. The battery cell according to any one of claims 1 to 5, characterized in that: The battery cell is a cylindrical battery cell, at least one of the elastic buffer pads and the electrode assembly are stacked along the radial direction of the electrode assembly, and the distance between the inner wall surfaces of the shell is equal to the diameter of the inner cavity of the shell.

13. The battery cell according to claim 12, characterized in that: The sum of the total thickness of the elastic buffer pad in a free state and the total thickness of the electrode assembly in a fully discharged state is 80% to 99% of the diameter of the inner cavity of the shell, optionally 85% to 98%, and further optionally 90% to 95%; and / or, The sum of the total thickness of the elastic buffer pad in a free state and the total thickness of the electrode assembly in a fully charged state is 85% to 110% of the diameter of the inner cavity of the shell, and can be optionally 98% to 105%, and further optionally 99% to 102%.

14. The battery cell according to claim 12 or 13, characterized in that: The elastic buffer pad is arranged between the electrode assembly and the shell, and the ratio of the extension distance of the elastic buffer pad in the circumferential direction of the electrode assembly to the circumference of the electrode assembly in a free state is 0.8 to 1.2, optionally 0.85 to 1.1, and further optionally 0.9 to 1.05; and / or, When the elastic buffer pad is in a free state, the ratio of the extension distance of the elastic buffer pad in the height direction of the electrode assembly to the height of the electrode assembly is 0.8 to 1.2, and can be optionally 0.85 to 1.1, and can further be optionally 0.9 to 1.

05.

15. The battery cell according to claim 14, characterized in that: When the elastic buffer pad is in a free state, the extension distance in the circumferential direction of the electrode assembly is less than or equal to the circumference of the electrode assembly; and / or, when the elastic buffer pad is in a free state, the extension distance in the height direction of the electrode assembly is less than or equal to the height of the electrode assembly.

16. The battery cell according to any one of claims 1 to 15, characterized in that: The thickness of a single elastic buffer pad in a free state is 2% to 15%, and optionally 5% to 10%, of the thickness of a single electrode assembly in a fully discharged state; and / or, The thickness of a single elastic buffer pad in a free state is 0.2 mm to 10.5 mm.

17. A battery, characterized in that: A battery cell comprising the battery cell according to any one of claims 1 to 16.

18. An electrical device, characterized in that: Comprising the battery of claim 17.

Images