Battery cell, battery apparatus and electrical apparatus

Abstract

A battery cell, a battery apparatus and an electrical apparatus. The battery cell comprises a casing, a first structural member and at least one electrode assembly; the electrode assembly and the first structural member are arranged within the casing; each electrode assembly comprises a negative electrode sheet and a positive electrode sheet; each positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer located on at least one side of the positive electrode current collector; each negative electrode sheet comprises a negative electrode current collector and a negative electrode film layer located on at least one side of the negative electrode current collector; each negative electrode film layer comprises a negative electrode active material; the negative electrode active material comprises a silicon-based material, and on the basis of the total mass of the negative electrode film layer, the mass content of silicon in the silicon-based material is 15%-90%; and the first structural member and the electrode assembly are stacked in a first direction, the first direction being the thickness direction of the electrode assembly.

Description

Battery cells, battery packs, and electrical devices

[0001] Cross-reference to related applications

[0002] This disclosure is based on and claims priority to Chinese Patent Application No. 202510192528.1, filed on February 20, 2025, entitled “Battery Cell, Battery Device and Electrical Device”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to the field of battery technology, and in particular to a battery cell, a battery device, and an electrical device. Background Technology

[0004] In recent years, with the increasingly wide range of applications, rechargeable batteries have been widely used in energy storage power systems such as hydropower, thermal power, wind power, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric cars, aerospace, and many other fields. With the rapid development of rechargeable batteries, higher requirements have been placed on their energy density and cycle performance.

[0005] Therefore, improving the energy density and cycle performance of secondary batteries has become an urgent technical problem to be solved. Summary of the Invention

[0006] This disclosure is made in view of the above-mentioned problems, and its object is to provide a battery cell, a battery device, and an electrical device, wherein the battery cell of the present disclosure has excellent energy density and cycle performance.

[0007] To achieve the above objectives, a first aspect of this disclosure provides a battery cell, including a casing, a first structural member, and at least one electrode assembly. The electrode assembly and the first structural member are disposed within the casing. The electrode assembly includes a negative electrode and a positive electrode. The positive electrode includes a positive current collector and a positive electrode film layer located on at least one side of the positive current collector. The negative electrode includes a negative current collector and a negative electrode film layer located on at least one side of the negative current collector. The negative electrode film layer includes a negative electrode active material, which is a silicon-based material. Based on the total mass of the negative electrode film layer, the silicon content in the silicon-based material is 15%-90% by mass. The first structural member and the electrode assembly are stacked along a first direction, which is the thickness direction of the electrode assembly. This results in a battery cell with excellent energy density and cycle performance.

[0008] In some embodiments, the first structural member is an elastic member. This reduces the risk of local deformation of the electrode assembly, reduces the breakage of active material particles and SEI film in the electrode sheets, and reduces the fatigue failure of the binder, which is beneficial to further improving the cycle performance of the battery cell.

[0009] In some embodiments, the elastic modulus of the first structural member is 0.1 MPa-3 MPa. This helps the first structural member effectively resist compressive stress and reduces the risk of excessive deformation.

[0010] In some embodiments, when the battery cell is at 0% SOC, the total thickness of the electrode assembly is 72%-92% of the dimension of the internal cavity of the housing along the first direction. This is beneficial for improving the energy density and cycle performance of the battery cell.

[0011] In some embodiments, when the battery cell is at 0% SOC, the total thickness of the electrode assembly is 82%-90% of the dimension of the internal cavity of the housing along the first direction. This is more conducive to improving the energy density and cycle performance of the battery cell.

[0012] In some implementations, the silicon content, based on the total mass of the negative electrode film, is greater than or equal to 40% and less than or equal to 65%. This is more conducive to improving the energy density of the battery cell.

[0013] In some embodiments, when the battery cell is at 0% SOC, the total thickness of the first structural member is 3%-18% of the dimension of the internal cavity of the housing along the first direction. By keeping the thickness of the first structural member within the above range, it is advantageous to accommodate changes in the electrode assembly due to different silicon contents.

[0014] In some embodiments, along a first direction, a first structural component is disposed between the electrode assembly and the casing. This effectively reduces the manufacturing process of the battery cell, and the internal structure of the battery cell is relatively simple, making the electrochemical reactions and ion transport pathways within the battery clearer and more stable. This helps reduce energy loss caused by complex structures, improves the battery's charge and discharge efficiency, ensures consistent battery performance, and facilitates subsequent maintenance and testing. It also allows for faster and more accurate identification of potential problems, facilitating troubleshooting and repair, thereby extending the overall lifespan of the battery cell. Furthermore, the arrangement of the first structural component effectively protects the electrode assembly, enhances its cycle performance, and makes the battery cell more stable during long-term, repeated charge and discharge processes.

[0015] In some embodiments, multiple electrode assemblies are provided, arranged sequentially along a first direction, with a first structural member disposed between two adjacent electrode assemblies. This allows for several advantages. First, during the charging and discharging process of the battery cell, especially at low SOC, the interlayer spacing between the positive and negative electrode plates in each electrode assembly can be reduced, thereby shortening the transport path of active ions, improving the specific capacity of the silicon-based material, and further increasing the energy density of the battery cell. Second, during charging, the first structural member can balance the expansion force between adjacent electrode assemblies, reducing the breakage of active material particles and the SEI film in each electrode assembly due to expansion and compression, and reducing the fatigue failure of the binder, thereby further improving the cycle performance of the battery cell.

[0016] In some embodiments, multiple electrode assemblies are provided. Among these multiple electrode assemblies, the two electrode assemblies located at opposite ends in the first direction are respectively the first electrode assembly and the second electrode assembly. A first structural member is arranged between the first electrode assembly and the housing, and / or, the first structural member is arranged between the second electrode assembly and the housing. Therefore, during battery charging and discharging, stress impacts can be effectively blocked, reducing the risk of local deformation of the electrode assembly and improving the reliability of the battery assembly.

[0017] In some embodiments, the electrode assembly is a wound electrode assembly, comprising a straight section and a corner section. Two corner sections are connected to opposite sides of the straight section in a second direction perpendicular to the first direction. The first structural member comprises a connected straight portion and at least one corner portion. Along the first direction, the straight portion and the straight section are stacked together, and the corner portion and the corner section are stacked together. Thus, by arranging the coverage area of ​​the first structural member, the electrode assembly can be effectively protected. During battery charging and discharging, it can effectively block stress impacts, reduce the risk of local deformation of the electrode assembly, and improve the reliability of the battery assembly.

[0018] In some embodiments, the connection between the straight section and the corner section is called a corner connection, and the end of the corner section away from the straight section is called the corner tip. In the winding direction of the electrode assembly, the dimension from the corner connection to the corner tip is c1, and the dimension c2 of the corner portion satisfies: 0 < c2 ≤ c1. Therefore, by arranging the coverage area of ​​the first structural member, the electrode assembly can be effectively protected. During battery charging and discharging, it can effectively block stress impacts, reduce the risk of local deformation of the electrode assembly, and improve the reliability of the battery assembly.

[0019] In some embodiments, the electrode assembly is a stacked electrode assembly with sheets stacked along a first direction. In a projection plane perpendicular to the first direction, the projection of the positive electrode sheet lies within the projection of the first structural member. Therefore, by arranging the coverage area of ​​the first structural member, the electrode assembly can be effectively protected, effectively blocking stress impacts during battery charging and discharging, reducing the risk of local deformation of the electrode assembly, and improving the reliability of the battery assembly.

[0020] In some embodiments, in a cross-section perpendicular to the first direction, the length L1 and width W1 of the first structural member, and the length L2 and width W2 of the positive electrode sheet satisfy the following relationship: L1-L2 = 2mm-3mm; and / or, W1-W2 = 2mm-3mm. The length and width of the first structural member are slightly larger than the length and width of the positive electrode sheet, which helps the first structural member to completely cover the surface of the electrode assembly, thereby providing sufficient cushioning.

[0021] In some embodiments, the density of the first structural member is less than or equal to 0.3 g / cm³. 3 This is beneficial for increasing the gravimetric energy density of individual battery cells.

[0022] In some embodiments, the first structural component exhibits a rebound rate of ≥80% under test pressure, and the test pressure is ≤3 MPa. Therefore, the first structural component possesses good rebound performance, enabling it to largely recover its original shape and size before compression.

[0023] In some embodiments, the compression set rate of the first structural member is less than or equal to 20%. This makes the first structural member less prone to permanent deformation, thereby extending its service life and maintaining a small interlayer spacing within the electrode assembly at a low state of charge (SOC).

[0024] In some embodiments, the stress relaxation rate of the first structural member is less than or equal to 20%. This allows the first structural member to better maintain its shape and size during battery cycling, which is beneficial to improving the long-term structural stability of the first structural member.

[0025] In some embodiments, the mass gain rate of the first structural component in dimethyl carbonate is less than or equal to 100%. Therefore, when the first structural component is immersed in the electrolyte within the inner cavity of the outer casing, the amount of electrolyte absorbed and the mass swelling rate can be reduced, which is beneficial for improving the long-term stability of the first structural component in the electrolyte.

[0026] In some embodiments, the first structural component includes at least one of polyimide, modified polyimide, silicone rubber, modified silicone rubber, and modified polyolefin. The aforementioned types of first structural components exhibit high resilience and support, providing strong resistance to expansion, compression, and deformation of the electrode assembly.

[0027] In some embodiments, the modified polyimide includes a polyimide-polysiloxane block copolymer.

[0028] In some embodiments, the modified silicone rubber includes silicone rubber containing phenyl groups.

[0029] In some embodiments, the surface of the phenyl-containing silicone rubber is provided with a fluorine-containing coating.

[0030] In some embodiments, the modified polyolefin includes a polyolefin-ethylene-vinyl alcohol copolymer.

[0031] In some implementations, the first structural component includes polyimide.

[0032] In some embodiments, the negative electrode active material also includes a carbon-based material, and the mass ratio of silicon-based material to carbon-based material is (50:50)-(95:5).

[0033] In some embodiments, the silicon-based material includes one or more of elemental silicon, silicon oxide, and silicon-carbon composites.

[0034] In some embodiments, the silicon-based material includes a silicon-carbon composite, which comprises porous carbon and a silicon-containing material dispersed in the pores of the porous carbon.

[0035] In some implementations, the carbon-based material includes synthetic graphite and / or natural graphite.

[0036] In some embodiments, the negative electrode film layer further includes a conductive agent, which includes one or more of conductive carbon black, carbon nanotubes, and graphene.

[0037] In some embodiments, the positive electrode film layer includes a positive electrode active material, which includes one or more of lithium transition metal oxides, lithium phosphates, and their respective modified compounds.

[0038] In some implementations, the battery cell is prismatic.

[0039] A second aspect of this disclosure provides a battery device, which includes the battery cell of the first aspect.

[0040] The third aspect of this disclosure provides an electrical device, which includes the battery device of the second aspect. Attached Figure Description

[0041] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this disclosure. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0042] Figure 1 is an exploded view of a battery cell according to an embodiment of the present disclosure.

[0043] Figure 2 is a cross-sectional view of a battery cell according to an embodiment of the present disclosure (the electrode assembly is a stacked electrode assembly).

[0044] Figure 3 is a cross-sectional view of a battery cell according to another embodiment of the present disclosure (the electrode assembly is a stacked electrode assembly).

[0045] Figure 4 is a cross-sectional view of a battery cell according to another embodiment of the present disclosure (the electrode assembly is a stacked electrode assembly).

[0046] Figure 5 is a cross-sectional view of a battery cell according to an embodiment of the present disclosure (the electrode assembly is a wound electrode assembly).

[0047] Figure 6 is a cross-sectional view of a battery cell according to another embodiment of the present disclosure (the electrode assembly is a wound electrode assembly).

[0048] Figure 7 is a cross-sectional view of a battery cell according to another embodiment of the present disclosure (the electrode assembly is a wound electrode assembly).

[0049] Figure 8 is a cross-sectional view of a wound battery assembly according to an embodiment of the present disclosure.

[0050] Figure 9 is a cross-sectional view of a wound battery assembly and a first structural member according to an embodiment of the present disclosure.

[0051] Figure 10 is an exploded view of a battery pack according to an embodiment of the present disclosure.

[0052] Figure 11 is a CT image of the electrode assembly of Embodiment 1 of this disclosure.

[0053] Figure 12 is a CT image of the electrode assembly of Comparative Example 1 of this disclosure.

[0054] Explanation of reference numerals in the attached drawings: 10. Housing; 11. First housing; 12. Second housing; 100. Battery pack; 20. Battery cell; 21. Top cover; 22. Outer shell; 30. Electrode assembly; 31. Straight section; 32. Corner section; 33. Corner connection; 34. Corner tip; 40. First structural component; 41. Straight section; 42. Corner section; X, First direction; Y, Second direction. Detailed Implementation

[0055] Hereinafter, embodiments of the battery cell, battery device, and power-consuming device of this disclosure will be described in detail with appropriate reference to the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this disclosure and are not intended to limit the subject matter of the claims.

[0056] The "range" disclosed in this disclosure is defined by a lower limit and an upper limit, whereby a given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and if maximum range values ​​3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this disclosure, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0057] Unless otherwise specified, all embodiments and optional embodiments of this disclosure can be combined to form new technical solutions.

[0058] Unless otherwise specified, all technical features and optional technical features of this disclosure can be combined to form new technical solutions.

[0059] Unless otherwise specified, all steps of this disclosure may be performed sequentially or randomly, preferably sequentially. For example, if a method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if it is mentioned that the method may also include step (c), it means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0060] Unless otherwise specified, the terminology used in this disclosure has the common meaning as commonly understood by those skilled in the art.

[0061] Unless otherwise specified, the values ​​of the parameters mentioned in this disclosure can be determined using various test methods commonly used in the art, for example, according to the test methods given in this disclosure.

[0062] Currently, to improve battery energy density, the industry typically incorporates silicon-based materials with high specific capacity into the negative electrode. However, silicon-based materials undergo volume expansion during battery cycling. This expansion force not only increases the internal resistance of the electrode assembly, affecting the battery's cycle life, but also significantly increases the overall volume of the electrode assembly. This leads to a reduction in the distance between the electrode assembly and the battery casing, or even direct contact, causing structural damage to both the electrode assembly and the battery casing.

[0063] Furthermore, because silicon-based materials expand significantly during charging and decrease in expansion during discharging, the electrode assembly undergoes repeated large-scale expansion and contraction during the long-term cycling of a battery cell. This repeated volume change can cause the active materials and SEI film in the electrode sheets to break easily, and the binders in the electrode sheets are also prone to fatigue failure, thus affecting the cycle performance of the battery cell.

[0064] Based on this, the present disclosure provides a battery cell, a battery device, and an electrical device, wherein the battery cell has excellent energy density and cycle performance.

[0065] The first aspect of this disclosure provides a battery cell, which includes a casing, a first structural member, and at least one electrode assembly. The electrode assembly and the first structural member are disposed within the casing. The electrode assembly includes a negative electrode and a positive electrode. The positive electrode includes a positive current collector and a positive electrode film layer located on at least one side of the positive current collector. The negative electrode includes a negative current collector and a negative electrode film layer located on at least one side of the negative current collector. The negative electrode film layer includes a negative electrode active material, which is a silicon-based material. Based on the total mass of the negative electrode film layer, the silicon content in the silicon-based material is 15%-90% by mass. The first structural member and the electrode assembly are stacked together along a first direction, which is the thickness direction of the electrode assembly.

[0066] In this disclosure, the silicon content in the negative electrode film is relatively high, indicating a high content of silicon-based material as the negative electrode active material, which is beneficial for improving the energy density of the battery cell. Due to the high silicon content, the silicon-based material will undergo significant volume expansion during battery charging and discharging. Therefore, this disclosure includes a first structural component inside the battery cell casing, which is stacked with the electrode assembly along a first direction. Thus, during battery charging and discharging, the first structural component can effectively block the stress impact generated by the volume expansion of the electrode assembly, reducing the risk of local deformation of the electrode assembly and thereby improving the cycle performance of the battery cell. Furthermore, during charging, the first structural component contracts under the expansion and compression of the electrode assembly, which can utilize the buffering effect of the first structural component to balance the distribution of large-area forces on the electrode assembly, thereby reducing the breakage of active material particles and the SEI film in the electrode sheets, and reducing the fatigue failure of the binder, further improving the cycle performance of the battery cell.

[0067] For example, based on the total mass of the negative electrode film, the silicon content is a value within a range of 15%, 16%, 17%, 18%, 19%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or any combination thereof. In some embodiments, it is preferably 40%-65%.

[0068] In this disclosure, the first direction (X) is the thickness direction of the battery module. When the battery module is a stacked battery module, the thickness direction of the battery module is the stacking direction of the positive electrode and the negative electrode. When the battery module is a wound battery module, the wound battery module includes a straight section and a corner section, and the thickness direction of the battery module is the stacking direction of the positive electrode and the negative electrode in the straight section (also called the "large part").

[0069] In this disclosure, the outer casing is the external protective shell of the battery cell, and an internal cavity is formed for encapsulating components such as electrode assemblies, first structural components, and electrolytes. The outer casing can be made of steel, aluminum, plastic (such as polypropylene), composite metal (such as copper-aluminum composite), or aluminum-plastic film, etc.

[0070] In some embodiments, the first structural member is an elastic member. Therefore, during battery charging and discharging, on the one hand, the first structural member is more effective in blocking the stress impact generated by the volume expansion of the electrode assembly, reducing the risk of local deformation of the electrode assembly; on the other hand, it is more effective in using the buffering effect of the first structural member to balance the distribution of large-area forces in the electrode assembly, thereby reducing the breakage of active material particles and the SEI film in the electrode sheet, and reducing the fatigue failure of the binder, which is beneficial to further improving the cycle performance of the battery cell.

[0071] In some embodiments, the elastic modulus of the first structural member is 0.1 MPa-3 MPa, optionally 0.1 MPa-2 MPa. An elastic modulus within this range is beneficial for improving the elasticity of the first structural member, enabling it to effectively resist compressive stress when subjected to expansion and compression from the electrode assembly, thus reducing the risk of excessive deformation. For example, the elastic modulus of the first structural member is a value within the range of 0.1 MPa, 0.3 MPa, 0.5 MPa, 0.8 MPa, 1 MPa, 1.3 MPa, 1.5 MPa, 1.8 MPa, 2 MPa, 2.3 MPa, 2.5 MPa, 2.8 MPa, 3 MPa, or any combination thereof.

[0072] In this disclosure, the term "elastic modulus" refers to the normal stress per unit area of ​​a material when subjected to an external force, divided by the strain in the direction of that stress. During the elastic deformation stage, the stress and strain of a material are directly proportional. The elastic modulus describes the magnitude of the unit strain caused by a unit stress when a material is subjected to force within a certain range. The larger the elastic modulus, the greater the elastic stiffness of the material, and the stronger its ability to maintain its shape under external force.

[0073] In this disclosure, the elastic modulus of the first structural component has a meaning known in the art and can be determined using instruments and methods known in the art. For example, it can be determined using at least one of the following methods: static tensile testing, dynamic testing, sound velocity method, nanoindentation method, and bending method. The testing instruments may include a nanoindenter, a compression testing machine, and a universal testing machine. Specifically, the battery cell is disassembled to obtain the first structural component, which is then cut into samples of specified dimensions (e.g., length 155 mm, width 110 mm, thickness 3 mm). The first structural component sample is placed on a universal testing machine and compressed to 10% of its original thickness. The stress-strain curve during this process is recorded, and the slope of the linear segment of the curve is the elastic modulus of the first structural component.

[0074] In some embodiments, when the battery cell is at 0% SOC, the total thickness of the electrode assembly is 72%-92% of the dimension of the internal cavity of the housing along the first direction. The ratio of the total thickness of the electrode assembly to the dimension of the internal cavity of the housing along the first direction is the group margin of the battery cell. In this disclosure, the low group margin of the battery cell at 0% SOC provides sufficient space for the volume expansion of the silicon-based material, avoids the interaction between the electrode assembly and the housing when not fully charged, and helps to reduce structural damage to the electrode assembly and the housing.

[0075] The inventors also discovered that during battery charging and discharging, due to the significant expansion of silicon-based materials, when the cell mass margin is low, the negative electrode undergoes a substantial volume change. This results in a larger interlayer spacing between the positive and negative electrodes within the electrode assembly, especially when the cell is not fully charged (i.e., in a low state of charge). This increased interlayer spacing lengthens the transport path of active ions and also causes electrolyte bridging (a disruption in the continuity of the electrolyte within the battery, preventing the formation of an effective ion transport path between the positive and negative electrodes). This further increases the transport path of active ions, preventing them from fully embedding and extracting into the silicon-based material during charging and discharging, thus affecting the specific capacity of the silicon-based material.

[0076] Therefore, the first structural component disposed inside the casing of the battery cell in this disclosure can reduce the volume change of the electrode assembly during charging and discharging. At the low SOC state of the battery cell, this allows for a smaller interlayer spacing between the positive and negative electrode plates within the electrode assembly, which is beneficial for shortening the transport path of active ions. The smaller interlayer spacing also maintains the distribution of electrolyte between the positive and negative electrode plates, reducing the occurrence of electrolyte bridging, further shortening the transport path of active ions, thereby reducing the polarization of the electrode assembly. This allows for sufficient insertion and extraction of active ions into the silicon-based material, improving the specific capacity of the silicon-based material and ultimately increasing the energy density of the battery cell.

[0077] In this disclosure, the battery cell can be cylindrical or prismatic, and when prismatic, it can be, for example, a cuboid. When the battery cell is cylindrical, there is one electrode assembly, and the first direction (i.e., the thickness direction of the electrode assembly) refers to the diameter direction (i.e., radial direction) of the electrode assembly. The dimension of the internal cavity of the housing along the first direction refers to the inner diameter of the cylindrical housing. When the battery cell is prismatic, the first direction is perpendicular to the large surface of the battery cell. The thickness of the electrode assembly refers to the dimension of the electrode assembly along the first direction, i.e., the dimension perpendicular to the large surface of the battery cell. The number of electrode assemblies can be one or more. In some embodiments, the number of electrode assemblies is multiple, and the multiple electrode assemblies are arranged along the first direction, and the total thickness of the electrode assemblies refers to the sum of the thicknesses of each individual electrode assembly. The dimension of the internal cavity of the housing along the first direction refers to the distance between the two inner walls of the housing along the direction perpendicular to the large surface of the battery cell.

[0078] In this disclosure, the 0% SOC state of a battery cell refers to the state of the battery cell being discharged at a constant current discharge rate of 0.33C to a discharge cutoff voltage of 2.5V, which corresponds to the 0% SOC state of the battery cell.

[0079] For example, when the battery cell is at 0% SOC, the total thickness of the electrode assembly is a value within a range of 92%, 91%, 90%, 89%, 88%, 87%, 86%, 85%, 84%, 83%, 82%, 81%, 80%, 79%, 78%, 77%, 76%, 75%, 74%, 73%, 72%, or any combination thereof, of the dimension of the internal cavity of the housing along a first direction. In some embodiments, it is preferably 82%-90%.

[0080] In some embodiments, when the silicon content, based on the total mass of the negative electrode film, is greater than or equal to 15% and less than 40%, the total thickness of the electrode assembly in the battery cell at 0% SOC is 84%-92% of the dimension of the internal cavity of the casing along the first direction (i.e., the group margin of the battery cell is 84%-92%). Within this range, the silicon content in the silicon-based material is relatively high, resulting in a higher specific capacity for the silicon-based negative electrode sheet. During charging, the silicon-based material undergoes significant volume expansion. In this case, maintaining a group margin of 84%-92% in the battery cell at 0% SOC provides sufficient space for the expansion of the electrode assembly, preventing the electrode assembly from interacting with the casing in a non-fully charged state. This reduces the probability of mechanical contact between the electrode assembly and the casing due to volume expansion, thereby reducing structural damage to the electrode assembly and casing, and ultimately improving the energy density and cycle performance of the battery cell.

[0081] In this disclosure, when the mass content of silicon element is greater than or equal to 15% and less than 40% based on the total mass of the negative electrode film layer, the battery cell group margin is controlled to be 80%-87%, achieving a battery cell group margin of 84%-92% at 0% SOC. The battery cell group margin refers to the percentage of the thickness of the electrode assembly (excluding the thickness of the first structural member) relative to the distance between the two opposing inner wall surfaces of the casing when the prepared electrode assembly is placed in the casing in this initial state.

[0082] In some embodiments, when the silicon content, based on the total mass of the negative electrode film, is greater than or equal to 40% and less than or equal to 65%, the total thickness of the electrode assembly in the battery cell at 0% SOC is 82%-90% of the dimension of the internal cavity of the casing along the first direction (i.e., the group margin of the battery cell is 82%-90%). Within this range, the silicon content in the silicon-based material further increases, resulting in a higher specific capacity for the negative electrode silicon-based material, and greater volume expansion during charging. In this case, further reducing the group margin of the battery cell at 0% SOC to 82%-90% provides more space for greater expansion of the electrode assembly, avoids contact and interaction between the electrode assembly and the casing in a non-fully charged state, thereby reducing the probability of mechanical contact between the electrode assembly and the casing due to volume expansion, reducing structural damage to the electrode assembly and casing, and improving the energy density and cycle performance of the battery cell.

[0083] In this disclosure, when the mass content of silicon element is greater than or equal to 40% and less than or equal to 65% based on the total mass of the negative electrode film layer, the group margin of the battery cell is controlled to be 72%-84%, thereby achieving a group margin of 82%-90% for the battery cell at 0% SOC.

[0084] In some implementations, when the silicon content, based on the total mass of the negative electrode film, is greater than 65% and less than or equal to 90%, the total thickness of the electrode assembly in the battery cell at 0% SOC is 72%-86% of the dimension of the internal cavity of the casing along the first direction (i.e., the group margin of the battery cell is 72%-86%). Further increasing the silicon content in the silicon-based material results in a higher specific capacity for the negative electrode silicon-based material, and also causes greater volume expansion of the silicon-based material during charging. In this case, further reducing the group margin of the battery cell at 0% SOC to 72%-86% provides more space for greater expansion of the electrode assembly, avoids contact and interaction between the electrode assembly and the casing in a non-fully charged state, thereby reducing the probability of mechanical contact between the electrode assembly and the casing due to volume expansion, reducing structural damage to the electrode assembly and casing, and improving the energy density and cycle performance of the battery cell.

[0085] In this disclosure, when the mass content of silicon element is greater than 65% and less than or equal to 90% based on the total mass of the negative electrode film layer, the group margin of the battery cell is controlled to be 60%-75%, thereby achieving a group margin of 72%-86% for the battery cell at 0% SOC.

[0086] In this disclosure, the mass content of silicon element, based on the total mass of the negative electrode film, can be determined by inductively coupled plasma atomic emission spectrometry (ICP). Specifically, the battery cell is disassembled to obtain the negative electrode sheet, which is then punched into a specified area (e.g., 1 cm²) using a punch. 2 Electrode samples were prepared by placing them in a polytetrafluoroethylene (PTFE) digestion vessel and adding a strong acid (a mixture of nitric acid and hydrofluoric acid), where the hydrofluoric acid was used to dissolve the silicon-containing substances. The sample was heated using a microwave digester or a hot plate until completely dissolved in the strong acid, forming a clear solution. The digested solution was transferred to a volumetric flask and diluted with deionized water to a specific volume to obtain the test solution. Inductively coupled plasma optical emission spectrometry (ICP-OES) was used to perform ICP testing on the test solution, determining the intensity of the characteristic spectral lines of silicon in the solution. The ICP-OES system automatically calculated the concentration of silicon (μg / mL) in the test solution based on a standard curve. The mass of silicon in the electrode sample was calculated by multiplying the concentration of silicon in the test solution by the volume of the test solution. This calculation yielded the mass content of silicon in the negative electrode film layer.

[0087] In some embodiments, when the battery cell is at 0% SOC, the total thickness of the first structural member is 3%-18% of the dimension of the internal cavity of the housing along the first direction. By keeping the thickness of the first structural member within this range, it is advantageous to accommodate variations in the electrode assembly due to different silicon contents. Exemplarily, when the battery cell is at 0% SOC, the total thickness of the first structural member is a value within a range of 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, or any combination thereof, of the dimension of the internal cavity of the housing along the first direction.

[0088] Figure 1 is an exploded structural diagram of a battery cell 20 provided in one embodiment of this disclosure. The battery cell 20 refers to the smallest unit constituting a battery device. The battery cell 20 includes a housing 22 and electrode assemblies 30. Exemplarily, as shown in Figure 1, the battery cell 20 includes a top cover 21, a housing 22, electrode assemblies 30, and other functional components. The housing 22 is a component used to cooperate with the top cover 21 to form the internal environment of the battery cell 20, wherein the formed internal environment can be used to accommodate the electrode assemblies 30, electrolyte, and other components. The electrode assemblies 30 are components in the battery cell 20 where electrochemical reactions occur. The housing 22 may contain one or more electrode assemblies 30. The electrode assemblies 30 are mainly formed by winding or stacking positive and negative electrode sheets, and typically a separator is provided between the positive and negative electrode sheets.

[0089] Figure 2 is a cross-sectional view of a battery cell according to an embodiment of the present disclosure. The battery cell 20 includes: a housing 22, an electrode assembly 30, and a first structural member 40. The electrode assembly 30 is located inside the housing 22 and includes a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode. The negative electrode includes a negative current collector and a negative electrode film layer disposed on at least one side of the negative current collector.

[0090] For example, the first structural member 40 is stacked with a portion of the negative electrode film layer.

[0091] For example, the first structural member 40 is stacked with the entire area of ​​the negative electrode film layer.

[0092] In some embodiments, along a first direction X, a first structural member 40 is disposed between the electrode assembly 30 and the housing 22.

[0093] For example, as shown in Figure 2 (the electrode assembly is a stacked electrode assembly), two first structural members 40 are provided, and the two first structural members 40 are respectively disposed on both sides of the electrode assembly 30. These two first structural members 40 can better balance the stress caused by the volume change of the negative electrode film layer of the battery cell 20 during charging and discharging, and can better optimize the stress distribution, thereby effectively preventing problems such as wrinkles and cracks in the electrode layer, improving the charging and discharging efficiency of the battery, and also significantly enhancing the cycle performance of the electrode assembly 30, making the battery cell 20 more stable during long-term repeated charging and discharging.

[0094] For example, as shown in Figure 3 (the electrode assembly is a stacked electrode assembly), the first structural member 40 is disposed on one side of the electrode assembly 30. The first structural member 40 can protect one side of the electrode assembly 30 to a certain extent. During the battery charging and discharging process, it can effectively block stress impacts, reduce the risk of local deformation of the electrode assembly 30, and improve the reliability of the battery assembly. Moreover, there is only one first structural member 40, which can reduce the arrangement cost of the first structural member 40.

[0095] The first structural component acts as a buffer for the stacked electrode assembly. On one hand, it reduces the volume change of the electrode assembly during charging and discharging. At the low SOC state of the battery cell, it allows for a smaller interlayer spacing between the positive and negative electrodes, which helps shorten the transport path of active ions, thereby improving the specific capacity of the silicon-based material and further increasing the energy density of the battery cell. On the other hand, it also balances the distribution of surface forces on the electrode assembly through its buffering effect, thereby reducing the breakage of active material particles and the SEI film during battery cycling and reducing binder fatigue failure, thus further improving the cycle performance of the battery cell.

[0096] In some embodiments, multiple electrode assemblies 30 are provided, and the multiple electrode assemblies 30 are arranged sequentially along a first direction X, with a first structural member 40 disposed between two adjacent electrode assemblies 30. Examples are shown in Figures 4 and 5. Figure 4 is a cross-sectional view of a battery cell according to one embodiment (the electrode assembly is a stacked electrode assembly). Figure 5 is a cross-sectional view of a battery cell according to another embodiment (the electrode assembly is a wound electrode assembly).

[0097] For example, two or more electrode assemblies 30 may be provided, but this disclosure does not impose any limitation.

[0098] For example, two electrode assemblies 30 are provided, and the first structural member 40 may be disposed between the two electrode assemblies 30.

[0099] For example, three electrode assemblies 30 are provided, and two first structural members 40 may be provided, with the two first structural members 40 respectively disposed between two adjacent electrode assemblies 30.

[0100] In Figures 4 and 5, a first structural member 40 is disposed between two electrode assemblies 30. The first structural member is optimally disposed between two adjacent electrode assemblies. On one hand, during the charging and discharging process of the battery cell, especially at low SOC, it reduces the interlayer spacing between the positive and negative electrode plates in each electrode assembly, thereby shortening the transport path of active ions, improving the specific capacity of the silicon-based material, and further increasing the energy density of the battery cell. On the other hand, during charging, the first structural member can also balance the expansion force between two adjacent electrode assemblies, reducing the breakage of active material particles and the SEI film in each electrode assembly due to expansion and compression, and reducing the fatigue failure of the binder, thereby further improving the cycle performance of the battery cell. Compared to disposing the first structural member between two adjacent electrode assemblies, when the first structural member is disposed between the casing and the electrode assembly, the heat dissipation effect inside the electrode assembly is poor, and the electrode assembly temperature is prone to overheating during high-power charging and discharging.

[0101] In some embodiments, multiple electrode assemblies 30 are provided. Among the multiple electrode assemblies 30, the two electrode assemblies 30 located at both ends of the first direction X are respectively the first electrode assembly and the second electrode assembly. The first structural member 40 is arranged between the first electrode assembly and the housing 22, and / or the first structural member 40 is arranged between the second electrode assembly and the housing 22.

[0102] For example, two electrode assemblies 30 are provided, namely a first electrode assembly and a second electrode assembly. For instance, as shown in FIG. 6 (the electrode assembly is a wound electrode assembly), two first structural members 40 can be provided, that is, one first structural member 40 can be provided between the first electrode assembly and the housing 22, and the other first structural member 40 can be provided between the second electrode assembly and the housing 22. Alternatively, as shown in FIG. 7 (the electrode assembly is a wound electrode assembly), one first structural member 40 can be provided, either between the first electrode assembly and the housing 22 or between the second electrode assembly and the housing 22. Furthermore, three first structural members 40 can also be provided, that is, the first first structural member 40 can be provided between the first electrode assembly and the housing 22, the second first structural member can be provided between the second electrode assembly and the housing 22, and the third first structural member 40 can be provided between the first electrode assembly and the second electrode assembly.

[0103] The first structural component acts as a buffer for the wound electrode assembly. On one hand, it reduces the volume change of the electrode assembly during charging and discharging. At the low SOC state of the battery cell, it allows for a smaller interlayer spacing between the positive and negative electrode plates, which helps shorten the transport path of active ions, thereby improving the specific capacity of the silicon-based material and further increasing the energy density of the battery cell. On the other hand, it also balances the distribution of surface forces on the electrode assembly through buffering, thereby reducing the breakage of active material particles and the SEI film during battery cycling, and reducing binder fatigue failure, thus further improving the cycle performance of the battery cell.

[0104] For example, three electrode assemblies 30 are provided, arranged sequentially along the first direction X. The three electrode assemblies 30 are respectively a first electrode assembly, a second electrode assembly, and a third electrode assembly, with the third electrode assembly located between the first and second electrode assemblies. For example, one first structural member 40 can be provided, which can be located between the first electrode assembly and the housing 22, or between the second electrode assembly and the housing 22. Alternatively, two first structural members 40 can be provided, that is, one first structural member 40 can be located between the first electrode assembly and the housing 22, and the other first structural member 40 can be located between the second electrode assembly and the housing 22. Furthermore, four first structural members 40 can be provided, that is, the first first structural member 40 can be located between the first electrode assembly and the housing 22, the second first structural member 40 can be located between the second electrode assembly and the housing 22, the third first structural member 40 can be located between the first and third electrode assemblies, and the fourth first structural member 40 can be located between the second and third electrode assemblies.

[0105] In the above technical solution, by setting the first structural component 40 at different positions, stress impact can be effectively blocked during battery charging and discharging, reducing the risk of local deformation of the electrode assembly 30 and improving the reliability of the battery assembly.

[0106] In some embodiments, as shown in Figures 4 and 5, the electrode assembly 30 is a wound electrode assembly, or the electrode assembly 30 is a stacked electrode assembly.

[0107] When the electrode assembly 30 is a wound electrode assembly, the tightly wound structure can accommodate a larger amount of active material within a limited space, which helps to improve the energy density of the battery. Moreover, this structure has good stability and can resist external impacts to a certain extent, ensuring the safety and reliability of the battery.

[0108] If the electrode assembly 30 is a stacked electrode assembly, the connection between the electrodes is tighter, the electron transport path is shorter and more uniform, which can reduce the internal resistance of the battery and improve charge / discharge performance and rate performance. The stacked structure can better adapt to the expansion and contraction of the battery, reduce electrode damage caused by stress concentration, and extend battery life, making it suitable for scenarios with high requirements for battery performance and lifespan.

[0109] In the above technical solution, the arrangement of the first structural component 40 can effectively protect the wound electrode assembly and the stacked electrode assembly. During the charging and discharging process of the battery, it can effectively block stress impact, reduce the risk of local deformation of the electrode assembly 30, and improve the reliability of the battery assembly.

[0110] Please refer to Figures 8 and 9. Figure 8 is a cross-sectional view of a wound electrode assembly according to one embodiment. Figure 9 is a cross-sectional view of a wound electrode assembly and a first structural member according to one embodiment. The electrode assembly 30 is a wound electrode assembly, which includes a straight section 31 and a corner section 32. There are two corner sections 32, which are respectively connected to both sides of the straight section 31 in a second direction Y. The second direction Y is perpendicular to the first direction X. The first structural member 40 includes a straight portion 41 and at least one corner portion 42 connected together. Along the first direction X, the straight portion 41 is stacked with the straight section 31, and the corner portion 42 is stacked with the corner section 32.

[0111] Here, we will explain the straight section 31 and the corner section 32 with reference to Figures 8 and 9. After the electrode assembly 30 is wound, the straight section 31 is the part that extends along the second direction Y. In the straight section 31, both the positive electrode sheet and the negative electrode sheet are straight sheets, while the corner section 32 is the part where the positive electrode sheet and the negative electrode sheet are bent.

[0112] For example, the first structural member 40 completely covers the straight section 31, thereby providing better protection for the straight section 31 of the electrode assembly 30. Furthermore, two corner portions 42 are constructed so that the corner sections 32 can also be better protected, and the connection between the straight section 31 and the corner sections 32 can also be better protected.

[0113] In the above technical solution, by arranging the coverage area of ​​the first structural member 40, the electrode assembly 30 can be effectively protected. During the charging and discharging process of the battery, it can effectively block stress impact, reduce the risk of local deformation of the electrode assembly 30, and improve the reliability of the battery assembly.

[0114] In some embodiments, as shown in Figures 8 and 9, the connection between the straight section 31 and the corner section 32 is a corner connection 33, and the end of the corner section 32 away from the straight section 31 is a corner tip 34. In the winding direction of the electrode assembly 30, the dimension from the corner connection 33 to the corner tip 34 is c1, and the dimension c2 of the corner portion 42 satisfies: 0 < c2 ≤ c1.

[0115] In other words, when the first structural member 40 covers the outer side of the electrode assembly 30, the first structural member 40 can extend from the straight section 31 toward the corner section 32, and the corner connection 33 covers the inner side of the first structural member 40, so that the corner connection 33 can also be well protected. Furthermore, by arranging the coverage area of ​​the corner portion 42 in this disclosure, not only can the electrode assembly 30 be well protected, but the material used in the corner portion 42 of the first structural member 40 can also be saved, thereby saving costs.

[0116] For example, the corner portion 42 can cover the corner connection 33.

[0117] For example, the corner portion 42 may extend from the corner connection 33 to the corner tip 34.

[0118] For example, one end of the corner portion 42 covers the corner connection 33, and the other end covers the corner tip 34, but does not cover the corner tip 34.

[0119] In the above technical solution, by arranging the coverage area of ​​the first structural member 40, the electrode assembly 30 can be effectively protected. During the charging and discharging process of the battery, it can effectively block stress impact, reduce the risk of local deformation of the electrode assembly 30, and improve the reliability of the battery assembly.

[0120] In some embodiments, the electrode assembly 30 is a stacked electrode assembly with sheets stacked along the first direction X. In the projection plane perpendicular to the first direction X, the projected area of ​​the positive electrode sheet is smaller than the projected area of ​​the first structural member 40, and the projection of the positive electrode sheet is located within the projection of the first structural member 40.

[0121] For example, in both the second direction Y and the third direction Z (the third direction is perpendicular to the second direction and perpendicular to the first direction), the size of the first structural member 40 is larger than the size of the positive electrode sheet, wherein the second direction Y and the third direction Z are perpendicular to each other.

[0122] For example, in the second direction Y and the third direction Z, the size of the first structural member 40 can be smaller than the size of the negative electrode sheet.

[0123] For example, in both the second direction Y and the third direction Z, the size of the first structural member 40 can be larger than the size of the negative electrode sheet.

[0124] In the above technical solution, by arranging the coverage area of ​​the first structural member 40, the electrode assembly 30 can be effectively protected. During the charging and discharging process of the battery, it can effectively block stress impact, reduce the risk of local deformation of the electrode assembly 30, and improve the reliability of the battery assembly.

[0125] In some embodiments, in a cross-section perpendicular to the first direction X, the length L1 and width W1 of the first structural member, and the length L2 and width W2 of the positive electrode sheet satisfy the following relationship: L1-L2 = 2mm-3mm; and / or, W1-W2 = 2mm-3mm. Therefore, the length and width of the first structural member are slightly larger than the length and width of the positive electrode sheet, which facilitates the complete coverage of the first structural member on the surface of the electrode assembly, thereby providing sufficient cushioning. For example, the difference (L1-L2) between the length of the first structural member and the length of the positive electrode sheet is a value within a range of 2mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, 3mm, or any two of these values; the difference (W1-W2) between the width of the first structural member and the width of the positive electrode sheet is a value within a range of 2mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, 3mm, or any two of these values.

[0126] In this disclosure, the length, width, and thickness of the first structural member can be measured using methods and instruments known in the art. For example, a micrometer (e.g., Mitutoyo 293-100 model, with an accuracy of 0.1 μm) can be used to measure the length, width, and thickness of the first structural member at at least 12 different locations along the length, width, and thickness directions, and then the average values ​​are taken as the length, width, and thickness of the first structural member.

[0127] In some embodiments, the density of the first structural member is less than or equal to 0.3 g / cm³. 3 The density of the first structural component is within the aforementioned range, which reduces its weight per unit volume, thereby reducing the overall weight of the battery cell and improving its gravimetric energy density. For example, the density of the first structural component is 0.3 g / cm³. 3 0.28g / cm 3 0.26g / cm 3 0.24g / cm 3 0.22g / cm 3 0.20g / cm 3 0.18g / cm 3 0.15g / cm 3 0.13g / cm 3 0.10 g / cm 3 0.08g / cm 3 0.05g / cm 3 Or the value between any two of them within a range.

[0128] In this disclosure, the density of the first structural component has a meaning known in the art and can be measured using instruments and methods known in the art. Specifically, the battery cell is disassembled to obtain the first structural component, and the mass of the first structural component is weighed and denoted as M; the length, width, and thickness of the first structural component are measured, and the product of the length, width, and thickness is taken as the volume of the first structural component and denoted as V. The density of the first structural component is calculated according to the formula: density = M / V.

[0129] In some embodiments, the rebound rate of the first structural component under the test pressure is greater than or equal to 80%, and the test pressure is less than or equal to 3 MPa. Under a test pressure less than or equal to 3 MPa, the first structural component with a rebound rate within the aforementioned range exhibits good rebound performance. When the first structural component is subjected to significant compressive stress from the electrode assembly, it undergoes compression, resulting in a reduction in thickness. During discharge contraction of the electrode assembly, the first structural component can rebound, allowing it to largely recover its shape and size before compression. Thus, a first structural component with a high rebound rate can reduce the volume change of the electrode assembly during charging and discharging, decrease the interlayer spacing between electrodes in the low SOC state of the battery cell, thereby shortening the transport path of active ions, improving the specific capacity of the silicon-based material, and further enhancing the energy density of the battery cell. For example, under a test pressure less than or equal to 3 MPa, the rebound rate of the first structural component is a value within a range of 80%, 82%, 84%, 86%, 88%, 90%, 92%, 94%, 96%, 98%, 100%, or any combination thereof.

[0130] In this disclosure, the term "springback" refers to the size of a material after it has been subjected to an external force and the force has been removed, divided by the initial size of the material in that stress direction. Springback reflects the ability of a material to deform after being subjected to an external force and to return to its original shape after the force has ceased to act; the higher the springback, the stronger the material's ability to recover from deformation.

[0131] In this disclosure, the resilience of the first structural component has a meaning known in the art and can be measured using instruments and methods known in the art. Specifically, the battery cell is disassembled to obtain the first structural component, which is then cut into samples of specified dimensions (e.g., length 155mm, width 110mm, thickness 3mm), and its original thickness H0 is measured. The first structural component sample is placed on a universal testing machine and compressed at a certain speed (e.g., 5mm / min) to reach a preset test pressure (e.g., 3MPa), and this test pressure is maintained for 60 minutes. The pressure is released, and the first structural component sample is allowed to recover freely for 10 minutes. The final thickness H1 of the first structural component sample after recovery is measured. The resilience of the first structural component is calculated according to the formula: Resilience = H1 / H0 × 100%.

[0132] In some embodiments, the compressive permanent deformation rate of the first structural member is less than or equal to 20%, optionally less than or equal to 15%, and more preferably less than or equal to 10%. A compressive permanent deformation rate within the aforementioned range is beneficial because, when the electrode assembly contracts during discharge, the first structural member can largely recover its shape and size before compression after the extrusion stress is removed. This makes the first structural member less prone to permanent deformation, thereby extending its service life and maintaining a smaller interlayer spacing within the electrode assembly at low SOC. Exemplarily, the compressive permanent deformation rate of the first structural member is a value within a range of 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, or any combination thereof.

[0133] In this disclosure, the term "compression set" refers to the degree to which a material, after being subjected to compressive stress, cannot fully recover to its original dimensions after the external force is removed. Compression set reflects the elastic recovery ability of a material; a higher compression set indicates greater permanent deformation and a greater susceptibility to permanent deformation.

[0134] In this disclosure, the compression set rate of the first structural component has a meaning known in the art and can be measured using instruments and methods known in the art. Specifically, the battery cell is disassembled to obtain the first structural component, which is then cut into samples of specified dimensions (e.g., length 155 mm, width 110 mm, thickness 3 mm), and its initial thickness is measured. The first structural component sample is placed on a compression testing machine, and a clamp is used to compress the first structural component sample to 70% of its initial thickness (or, according to design requirements, for example, the compression ratio corresponding to a pressure of 3 MPa). The compression limit thickness is 70% of the initial thickness. Maintaining this compressed state, the clamp and the first structural component sample are placed in a constant temperature chamber at 60°C for 2 hours. The clamp and the first structural component sample are then removed, cooled at room temperature for 30 minutes, and the clamp is released. The final thickness of the first structural component sample after recovery is measured, and the compression set rate is calculated. Compression set rate = (initial thickness - final thickness) / (initial thickness - compression limit thickness) × 100%.

[0135] In some embodiments, the stress relaxation rate of the first structural member is less than or equal to 20%. A stress relaxation rate within this range allows the first structural member to better maintain its shape and dimensions during battery cycling, when subjected to prolonged compressive stress from the electrode assembly, thus improving the long-term structural stability of the first structural member. Exemplarily, the stress relaxation rate of the first structural member is a value within a range of 20%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, or any combination thereof.

[0136] In this disclosure, the term "stress relaxation" refers to the phenomenon that the internal stress of a material gradually decreases over time while maintaining a constant total deformation (including elastic and plastic deformation). The stress relaxation rate reflects the rate at which the internal stress of a material decreases over time under constant strain conditions. The larger the stress relaxation rate, the faster the internal stress of the material decreases under constant strain conditions, and the worse the stability of the material.

[0137] In this disclosure, the stress relaxation rate of the first structural component has a meaning known in the art and can be measured using instruments and methods known in the art. Specifically, the battery cell is disassembled to obtain the first structural component, which is then cut into samples of specified dimensions (e.g., length 155 mm, width 110 mm, thickness 3 mm). The first structural component sample is placed on a compression testing machine and compressed at a constant speed to a fixed deformation state (e.g., 50% strain, or strain corresponding to a pressure of 3 MPa), and the initial stress is recorded. This deformation state is maintained constant, and the pressure required to maintain this deformation state over time is recorded. The test temperature is 45°C, and the test time is 600 h. The stress at 600 h is recorded, and the stress relaxation rate is calculated. Stress relaxation rate = (initial stress - stress at 600 h) / initial stress × 100%.

[0138] In some embodiments, the mass gain rate of the first structural component in dimethyl carbonate is less than or equal to 100%. A mass gain rate of the first structural component in dimethyl carbonate within the aforementioned range reflects a low amount of dimethyl carbonate absorption by the first structural component. When the first structural component is immersed in the electrolyte within the inner cavity of the casing, it reduces the amount of electrolyte absorbed and lowers the mass swelling rate, which is beneficial for improving the long-term stability of the first structural component in the electrolyte. Exemplarily, the mass gain rate of the first structural component in dimethyl carbonate is a value within a range of 100%, 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, or any combination thereof.

[0139] In this disclosure, the term "mass increase rate" is used to characterize the degree of absorption of dimethyl carbonate by the first structural component. The mass increase rate can be determined by the following method: disassembling the battery cell to obtain the first structural component, and measuring the original mass M0 of the first structural component. The first structural component is completely immersed in dimethyl carbonate, soaked at a specific temperature (e.g., 25°C) for a specified time (e.g., 200 h), then removed, and the surface residual droplets are quickly wiped dry with filter paper, and its mass M1 is immediately measured. The mass increase rate of the first structural component in dimethyl carbonate is calculated by the following formula: Mass increase rate = [(M1-M0) / M0] × 100%.

[0140] In some embodiments, the first structural component includes at least one of polyimide, modified polyimide, silicone rubber, modified silicone rubber, and modified polyolefin. Optionally, the first structural component includes polyimide. The aforementioned types of first structural components exhibit high resilience and support, providing strong resistance to expansion, compression, and deformation of the electrode assembly. Furthermore, these types of first structural components exhibit extremely low swelling and absorption rates in highly polar organic solvent systems, thereby reducing the amount of electrolyte absorbed.

[0141] In some embodiments, the first structural component includes polyimide. Polyimide has an imide ring structure (-CO-NR-CO-), a rigid structure that gives it high resilience and support, effectively resisting expansion, compression, and deformation of the electrode assembly, reducing volume changes during charge and discharge, and decreasing interlayer spacing between electrodes in the low SOC state of the battery cell. Polyimide also exhibits excellent chemical stability and low absorption rate to highly polar organic solvent systems, reducing electrolyte absorption when the polyimide is immersed in the electrolyte for extended periods as the first structural component.

[0142] In some embodiments, the modified polyimide comprises a polyimide-polysiloxane block copolymer. Modified polyimides can further improve the mechanical strength and thermal conductivity of polyimides and reduce their electrolyte absorption.

[0143] In some embodiments, the modified silicone rubber includes silicone rubber containing phenyl groups. Silicone rubber itself has good resilience. By introducing phenyl groups into silicone rubber through molecular structure design, the resilience and support of silicone rubber can be further improved, thereby helping to reduce the volume change of the electrode assembly during charging and discharging and reduce the interlayer spacing between electrodes in the low SOC state of the battery cell.

[0144] In some embodiments, the modified silicone rubber includes phenyl-containing silicone rubber with a fluorinated coating on its surface. Silicone rubber itself has good resilience; by introducing phenyl groups into the silicone rubber through molecular structure design, the resilience and support of the silicone rubber can be further improved, thereby helping to reduce the volume change of the electrode assembly during charging and discharging, and reducing the interlayer spacing between electrodes in the low SOC state of the battery cell. Furthermore, the fluorinated coating on the surface of the phenyl-containing silicone rubber is stable in the electrolyte and prevents the electrolyte from contacting the phenyl-containing silicone rubber, thereby reducing the amount of electrolyte absorbed by the phenyl-containing silicone rubber.

[0145] In some embodiments, the modified polyolefin includes a polyolefin-ethylene-vinyl alcohol copolymer. The modified polyolefin material (POE) exhibits good resilience and support, reducing volume change of the electrode assembly during discharge and decreasing the interlayer spacing between electrodes. The ethylene-vinyl alcohol copolymer (EVOH) possesses good gas / solvent barrier properties. By preparing a polyolefin-ethylene-vinyl alcohol copolymer from the polyolefin material and ethylene-vinyl alcohol, a modified polyolefin is obtained, which not only possesses good resilience and support but also exhibits low electrolyte absorption.

[0146] In some embodiments, the negative electrode active material further includes a carbon-based material, with a silicon-based material to carbon-based material mass ratio of (50:50) to (95:5). Silicon-based materials have higher specific capacity, which is beneficial for improving the energy density of the battery cell. Carbon-based materials have higher structural stability, which is beneficial for improving the cycle performance of the battery cell. A silicon-based material to carbon-based material mass ratio within the above range is beneficial for improving the energy density and cycle performance of the battery cell. Exemplarily, the silicon-based material to carbon-based material mass ratio is a value between 50:50, 55:45, 60:40, 65:35, 70:30, 75:25, 80:20, 85:15, 90:10, 95:5, or any combination thereof.

[0147] In some embodiments, the silicon-based material includes one or more of elemental silicon, silicon oxide, and silicon-carbon composites.

[0148] In some embodiments, the silicon-based material includes a silicon-carbon composite, which comprises porous carbon and silicon-containing material dispersed in the pores of the porous carbon. The porous carbon, acting as a carrier for the silicon-containing material, provides support for the material and, simultaneously, allows for expansion space for the silicon-containing particles, thus mitigating stress caused by expansion during charging. Especially when the silicon-containing particles are nanometer-sized, the specific capacity is higher, which is beneficial for dispersion within the pores of the porous carbon, and the buffering effect of the porous carbon's pores on expansion can be utilized more fully.

[0149] In some implementations, the porous carbon is hard carbon. When the porous carbon is hard carbon, it has stronger support, a more stable pore structure, and is harder, thus providing better porosity for the negative electrode active layer, providing a smoother path for active ion transport, and improving the charging capability of the battery cell.

[0150] In some embodiments, the silicon-containing material includes crystalline silicon, thereby further improving the structural stability of the silicon-containing material and the energy density of the battery cell.

[0151] In some implementations, the carbon-based material includes synthetic graphite and / or natural graphite.

[0152] In some embodiments, the negative electrode film layer further includes a conductive agent, which includes one or more of conductive carbon black, carbon nanotubes, and graphene. Optionally, the conductive agent is carbon nanotubes.

[0153] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0154] In some embodiments, the negative electrode film layer may optionally include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0155] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0156] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as the negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0157] Positive electrode sheet

[0158] In this disclosure, the positive electrode sheet includes a positive current collector and a positive electrode film layer disposed on at least one side of the surface of the positive current collector, the positive electrode film layer including a positive electrode active material.

[0159] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0160] In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0161] In some embodiments, the positive electrode active material includes at least one of the following materials: lithium transition metal oxides, lithium-containing phosphates, and their respective modified compounds. Examples of lithium-containing phosphates include, but are not limited to, at least one of lithium iron phosphate (e.g., LiFePO4 (also abbreviated as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (e.g., LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Examples of lithium transition metal oxides include, but are not limited to, lithium cobalt oxides (e.g., LiCoO2), lithium nickel oxides (e.g., LiNiO2), lithium manganese oxides (e.g., LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (e.g., LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.1 Al 0.05 At least one of O2 and its modified compounds. Examples of lithium phosphates with an olivine structure include, but are not limited to, lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0162] During the charging and discharging process, lithium ions are intercalated and deintercalated, resulting in varying molar content of Li at different discharge states. In the examples of positive electrode active materials in this disclosure, the molar content of Li refers to the initial state of the material, i.e., before feeding. When the positive electrode active material is applied to the battery system, the molar content of Li changes after charge-discharge cycles.

[0163] In the examples of positive electrode active materials in this disclosure, the molar content of O is only a theoretical value. Oxygen release from the crystal lattice will cause changes in the molar content of oxygen, and the actual molar content of O will fluctuate.

[0164] In some embodiments, the positive electrode film layer may optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0165] In some embodiments, the positive electrode film may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0166] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0167] electrolytes

[0168] The electrolyte plays a role in conducting ions between the positive and negative electrode plates.

[0169] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.

[0170] In some embodiments, the electrolyte salt includes at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate; optionally, the electrolyte salt includes lithium hexafluorophosphate.

[0171] In some embodiments, the solvent includes at least one selected from ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, ethylene carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent may also be an ether solvent. Ether solvents may include one or more selected from ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ethers. Optionally, the solvent includes one or more selected from ethylene carbonate and dimethyl carbonate.

[0172] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0173] Separating membrane

[0174] In some embodiments, the battery cell also includes a separator. This disclosure does not impose any particular limitation on the type of separator; any known porous separator with good chemical and mechanical stability can be selected.

[0175] In some embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0176] In some embodiments, the electrode assembly is a wound structure. The positive electrode and the negative electrode are wound into a wound structure.

[0177] In some implementations, the electrode assembly is a stacked structure.

[0178] As an example, multiple positive and negative electrode plates can be set, and multiple positive and multiple negative electrode plates can be stacked alternately.

[0179] As an example, multiple positive electrode sheets can be set, and negative electrode sheets are folded to form multiple stacked folded segments, with a positive electrode sheet sandwiched between adjacent folded segments.

[0180] As an example, both the positive and negative electrode sheets are folded to form multiple stacked folded segments.

[0181] As an example, multiple separators can be provided, each positioned between any adjacent positive or negative electrode plates.

[0182] As an example, the separator can be continuously installed between any adjacent positive or negative electrode plates by folding or rolling.

[0183] The term "battery cell" mentioned in this article can refer to a secondary battery, which is a battery cell that can be recharged to activate the active materials and continue to be used after the battery cell has been discharged.

[0184] For example, the battery cell can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc., and this disclosure does not limit it.

[0185] In some embodiments, the electrode assembly is the component within the battery cell where electrochemical reactions occur. The electrode assembly is typically stacked along the thickness direction (lamination direction) of the battery cell. The electrode assembly includes a positive electrode, a negative electrode, an electrolyte, and a separator. During the charging and discharging process of the battery cell, active ions (e.g., lithium ions) repeatedly insert and extract between the positive and negative electrode plates. The separator, positioned between the positive and negative electrode plates, prevents short circuits while allowing active ions to pass through.

[0186] In some embodiments, the electrode assembly is provided with tabs that can either draw current from or introduce current into the electrode assembly. The tabs include positive and negative tabs.

[0187] In some implementations, the battery cell may include an outer packaging. This outer packaging may be used to encapsulate the electrode assembly and the electrolyte.

[0188] In some embodiments, the outer packaging of the battery cell can be a rigid shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of the battery cell can also be a flexible package, such as a pouch. The material of the flexible package can be plastic; examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0189] Battery device

[0190] A second aspect of this disclosure provides a battery apparatus that may include one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly may include multiple battery cells as provided in the first aspect, the multiple battery cells being connected in series, parallel, or mixed connections via a busbar.

[0191] In some implementations, a battery cell assembly is typically formed by arranging multiple battery cells.

[0192] As an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells together to form an independent module. As another example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0193] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0194] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0195] As an example, the enclosure may include a first enclosure and a second enclosure. The first enclosure and the second enclosure are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first enclosure may be a top cover or a bottom plate.

[0196] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual battery cells.

[0197] In some implementations, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0198] In some embodiments, the battery device can be a battery pack, which includes a housing and one or more individual battery cells housed within the housing. As shown in FIG10, in one embodiment, the battery pack 100 includes a housing 10 and multiple individual battery cells 20 arranged sequentially within the housing 10 along a first direction X. The housing 10 may include a first housing 11 and a second housing 12. The first housing 11 and the second housing 12 are fastened together to form a closed space inside the housing 10 for housing the individual battery cells.

[0199] The technical solutions described in the embodiments of this disclosure are applicable to various electrical devices that use individual battery cells, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, power tools, vehicles, ships, and spacecraft. For example, spacecraft include airplanes, rockets, space shuttles, and spacecraft.

[0200] Electrical appliances

[0201] A third aspect of the present disclosure also provides an electrical device, which will be described below with appropriate reference to the accompanying drawings.

[0202] The electrical devices mentioned in the embodiments of this disclosure include the battery devices provided in the second aspect of this disclosure. The battery device can be the power source of the electrical device or the energy storage unit of the electrical device. Electrical devices may include, but are not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., 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, energy storage systems, etc.

[0203] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a single battery cell as their power source.

[0204] Example

[0205] The following describes embodiments of this disclosure. The embodiments described below are exemplary and are only used to explain this disclosure, and should not be construed as limiting this disclosure. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0206] Example 1

[0207] Preparation of battery cells:

[0208] 1. Preparation of negative electrode sheet

[0209] Silicon-based material (silicon-carbon composite, silicon content 60wt%), carbon-based material (artificial graphite), conductive agent (conductive carbon black), and binder (a mixture of sodium carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR), with a CMC to SBR mass ratio of 1:2.5) are thoroughly mixed in an appropriate amount of deionized water at a weight ratio of 75:20:1.5:3.5 to form a negative electrode slurry. The negative electrode slurry is coated onto a copper foil current collector to form a negative electrode film. After drying and cold pressing, a negative electrode sheet is obtained.

[0210] 2. Preparation of positive electrode sheet

[0211] The positive electrode active material (LiNi) 0.8 Co 0.1 Mn 0.1 O2, NCM 811 The positive electrode slurry is formed by mixing the conductive agent (conductive carbon black) and the binder (polyvinylidene fluoride) in a weight ratio of 96.5:1.5:2.0 and then adding them to the solvent N-methylpyrrolidone and stirring evenly. The positive electrode slurry is then coated onto the positive electrode current collector aluminum foil to form a positive electrode film layer. After drying and cold pressing, the positive electrode sheet is obtained.

[0212] 3. Preparation of electrolyte

[0213] Ethylene carbonate (EC) and dimethyl carbonate (DMC) were mixed in a volume ratio of 3:7 to form an organic solvent. LiPF6 was then dissolved in the organic solvent to obtain an electrolyte with a LiPF6 concentration of 1 mol / L.

[0214] 4. Separating membrane

[0215] A 12μm thick polypropylene film was used as the separator.

[0216] 5. First structural component

[0217] Polyimide foam is used as the first structural component, which has a length of 155mm, a width of 110mm, and a thickness of 3mm.

[0218] 6. Preparation of battery cells

[0219] The positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the positive and negative electrodes to provide isolation, thus forming a stacked electrode assembly. Another electrode assembly is then prepared following the same steps, resulting in two identical electrode assemblies. Referring to Figure 4, the two electrode assemblies are arranged parallel to each other within the casing, with a 78% casing clearance for the battery cell. The first structural component is placed between the two electrode assemblies. After drying, the prepared electrolyte is injected. Following vacuum sealing, settling, formation, and shaping processes, the battery cell is obtained.

[0220] Parameter testing of the negative electrode:

[0221] Silicon content test

[0222] Disassemble the battery cell to obtain the negative electrode sheet, and use a punch to cut the negative electrode sheet into pieces with an area of ​​1 cm². 2 Electrode samples were placed in a polytetrafluoroethylene digestion vessel, and a strong acid (a mixture of nitric acid and hydrofluoric acid) was added. The mixture was then heated using a microwave digester or a hot plate to completely dissolve the electrode sample in the acid, forming a clear solution. The digested solution was transferred to a volumetric flask and diluted with deionized water to a specific volume to obtain the test solution. Inductively coupled plasma optical emission spectrometry (ICP-OES) was used to perform ICP testing on the test solution, determining the intensity of the characteristic spectral lines of silicon in the solution. The ICP-OES system automatically calculated the concentration of silicon in the test solution (μg / mL) based on a standard curve. The mass of silicon in the electrode sample was calculated by multiplying the concentration of silicon in the test solution by the volume of the test solution. This calculation yielded the mass content of silicon in the negative electrode film layer.

[0223] In Example 1, based on the total mass of the negative electrode film, the silicon content is 45%.

[0224] Parameter testing of the first structural component:

[0225] (1) Density test

[0226] Disassemble the battery cell to obtain the first structural component. Weigh the first structural component and record its mass as M. Measure the length, width, and height of the first structural component, and use length × width × height as the volume of the first structural component, recorded as V. Calculate the density of the first structural component using the formula: density = M / V.

[0227] (2) Elastic modulus test

[0228] Disassemble the battery cell to obtain the first structural component. Place the sample of the first structural component on a universal testing machine and compress the sample to 10% of its original thickness. Record the stress-strain curve during this process. The slope of the linear segment of the curve is the elastic modulus of the first structural component.

[0229] (3) Rebound rate test

[0230] Disassemble the battery cell to obtain the first structural component and measure its original thickness H0. Place the first structural component sample on a universal testing machine and compress it at a speed of 5 mm / min until it reaches the preset test pressure (3 MPa), maintaining this test pressure for 60 minutes. Release the pressure and allow the first structural component sample to recover freely for 10 minutes. Measure the final thickness H1 of the recovered first structural component sample. Calculate the springback rate of the first structural component using the formula: Springback Rate = H1 / H0 × 100%.

[0231] (4) Compression permanent deformation rate test

[0232] Disassemble the battery cell to obtain the first structural component and measure its initial thickness. Place the first structural component sample on a compression testing machine and compress it to 70% of its initial thickness using a clamp. The compression limit thickness is 70% of the initial thickness. Maintain this compression state and place the clamp and the first structural component sample in a 60°C constant temperature chamber for 2 hours. Remove the clamp and the first structural component sample, allow it to cool at room temperature for 30 minutes, then release the clamp and measure the final thickness of the first structural component sample after recovery. Calculate the compression set rate. Compression set rate = (initial thickness - final thickness) / (initial thickness - compression limit thickness) × 100%.

[0233] (5) Stress relaxation rate test

[0234] Disassemble the battery cell to obtain the first structural component. Place the first structural component sample on a compression testing machine and compress it at a constant speed to a fixed deformation state (50% strain), recording the initial stress. Maintain this deformation state and record the pressure required to maintain it over time. The test temperature is 45℃, and the test time is 600 hours. Record the stress at 600 hours and calculate the stress relaxation rate. Stress relaxation rate = (initial stress - stress at 600 hours) / initial stress × 100%.

[0235] (6) Quality increase rate test

[0236] The battery cell was disassembled to obtain the first structural component, and its original volume M0 was measured. The first structural component was completely immersed in dimethyl carbonate and soaked in dimethyl carbonate at 25°C for 200 hours. After removal, the surface residual droplets were quickly wiped dry with filter paper, and its mass M1 was immediately measured. The mass increase rate of the first structural component in dimethyl carbonate = [(M1-M0) / M0]×100%.

[0237] Battery cell performance testing:

[0238] (1) Energy density test

[0239] At 25℃, the battery cell was charged at a constant current of 0.33C to 4.25V, and then charged at a constant voltage of 4.25V to a current of 0.05C. At this point, the secondary battery was fully charged. After the fully charged secondary battery was left to stand for 5 minutes, it was discharged at a constant current of 0.33C to 2.5V. The discharge capacity at this point is the actual capacity of the battery cell at 0.33C, denoted as C0. Then, the battery cell was charged at a constant current of 0.33C0 to the cutoff voltage of 4.25V, and then charged at a constant voltage to a current of 0.05C. At this point, the battery cell was fully charged. After the fully charged battery cell was left to stand for 5 minutes, it was discharged at a constant current of 0.33C0 to 2.5V, and the discharge energy Q of the battery cell was obtained. The gravimetric energy density of the battery cell (Wh / Kg) = discharge energy Q of the battery cell / weight M of the battery cell. The test results are recorded in Table 2 below.

[0240] (2) Cyclic performance test

[0241] At 25℃, the battery cell was charged at a constant current of 0.33C to 4.25V, then charged at a constant voltage of 4.25V to a current of 0.05C, and then discharged at a constant current of 0.33C to 2.5V. This constitutes the first cycle, and the discharge capacity of the first cycle is recorded as E0. The above charge-discharge cycle is repeated until the discharge capacity drops to 80% of E0. The number of cycles completed by the battery cell at this point is recorded, and the test results are recorded in Table 2 below.

[0242] (3) Group wealth test

[0243] At 25°C, the battery cell was discharged at a constant current of 0.33C to the discharge cutoff voltage of 2.5V, at which point the battery cell was at 0% SOC. The battery cell at 0% SOC was disassembled, and the ratio of the total thickness of the electrode assembly to the dimension of the internal cavity of the casing along the first direction was measured. This ratio is the group margin of the battery cell at 0% SOC. The test results are recorded in Table 2 below.

[0244] (4) Interlayer spacing test

[0245] At 25°C, the battery cell is charged at a constant current of 0.33C to 4.25V, and then charged at a constant voltage of 4.25V to a current of 0.05C, at which point the battery cell is fully charged; then it is discharged at a constant current of 0.33C to a state of charge of 30% SOC.

[0246] The battery cells at 30% SOC were disassembled, and the casing and electrolyte were removed to obtain two electrode assemblies and the first structural component between them, which served as the test sample. The test sample was placed on the sample stage of an X-ray computed tomography (CT) scanner, ensuring its correct and stable position. The CT scanner parameters were adjusted as follows: X-ray source intensity of 100 kV (voltage) / 100 μA (current), exposure time of 500 ms, and detector resolution of 1024 × 1024 pixels. The CT scan was initiated, and the scanner performed X-ray imaging from multiple angles to obtain projection data. Image reconstruction was performed using computer algorithms to generate a two-dimensional image of the test sample's interior. Image analysis software was used to identify the positions of the positive and negative electrode plates in the electrode assemblies within the image, and measurement software was used to measure the interlayer spacing between the five electrode plates.

[0247] Figure 11 is a CT scan image of Example 1. As shown in Figure 11, the interlayer spacing of the five layers of the electrode assembly in Example 1 at 30% SOC is 1.5 mm.

[0248] Examples 2 to 5

[0249] The battery cells were prepared using the same method as in Example 1, except that the type and amount of silicon-based material in the negative electrode sheet, the battery cell packing margin, and the thickness of the first structural component were different. Please refer to Table 1 and Table 2 below for details.

[0250] Example 6

[0251] The battery cell is prepared using the same method as in Example 1, except that the positive electrode, separator, and negative electrode are stacked sequentially, with the separator positioned between the positive and negative electrodes to provide isolation. Then, the electrode assembly is formed by bending and winding (the dimension from the corner connection to the corner tip is c1, and the corner dimension is c2, where c1 and c2 satisfy: 0 < c2 ≤ c1). Another electrode assembly is prepared following the same steps, resulting in two identical electrode assemblies. Referring to Figure 5, the two electrode assemblies are arranged parallel to each other in the casing, with the first structural component positioned between them. After drying, the prepared electrolyte is injected, and the battery cell undergoes vacuum sealing, settling, formation, and shaping processes to obtain the battery cell.

[0252] Comparative Example 1

[0253] The battery cell was prepared using the same method as in Example 1, except that, during the preparation of the battery cell, two electrode assemblies were arranged in parallel within the casing, but no first structural component was provided between the two electrode assemblies.

[0254] The interlayer spacing of the electrode assembly of Comparative Example 1 was tested using the same test method as in Example 1. Figure 12 shows a CT scan image of the electrode assembly of Comparative Example 1. As shown in Figure 12, the interlayer spacing of the 5 layers of the electrode assembly of Comparative Example 1 at 30% SOC is 1.8 mm. Compared with Example 1, since the battery cell of Comparative Example 1 does not contain a first structural component, the interlayer spacing between the electrodes of the electrode assembly of Comparative Example 1 is increased at 30% SOC.

[0255] Comparative Examples 2 and 3

[0256] Battery cells were prepared using the same method as in Example 1, except that the type and amount of silicon-based material in the negative electrode sheet and the battery cell packing margin were different. Please refer to Table 1 and Table 2 below for details.

[0257] The mass content of silicon in the negative electrode film of Examples 2 to 6 and Comparative Examples 1 to 3 was determined according to the same test method as in Example 1, and the performance of the battery cells prepared in Examples 2 to 6 and Comparative Examples 1 to 3 was tested according to the same test method as in Example 1. The results are shown in Tables 1 and 2 below.

[0258] Table 1

[0259] Table 2

[0260] In Table 2, “Group margin at 0% SOC” refers to the ratio of the total thickness of the electrode assembly to the dimension of the internal cavity of the casing along the first direction when the battery cell is at 0% SOC; “D2 / D1 at 0% SOC” refers to the ratio of the total thickness of the first structural component to the dimension of the internal cavity of the casing along the first direction when the battery cell is at 0% SOC.

[0261] As can be seen from the data in Tables 1 and 2, in Examples 1 to 6, by controlling the total mass of the negative electrode film layer, the mass content of silicon element is 15%-90%, and a first structural component is provided inside the shell of the battery cell. The first structural component and the electrode assembly are stacked along the first direction, which can maintain a small electrode layer spacing at low SOC, so that the prepared battery cell has excellent energy density and cycle performance.

[0262] Because Comparative Example 1 did not have a first structural component, the interlayer spacing of the electrode assembly in Comparative Example 1 increased under the condition of having the same silicon content as Example 1, and the expansion force between the electrode assemblies was not balanced, resulting in a decrease in the energy density and cycle performance of the battery cell in Comparative Example 1 compared to Example 1.

[0263] In Comparative Example 2, based on the total mass of the negative electrode film, the silicon content is less than 15%, which leads to a significant reduction in the energy density of the battery cell.

[0264] In Comparative Example 3, based on the total mass of the negative electrode film, the silicon content exceeds 90%, leading to excessive volume change of the negative electrode sheet. During battery cycling, the electrode assembly contacts the casing, causing a top-shell phenomenon. This results in excessive pressure on the electrode sheet and insufficient interlayer spacing, causing lithium plating to occur when the positive and negative electrodes come into contact, significantly reducing the cycle performance of the battery cell. Furthermore, because Comparative Example 3 experiences a top-shell phenomenon during battery cycling, even with a silicon content exceeding 90%, the final energy density of the battery cell deviates significantly from its intended performance.

[0265] Example 7

[0266] The battery cell is prepared using the same method as in Example 1, except that the thickness and placement of the first structural member are different. In the battery cell of Example 7, the first structural member is disposed on one side surface of the first electrode assembly and is positioned opposite to the straight portion of the first electrode assembly. The first structural member is located between the outer casing and the first electrode assembly.

[0267] Example 8

[0268] The battery cell was prepared using the same method as in Example 1, except that the thickness, number, and placement of the first structural member were different. The battery cell of Example 8 includes two identical first structural members: first structural member I is disposed on one side surface of the first electrode assembly and opposite to the straight portion of the first electrode assembly, located between the outer casing and the first electrode assembly; first structural member II is disposed on one side surface of the second electrode assembly and opposite to the straight portion of the second electrode assembly, located between the outer casing and the second electrode assembly.

[0269] Example 9

[0270] The battery cell was prepared using the same method as in Example 1, except that the number of electrode assemblies and the thickness of the first structural member were different. The battery cell of Example 9 includes an electrode assembly, and a first structural member is disposed on one side surface of the electrode assembly and is positioned opposite the flat portion of the electrode assembly. The first structural member is located between the electrode assembly and the outer casing.

[0271] Example 10

[0272] The battery cell was prepared using the same method as in Example 9, except that the thickness, number, and placement of the first structural member were different. The battery cell of Example 10 included two identical first structural members, which were respectively disposed on both sides of the electrode assembly and respectively positioned opposite the straight portion of the electrode assembly. Both first structural members were located between the outer casing and the electrode assembly.

[0273] Since the material of the first structural component used in Examples 7 to 10 is exactly the same as that of the first structural component used in Example 1, the first structural component in Examples 7 to 10 has the same performance parameters as the first structural component in Example 1.

[0274] The battery cells prepared in Examples 7 to 10 were subjected to performance tests using the same test methods as in Example 1. The performance test results of the battery cells in Examples 7 to 10 and the thickness of the first structural component are shown in Table 3 below. For ease of comparison, the results of Example 1 are also shown.

[0275] Table 3

[0276] In Table 3, “Group margin at 0% SOC” refers to the ratio of the total thickness of the electrode assembly to the dimension of the internal cavity of the casing along the first direction when the battery cell is at 0% SOC; “D2 / D1 at 0% SOC” refers to the ratio of the total thickness of the first structural component to the dimension of the internal cavity of the casing along the first direction when the battery cell is at 0% SOC.

[0277] As can be seen from Table 3, by placing the first structural member between two adjacent electrode assemblies, and / or placing the first structural member between the housing and the electrode assembly, and controlling the battery cell to be in a 0% SOC state, the total thickness of the first structural member is 3%-18% of the dimension of the internal cavity of the housing along the first direction, so that the prepared battery cell has excellent energy density and cycle performance.

[0278] Example 11

[0279] Battery cells were prepared using the same method as in Example 1, except that the first structural component was modified polyimide foam, while the length, width, and thickness of the first structural component remained unchanged. The preparation method of the modified polyimide foam is as follows:

[0280] (1) Precursor synthesis: 4,4'-diaminodiphenyl ether (ODA) and amino-terminated polydimethylsiloxane (PDMS) are dissolved in a polar solvent (such as DMF), and pyromellitic dianhydride (PMDA) is slowly added under nitrogen protection and an ice-water bath to generate a polyamic acid-polysiloxane block copolymer, thus obtaining a precursor solution.

[0281] (2) Chemical foaming and imidization: Supercritical CO2 is injected into the precursor solution to achieve micro-foaming through pressure release. At the same time, thermal imidization is completed by procedural heating to 300℃ to obtain polyimide-polysiloxane block copolymer foam as modified polyimide foam.

[0282] Example 12

[0283] The battery cells were prepared using the same method as in Example 1, except that the first structural component was made of silicone rubber foam. The length, width, and thickness of the first structural component remained unchanged.

[0284] Example 13

[0285] Battery cells were prepared using the same method as in Example 1, except that the first structural component was modified silicone rubber foam, specifically silicone rubber foam containing phenyl groups. The length, width, and thickness of the first structural component remained unchanged. The preparation method of the modified silicone rubber foam in Example 13 is as follows:

[0286] (1) Dehydration treatment: Octamethylcyclotetrasiloxane, methylphenylcyclosiloxane (the mass ratio of octamethylcyclotetrasiloxane to methylphenylcyclosiloxane is 70:30 to introduce about 30 mol% phenyl) and hexamethyldisiloxane are added to the reactor and dehydrated for 1-2 hours at 110℃-120℃ and vacuum degree of -0.095MPa.

[0287] (2) Ring-opening polymerization: Cool the system to 80℃-90℃, add a measured amount of tetramethylammonium hydroxide catalyst (0.1% of the total monomer mass), and gradually raise the temperature to 130℃-140℃ under nitrogen protection for 4-6 hours. The degree of polymerization is determined by monitoring the viscosity of the reactants. The reaction is terminated when the predetermined viscosity (12,000-18,000 cP) is reached.

[0288] (3) Catalyst decomposition and purification: The reaction system was heated to 160℃-170℃ and maintained for 1 hour to thermally decompose and deactivate tetramethylammonium hydroxide. Then, low-boiling substances were removed under a high vacuum of -0.098MPa to obtain silicone rubber foam containing phenyl groups, which was used as the modified silicone rubber foam in Example 13.

[0289] Example 14

[0290] The battery cell was prepared using the same method as in Example 1, except that the first structural component was a modified silicone rubber foam containing phenyl groups, and the surface of the phenyl-containing silicone rubber foam was coated with a fluorine-containing coating with a thickness of 3 μm. The length, width, and thickness of the first structural component remained unchanged. The preparation method of the modified silicone rubber foam in Example 14 is as follows:

[0291] (1) Prepare silicone rubber foam containing phenyl groups according to the same method as in Example 13.

[0292] (2) Preparation of coating solution: Dissolve PVDF powder in N-methylpyrrolidone to prepare a uniform solution with a solid content of 5wt% as PVDF coating solution, and let it stand to remove bubbles for later use.

[0293] (3) Substrate pretreatment: The silicone rubber foam containing phenyl prepared above is cut into the required size and treated with a plasma treatment instrument at 100W power for 1 minute to improve its surface energy and enhance the adhesion of the coating.

[0294] (4) Immersion and lifting coating: Immerse the pretreated silicone rubber foam containing phenyl into the PVDF coating solution for 5 minutes to allow the solution to fully wet the foam. Then, lift the silicone rubber foam containing phenyl vertically out of the liquid surface at a constant speed of 100 mm / min to ensure uniform coating coverage.

[0295] (5) Gradient curing: The coated sample was initially dried in an 80℃ oven for 30 minutes to remove most of the solvent. Then it was transferred to a 120℃ vacuum oven for further curing for 2 hours to allow the coating to fully form and remove residual solvent. Finally, a modified silicone rubber foam with a fluorine-containing coating thickness of about 3μm was obtained.

[0296] Example 15

[0297] Battery cells were prepared using the same method as in Example 1, except that the first structural component was a modified polyolefin foam, specifically a polyolefin-ethylene-vinyl alcohol copolymer. The length, width, and thickness of the first structural component remained unchanged. The preparation method of the modified polyolefin foam is as follows:

[0298] (1) Raw material premixing and internal mixing: Polyolefin elastomer POE, ethylene-vinyl alcohol EVOH, and compatibilizer are premixed in a high-speed mixer at a mass ratio of 80:15:5 for 5-10 minutes to ensure initial uniform dispersion. The premixed material is then added to an internal mixer and internally mixed at a temperature of 165℃-175℃ and a speed of 50rpm-60rpm for 8-10 minutes to achieve microscale dispersion of EVOH in the POE matrix, forming a polyolefin-ethylene-vinyl alcohol copolymer.

[0299] (2) Preparation of foaming masterbatch: The above-mentioned polyolefin-ethylene-vinyl alcohol copolymer is mixed evenly with the foaming agent azodicarbonamide (5% of the total mass of the blend), the foaming activator zinc oxide (2%), and the antioxidant (0.3%) on a two-roll mill at 120℃-130℃, and then sheeted. The sheet is then granulated to obtain the foaming masterbatch.

[0300] (3) Compression molding foaming: The foaming masterbatch is placed into a preheated flat vulcanizing mold and heated for 8-12 minutes at 155℃-165℃ and 10MPa-15MPa pressure to melt the material and inhibit premature foaming. Then, the pressure is quickly released and the mold is opened to the predetermined opening distance. The material foams rapidly due to the instantaneous pressure relief. The foamed product is then quickly cooled and shaped to obtain modified polyolefin foam.

[0301] The first structural components of Examples 11 to 15 were subjected to parameter tests using the same test methods as in Example 1, and the battery cells prepared in Examples 11 to 15 were subjected to performance tests using the same test methods as in Example 1. The results are shown in Tables 4 and 5 below. For ease of comparison, the results of Example 1 are also shown.

[0302] Table 4

[0303] Table 5

[0304] In Table 5, “Group margin at 0% SOC” refers to the ratio of the total thickness of the electrode assembly to the dimension of the internal cavity of the casing along the first direction when the battery cell is at 0% SOC; “D2 / D1 at 0% SOC” refers to the ratio of the total thickness of the first structural component to the dimension of the internal cavity of the casing along the first direction when the battery cell is at 0% SOC.

[0305] As can be seen from Tables 4 and 5, Examples 11 to 15, by using a first structural component made of at least one of polyimide, modified polyimide, silicone rubber, modified silicone rubber, and modified polyolefin, resulted in battery cells with excellent energy density and cycle performance.

[0306] It should be noted that this disclosure is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same essential structure and achieving the same effect as the technical concept within the scope of this disclosure are included in the technical scope of this disclosure. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, are also included in the scope of this disclosure without departing from the spirit of this disclosure.

Claims

1. A battery cell, wherein, The device includes a housing, a first structural member, and at least one electrode assembly. The electrode assembly and the first structural member are disposed within the housing. The electrode assembly includes a negative electrode and a positive electrode. The positive electrode includes a positive current collector and a positive electrode film layer located on at least one side of the positive current collector. The negative electrode includes a negative current collector and a negative electrode film layer located on at least one side of the negative current collector. The negative electrode film layer includes a negative electrode active material, which is a silicon-based material. Based on the total mass of the negative electrode film layer, the silicon content in the silicon-based material is 15%-90% by mass. The first structural member and the electrode assembly are stacked together along a first direction, which is the thickness direction of the electrode assembly.

2. The battery cell according to claim 1, wherein, The first structural component is an elastic component.

3. The battery cell according to claim 1 or 2, wherein, The elastic modulus of the first structural component is 0.1MPa-3MPa.

4. The battery cell according to any one of claims 1 to 3, wherein, When the battery cell is at 0% SOC, the total thickness of the electrode assembly is 72%-92% of the dimension of the internal cavity of the housing along the first direction.

5. The battery cell according to claim 4, wherein, When the battery cell is at 0% SOC, the total thickness of the electrode assembly is 82%-90% of the dimension of the internal cavity of the housing along the first direction.

6. The battery cell according to any one of claims 1 to 5, wherein, Based on the total mass of the negative electrode film, the mass content of silicon element is greater than or equal to 40% and less than or equal to 65%.

7. The battery cell according to any one of claims 1 to 6, wherein, When the battery cell is at 0% SOC, the total thickness of the first structural component is 3%-18% of the dimension of the internal cavity of the housing along the first direction.

8. The battery cell according to any one of claims 1 to 7, wherein, Along the first direction, the first structural member is disposed between the electrode assembly and the housing.

9. The battery cell according to any one of claims 1 to 8, wherein, The electrode assembly is provided in multiple ways, and the multiple electrode assemblies are arranged sequentially along the first direction. The first structural member is disposed between two adjacent electrode assemblies.

10. The battery cell according to claim 8, wherein, The electrode assembly is provided in multiple ways. Among the multiple electrode assemblies, the two electrode assemblies located at both ends of the first direction are respectively the first electrode assembly and the second electrode assembly. The first structural member is arranged between the first electrode assembly and the outer shell, and / or the first structural member is arranged between the second electrode assembly and the outer shell.

11. The battery cell according to any one of claims 1 to 10, wherein, The electrode assembly is a wound electrode assembly, which includes a straight section and a corner section. The corner section includes two corner sections, which are respectively connected to both sides of the straight section in a second direction, and the second direction is perpendicular to the first direction. The first structural member includes a straight portion and at least one corner portion connected together. Along the first direction, the straight portion is stacked with the straight segment, and the corner portion is stacked with the corner segment.

12. The battery cell according to claim 11, wherein, The connection between the straight section and the corner section is a corner connection, and the end of the corner section away from the straight section is a corner tip. In the winding direction of the electrode assembly, the dimension from the corner connection to the corner tip is c1, and the dimension c2 of the corner portion satisfies: 0 < c2 ≤ c1.

13. The battery cell according to any one of claims 1 to 10, wherein, The electrode assembly is a stacked electrode assembly with sheets stacked along the first direction. In a projection plane perpendicular to the first direction, the projection of the positive electrode sheet is located within the projection of the first structural member.

14. The battery cell according to claim 13, wherein, In a cross-section perpendicular to the first direction, the length L1 and width W1 of the first structural member, and the length L2 and width W2 of the positive electrode sheet satisfy the following relationship: L1-L2 = 2mm-3mm; and / or, W1-W2 = 2mm-3mm.

15. The battery cell according to any one of claims 1 to 14, wherein, The density of the first structural component is less than or equal to 0.3 g / cm³. 3 .

16. The battery cell according to any one of claims 1 to 15, wherein, The first structural component has a springback rate of ≥80% under test pressure, and the test pressure is ≤3MPa.

17. The battery cell according to any one of claims 1 to 16, wherein, The compression set of the first structural member is less than or equal to 20%.

18. The battery cell according to any one of claims 1 to 17, wherein, The stress relaxation rate of the first structural component is less than or equal to 20%.

19. The battery cell according to any one of claims 1 to 18, wherein, The mass increase rate of the first structural component in dimethyl carbonate is less than or equal to 100%.

20. The battery cell according to any one of claims 1 to 19, wherein, The first structural component includes at least one of polyimide, modified polyimide, silicone rubber, modified silicone rubber, and modified polyolefin.

21. The battery cell according to claim 20, wherein, The modified polyimide includes a polyimide-polysiloxane block copolymer.

22. The battery cell according to claim 20 or 21, wherein, The modified silicone rubber includes silicone rubber containing phenyl groups.

23. The battery cell according to claim 22, wherein, The surface of the phenyl-containing silicone rubber is provided with a fluorine-containing coating.

24. The battery cell according to claim 20, wherein, The modified polyolefin includes a polyolefin-ethylene-vinyl alcohol copolymer.

25. The battery cell according to any one of claims 1 to 24, wherein, The first structural component includes polyimide.

26. The battery cell according to any one of claims 1 to 25, wherein, The negative electrode active material also includes a carbon-based material, and the mass ratio of the silicon-based material to the carbon-based material is (50:50)-(95:5).

27. The battery cell according to any one of claims 1 to 26, wherein, The silicon-based material includes one or more of elemental silicon, silicon oxide, and silicon-carbon composites.

28. The battery cell according to any one of claims 1 to 27, wherein, The silicon-based material includes a silicon-carbon composite, which comprises porous carbon and a silicon-containing material dispersed in the pores of the porous carbon.

29. The battery cell according to any one of claims 26 to 28, wherein, The carbon-based materials include artificial graphite and / or natural graphite.

30. The battery cell according to any one of claims 1 to 29, wherein, The negative electrode film layer also includes a conductive agent, which includes one or more of conductive carbon black, carbon nanotubes, and graphene.

31. The battery cell according to any one of claims 1 to 30, wherein, The positive electrode film layer includes a positive electrode active material, which includes one or more of lithium transition metal oxides, lithium phosphates, and their respective modified compounds.

32. The battery cell according to any one of claims 1 to 31, wherein, The battery cell is prismatic in shape.

33. A battery device comprising a battery cell according to any one of claims 1 to 32.

34. An electrical device comprising the battery device of claim 33.

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