Battery cell, battery device, and electric device

Abstract

This application provides a battery cell, a battery device, and an electrical appliance. The battery cell includes a casing, electrode terminals, an electrode assembly, and a first insulating member. The casing includes a first wall and a receiving cavity, the first wall having an electrode lead-out hole communicating with the receiving cavity. The electrode terminals are located in the electrode lead-out hole. The electrode assembly is received within the receiving cavity, and the electrode assembly includes a first tab and a second tab with opposite polarities, the first tab being electrically connected to the electrode terminal, and the second tab being electrically connected to the first wall. At least a portion of the first insulating member is fixed between the electrode terminal and the first wall to insulate at least a portion of the electrode terminal from the first wall, and the thermal decomposition temperature of the first insulating member is greater than or equal to 300°C.

Description

Battery cells, battery devices and electrical equipment Technical Field

[0001] This application relates to the field of battery technology, and more specifically, to a battery cell, a battery device, and an electrical appliance. Background Technology

[0002] Battery cells are widely used in electronic devices such as mobile phones, laptops, electric vehicles, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and power tools, etc.

[0003] In the development of battery technology, improving the reliability of individual battery cells is a key research direction.

[0004] Summary of the Invention

[0005] This application provides a battery cell, a battery device, and an electrical appliance that can improve reliability.

[0006] In a first aspect, embodiments of this application provide a battery cell, which includes a casing, electrode terminals, an electrode assembly, and a first insulating member. The casing includes a first wall and a receiving cavity, the first wall having an electrode lead-out hole communicating with the receiving cavity. The electrode terminals are disposed in the electrode lead-out hole. The electrode assembly is received within the receiving cavity, and the electrode assembly includes a first tab and a second tab with opposite polarities, the first tab being electrically connected to the electrode terminal, and the second tab being electrically connected to the first wall. At least a portion of the first insulating member is fixed between the electrode terminal and the first wall to insulate at least a portion of the electrode terminal from the first wall, and the thermal decomposition temperature of the first insulating member is greater than or equal to 300°C.

[0007] When a battery cell experiences thermal runaway due to an internal short circuit or other reasons, the battery cell may remain at a high temperature for a period of time. The first insulating member has a thermal decomposition temperature greater than or equal to 300°C, making it less prone to weight loss or experiencing minimal weight loss during battery cell thermal runaway. This allows the first insulating member to remain between the first wall and the electrode terminals, reducing the risk of continuity between the electrode terminals and the first wall. Correspondingly, even if the electrode terminals and the first wall are electrically connected to other battery cells or an external power source, the first insulating member can suppress the current between the electrode terminals and the first wall, reducing continuous heat generation between the electrode terminals and the first wall, minimizing the thermal impact on surrounding battery cells, reducing the risk of thermal runaway in other battery cells, and improving reliability.

[0008] In some embodiments, the thermal weight loss temperature of the first insulating member is greater than or equal to 350°C, and optionally, the thermal weight loss temperature of the first insulating member is greater than or equal to 500°C. The embodiments of this application can further reduce the weight loss rate of the first insulating member during thermal runaway of a battery cell, reduce the risk of failure of the first insulating member, reduce the continuous heat generation of the electrode terminals and the first wall, reduce the thermal impact on other surrounding battery cells, reduce the risk of thermal runaway in other battery cells, and improve reliability.

[0009] In some embodiments, the material of the first insulating member includes a thermosetting material. Thermosetting materials have excellent heat resistance and maintain good stability at high temperatures, and are not easily softened, deformed, or decomposed. During thermal runaway of a battery cell, the internal pressure of the casing increases, increasing the risk of deformation of the first wall. When the first wall deforms, the pressure on the first insulating member increases. The first insulating member, containing a thermosetting material, is less prone to softening at high temperatures. This reduces the deformation of the first insulating member under pressure, lowers the risk of localized thinning and puncture, thereby improving insulation performance, reducing the risk of insulation failure, and increasing reliability.

[0010] In some embodiments, the material of the first insulating member includes one or more thermosetting polyimides and their derivatives. Thermosetting polyimides have excellent heat resistance. In the event of thermal runaway of a battery cell, the first insulating member containing thermosetting polyimide can maintain good performance stability at high temperatures, and it is less prone to weight loss or has minimal weight loss, thereby reducing the risk of insulation failure.

[0011] In some embodiments, the material of the first insulating member includes one or more of bismaleimide, ethynyl-terminated polyimide, and norbornene-terminated polyimide. Bismaleimide, ethynyl-terminated polyimide, and norbornene-terminated polyimide have advantages such as excellent high-temperature resistance, high mechanical strength, and strong chemical corrosion resistance.

[0012] In some embodiments, the first insulating member is bonded to at least one of the electrode terminal and the first wall. Bonding the first insulating member to the electrode terminal and / or the first wall can improve the stability of the first insulating member, reduce the displacement of the first insulating member when the battery cell is subjected to external impact, and reduce the risk of insulation failure. The bonding process is easy to implement, and the bonding interface has good sealing performance.

[0013] In some embodiments, the battery cell further includes an adhesive layer. The adhesive layer bonds the first insulating member to the surface of the first wall, and / or, the adhesive layer bonds the first insulating member to the surface of the electrode terminal. The adhesive layer can secure the first insulating member to reduce the risk of displacement of the first insulating member during use of the battery cell.

[0014] In some embodiments, the thickness of the first insulating member is greater than or equal to the thickness of the adhesive layer. Compared to the adhesive layer, the first insulating member can have a larger thickness to reduce the risk of the first insulating member being crushed or punctured, thereby improving insulation reliability.

[0015] In some embodiments, the ratio of the thickness t5 of the first insulating member to the thickness t6 of the adhesive layer is 1-5. Limiting t5 / t6 to greater than or equal to 1 allows the first insulating member to have a larger thickness, reducing the risk of the first insulating member being crushed or punctured, and improving insulation reliability. Limiting t5 / t6 to less than or equal to 5 allows the adhesive layer to have higher adhesive strength, reducing the risk of the first insulating member detaching.

[0016] In some embodiments, the first insulating member is bonded to the first wall. Compared to the electrode terminals, the first wall typically has a simpler and flatter structure. Bonding the first insulating member to the first wall can improve the morphology of the bonding interface and enhance the bonding stability of the first insulating member.

[0017] In some embodiments, at least a portion of the first insulating member is located between the outer surface of the first wall and the electrode terminal in the thickness direction of the first wall. The first insulating member, located on the outer side of the first wall, can separate the portion of the electrode terminal located on the outer side of the first wall from the first wall. When high-temperature particles emitted from other battery cells sputter onto the first insulating member, the first insulating member exhibits good heat resistance and is less prone to failure under the influence of high-temperature particles, thereby reducing the risk of short circuits in the battery cells.

[0018] In some embodiments, at least a portion of the first insulating member is located between the inner surface of the first wall and the electrode terminal in the thickness direction of the first wall.

[0019] In some embodiments, the first insulating member includes a first insulating portion and a second insulating portion connected to the first insulating portion. The first insulating portion is disposed on the outer surface of the first wall, and the second insulating portion is disposed on the hole wall surface. The first insulating member can cover the junction between the outer surface of the first wall and the hole wall surface, thereby reducing the risk of contact between the junction between the outer surface of the first wall and the hole wall surface and the electrode terminal when the first wall bulges outward.

[0020] In some embodiments, the battery cell further includes a second insulating member. At least a portion of the second insulating member is disposed between the first insulating member and the first wall; and / or, at least a portion of the second insulating member is disposed between the first insulating member and the electrode terminal. By providing the first insulating member and the second insulating member, a double-layer insulation structure can be formed between the first wall and the electrode terminal, thereby further improving the insulation effect and reducing the risk of the first wall and the electrode terminal conducting during thermal runaway of the battery cell.

[0021] In some embodiments, the compressive modulus of the second insulating member is less than that of the first insulating member. During the use of a battery cell, the first wall may deform due to changes in the internal pressure of the battery cell; in particular, during thermal runaway of the battery cell, the internal pressure of the casing increases rapidly, which may also cause the first wall to bulge outward. The second insulating member has a lower compressive modulus, and when the first wall deforms, it can release stress through compressive deformation, thereby reducing the stress on the first insulating member and lowering the risk of cracking and insulation failure.

[0022] In some embodiments, the material of the second insulating member includes a thermoplastic material. The second insulating member containing a thermoplastic material is easy to mold, and its shape can be adapted to electrode terminals with complex structures. When subjected to external force, the second insulating member containing a thermoplastic material can undergo a certain degree of deformation without easily breaking, exhibiting good toughness and impact resistance, thus improving the insulation effect.

[0023] In some embodiments, at least a portion of the first insulating member and at least a portion of the second insulating member are stacked between the first wall and the electrode terminal in the thickness direction of the first wall. To secure the electrode terminal to the first wall, there is typically an interaction force between the electrode terminal and the first wall in the thickness direction. The stacking of at least a portion of the first insulating member and at least a portion of the second insulating member in the thickness direction can reduce the risk of insulation failure.

[0024] In some embodiments, at least a portion of the second insulating member is disposed between the first insulating member and the electrode terminal in the thickness direction of the first wall. During the installation of the electrode terminal onto the first wall, it is typically necessary to press the electrode terminal against the first wall. The second insulating member can separate the first insulating member from the electrode terminal, thereby reducing the stress on the first insulating member during electrode terminal installation, lowering the risk of the first insulating member being crushed, and improving the insulation effect.

[0025] In some embodiments, the electrode terminal includes a terminal body, a first limiting portion, and a second limiting portion. At least a portion of the terminal body is accommodated in an electrode lead-out hole. Both the first and second limiting portions are connected to the terminal body. At least a portion of the first limiting portion protrudes from the outer peripheral surface of the terminal body, and at least a portion of the second limiting portion also protrudes from the outer peripheral surface of the terminal body. At least a portion of a first insulating member is attached to the surface of a first wall facing the first limiting portion. In the thickness direction of the first wall, the first and second limiting portions are located on opposite sides of the first wall, and at least a portion of the second insulating member is disposed between the first limiting portion and the first insulating member. To improve the stability of the electrode terminal, the first and second limiting portions can clamp the first wall from both sides. The second insulating member can separate the first insulating member from the first limiting portion, thereby reducing the pressure exerted by the first limiting portion on the first insulating member, reducing the risk of the first insulating member being crushed, and improving the insulation effect.

[0026] In some embodiments, the electrode terminal is riveted to the first wall; the first limiting portion is configured to be formed after the electrode terminal passes through the electrode lead-out hole. During the forming process of the first limiting portion, the second insulating member can separate the first limiting portion from the first insulating member, thereby reducing the force transmitted to the first insulating member, reducing the risk of the first insulating member being crushed, and improving the insulation effect.

[0027] In some embodiments, in the thickness direction of the first wall, the minimum thickness of the portion of the first insulating member located between the first wall and the electrode terminal is t1, and the minimum thickness of the portion of the second insulating member located between the first wall and the electrode terminal is t2, where t2 is greater than t1. By providing a second insulating member with a larger thickness, the creepage distance between the first wall and the electrode terminal can be increased, thereby improving insulation performance. The first insulating member with a higher thermogravimetric temperature can have a smaller thickness to reduce the molding difficulty of the first insulating member and lower costs.

[0028] In some embodiments, the battery cell also includes a pressure relief mechanism disposed in the casing. In the event of thermal runaway of the battery cell, the pressure relief mechanism can release the temperature and pressure inside the battery cell, thereby reducing the risk of battery cell explosion.

[0029] In some embodiments, the pressure relief mechanism includes a pressure relief section and a weak portion disposed along the outer periphery of the pressure relief section. The area of ​​the pressure relief section is larger than the area of ​​the electrode lead-out hole. Compared to the electrode lead-out hole, the pressure relief section can have a larger area, which allows for rapid release of the internal temperature and pressure of the battery cell in the event of thermal runaway. Compared to the pressure relief section, the electrode lead-out hole can have a smaller area, which reduces the impact of the electrode lead-out hole on the strength of the first wall, reduces deformation of the portion of the first wall near the electrode lead-out hole, and reduces the risk of failure of the first insulating member.

[0030] In some embodiments, the housing includes a second wall, and the pressure relief mechanism is disposed on the second wall. Distributing the electrode terminals and the pressure relief mechanism on different walls can reduce the impact on the first insulating member during thermal runaway of the battery cell, thereby reducing the risk of failure of the first insulating member.

[0031] In some embodiments, the pressure relief mechanism includes a pressure relief section and a weak section disposed along the outer periphery of the pressure relief section. The area enclosed by the outer contour of the projection of the second wall along its own thickness direction is S1, and the area of ​​the projection of the pressure relief section in the thickness direction of the second wall is S2; 0.1≤S2 / S1≤0.8.

[0032] Setting S2 / S1 to greater than or equal to 0.1 allows the pressure relief mechanism to form a larger pressure relief channel in the event of thermal runaway in a battery cell, increasing the rate of temperature and pressure release within the battery cell and reducing the risk of battery cell explosion. Setting S2 / S1 to greater than or equal to 0.1 also shortens the time the first insulating component is exposed to high-temperature environments, reducing weight loss in the first insulating component, lowering the risk of insulation failure, and improving the reliability of the battery cell. Setting S2 / S1 to less than or equal to 0.8 limits the range of weak points, reduces the impact of weak points on the strength of the second wall, lowers the risk of weak points rupturing during normal use of the battery cell, and improves the reliability of the battery cell.

[0033] In some embodiments, 0.3 ≤ S2 / S1 ≤ 0.7 can further improve the reliability of the battery cell.

[0034] In some embodiments, the battery cell is a cylindrical battery cell, and the first wall and the second wall are arranged opposite each other along the axial direction of the cylindrical battery cell. The pressure relief mechanism includes a pressure relief part and a weak part arranged along the outer periphery of the pressure relief part, and the pressure relief part is circular. The diameter φ1 of the pressure relief part and the diameter φ2 of the cylindrical battery cell satisfy the following relationship: 0.35≤φ1 / φ2≤0.85.

[0035] Limiting φ1 / φ2 to greater than or equal to 0.35 allows the pressure relief mechanism to form a larger pressure relief channel in the event of thermal runaway in a battery cell, increasing the rate of temperature and pressure release within the battery cell and reducing the risk of battery cell explosion. Limiting φ1 / φ2 to greater than or equal to 0.35 also shortens the time the first insulating component is exposed to high-temperature environments, reducing weight loss in the first insulating component, lowering the risk of insulation failure, and improving the reliability of the battery cell. Limiting φ1 / φ2 to less than or equal to 0.85 restricts the range of weak points, reduces the impact of weak points on the strength of the second wall, lowers the risk of weak points rupturing during normal use of the battery cell, and improves the reliability of the battery cell.

[0036] In some embodiments, the thickness of the first wall is greater than the thickness of the second wall. During thermal runaway of a battery cell, the deformation of the first wall is smaller than that of the second wall, thereby reducing the risk of the first insulating member shifting between the first wall and the electrode terminals, as well as the risk of the first insulating member being crushed, improving insulation performance and increasing the reliability of the battery cell. During thermal runaway of a battery cell, the second wall is more prone to outward deformation than the first wall, which can increase the gas flow channels inside the second wall and improve gas emission efficiency.

[0037] In some embodiments, the first wall and the second wall are located on opposite sides of the electrode assembly. The housing also includes sidewalls that surround the electrode assembly and connect the first wall and the second wall. In this embodiment, the electrode terminals and the pressure relief mechanism are respectively disposed on opposite sides of the electrode assembly. This reduces the deformation of the first wall during the release of high-temperature gas, lowers the risk of the first insulating member shifting between the first wall and the electrode terminals, and reduces the risk of the first insulating member being crushed, thereby improving insulation performance and increasing the reliability of the battery cell.

[0038] In some embodiments, the thickness of the first wall is greater than the thickness of the sidewalls. During thermal runaway of a battery cell, the thicker first wall deforms less, thereby reducing the risk of the first insulating member shifting between the first wall and the electrode terminals, and the risk of the first insulating member being crushed, improving insulation performance and increasing the reliability of the battery cell. During thermal runaway of a battery cell, the thinner sidewalls can bulge outwards, increasing the distance between the sidewalls and the electrode assembly, which facilitates gas venting.

[0039] In some embodiments, the housing includes a shell and an end cap. The shell includes an integrally formed first wall and a side wall, and the end cap is a second wall, which is sealed to the side wall. The first wall and the side wall are integrally formed, and the connection strength between the first wall and the side wall is high. In the event of thermal runaway of the battery cell, the side wall can restrain the first wall, reduce the deformation of the first wall, reduce the risk of the first insulating member shifting between the first wall and the electrode terminal, and reduce the risk of the first insulating member being crushed, thereby improving the insulation effect and increasing the reliability of the battery cell.

[0040] In some embodiments, the electrode assembly has a first through hole at its center. The first through hole is located between the electrode terminal and the pressure relief mechanism along its extending direction. During thermal runaway of a single battery cell, gas between the electrode assembly and the first wall can flow through the first through hole to the pressure relief mechanism, thereby reducing the pressure on the first wall and the electrode terminal, minimizing deformation of the first wall, reducing the risk of the first insulating member shifting between the first wall and the electrode terminal, and reducing the risk of the first insulating member being crushed, thus improving insulation reliability.

[0041] In some embodiments, a first tab is disposed at one end of the electrode assembly facing the first wall, and a second tab is disposed at one end of the electrode assembly facing the second wall. The battery cell also includes a first current collector and a second current collector. The first current collector connects the first tab and the electrode terminal, the second tab is connected to the second current collector, and at least one of a sidewall and a second wall is connected to the second current collector, such that the sidewall is electrically connected to the first wall and the second current collector. Before thermal runaway of the battery cell and actuation of the pressure relief mechanism, the sidewall or the second wall can restrain the first wall of the electrode terminal through the second current collector, the electrode assembly, and the first current collector, reducing the deformation of the first wall during the increase of internal pressure in the battery cell.

[0042] In some embodiments, the second current collector is connected to the second wall.

[0043] In some embodiments, the electrode terminal includes a terminal body and a first limiting portion. At least a portion of the terminal body is accommodated in an electrode lead-out hole, and the first limiting portion is connected to the terminal body, with at least a portion protruding from the outer peripheral surface of the terminal body. In the thickness direction of the first wall, the first limiting portion at least partially overlaps with the first wall, and at least a portion of the first insulating member is located between the first wall and the first limiting portion. In the event of thermal runaway of a battery cell, the first insulating member can be held between the first limiting portion and the first wall, reducing the risk of direct contact between the first limiting portion and the first wall, thereby suppressing the current between the electrode terminal and the first wall and reducing continuous heat generation between the electrode terminal and the first wall.

[0044] In some embodiments, the electrode terminal further includes a second limiting portion connected to the terminal body, at least a portion of the second limiting portion protruding from the outer peripheral surface of the terminal body. In the thickness direction of the first wall, the first limiting portion and the second limiting portion are located on opposite sides of the first wall. The battery cell includes a seal, at least a portion of which is disposed between the second limiting portion and the first wall in the thickness direction of the first wall. The thermal decomposition temperature of the seal is greater than or equal to 200°C. The seal is less prone to weight loss or experiences minimal weight loss during thermal runaway of the battery cell, thereby allowing the seal to remain between the first wall and the electrode terminal, reducing the risk of direct contact between the electrode terminal and the first wall.

[0045] In some embodiments, the seal comprises a thermosetting material. A seal comprising a thermosetting material maintains good stability at high temperatures and can isolate the second limiting portion from the first wall in the event of thermal runaway of a battery cell.

[0046] In some embodiments, portions of the sealing member and the first insulating member are stacked in the thickness direction of the first wall to separate the hole wall of the electrode lead-out hole from the terminal body. Embodiments of this application can reduce the risk of the terminal body contacting the first wall.

[0047] In some embodiments, the seal includes a first sealing portion and a second sealing portion connected together, at least a portion of the first sealing portion being located between a second limiting portion and a first wall, and at least a portion of the second sealing portion being located within an electrode lead-out hole. The first insulating member includes a first insulating portion and a second insulating portion connected together, at least a portion of the first insulating portion being located between the first limiting portion and the first wall, and at least a portion of the second insulating portion being located within an electrode lead-out hole. In the radial direction of the electrode lead-out hole, the second insulating portion and the second sealing portion at least partially overlap within the electrode lead-out hole. The second insulating portion and the second sealing portion can provide dual isolation in the radial direction of the electrode lead-out hole, reducing the risk of contact between the electrode terminals and the first wall in the event of thermal runaway of a battery cell.

[0048] In some embodiments, the electrode assembly includes a positive electrode sheet, which includes a positive current collector and a positive electrode film layer disposed on at least one side of the positive current collector. The positive electrode film layer includes a positive electrode active material, which includes a layered transition metal oxide. The layered transition metal oxide includes a material with the chemical formula Li. a Ni b Co c M d O e A f The compound and its modified compounds contain at least one of the following: 0.8≤a≤1.2, 0.8≤b≤0.95, 0<c<1, 0<d<1, 1≤e≤2, 0≤f≤1, M includes at least one of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, and A includes at least one of N, F, S and Cl.

[0049] Battery cells with high nickel content have advantages such as high energy density, good low-temperature performance, and good charge-discharge performance. However, high-nickel-content battery cells have relatively poor thermal stability; during thermal runaway, they generate more heat, resulting in a higher temperature rise. In this embodiment, a high-temperature-resistant first insulating member is provided between the first wall and the electrode terminals. This first insulating member can withstand the high temperatures generated by the high-nickel battery cell during thermal runaway, thereby suppressing the current between the electrode terminals and the first wall and reducing the continuous heat generation between the electrode terminals and the first wall.

[0050] In some embodiments, the battery cell further includes an electrolyte contained within a casing. The electrolyte comprises a chain ester solvent, wherein the chain ester solvent comprises 25.5 wt% to 76.5 wt% by mass in the electrolyte.

[0051] In this embodiment, the mass percentage of the chain-like ester solvent is greater than or equal to 25.5 wt%, resulting in a relatively high electrolyte conductivity. This is beneficial for improving the liquid-phase transport capability of active ions, enhancing the fast charging and discharging capability of the battery cells, and thus improving the rate performance of the battery cells. The mass percentage of the chain-like ester solvent is also greater than or equal to 25.5 wt%, which also results in a relatively low viscosity of the electrolyte system, making it easier to flow and wet the electrode components. This further improves the fast charging and discharging capability of the battery cells, thereby enhancing their rate performance.

[0052] Chain-like ester solvents may decompose and generate gas during the cyclic charging and discharging of battery cells. In this embodiment, the mass percentage of chain-like ester solvents is set to less than or equal to 76.5 wt%, which can limit the internal pressure of the battery cell, reduce the deformation of the casing, reduce the risk of battery cell failure, and improve reliability.

[0053] In some embodiments, the chain ester solvent has a mass percentage of 42.5 wt% to 70 wt% in the electrolyte, which can further balance the rate performance and reliability of the battery cells and improve the cycle performance of the battery cells.

[0054] In some embodiments, the thermal conductivity of the first insulating member is less than that of the first wall, and the thermal conductivity of the first insulating member is less than that of the electrode terminals. Compared to the first wall and the electrode terminals, the first insulating member has a smaller thermal conductivity. In the event of thermal runaway of a battery cell, the first insulating member can slow down heat conduction, reduce weight loss, and lower the risk of insulation failure.

[0055] In some embodiments, the thermal conductivity of the first wall is lower than that of the electrode terminals. During thermal runaway of a single battery cell, the first wall has a larger heat-receiving area and is more prone to temperature rise. The lower thermal conductivity of the first wall reduces heat conduction from the first wall to the first insulating member, thereby reducing thermal weight loss of the first insulating member and lowering the risk of insulation failure.

[0056] In some embodiments, the battery cell is a cylindrical battery cell with a diameter greater than or equal to 35 mm and less than or equal to 70 mm. Setting the diameter of the cylindrical battery cell to be greater than or equal to 35 mm can improve the capacity and energy density of the cylindrical battery cell. The diameter of the cylindrical battery cell is related to the heat generation during thermal runaway. Setting the diameter of the cylindrical battery cell to be less than or equal to 70 mm limits the maximum temperature of the cylindrical battery cell during thermal runaway and reduces the risk of failure of the first insulating component.

[0057] Secondly, embodiments of this application provide a battery device including a plurality of battery cells provided in any of the embodiments of the first aspect.

[0058] In some embodiments, at least two battery cells are connected in parallel.

[0059] Thirdly, embodiments of this application provide an electrical device including a battery device provided in any of the embodiments of the second aspect, the battery device being used to provide electrical energy. Attached Figure Description

[0060] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0061] Figure 1 is a structural schematic diagram of a vehicle provided in some embodiments of this application;

[0062] Figure 2 is a schematic diagram of a battery device provided in some embodiments of this application;

[0063] Figure 3 is a schematic diagram of the battery module shown in Figure 2;

[0064] Figure 4 is a schematic diagram of the structure of a single battery cell in some embodiments of this application;

[0065] Figure 5 is a schematic diagram of the explosion of the battery cell shown in Figure 4;

[0066] Figure 6 is a cross-sectional schematic diagram of the electrode assembly of a battery cell provided in some embodiments of this application;

[0067] Figure 7 is a schematic diagram of the positive electrode sheet of the electrode assembly of a battery cell provided in some embodiments of this application after being unfolded;

[0068] Figure 8 is a schematic diagram of the negative electrode sheet of the electrode assembly of a battery cell provided in some embodiments of this application after being unfolded;

[0069] Figure 9 is a cross-sectional schematic diagram of a battery cell provided in some embodiments of this application;

[0070] Figure 10 is an enlarged view of Figure 9 at box A;

[0071] Figure 11 is an enlarged view of Figure 10 at the circular frame;

[0072] Figure 12 is an enlarged view of Figure 11 at the circular frame;

[0073] Figure 13 is an enlarged view of the area at box B in Figure 9;

[0074] Figure 14 is an enlarged view of Figure 13 at the circular frame;

[0075] Figure 15 is a partial cross-sectional schematic diagram of a battery cell provided in some embodiments of this application;

[0076] Figure 16 is an enlarged view of Figure 15 at the boxed area;

[0077] Figure 17 is a partial cross-sectional schematic diagram of a battery cell provided in some embodiments of this application;

[0078] Figure 18 is an enlarged view of Figure 17 at the boxed area;

[0079] Figure 19 is an enlarged view of Figure 18 at the boxed area;

[0080] Figure 20 is a partial cross-sectional schematic diagram of a battery cell provided in some other embodiments of this application;

[0081] Figure 21 is an enlarged view of Figure 20 at the boxed area;

[0082] Figure 22 is a partial cross-sectional schematic diagram of a battery cell provided in some other embodiments of this application;

[0083] Figure 23 is a partial cross-sectional schematic diagram of a battery cell provided in some other embodiments of this application;

[0084] Figure 24 is an enlarged view of Figure 23 at the boxed area;

[0085] Figure 25 is a partial cross-sectional schematic diagram of a battery cell provided in some other embodiments of this application;

[0086] Figure 26 is an enlarged view of Figure 25 at the boxed area;

[0087] Figure 27 is a partial cross-sectional schematic diagram of a battery cell provided in some other embodiments of this application;

[0088] Figure 28 is a schematic diagram of the first insulating member and adhesive layer of a battery cell provided in some embodiments of this application;

[0089] Figure 29 is an exploded schematic diagram of a battery cell provided in some other embodiments of this application;

[0090] Figure 30 is a partial cross-sectional schematic diagram of a battery cell provided in some other embodiments of this application;

[0091] Figure 31 is a simplified schematic diagram of a battery device provided in some other embodiments of this application.

[0092] The annotations in the attached figures are explained as follows:

[0093] 1. Vehicle; 2. Battery unit; 3. Controller; 4. Motor; 5. Housing; 5a. First housing; 5b. Second housing; 6. Battery module; 7. Battery cell; 7a. Battery unit; 8. Busbar component;

[0094] 10. Electrode assembly; 10a. First tab; 10b. Second tab; 10c. Electrode body; 10d. First through hole; 11. Positive electrode plate; 111. Positive current collector; 1111. Positive tab; 112. Positive electrode film; 12. Negative electrode plate; 121. Negative current collector; 1211. Negative tab; 122. Negative electrode film; 13. Separator;

[0095] 20. Outer shell; 20a. Second wall; 20b. Receiving cavity; 21. Housing; 211. First wall; 2111. Electrode lead-out hole; 2112. Outer surface; 2113. Inner surface; 2114. First recess; 212. Side wall; 2121. Protrusion; 2122. Second recess; 2123. Press-fit part; 22. End cap; 221. Third recess;

[0096] 30. Electrode terminal; 31. Terminal body; 311. Second through hole; 32. First limiting part; 33. Second limiting part; 331. Sixth recess; 34. Terminal recess;

[0097] 40. First insulating member; 41. First insulating part; 42. Second insulating part; 43. Third insulating part;

[0098] 50. Pressure relief mechanism; 51. Pressure relief section; 52. Weak point; 60. Seal; 61. First sealing section; 62. Second sealing section;

[0099] 70. Second insulating member; 71. Fourth insulating part; 72. Fifth insulating part; 73. Fourth recess;

[0100] 80. Third insulating component; 80a. Fifth recess; 81. First current collector; 82. Cover plate; 83. Sealing pin; 84. Second current collector; 85. Fourth insulating component; 86. Adhesive layer; 87. Fifth insulating component; 90. Electrode lead-out portion;

[0101] V, winding direction; Z, thickness direction. Detailed Implementation

[0102] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0103] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0104] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0105] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0106] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0107] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0108] In this application, "multiple" means two or more (including two).

[0109] Currently, judging from market trends, battery applications are becoming increasingly widespread. Batteries are not only used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, but also extensively in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in aerospace and other fields. With the continuous expansion of battery applications, market demand is also constantly increasing.

[0110] A battery device typically refers to a single physical module comprising multiple battery cells to provide higher voltage and capacity. A battery cell can be the smallest unit that makes up a battery device.

[0111] A battery cell typically includes a casing, an electrode assembly housed within the casing, and a positive electrode lead and a negative electrode lead disposed on the casing. The electrode assembly typically includes a positive electrode plate and a negative electrode plate, with the positive electrode lead electrically connected to the positive electrode plate and the negative electrode lead electrically connected to the negative electrode plate. The positive and negative electrode leads are used for electrical connection to an external circuit to enable charging or discharging of the battery cell.

[0112] In some embodiments, a single battery cell includes electrode terminals; one of the positive electrode lead and the negative electrode lead includes electrode terminals, and the other includes the shell wall of the outer casing.

[0113] When a battery cell in a battery device experiences thermal runaway due to an accident (such as an internal short circuit), that battery cell may remain at a high temperature for a period of time. At this high temperature, the insulating components used to insulate the electrode terminals and the casing may fail, causing current from other battery cells or from an external power source to continuously flow between the electrode terminals and the casing. This results in continuous localized heat generation in the affected battery cell, potentially triggering abnormal temperature increases and thermal runaway in other normal battery cells, leading to heat propagation.

[0114] For example, when a conductive path is formed between the electrode terminals and the casing of the battery cell, a closed loop is formed between the battery cell and the battery cells connected in parallel with the battery cell, and current will continuously flow through the battery cell, causing the battery cell to generate heat locally.

[0115] In view of this, the present application provides a battery cell that, by providing an insulating member with a high thermal runaway temperature between the electrode terminals and the casing, reduces the risk of conduction between the electrode terminals and the casing when the battery cell experiences thermal runaway, reduces the continuous heat generation of the thermally runaway battery cell, reduces the risk of thermal runaway in other battery cells, and improves reliability.

[0116] The battery cells described in this application are applicable to battery devices and electrical equipment using battery devices. Electrical equipment can be devices that use battery devices as a power source or various energy storage systems that use battery devices as energy storage elements. Electrical equipment can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0117] For ease of explanation, the following embodiments use a vehicle as an example of electrical equipment.

[0118] Figure 1 is a schematic diagram of the structure of a vehicle provided in some embodiments of this application.

[0119] As shown in Figure 1, a battery device 2 is installed inside the vehicle 1. The battery device 2 can be located at the bottom, front, or rear of the vehicle 1. The battery device 2 can be used to power the vehicle 1; for example, the battery device 2 can serve as the operating power source for the vehicle 1.

[0120] The vehicle 1 may also include a controller 3 and a motor 4. The controller 3 is used to control the battery device 2 to supply power to the motor 4, for example, for the power needs of the vehicle 1 during starting, navigation and driving.

[0121] In some embodiments of this application, the battery device 2 can not only serve as the operating power source for the vehicle 1, but also as the driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0122] Figure 2 is a schematic diagram of a battery device provided in some embodiments of this application.

[0123] In some embodiments, the battery device 2 may include one or more battery cell assemblies for providing voltage and capacity.

[0124] A battery cell assembly may include multiple battery cells (not shown in Figure 2), which are connected in series, parallel, or mixed connection via a busbar. Mixed connection refers to multiple battery cells being connected in both series and parallel connections.

[0125] A battery cell can be a rechargeable battery cell, which refers to a battery cell that can be recharged after being discharged to activate the active materials and continue to be used.

[0126] As an example, a single battery cell can be a lithium-ion battery cell, a sodium-ion battery cell, a sodium-lithium-ion battery cell, a lithium metal battery cell, a sodium metal battery cell, a lithium-sulfur battery cell, a magnesium-ion battery cell, a nickel-metal hydride battery cell, a nickel-cadmium battery cell, a lead-acid battery cell, etc.

[0127] As an example, a battery cell can be a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes. Prismatic battery cells include prismatic battery cells, blade-shaped battery cells, and multi-prismatic battery cells, such as hexagonal prismatic battery cells.

[0128] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells; as an example, a battery cell assembly can be a battery module 6, which is formed by arranging and fixing multiple battery cells into a single module. As an example, a battery module 6 can be formed by bundling multiple battery cells together with cable ties.

[0129] In some embodiments, the battery device 2 may be a battery pack, which includes a housing 5 and one or more battery cell assemblies housed within the housing 5. As an example, the battery cell assembly may be a battery module 6, which can be housed within the housing by securing the battery module 6 to the housing. Alternatively, the battery cell assembly may be housed within the housing by directly securing multiple battery cells to the housing.

[0130] In some embodiments, the housing 5 is used to house individual battery cells, and the housing 5 can have various structures.

[0131] In some embodiments, the housing 5 may include a first housing 5a and a second housing 5b. The first housing 5a and the second housing 5b are fastened together to form a closed space inside the housing 5 to house the battery cell assembly. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first housing may be a top cover or a bottom plate.

[0132] In some embodiments, the housing 5 may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are respectively connected to the frame, forming an enclosed space inside the housing to accommodate individual battery cells. As an example, the frame may include multiple side beams.

[0133] In some embodiments, the housing 5 may be part of the vehicle's chassis structure. For example, a portion of the housing 5 may be at least a portion of the vehicle's floor, or a portion of the housing 5 may be at least a portion of the vehicle's crossbeams and longitudinal beams.

[0134] In some embodiments, the battery device 2 may be an energy storage device.

[0135] Energy storage devices can be used in energy storage power stations, wind power generation systems, solar power generation systems, mobile power systems, or temporary power supply systems. Energy storage devices can store electrical energy as needed and output it when appropriate. For example, energy storage devices can store electrical energy during off-peak hours and provide power to relevant users or electrical equipment during peak hours.

[0136] In some embodiments, the energy storage device includes an energy storage container, an energy storage cabinet, etc.

[0137] Figure 3 is a schematic diagram of the battery module shown in Figure 2.

[0138] In some embodiments, as shown in FIG3, there are multiple battery cells 7, which are first connected in series, parallel, or mixed to form a battery module 6. The multiple battery modules 6 are then connected in series, parallel, or mixed to form a whole and housed in a casing.

[0139] Multiple battery cells 7 in battery module 6 can be electrically connected through a busbar to achieve parallel, series, or mixed connection of multiple battery cells 7 in battery module 6. There can be one or more busbars, each used to electrically connect at least two battery cells 7.

[0140] Figure 4 is a structural schematic diagram of a battery cell in some embodiments of this application; Figure 5 is an exploded schematic diagram of the battery cell shown in Figure 4; Figure 6 is a cross-sectional schematic diagram of the electrode assembly of a battery cell provided in some embodiments of this application; Figure 7 is a schematic diagram of the positive electrode sheet of the electrode assembly of a battery cell provided in some embodiments of this application after being unfolded; Figure 8 is a schematic diagram of the negative electrode sheet of the electrode assembly of a battery cell provided in some embodiments of this application after being unfolded.

[0141] Referring to Figures 4 to 8, an embodiment of this application provides a battery cell 7, which includes a housing 20 and an electrode assembly 10 housed within the housing 20.

[0142] In some embodiments, the outer casing 20 may be a steel casing, an aluminum casing, or a composite metal casing (such as a copper-aluminum composite casing).

[0143] The outer shell 20 may be a hollow structure, with an internal cavity 20b for accommodating the electrode assembly 10 and the electrolyte.

[0144] In some embodiments, the casing 20 of the battery cell 7 is a cylindrical casing, a square casing, a prismatic casing, or a casing of other shapes.

[0145] In some embodiments, the housing 20 includes a housing 21 and an end cap 22, the housing 21 having an opening, and the end cap 22 being connected to the housing 21 and covering the opening;

[0146] The housing 21 is a component used to fit the end cap 22 to form the internal cavity of the battery cell 7. The formed internal cavity can be used to accommodate the electrode assembly 10, the electrolyte, and other components.

[0147] The housing 21 and the end cap 22 can be separate components. For example, an opening can be provided on the housing 21, and the end cap 22 can be used to close the opening to form an internal cavity for the battery cell 7.

[0148] The housing 21 can be of various shapes and sizes, such as cuboid or cylindrical. Specifically, the shape of the housing 21 can be determined according to the specific shape and size of the electrode assembly 10. The housing 21 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc.

[0149] The shape of the end cap 22 can be adapted to the shape of the housing 21 to fit the housing 21. The material of the end cap 22 can be the same as or different from the material of the housing 21. Optionally, the end cap 22 can be made of a material with a certain hardness and strength (such as copper, iron, aluminum, stainless steel, aluminum alloy, etc.), so that the end cap 22 is not easily deformed when subjected to compression and impact, so that the battery cell 7 can have higher structural strength and improve reliability.

[0150] The end cap 22 is connected to the housing 21 by welding, bonding, snap-fitting or other means.

[0151] The housing 21 may be open at one end or open at both ends. In some examples, the housing 21 may be a structure with an opening on one side, and one end cap 22 is provided to cover the housing 21. In other examples, the housing 21 may also be a structure with openings on both sides, and two end caps 22 are provided, with the two end caps 22 respectively covering the two openings of the housing 21.

[0152] Electrode assembly 10 is a component in the battery cell 7 where electrochemical reactions occur. The housing 21 may contain one or more electrode assemblies 10.

[0153] In some embodiments, the electrode assembly 10 includes a positive electrode 11, a negative electrode 12, and a separator 13, wherein the positive electrode 11 and the negative electrode 12 have opposite polarities, and the separator 13 separates the positive electrode 11 and the negative electrode 12.

[0154] At least a portion of the separator 13 is located between the positive electrode 11 and the negative electrode 12. During the charging and discharging process of the battery cell 7, active ions (e.g., lithium ions) repeatedly insert and extract between the positive electrode 11 and the negative electrode 12. The separator 13, located between the positive electrode 11 and the negative electrode 12, serves to prevent short circuits between the positive and negative electrodes while allowing active ions to pass through.

[0155] In some embodiments, the positive electrode 11 may include a positive current collector 111 and a positive electrode film layer 112 disposed on at least one surface of the positive current collector 111.

[0156] As an example, the positive current collector 111 has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer 112 is disposed on either or both of the two opposite surfaces of the positive current collector 111.

[0157] As an example, the positive current collector 111 can be made of metal foil, conductive polymer material, carbon material, or composite current collector. For example, as a metal foil, pure metal, alloy, or surface-treated metal can be used, including but not limited to stainless steel, copper, aluminum, nickel, nickel alloy, titanium, or silver. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0158] As an example, the positive electrode film 112 includes a positive electrode active material, which may include at least one of the following materials: lithium phosphate, lithium transition metal oxide, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium phosphate include, but are not limited to, at least one of 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 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 oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (such as 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 Co0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.8 Co 0.15 Al 0.05 At least one of O2 and its modified compounds. Modified compounds refer to substances obtained by modification methods such as doping or coating based on the above-mentioned substances.

[0159] In some embodiments, the negative electrode 12 may include a negative current collector 121.

[0160] As an example, the negative electrode current collector 121 can be made of metal foil, conductive polymer material, carbon material, or composite current collector. For example, as a metal foil, pure metal, alloy, or surface-treated metal can be used, including but not limited to stainless steel, copper, aluminum, nickel, nickel alloy, titanium, or silver. The composite current collector may include a polymer material substrate and a metal layer. The composite current collector can 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, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0161] As an example, the negative electrode 12 may include a negative electrode current collector 121 and a negative electrode film layer 122 disposed on at least one surface of the negative electrode current collector 121.

[0162] As an example, the negative electrode current collector 121 has two surfaces opposite each other in its own thickness direction, and the negative electrode film layer 122 is disposed on either or both of the two opposite surfaces of the negative electrode current collector 121.

[0163] As an example, the negative electrode film 122 includes a negative electrode active material, which may be a negative electrode active material known in the art for use in battery cells. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials in battery cells may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0164] In some embodiments, the positive current collector 111 can be made of aluminum, and the negative current collector 121 can be made of copper.

[0165] In some embodiments, the separator 13 includes a separator membrane. The separator membrane of this application can be any known porous membrane with good chemical and mechanical stability.

[0166] As an example, the main material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramics. 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.

[0167] Inorganic particle coating, organic particle coating, or organic / inorganic composite coating can also be applied to the surface of the separator.

[0168] The separator 13 can be a single component located between the positive electrode 11 and the negative electrode 12, or it can be attached to the surface of the positive electrode 11 or the surface of the negative electrode 12.

[0169] In some embodiments, the separator 13 is a solid electrolyte. The solid electrolyte is disposed between the positive electrode 11 and the negative electrode 12, and serves to both transport ions and isolate the positive and negative electrodes.

[0170] In some embodiments, the battery cell 7 further includes an electrolyte, which acts as a conductor of ions between the positive electrode 11 and the negative electrode 12. The electrolyte used in this application can be selected according to requirements. The electrolyte can be liquid, gel-like, or solid.

[0171] In some embodiments, the liquid electrolyte includes an electrolyte salt and a solvent.

[0172] In some embodiments, the electrolyte salt may be selected from 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.

[0173] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl 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 of 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.

[0174] 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 additives that can improve certain properties of the battery cell, such as additives that improve the overcharge / fast charge performance of the battery cell, additives that improve the high-temperature performance of the battery cell, and additives that improve the low-temperature performance of the battery cell.

[0175] In some embodiments, the gel electrolyte comprises a polymer as a backbone network and can be used in conjunction with an ionic liquid-lithium salt.

[0176] In some embodiments, the solid electrolyte includes a polymer solid electrolyte, an inorganic solid electrolyte, and a composite solid electrolyte.

[0177] As an example, the polymers of polymeric solid electrolytes may include polyethers (polyoxyethylene), polysiloxanes, polycarbonates, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, monoionic polymers, polyionic liquids, cellulose, etc.

[0178] As an example, inorganic solid electrolytes can be one or more of the following: oxide solid electrolytes (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous LiPON thin film), sulfide solid electrolytes (crystalline lithium superconducting ion conductor (lithium germanium phosphorus sulfide, silver sulfide germanium ore), amorphous sulfides), halide solid electrolytes, nitride solid electrolytes, and hydride solid electrolytes.

[0179] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0180] In some embodiments, the electrode assembly 10 can be a wound structure, a stacked structure, or a hybrid structure of wound and stacked.

[0181] In some embodiments, the electrode assembly 10 is a wound structure. The positive electrode 11 and the negative electrode 12 are wound into a wound structure.

[0182] In some embodiments, the electrode assembly 10 has a stacked structure.

[0183] As an example, multiple positive electrode plates 11 and multiple negative electrode plates 12 can be provided, with multiple positive electrode plates 11 and multiple negative electrode plates 12 being stacked alternately. As an example, multiple positive electrode plates 11 can be provided, and multiple negative electrode plates 12 can be folded to form multiple stacked folded segments, with a positive electrode plate 11 sandwiched between adjacent folded segments.

[0184] As an example, both the positive electrode 11 and the negative electrode 12 are folded to form multiple stacked folded segments.

[0185] As an example, multiple separators 13 can be provided, respectively disposed between any adjacent positive electrode 11 or negative electrode 12.

[0186] As an example, the separator 13 can be continuously arranged and disposed between any adjacent positive electrode 11 or negative electrode 12 by means of folding or rolling.

[0187] In some embodiments, the electrode assembly 10 may be cylindrical, flat, or polygonal in shape.

[0188] In some embodiments, the positive current collector 111 may include a positive tab 1111, and the negative current collector 121 may include a negative tab 1211. The positive tab 1111 and the negative tab 1211 can be used to transmit current. As an example, at least a portion of the positive tab 1111 is not coated with the positive electrode film 112, and at least a portion of the negative tab 1211 is not coated with the negative electrode film 122.

[0189] In some embodiments, the electrode assembly 10 has a wound structure. The positive electrode tab 1111 is wound multiple turns along the winding direction V. Optionally, the end of the positive electrode tab 1111 is bent by a flattening or smoothing process to form a multi-layer structure stacked in the axial direction of the electrode assembly 10. Optionally, the positive electrode tab 1111 is annular.

[0190] In some embodiments, the negative electrode tab 1211 is wound multiple turns along the winding direction V. Optionally, the ends of the negative electrode tab 1211 are bent by a flattening or smoothing process to form a multilayer structure stacked in the axial direction of the electrode assembly 10. The negative electrode tab 1211 is annular.

[0191] In some embodiments, the electrode assembly 10 includes an electrode body 10c. As an example, the electrode body 10c includes a positive electrode film 112, a portion of a positive electrode current collector 111 covered by the positive electrode film 112, a negative electrode film 122, a portion of a negative electrode current collector 121 covered by the negative electrode film 122, and a separator 13.

[0192] The positive tab 1111 and the negative tab 1211 can be led out from the same end of the electrode body 10c, or they can be led out from opposite ends of the electrode body 10c. At least a portion of the positive tab 1111 protrudes to the outside of the insulating member 13, and at least a portion of the negative tab 1211 protrudes to the outside of the insulating member 13.

[0193] Figure 9 is a cross-sectional schematic diagram of a battery cell provided in some embodiments of this application; Figure 10 is an enlarged schematic diagram of Figure 9 at box A; Figure 11 is an enlarged schematic diagram of Figure 10 at the circular frame; Figure 12 is an enlarged schematic diagram of Figure 11 at the circular frame; Figure 13 is an enlarged schematic diagram of Figure 9 at box B; Figure 14 is an enlarged schematic diagram of Figure 13 at the circular frame.

[0194] Referring to Figures 4 to 14, an embodiment of this application provides a battery cell 7, which includes a housing 20, electrode terminals 30, an electrode assembly 10, and a first insulating member 40. The housing 20 includes a receiving cavity 20b, within which the electrode assembly 10 is received. The housing 20 includes a first wall 211, which has an electrode lead-out hole 2111 communicating with the receiving cavity 20b. The electrode terminal 30 is disposed in the electrode lead-out hole 2111. The electrode assembly 10 includes a first tab 10a and a second tab 10b with opposite polarities. The first tab 10a is electrically connected to the electrode terminal 30, and the second tab 10b is electrically connected to the first wall 211. At least a portion of the first insulating member 40 is fixed between the electrode terminal 30 and the first wall 211 to insulate at least a portion of the electrode terminal 30 from the first wall 211. The thermal decomposition temperature of the first insulating member 40 is greater than or equal to 300°C.

[0195] As an example, the first wall 211 can be an end cap 22 or a wall of the housing 21.

[0196] One of the first electrode tab 10a and the second electrode tab 10b is a positive electrode tab 1111, and the other is a negative electrode tab 1211. The polarity of the electrode terminal 30 corresponds to the polarity of the first electrode tab 10a. In some examples, the first electrode tab 10a is a positive electrode tab 1111, and the electrode terminal 30 is a positive terminal; in other examples, the first electrode tab 10a is a negative electrode tab 1211, and the electrode terminal 30 is a negative terminal.

[0197] As an example, the first tab 10a and the second tab 10b can be disposed at the same end of the electrode assembly 10, or they can be disposed at opposite ends of the electrode assembly 10.

[0198] The first tab 10a can be directly connected to the electrode terminal 30, or it can be indirectly connected to the electrode terminal 30 through other conductive structures.

[0199] The second tab 10b can be directly connected to the first wall 211, or it can be indirectly connected to the first wall 211 through other conductive structures.

[0200] Electrode lead-out hole 2111 penetrates the first wall 211. As an example, along the thickness direction Z of the first wall 211, the electrode lead-out hole 2111 penetrates the first wall 211, and the projection of the electrode terminal 30 at least partially overlaps with the projection of the electrode lead-out hole 2111.

[0201] As an example, the electrode lead-out hole 2111 can be a round hole, a square hole, a racetrack-shaped hole, an elliptical hole, or a hole of other shapes.

[0202] In some examples, at least a portion of the electrode terminal 30 is located outside the first wall 211 and covers the electrode lead-out hole 2111. Optionally, the electrode terminal 30 may be entirely located outside the first wall 211; alternatively, the electrode terminal 30 may pass through the electrode lead-out hole 2111, with a portion of the electrode terminal 30 located outside the first wall 211 and a portion of the electrode terminal 30 located inside the first wall 211.

[0203] The electrode terminal 30 is insulated from the first wall 211.

[0204] The first insulating member 40 can be entirely disposed between the electrode terminal 30 and the first wall 211, or only a portion of it can be located between the electrode terminal 30 and the first wall 211.

[0205] As an example, the thermal decomposition temperature of the first insulating member 40 may be 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, or 1000°C.

[0206] For example, the thermogravimetric temperature of the first insulating member 40 can be the 5% thermogravimetric temperature; the 5% thermogravimetric temperature can be the temperature at which the mass of the test sample is lost by 5% relative to the initial mass in thermogravimetric analysis. The thermogravimetric temperature of the first insulating member can be measured with reference to GB / T27761-2011 Test Method for Weight Loss and Residual Weight of Thermogravimetric Analyzer.

[0207] When a battery cell 7 experiences thermal runaway due to an internal short circuit or other reasons, the battery cell 7 may remain at a high temperature for a period of time. The thermal decomposition temperature of the first insulating member 40 is greater than or equal to 300°C, and it is less likely to lose weight or lose less weight when the battery cell 7 experiences thermal runaway. This allows the first insulating member 40 to remain between the first wall 211 and the electrode terminal 30, reducing the risk of conduction between the electrode terminal 30 and the first wall 211. Correspondingly, even if the electrode terminal 30 and the first wall 211 are electrically connected to other battery cells 7 or an external power source, the first insulating member 40 can suppress the current between the electrode terminal 30 and the first wall 211, reduce the continuous heat generation between the electrode terminal 30 and the first wall 211, reduce the thermal impact on other surrounding battery cells 7, reduce the risk of thermal runaway in other battery cells 7, and improve reliability.

[0208] For example, when the first wall 211 and electrode terminal 30 of a normal battery cell 7 are electrically connected to the first wall 211 and electrode terminal 30 of a thermally runaway battery cell 7, the first insulating member 40 can cut off the circuit between the two battery cells 7, reduce the continuous heat generation of the electrode terminal 30 and the first wall 211 of the thermally runaway battery cell 7, reduce the thermal impact on other battery cells 7 in the vicinity, reduce the risk of thermal runaway in other battery cells 7, and improve reliability.

[0209] The first wall 211 and the electrode terminal 30 can serve as two electrodes of the battery cell 7 and are located on the same side of the battery cell 7. When multiple battery cells 7 are assembled into a group, it facilitates the connection between the busbar and the first wall 211 or the busbar and the electrode terminal 30, simplifying the structure of the battery device. Although the first wall 211 and the electrode terminal 30 have opposite polarities, the first insulating member 40 can also suppress the current between the first wall 211 and the electrode terminal 30 in the event of thermal runaway of the battery cell 7, reducing the continuous heat generation between the electrode terminal 30 and the first wall 211 and improving reliability.

[0210] In some embodiments, the thermal weight loss temperature of the first insulating member 40 is greater than or equal to 350°C, which can further reduce the weight loss rate of the first insulating member 40 during thermal runaway of the battery cell 7, reduce the risk of failure of the first insulating member 40, reduce the continuous heat generation of the electrode terminal 30 and the first wall 211, reduce the thermal impact on other battery cells 7 in the surrounding area, reduce the risk of thermal runaway of other battery cells 7, and improve reliability.

[0211] In some embodiments, the thermal weight loss temperature of the first insulating member 40 is greater than or equal to 500°C, which can further reduce the weight loss rate of the first insulating member 40 during thermal runaway of the battery cell 7, reduce the risk of failure of the first insulating member 40, reduce the continuous heat generation of the electrode terminal 30 and the first wall 211, reduce the thermal impact on other battery cells 7 in the surrounding area, reduce the risk of thermal runaway of other battery cells 7, and improve reliability.

[0212] In some embodiments, the thermal weight loss temperature of the first insulating member 40 is greater than or equal to 550°C.

[0213] In some embodiments, the material of the first insulating member 40 includes a thermosetting material.

[0214] Thermosetting materials possess excellent heat resistance, maintaining good stability at high temperatures and resisting softening, deformation, or decomposition. During thermal runaway of the battery cell 7, the internal pressure of the casing 20 increases, increasing the risk of deformation of the first wall 211. When the first wall 211 deforms, the pressure on the first insulating member 40 increases. Since the first insulating member 40, containing thermosetting materials, is less prone to softening at high temperatures, this reduces the deformation of the first insulating member 40 under pressure, lowering the risk of localized thinning or puncture, thereby improving insulation performance and reducing the risk of insulation failure.

[0215] In some embodiments, the thermosetting material may include at least one of thermosetting polyimide, thermosetting phenolic resin, or other high-temperature resistant thermosetting materials.

[0216] In some embodiments, the material of the first insulating member 40 includes one or more thermosetting polyimides and their derivatives.

[0217] For example, a derivative can refer to a product derived from the substitution of hydrogen atoms or groups of atoms in a polymer by other atoms or groups of atoms.

[0218] Thermosetting polyimide exhibits excellent heat resistance. In the event of thermal runaway of the battery cell 7, the first insulating component 40, which contains thermosetting polyimide, maintains good performance stability at high temperatures, exhibiting minimal or no weight loss, thereby reducing the risk of insulation failure.

[0219] Thermosetting polyimide has high strength. In the event of thermal runaway of the battery cell 7, the first insulating member 40 containing thermosetting polyimide can withstand a large load and is not easily cracked or punctured under the pressure of the first wall 211, thereby reducing the risk of insulation failure.

[0220] Thermosetting polyimide has low creep. During the long-term use of the battery cell 7, the first insulating member 40 containing thermosetting polyimide exhibits less creep, and its size and shape can maintain good stability, thereby reducing the risk of insulation failure.

[0221] Thermosetting polyimide has good corrosion resistance. During the assembly or use of the battery cell 7, the first insulating component 40 containing thermosetting polyimide is not easily corroded by the electrolyte, thereby reducing the risk of insulation failure.

[0222] In some embodiments, the material of the first insulating member 40 includes one or more of bismaleimide, ethynyl-terminated polyimide, and norbornene-terminated polyimide.

[0223] Bismaleimide, ethynyl-terminated polyimide, and norbornene-terminated polyimide have advantages such as excellent high temperature resistance, high mechanical strength, and strong chemical corrosion resistance.

[0224] In some embodiments, the material of the first insulating member 40 comprises a polyimide-siloxane resin. Polyimide itself has high thermal stability, and the introduction of siloxane further enhances this property. Polyimide has high strength and modulus, while the addition of siloxane can, to some extent, adjust the mechanical properties of the material, giving it better toughness and impact resistance. Simultaneously, the polyimide-siloxane resin also has high elongation at break, which allows the first insulating member 40 to undergo a certain degree of deformation under external force without easily breaking, thus improving the reliability and service life of the first insulating member 40.

[0225] In some embodiments, the material of the first insulating member 40 comprises cyanate ester resin-modified polyimide. Cyanate ester resin itself has high heat resistance, and the resulting triazine ring structure ensures its stability at high temperatures. Polyimide is also a high-temperature resistant material; combining the two further enhances the heat resistance of the modified material, increasing its thermal decomposition temperature and maintaining good performance even at high temperatures. Polyimide possesses excellent strength and modulus, which can enhance the mechanical properties of cyanate ester resin. The modified material exhibits high tensile strength, flexural strength, and hardness, while maintaining good toughness and impact resistance, making it less prone to damage under external forces.

[0226] In some embodiments, the material of the first insulating member 40 includes a thermosetting phenolic resin. Thermosetting phenolic resins have good heat resistance, dimensional stability, and corrosion resistance.

[0227] In the event of thermal runaway of the battery cell 7, the first insulating component 40, comprising thermosetting phenolic resin, maintains good performance stability at high temperatures, exhibiting minimal or no weight loss, thereby reducing the risk of insulation failure. The three-dimensional network structure formed after the thermosetting phenolic resin is cured provides it with good dimensional stability. During long-term use of the battery cell 7, the size and shape of the first insulating component 40, comprising thermosetting polyimide, maintain good stability, further reducing the risk of insulation failure.

[0228] In some embodiments, the first insulating member 40 is fixed to at least one of the electrode terminal 30 and the first wall 211.

[0229] As an example, the first insulating member 40 can be fixed to the electrode terminal 30 and / or the first wall 211 by bonding, pressing or other means. For example, the electrode terminal 30 and the first wall 211 press the first insulating member 40 from both sides to fix the first insulating member 40.

[0230] Fixing the first insulating member 40 to the electrode terminal 30 and / or the first wall 211 can improve the stability of the first insulating member 40, reduce the displacement of the first insulating member 40 when the battery cell 7 is subjected to external impact, and reduce the risk of insulation failure.

[0231] In some embodiments, the first insulating member 40 is bonded to at least one of the electrode terminal 30 and the first wall 211.

[0232] In some examples, the first insulating member 40 is bonded to the electrode terminal 30. The first insulating member 40 can be directly bonded to the electrode terminal 30; for example, an adhesive insulating material (e.g., a thermosetting material) can be directly coated onto the surface of the electrode terminal 30, and the insulating material cures to form the first insulating member 40. The first insulating member 40 can also be bonded to the electrode terminal 30 using other materials; for example, an adhesive can be coated onto the surface of the first insulating member 40 and then bonded to the electrode terminal 30 using the adhesive.

[0233] In some examples, the first insulating member 40 is bonded to the first wall 211. The first insulating member 40 can be directly bonded to the first wall 211; for example, an adhesive insulating material (e.g., a thermosetting material) can be directly coated onto the surface of the first wall 211, and the insulating material, after curing, forms the first insulating member 40. The first insulating member 40 can also be bonded to the first wall 211 using other materials; for example, an adhesive can be coated onto the surface of the first insulating member 40 and then bonded to the first wall 211 using the adhesive.

[0234] In some examples, the first insulating member 40 is simultaneously bonded to the first wall 211 and the electrode terminal 30.

[0235] Bonding the first insulating member 40 to the electrode terminal 30 and / or the first wall 211 can improve the stability of the first insulating member 40, reduce the displacement of the first insulating member 40 when the battery cell 7 is subjected to external impact, and reduce the risk of insulation failure. The bonding process is easy to implement and the bonding interface has good sealing performance.

[0236] In some embodiments, the first wall 211 includes an outer surface 2112 and an inner surface 2113 disposed along the thickness direction Z. The hole wall of the electrode lead-out hole 2111 connects the outer surface 2112 and the inner surface 2113.

[0237] In some embodiments, the first insulating member 40 is bonded to the first wall 211.

[0238] For example, the first insulating member 40 can be bonded to the inner surface 2113 of the first wall 211, or to the outer surface 2112 of the first wall 211, or to both the inner surface 2113 and the outer surface 2112 of the first wall 211.

[0239] Compared to the electrode terminal 30, the first wall 211 is usually simple in structure and relatively flat. Attaching the first insulating member 40 to the first wall 211 can improve the morphology of the bonding interface and enhance the bonding stability of the first insulating member 40.

[0240] In some embodiments, at least a portion of the first insulating member 40 is located between the outer surface 2112 of the first wall 211 and the electrode terminal 30 in the thickness direction Z of the first wall 211.

[0241] At least a portion of the first insulating member 40 is located outside the first wall 211, and the first insulating member 40 can separate the portion of the electrode terminal 30 located outside the first wall 211 from the first wall 211. When high-temperature particles emitted by other battery cells 7 are sputtered onto the first insulating member 40, the first insulating member 40 has good heat resistance and is not easily damaged by the high-temperature particles, thereby reducing the risk of short circuit in the battery cells 7.

[0242] In some embodiments, at least a portion of the first insulating member 40 is adhered to the outer surface 2112 of the first wall 211.

[0243] In some embodiments, the first insulating member 40 protrudes from the wall surface of the electrode lead-out hole 2111 toward the central axis of the electrode lead-out hole 2111.

[0244] When the battery cell 7 experiences thermal runaway, the internal pressure of the casing 20 increases, and the first wall 211 may bulge outward and deform. The first insulating member 40 can cover the junction between the outer surface 2112 of the first wall 211 and the hole wall, thereby reducing the risk of the junction between the outer surface 2112 of the first wall 211 and the hole wall coming into contact with the electrode terminal 30 when the first wall 211 bulges outward and deforms.

[0245] In some embodiments, the first insulating member 40 comprises a thermosetting material. The first insulating member 40 comprises a thermosetting material that is not easily softened in the event of thermal runaway of the battery cell 7, thereby reducing the risk of the first insulating member 40 being punctured by the outer surface 2112 of the first wall 211 and the hole wall surface, and improving the insulation performance.

[0246] In some embodiments, the first insulating member 40 includes a first insulating portion 41 and a second insulating portion 42 connected to the first insulating portion 41. The first insulating portion 41 is disposed on the outer surface 2112 of the first wall 211, and the second insulating portion 42 is disposed on the hole wall surface of the electrode lead-out hole 2111.

[0247] The first insulating member 40 can cover the junction of the outer surface 2112 of the first wall 211 and the hole wall, thereby reducing the risk of the junction of the outer surface 2112 of the first wall 211 and the hole wall coming into contact with the electrode terminal 30 when the first wall 211 bulges outward and deforms.

[0248] In some embodiments, the first insulating part 41 is bonded to the outer surface 2112, and the second insulating part 42 is bonded to the wall surface of the electrode lead-out hole 2111.

[0249] In some embodiments, a first recess 2114 is provided on one side of the first wall 211 along the thickness direction Z, and an electrode lead-out hole 2111 is provided on the bottom wall of the first recess 2114.

[0250] In some embodiments, the first insulating portion 41 is at least attached to the bottom surface of the first recess 2114. Optionally, the first insulating portion 41 is entirely housed within the first recess 2114 to save space occupied by the first insulating portion 41.

[0251] In some embodiments, the thickness of the first insulating portion 41 is less than the depth of the first recess 2114 in the thickness direction Z.

[0252] In some embodiments, the first insulating portion 41 is further attached to the side of the first recess 2114.

[0253] In some embodiments, the outer surface 2112 of the first wall 211 defines the first recess 2114, that is, the outer surface 2112 of the first wall 211 includes the bottom surface of the first recess 2114 and the side surface of the first recess 2114.

[0254] In some embodiments, the outer surface 2112 further includes a planar region surrounding the first recess 2114, the planar region being connected to the side surface of the first recess 2114, the first recess 2114 being recessed relative to the planar region.

[0255] In some embodiments, the first insulating portion 41 is also attached to the planar region.

[0256] In some embodiments, the battery cell 7 further includes a second insulating member 70. At least a portion of the second insulating member 70 is disposed between the electrode terminal 30 and the first wall 211 to insulate at least a portion of the electrode terminal 30 from the first wall 211.

[0257] In some embodiments, at least a portion of the second insulating member 70 is disposed between the first insulating member 40 and the electrode terminal 30.

[0258] The second insulating member 70 may be entirely disposed between the first insulating member 40 and the electrode terminal 30, or it may be partially disposed between the first insulating member 40 and the electrode terminal 30. In some examples, a portion of the second insulating member 70 is also disposed between the first insulating member 40 and the first wall 211.

[0259] By setting the first insulating member 40 and the second insulating member 70, a double-layer insulating structure can be formed between the first wall 211 and the electrode terminal 30, thereby further improving the insulation effect and reducing the risk of the first wall 211 and the electrode terminal 30 conducting when the battery cell 7 experiences thermal runaway.

[0260] In some embodiments, the compressive modulus of the second insulating member 70 is less than that of the first insulating member 40.

[0261] As an example, the compression modulus of the second insulating member 70 and the compression modulus of the first insulating member 40 can be measured with reference to GB / T 1041-2008 Determination of Compression Properties of Plastics.

[0262] During the use of the battery cell 7, the first wall 211 may deform due to changes in the internal pressure of the battery cell 7; in particular, during thermal runaway of the battery cell 7, the internal pressure of the outer casing 20 increases rapidly, which may also cause the first wall 211 to bulge outward. The second insulating member 70 has a lower compressive modulus, and when the first wall 211 deforms, it can release stress through compressive deformation, thereby reducing the stress on the first insulating member 40 and reducing the risk of cracking and insulation failure of the first insulating member 40.

[0263] In some embodiments, the material of the second insulating member 70 includes a thermoplastic material.

[0264] Thermoplastic materials have advantages such as easy molding, good flexibility, high chemical stability, and excellent electrical insulation.

[0265] The second insulating member 70, which contains thermoplastic material, is easy to mold, and its shape can be adapted to the electrode terminal 30 with a complex structure. When subjected to external force (such as the pressure generated by the deformation of the first wall), the second insulating member 70 containing thermoplastic material can undergo a certain degree of deformation without easily breaking, and has good toughness and impact resistance, thus improving the insulation effect.

[0266] In some embodiments, the thermal weight loss temperature of the second insulating member 70 is lower than that of the first insulating member 40.

[0267] When the battery cell 7 experiences thermal runaway, the second insulating member 70 softens and loses weight under high temperature. This reduces the pressure exerted on the first insulating member 40 by the first wall 211 and the electrode terminal 30 when the first wall 211 bulges outward, thereby reducing the risk of cracking of the first insulating member 40 and the risk of insulation failure.

[0268] In some embodiments, at least a portion of the first insulating member 40 and at least a portion of the second insulating member 70 are stacked between the first wall 211 and the electrode terminal 30 in the thickness direction Z of the first wall 211.

[0269] In some examples, at least a portion of the first insulating member 40 is stacked between the first wall 211 and the second insulating member 70 in the thickness direction Z of the first wall 211; in other examples, at least a portion of the first insulating member 40 is stacked between the electrode terminal 30 and the second insulating member 70 in the thickness direction Z of the first wall 211.

[0270] To secure the electrode terminal 30 to the first wall 211, there is typically an interaction force between the electrode terminal 30 and the first wall 211 along the thickness direction Z. At least a portion of the first insulating member 40 and at least a portion of the second insulating member 70 are stacked along the thickness direction Z, which can reduce the risk of insulation failure.

[0271] In some embodiments, at least a portion of the second insulating member 70 is disposed between the first insulating member 40 and the electrode terminal 30 in the thickness direction Z of the first wall 211.

[0272] During the installation of electrode terminal 30 onto first wall 211, it is usually necessary to press electrode terminal 30 against first wall 211. Second insulating member 70 can separate first insulating member 40 from electrode terminal 30, thereby reducing the stress on first insulating member 40 during electrode terminal 30 installation, reducing the risk of first insulating member 40 being crushed, and improving insulation effect.

[0273] In some embodiments, in the thickness direction Z of the first wall 211, the minimum thickness of the portion of the first insulating member 40 located between the first wall 211 and the electrode terminal 30 is t1, and the minimum thickness of the portion of the second insulating member 70 located between the first wall 211 and the electrode terminal 30 is t2, where t2 is greater than t1.

[0274] By providing a second insulating member 70 with a larger thickness, the creepage distance between the first wall 211 and the electrode terminal 30 can be increased, thereby improving insulation performance. The first insulating member 40, which has a higher thermogravimetric temperature, can have a smaller thickness to reduce the molding difficulty of the first insulating member 40 and lower costs.

[0275] In some embodiments, the first insulating member 40 is bonded to the first wall 211, and at least a portion of the second insulating member 70 is sandwiched between the electrode terminal 30 and the first insulating member 40.

[0276] In some embodiments, the second insulating member 70 is made of plastic. For example, the second insulating member 70 is made of PFA (tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer).

[0277] In some embodiments, the electrode terminal 30 includes a terminal body 31 and a first limiting portion 32. At least a portion of the terminal body 31 is accommodated in the electrode lead-out hole 2111, and the first limiting portion 32 is connected to the terminal body 31. At least a portion of the first limiting portion 32 protrudes from the outer peripheral surface of the terminal body 31.

[0278] In some examples, the first limiting part 32 and the terminal body 31 can be integrally formed. In other examples, the first limiting part 32 and the terminal body 31 are formed independently and connected by welding, riveting, bonding or other means.

[0279] The first limiting part 32 can be located inside the first wall 211 or outside the first wall 211.

[0280] In some embodiments, the first limiting portion 32 at least partially overlaps with the first wall 211 in the thickness direction Z of the first wall 211.

[0281] The first wall 211 and the first limiting part 32 can limit each other in the thickness direction Z, thereby improving the stability of the electrode terminal 30.

[0282] In some embodiments, at least a portion of the first insulating member 40 is located between the first wall 211 and the first limiting portion 32 in the thickness direction Z of the first wall 211.

[0283] The first insulating member 40 may be entirely located between the first wall 211 and the first limiting part 32, or it may be only partially located between the first wall 211 and the first limiting part 32.

[0284] When the battery cell 7 experiences thermal runaway, the first insulating member 40 can remain between the first limiting part 32 and the first wall 211, reducing the risk of direct contact between the first limiting part 32 and the first wall 211, thereby suppressing the current between the electrode terminal 30 and the first wall 211 and reducing the continuous heat generation between the electrode terminal 30 and the first wall 211.

[0285] In some embodiments, the first limiting part 32 and the terminal body 31 are integrally formed.

[0286] In some embodiments, the electrode terminal 30 further includes a second limiting portion 33 connected to the terminal body 31. At least a portion of the second limiting portion 33 protrudes from the outer peripheral surface of the terminal body 31. In the thickness direction Z of the first wall 211, the first limiting portion 32 and the second limiting portion 33 are respectively located on both sides of the first wall 211.

[0287] In some examples, the second limiting part 33 and the terminal body 31 can be integrally formed. In other examples, the second limiting part 33 and the terminal body 31 are formed independently and connected by welding, riveting, bonding or other means.

[0288] One of the first limiting part 32 and the second limiting part 33 is located inside the first wall 211, and the other is located outside the first wall 211.

[0289] The first limiting part 32 and the second limiting part 33 can fix the electrode terminal 30 in the thickness direction Z of the first wall 211.

[0290] In some embodiments, one of the first limiting portion 32 and the second limiting portion 33 is formed after the electrode terminal 30 passes through the electrode lead-out hole 2111.

[0291] In some examples, the first limiting portion 32 is located on the outer side of the first wall 211, and the electrode terminal 30 is riveted to the first wall 211 from the outer side to form the first limiting portion 32. In some examples, the first limiting portion 32 is located on the inner side of the first wall 211; for example, the electrode terminal 30 is riveted to the first wall 211 from the inner side to form the first limiting portion 32. In some examples, the second limiting portion 33 is located on the outer side of the first wall 211, and the electrode terminal 30 is riveted to the first wall 211 from the outer side to form the second limiting portion 33. In some examples, the second limiting portion 33 is located on the inner side of the first wall 211; for example, the electrode terminal 30 is riveted to the first wall 211 from the inner side to form the second limiting portion 33.

[0292] In some embodiments, the first limiting portion 32 is located on the outer side of the first wall 211, and the second limiting portion 33 is located on the inner side of the first wall 211.

[0293] In some embodiments, the first recess 2114 is disposed on the side of the first wall 211 facing the first limiting portion 32.

[0294] In some embodiments, at least a portion of the first limiting portion 32 is accommodated in the first recess 2114.

[0295] In some embodiments, the electrode terminal 30 includes a terminal body 31, a first limiting portion 32, and a second limiting portion 33. At least a portion of the terminal body 31 is accommodated in an electrode lead-out hole 2111. The first limiting portion 32 and the second limiting portion 33 are both connected to the terminal body 31. At least a portion of the first limiting portion 32 protrudes from the outer peripheral surface of the terminal body 31, and at least a portion of the second limiting portion 33 protrudes from the outer peripheral surface of the terminal body 31. At least a portion of the first insulating member 40 is attached to the surface of the first wall 211 facing the first limiting portion 32. In the thickness direction Z of the first wall 211, the first limiting portion 32 and the second limiting portion 33 are located on opposite sides of the first wall 211, and at least a portion of the second insulating member 70 is disposed between the first limiting portion 32 and the first insulating member 40.

[0296] To improve the stability of the electrode terminal 30, the first limiting part 32 and the second limiting part 33 can clamp the first wall 211 from both sides. The second insulating member 70 can separate the first insulating member 40 from the first limiting part 32, thereby reducing the pressure exerted by the first limiting part 32 on the first insulating member 40, reducing the risk of the first insulating member 40 being crushed, and improving the insulation effect.

[0297] In some embodiments, the electrode terminal 30 is riveted to the first wall 211. The first limiting portion 32 is configured to be formed after the electrode terminal 30 passes through the electrode lead-out hole 2111.

[0298] For example, when assembling the first wall 211 and the electrode terminal 30, the electrode terminal 30 can be passed through the electrode lead-out hole 2111 first, and then the end of the electrode terminal 30 can be squeezed to form a flange structure, which can serve as the first limiting part 32.

[0299] During the molding process of the first limiting part 32, the second insulating member 70 can separate the first limiting part 32 from the first insulating member 40, thereby reducing the force transmitted to the first insulating member 40, reducing the risk of the first insulating member 40 being crushed, and improving the insulation effect.

[0300] In some embodiments, the first insulating member 40 includes a first insulating portion 41 and a second insulating portion 42 connected together. At least a portion of the first insulating portion 41 is located between the first limiting portion 32 and the first wall 211, and at least a portion of the second insulating portion 42 is located within the electrode lead-out hole 2111. The first insulating portion 41 isolates the first limiting portion 32 from the first wall 211, and the second insulating portion 42 isolates at least a portion of the terminal body 31 from the first wall 211, thereby reducing the risk of direct contact between the first wall 211 and the electrode terminal 30.

[0301] In some embodiments, the second insulating member 70 is disposed around the terminal body 31.

[0302] In some embodiments, the second insulating member 70 includes a fourth insulating portion 71 and a fifth insulating portion 72. At least a portion of the fourth insulating portion 71 is disposed between the first wall 211 and the first limiting portion 32, and at least a portion of the fifth insulating portion 72 is disposed in the electrode lead-out hole 2111 and is located between the hole wall surface of the electrode lead-out hole 2111 and the terminal body 31.

[0303] In some embodiments, the battery cell 7 includes a seal 60, at least a portion of which is disposed between the second limiting portion 33 and the first wall 211 in the thickness direction Z of the first wall 211.

[0304] The second limiting part 33 and the first wall 211 can clamp the sealing member 60 in the thickness direction Z to achieve the sealing of the electrode lead-out hole 2111.

[0305] In some embodiments, the thermal weight loss temperature of the seal 60 is greater than or equal to 200°C. As an example, the thermal weight loss temperature of the seal 60 may be 200°C, 250°C, 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, or 800°C.

[0306] For example, the thermogravimetric temperature of the seal 60 can be the 5% thermogravimetric temperature. The thermogravimetric temperature of the seal 60 can be measured with reference to GB / T27761-2011 Test Method for Weight Loss and Residual Weight by Thermogravimetric Analyzer.

[0307] The seal 60 is less likely to lose weight or lose less weight when the battery cell 7 experiences thermal runaway, thus enabling the seal 60 to remain between the first wall 211 and the electrode terminal 30, reducing the risk of direct contact between the electrode terminal 30 and the first wall 211.

[0308] In some embodiments, the seal 60 is electrically insulating. Exemplarily, the seal 60 is made of an insulating material. After thermal runaway of the battery cell 7, the seal 60 can suppress the current between the second limiting portion 33 and the first wall 211, reducing the continuous heat generation between the electrode terminals 30 and the first wall 211, lowering the risk of thermal runaway in other battery cells 7, and improving reliability.

[0309] In some embodiments, the thermal weight loss temperature of the seal 60 is lower than that of the first insulating member 40. To achieve a seal, the seal 60 is typically in a compressed state; even if the weight loss rate of the seal 60 is greater than that of the first insulating member 40 in the event of thermal runaway in the battery cell 7, it can still fill the space between the second limiting portion 33 and the first wall 211, reducing the risk of direct contact between the second limiting portion 33 and the first wall 211.

[0310] In some embodiments, the seal 60 comprises a thermosetting material. The seal 60 comprising a thermosetting material can maintain good stability at high temperatures and can isolate the second limiting portion 33 from the first wall 211 in the event of thermal runaway of the battery cell 7.

[0311] In some embodiments, the material of the seal 60 includes fluororubber. Optionally, the material of the seal 60 includes thermosetting fluororubber.

[0312] In some embodiments, a first insulating member 40 is disposed around a terminal body 31. A seal 60 is disposed around a terminal body 31.

[0313] In some embodiments, the second insulating portion 42 may abut against the seal 60 in the thickness direction Z. The first insulating member 40 and the seal 60 may together separate the first wall 211 from the electrode terminal 30.

[0314] In some embodiments, portions of the seal 60 and the first insulating member 40 are stacked in the thickness direction Z of the first wall 211 to separate the hole wall of the electrode lead-out hole 2111 from the terminal body 31. Embodiments of this application can reduce the risk of contact between the terminal body 31 and the first wall 211.

[0315] In some embodiments, the seal 60 includes a first sealing portion 61 and a second sealing portion 62 connected together, at least a portion of the first sealing portion 61 being located between the second limiting portion 33 and the first wall 211, and at least a portion of the second sealing portion 62 being located within the electrode lead-out hole 2111.

[0316] The first sealing part 61 can isolate the second limiting part 33 from the first wall 211, and the second sealing part 62 can isolate at least a portion of the terminal body 31 from the first wall 211, thereby reducing the risk of direct contact between the first wall 211 and the electrode terminal 30.

[0317] In some embodiments, the second sealing portion 62 and the second insulating portion 42 abut against each other in the thickness direction Z to completely isolate the terminal body 31 from the hole wall of the electrode lead-out hole 2111.

[0318] In some embodiments, the fifth insulating portion 72 abuts against the second sealing portion 62 along the thickness direction Z.

[0319] In some embodiments, the battery cell 7 further includes a third insulating member 80, at least a portion of which is disposed between the second limiting portion 33 and the first wall 211 in the thickness direction Z.

[0320] When the battery cell 7 is operating normally, the third insulating member 80 can separate the second limiting part 33 from the first wall 211 to reduce the risk of short circuit in the battery cell 7. In the event of thermal runaway of the battery cell 7, even if the third insulating member 80 melts at high temperature, the seal 60 can remain between the second limiting part 33 and the first wall 211, reducing the risk of contact between the second limiting part 33 and the first wall 211 and suppressing the current between the electrode terminal 30 and the first wall 211.

[0321] In some embodiments, at least a portion of the third insulating member 80 is disposed between the first wall 211 and the first tab 10a.

[0322] In some embodiments, the material of the third insulating member 80 includes a thermoplastic material. Optionally, the material of the third insulating member 80 is plastic.

[0323] In some embodiments, a third insulating member 80 is disposed around the terminal body 31.

[0324] In some embodiments, the outer periphery of the third insulating member 80 extends beyond the first tab 10a in a direction away from the terminal body 31.

[0325] In some embodiments, the thermal conductivity of the first insulating member 40 is less than that of the first wall 211, and the thermal conductivity of the first insulating member 40 is less than that of the electrode terminal 30.

[0326] Compared to the first wall 211 and the electrode terminal 30, the first insulating member 40 has a smaller thermal conductivity. The first insulating member 40 can slow down the heat conduction and reduce the weight loss of the first insulating member 40 when the battery cell 7 experiences thermal runaway, thereby reducing the risk of insulation failure.

[0327] In some embodiments, the thermal conductivity of the first wall 211 is lower than that of the electrode terminal 30. During thermal runaway of the battery cell 7, the first wall 211 has a larger heat-receiving area and is more prone to heating. The lower thermal conductivity of the first wall 211 reduces the heat conducted from it to the first insulating member 40, thereby reducing thermal weight loss of the first insulating member 40 and lowering the risk of insulation failure.

[0328] In some embodiments, the thermal conductivity of the first wall 211 is less than or equal to 100 W / (m·K).

[0329] In some embodiments, the first wall 211 is made of steel. The electrode terminal 30 is made of aluminum or an aluminum alloy.

[0330] In some embodiments, the battery cell 7 further includes a pressure relief mechanism 50 disposed on the housing 20.

[0331] The pressure relief mechanism 50 can be installed on the first wall 211 or on other walls of the outer casing 20.

[0332] As an example, the pressure relief mechanism 50 is actuated to release internal pressure or temperature when the internal pressure or temperature of the battery cell 7 reaches a predetermined threshold. When the internal pressure or temperature of the battery cell 7 reaches the predetermined threshold, the pressure relief mechanism 50 performs its action or a weak structure provided in the pressure relief mechanism 50 is destroyed, thereby forming an opening or channel for the release of internal pressure or temperature. The threshold design varies depending on design requirements. The threshold may depend on the materials of one or more of the positive electrode, negative electrode, electrolyte, and separator in the battery cell 7.

[0333] The term "actuation" as used in this application refers to the activation or actuation of the pressure relief mechanism to a certain state, thereby releasing the internal pressure and temperature of the battery cell. The actions of the pressure relief mechanism may include, but are not limited to: movement of components within the mechanism to form an exhaust channel, rupture, breakage, tearing, or opening of at least a portion of the mechanism, etc. When the pressure relief mechanism is activated, the high-temperature, high-pressure substances inside the battery cell are discharged as waste from the activated portion. This method allows for pressure and temperature relief of the battery cell under controllable pressure or temperature, thereby preventing potentially more serious accidents.

[0334] In the event of thermal runaway of the battery cell 7, the pressure relief mechanism 50 can release the temperature and pressure inside the battery cell 7, thereby reducing the risk of the battery cell 7 exploding.

[0335] After the pressure relief mechanism 50 is activated, the temperature of the housing 20 and the electrode terminal 30 gradually decreases, thereby reducing the risk of failure of the first insulating component 40.

[0336] In some embodiments, the pressure relief mechanism 50 includes a pressure relief portion 51 and a weak portion 52 disposed along the outer periphery of the pressure relief portion 51.

[0337] The weak point 52 is a relatively weak part of the pressure relief mechanism 50, which is a part of the pressure relief mechanism 50 that is prone to breakage, fracture, tearing, or opening. For example, the strength of the pressure relief mechanism 50 is less than the strength of the portion of the pressure relief mechanism 50 near the weak point 52.

[0338] In some examples, this application may create grooves, notches, through holes, or other structures in a predetermined area of ​​the pressure relief mechanism 50 to reduce the local strength of the pressure relief mechanism 50, thereby forming a weak portion 52 in the pressure relief mechanism 50. For example, a thinning process may be performed on a predetermined area of ​​the pressure relief mechanism 50, and the thinned portion of the pressure relief mechanism 50 forms the weak portion 52. In other examples, the predetermined area of ​​the pressure relief mechanism 50 may be material-treated so that the strength of this area is weaker than that of other areas; in other words, this area is the weak portion 52.

[0339] The weak part 52 can rupture when the internal pressure or temperature of the battery cell 7 reaches a threshold; the pressure relief part 51 can be the part of the pressure relief mechanism 50 used to form a pressure relief channel when the weak part 52 ruptures.

[0340] In some examples, the weak portion 52 may surround the pressure relief portion 51. In the event of thermal runaway of the battery cell 7, the weak portion 52 ruptures at least partially; for example, the weak portion 52 ruptures completely, and the pressure relief portion 51 detaches from the casing 20, thereby forming a pressure relief channel; for example, the weak portion 52 ruptures partially, and the pressure relief portion 51 flips outward under the internal pressure of the battery cell 7 to form a pressure relief channel.

[0341] In other examples, the weak portion 52 may also partially surround the pressure relief portion 51. The line connecting the two ends of the weak portion 52 and the weak portion 52 together define the pressure relief portion 51. During thermal runaway of the battery cell 7, the weak portion 52 ruptures, and the pressure relief portion 51 can, under the internal pressure of the battery cell 7, rotate outward about the line connecting the two ends of the weak portion 52 as an axis to form a pressure relief channel. Optionally, with the center of the pressure relief portion 51 as the center, the line connecting one end of the weak portion 52 to the center is L1, and the line connecting the other end of the weak portion 52 to the center is L2. The angle α between L1 and L2 is greater than or equal to 180°, and the angle α is opposite to the weak portion 52. Optionally, α is greater than or equal to 270°.

[0342] In some embodiments, the area of ​​the pressure relief portion 51 is larger than the area of ​​the electrode lead-out hole 2111.

[0343] For example, the area of ​​the electrode lead-out hole 2111 can be the area of ​​the smallest cross-section of the electrode lead-out hole 2111 perpendicular to its own axial direction. The area of ​​the pressure relief part 51 can be the area of ​​the smallest cross-section of the pressure relief part 51 perpendicular to its own thickness direction Z.

[0344] Compared to the electrode lead-out hole 2111, the pressure relief section 51 can have a larger area, which allows for rapid release of internal temperature and pressure in the battery cell 7 during thermal runaway. Compared to the pressure relief section 51, the electrode lead-out hole 2111 can have a smaller area, which reduces the impact of the electrode lead-out hole 2111 on the strength of the first wall 211, reduces deformation of the portion of the first wall 211 near the electrode lead-out hole 2111, and lowers the risk of failure of the first insulating member 40.

[0345] In some embodiments, the pressure relief part 51 is circular, and the diameter φ1 of the pressure relief part 51 satisfies: 20mm≤φ1≤35mm. Optionally, 22mm≤φ1≤32mm.

[0346] In some embodiments, the electrode lead-out hole 2111 is a circular hole, and the diameter φ3 of the electrode lead-out hole 2111 satisfies: 8mm≤φ3≤25mm. Optionally, 10mm≤φ3≤20mm.

[0347] In some embodiments, the housing 20 includes a second wall 20a, and the pressure relief mechanism 50 is disposed on the second wall 20a.

[0348] For example, the second wall 20a can be a wall of the outer casing 20 that is directly connected to the first wall 211, or it can be a wall of the outer casing 20 that is opposite to the first wall 211.

[0349] In some examples, the pressure relief mechanism 50 and the second wall 20a are separately formed components, which can be connected by welding, bonding or other means. In other embodiments, the pressure relief mechanism 50 and the second wall 20a are integrally formed components; in other words, the pressure relief mechanism 50 may form part of the second wall 20a.

[0350] In this embodiment, the electrode terminal 30 and the pressure relief mechanism 50 are disposed on different walls, which can reduce the impact on the first insulating member 40 when the battery cell 7 experiences thermal runaway, and reduce the risk of failure of the first insulating member 40.

[0351] Specifically, when the battery cell 7 experiences thermal runaway, high-temperature gas is discharged outward through the pressure relief mechanism 50. The area of ​​the outer casing 20 near the pressure relief mechanism 50 is affected by the airflow and is prone to deformation. In this embodiment, the pressure relief mechanism 50 is disposed on the second wall 20a, which can reduce the impact of airflow on the first wall 211, reduce the deformation of the first wall 211, reduce the risk of the first insulating member 40 slipping between the first wall 211 and the electrode terminal 30, and reduce the risk of the first insulating member 40 being crushed, thereby improving the insulation effect.

[0352] In addition, when high-temperature gas is discharged, the temperature of the area of ​​the outer casing 20 near the pressure relief mechanism 50 is high; by placing the pressure relief mechanism 50 on the second wall 20a, the heat conducted to the first insulating member 40 can also be reduced.

[0353] By placing the pressure relief mechanism 50 on the second wall 20a, the high-temperature particles sputtered near the electrode terminal 30 can be reduced, thereby reducing the risk of insulation failure between the first wall 211 and the electrode terminal 30.

[0354] In some embodiments, the pressure relief mechanism 50 includes a pressure relief portion 51 and a weak portion 52 disposed along the outer periphery of the pressure relief portion 51. The area enclosed by the outer contour of the projection of the second wall 20a along its own thickness direction Z is S1, and the area of ​​the projection of the pressure relief portion onto the thickness direction Z of the second wall 20a is S2. 0.1≤S2 / S1≤0.8.

[0355] As an example, S2 / S1 can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7 or 0.8.

[0356] In this embodiment, limiting S2 / S1 to greater than or equal to 0.1 allows the pressure relief mechanism 50 to form a larger pressure relief channel in the event of thermal runaway of the battery cell 7, thereby increasing the rate of temperature and pressure release within the battery cell 7 and reducing the risk of explosion. Limiting S2 / S1 to greater than or equal to 0.1 also shortens the time the first insulating member 40 is exposed to high-temperature environments, reduces weight loss of the first insulating member 40, lowers the risk of insulation failure, and improves the reliability of the battery cell 7.

[0357] Limiting S2 / S1 to less than or equal to 0.8 can restrict the range of the weak part 52, reduce the impact of the weak part 52 on the strength of the second wall 20a, reduce the risk of the weak part 52 breaking during normal use of the battery cell 7, and improve the reliability of the battery cell 7.

[0358] In some embodiments, 0.3 ≤ S2 / S1 ≤ 0.7 can further improve the reliability of the battery cell 7.

[0359] In some embodiments, the pressure relief mechanism 50 is integrally formed with the second wall 20a. Exemplarily, the second wall 20a is provided with a third recess 221, and the weak portion 52 includes the bottom wall of the third recess 221. The third recess 221 is disposed around the pressure relief portion 51.

[0360] In some embodiments, the battery cell 7 is a cylindrical battery cell. Cylindrical battery cells have advantages such as mature manufacturing processes, good consistency, good heat dissipation performance, and high packing efficiency.

[0361] In some embodiments, the first wall 211 and the second wall 20a are arranged opposite each other along the axial direction of the cylindrical battery cell. The pressure relief mechanism 50 includes a pressure relief portion 51 and a weak portion 52 disposed along the outer periphery of the pressure relief portion 51, the pressure relief portion 51 being circular. The diameter φ1 of the pressure relief portion 51 and the diameter φ2 of the cylindrical battery cell satisfy the following relationship: 0.35≤φ1 / φ2≤0.85.

[0362] As an example, φ1 / φ2 can be 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, or 0.85.

[0363] As an example, the axial direction of a cylindrical battery cell is parallel to the thickness direction Z.

[0364] In this embodiment, limiting φ1 / φ2 to greater than or equal to 0.35 allows the pressure relief mechanism 50 to form a larger pressure relief channel in the event of thermal runaway of the battery cell 7, thereby increasing the rate of temperature and pressure release within the battery cell 7 and reducing the risk of explosion. Limiting φ1 / φ2 to greater than or equal to 0.35 also shortens the time the first insulating member 40 is exposed to high-temperature environments, reduces weight loss in the first insulating member 40, lowers the risk of insulation failure, and improves the reliability of the battery cell 7.

[0365] Limiting φ1 / φ2 to less than or equal to 0.85 can restrict the range of the weak part 52, reduce the impact of the weak part 52 on the strength of the second wall 20a, reduce the risk of the weak part 52 breaking during normal use of the battery cell 7, and improve the reliability of the battery cell 7.

[0366] In some embodiments, the battery cell 7 is a cylindrical battery cell with a diameter φ2 greater than or equal to 35 mm and less than or equal to 70 mm.

[0367] As an example, the diameter φ2 of the cylindrical battery cell is 35mm, 40mm, 45mm, 50mm, 55mm, 60mm, 65mm or 70mm.

[0368] Setting the diameter φ2 of the cylindrical battery cell to be greater than or equal to 35 mm can improve the capacity and energy density of the cylindrical battery cell. The diameter of the cylindrical battery cell is related to the heat generation during thermal runaway. Setting the diameter of the cylindrical battery cell to be less than or equal to 70 mm can limit the maximum temperature of the cylindrical battery cell during thermal runaway and reduce the risk of failure of the first insulating component 40.

[0369] Optionally, the diameter φ2 of the cylindrical battery cell is 45mm to 60mm.

[0370] In some embodiments, the height of the housing 20 is 50 mm to 150 mm. For example, the height of the housing 20 is 50 mm, 55 mm, 60 mm, 65 mm, 70 mm, 75 mm, 80 mm, 85 mm, 90 mm, 95 mm, 100 mm, 105 mm, 110 mm, 115 mm, 120 mm, 125 mm, 130 mm, 135 mm, 140 mm, 145 mm, or 150 mm.

[0371] Optionally, the height of the housing 20 is 60mm-100mm.

[0372] In some embodiments, the height of the housing 20 is 1.3 to 4 times the diameter of the housing 20. Exemplarily, the height of the housing 20 may be the dimension of the housing 20 along the axial direction of the cylindrical battery cell.

[0373] Optionally, the height of the outer casing 20 is 1.3 times, 1.4 times, 1.5 times, 1.6 times, 1.7 times, 1.8 times, 1.9 times, 2.0 times, 2.1 times, 2.2 times, 2.3 times, 2.4 times, 2.5 times, 2.6 times, 2.7 times, 2.8 times, 2.9 times, 3.0 times, 3.1 times, 3.2 times, 3.3 times, 3.4 times, 3.5 times, 3.6 times, 3.7 times, 3.8 times, 3.9 times, or 4.0 times the diameter of the outer casing 20.

[0374] When the housing 20 meets the above-mentioned dimensional requirements, the structural stability of the housing 20 is high, which can improve the reliability of the cylindrical battery cell.

[0375] In some embodiments, the height of the housing 20 is 1.5 to 2.5 times the diameter of the housing 20.

[0376] In some embodiments, the thickness t3 of the first wall 211 is greater than the thickness t4 of the second wall 20a.

[0377] In the event of thermal runaway of the battery cell 7, the deformation of the first wall 211 is smaller than that of the second wall 20a. This reduces the risk of the first insulating member 40 shifting between the first wall 211 and the electrode terminal 30, as well as the risk of the first insulating member 40 being crushed, thus improving the insulation effect and increasing the reliability of the battery cell 7. In the event of thermal runaway of the battery cell 7, the second wall 20a is more likely to bulge outwards than the first wall 211. This increases the gas flow channel inside the second wall 20a, improving gas emission efficiency.

[0378] In some embodiments, t3 / t4 ≥ 1.5.

[0379] In some embodiments, 0.5mm ≤ t3 ≤ 2mm. Optionally, 0.5mm ≤ t3 ≤ 1.5mm.

[0380] In some embodiments, 0.3mm ≤ t4 ≤ 1.8mm. Optionally, 0.4mm ≤ t4 ≤ 1.3mm.

[0381] In some embodiments, the first wall 211 and the second wall 20a are located on opposite sides of the electrode assembly 10. The housing 20 also includes a side wall 212. The side wall 212 surrounds the electrode assembly 10 and connects the first wall 211 and the second wall 20a.

[0382] In some examples, the sidewall 212 and the first wall 211 may be integrally formed. In other examples, the sidewall 212 and the first wall 211 may also be formed independently and joined together by bonding, snap-fitting, welding or other means.

[0383] In some examples, the sidewall 212 and the second wall 20a may be integrally formed. In other examples, the sidewall 212 and the second wall 20a may also be formed independently and joined together by bonding, snap-fitting, welding or other means.

[0384] In some examples, the battery cell 7 is a cylindrical battery cell, and the side wall 212 may be a cylindrical structure. In other examples, the battery cell 7 is a prismatic battery cell, and the side wall 212 may be a prismatic structure.

[0385] When the battery cell 7 experiences thermal runaway, high-temperature gas will flow through the pressure relief channel formed by the pressure relief mechanism 50. During the release of high-temperature gas, the part of the outer casing 20 near the pressure relief channel is prone to deformation under the action of airflow.

[0386] In this embodiment, the electrode terminal 30 and the pressure relief mechanism 50 are respectively disposed on both sides of the electrode assembly 10. During the process of releasing high-temperature gas, the deformation of the first wall 211 can be reduced, the risk of the first insulating member 40 shifting between the first wall 211 and the electrode terminal 30 and the risk of the first insulating member 40 being crushed can be reduced, the insulation effect can be improved, and the reliability of the battery cell 7 can be increased.

[0387] During the release of high-temperature gas, some of the heat will be conducted to the second wall 20a. The second wall 20a is farther away from the first wall 211, which can reduce the heat conducted to the first wall 211 and the first insulating member 40, thereby reducing the thermal weight loss of the first insulating member 40, improving the insulation effect, and increasing the reliability of the battery cell 7.

[0388] In some embodiments, the thickness of the first wall 211 is greater than the thickness of the side wall 212.

[0389] In the event of thermal runaway of the battery cell 7, the deformation of the thicker first wall 211 is smaller, thereby reducing the risk of the first insulating member 40 shifting between the first wall 211 and the electrode terminal 30 and the risk of the first insulating member 40 being crushed, improving the insulation effect and enhancing the reliability of the battery cell 7. In the event of thermal runaway of the battery cell 7, the thinner sidewall 212 can bulge outwards, increasing the distance between the sidewall 212 and the electrode assembly 10, which facilitates gas venting.

[0390] In some embodiments, the housing 20 includes a housing 21 and an end cap 22. The housing 21 includes an integrally formed first wall 211 and a side wall 212. The end cap 22 is a second wall 20a and is sealed to the side wall 212.

[0391] The end cap 22 can be insulated from the side wall 212 or electrically connected.

[0392] The end of the housing 21 away from the first wall 211 has an opening, and the end cap 22 covers the opening of the housing 21.

[0393] The first wall 211 and the side wall 212 are integrally formed, and the connection strength between the first wall 211 and the side wall 212 is high. When the battery cell 7 experiences thermal runaway, the side wall 212 can restrain the first wall 211, reduce the deformation of the first wall 211, reduce the risk of the first insulating member 40 shifting between the first wall 211 and the electrode terminal 30, and reduce the risk of the first insulating member 40 being crushed, thereby improving the insulation effect and increasing the reliability of the battery cell 7.

[0394] In some embodiments, the sidewall 212 is made of steel.

[0395] In some embodiments, the thickness of the sidewall 212 is 0.3 mm to 1.5 mm.

[0396] As an example, the thickness of the sidewall 212 is 0.3mm, 0.31mm, 0.32mm, 0.33mm, 0.35mm, 0.38mm, 0.40mm, 0.42mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, 0.95mm, 1mm, 1.05mm, 1.1mm, 1.15mm, 1.2mm, 1.3mm, 1.35mm, 1.4mm, 1.45mm, or 1.5mm.

[0397] In the embodiments of this application, the thickness of the sidewall 212 has a meaning known in the art and can be detected using equipment and methods known in the art, such as a micrometer or vernier caliper.

[0398] As an example, the material of sidewall 212 includes stainless steel.

[0399] In some embodiments, the thickness of the sidewall 212 is 0.3 mm to 1.2 mm.

[0400] In some embodiments, the thickness of the sidewall 212 is 0.3 mm to 0.9 mm, optionally 0.3 mm to 0.6 mm.

[0401] In some embodiments, the material of the first wall 211 is the same as the material of the side wall 212.

[0402] In some embodiments, the end cap 22 is made of steel.

[0403] In some embodiments, the electrode assembly 10 has a first through hole 10d at its center.

[0404] In some examples, the electrode assembly 10 is a wound structure, and the first through hole 10d is formed at the winding center of the electrode assembly 10.

[0405] In some embodiments, the first through hole 10d is disposed between the electrode terminal 30 and the pressure relief mechanism 50 along the extending direction of the first through hole 10d.

[0406] When the battery cell 7 experiences thermal runaway, the gas between the electrode assembly 10 and the first wall 211 can flow to the pressure relief mechanism 50 through the first through hole 10d, thereby reducing the pressure on the first wall 211 and the electrode terminal 30, reducing the deformation of the first wall 211, reducing the risk of the first insulating member 40 shifting between the first wall 211 and the electrode terminal 30, and reducing the risk of the first insulating member 40 being crushed, thus improving insulation reliability.

[0407] In some embodiments, the extension direction of the first through hole 10d is parallel to the thickness direction Z of the first wall 211.

[0408] In some embodiments, a first tab 10a is disposed at one end of the electrode assembly 10 facing the first wall 211, and a second tab 10b is disposed at one end of the electrode assembly 10 facing the second wall 20a. The first tab 10a and the second tab 10b are respectively disposed at opposite ends of the electrode assembly 10, which can reduce the risk of the first tab 10a and the second tab 10b coming into contact.

[0409] In other embodiments, both the first tab 10a and the second tab 10b are disposed at the end of the electrode assembly 10 facing the first wall 211. The second tab 10b can be directly connected to the first wall 211, or it can be indirectly connected to the first wall 211 through other conductive structures.

[0410] In some embodiments, the battery cell 7 further includes a first current collector 81, which is connected to the first tab 10a and the electrode terminal 30.

[0411] In some embodiments, the first current collector 81 is located on the side of the first tab 10a facing the first wall 211 and is connected to the first tab 10a. The electrode terminal 30 abuts against and is connected to the surface of the first current collector 81 facing the first wall 211.

[0412] The first current collector 81 can act as a converter to realize the electrical connection between the first tab 10a and the electrode terminal 30.

[0413] In some embodiments, the electrode terminal 30 is provided with a terminal recess 34. The bottom wall of the terminal recess 34 is welded to the first current collector 81.

[0414] The terminal recess 34 can be provided on the side of the electrode terminal 30 facing the first current collector 81, or it can be provided on the side of the electrode terminal 30 away from the first current collector 81.

[0415] By providing the terminal recess 34, the thickness of the bottom wall of the terminal recess 34 can be reduced, the power required to weld the electrode terminal 30 to the first current collector 81 from the outside can be reduced, the risk of welding particles falling into the casing 20 can be reduced, and the reliability of the battery cell 7 can be improved.

[0416] In some embodiments, the electrode terminal 30 has a terminal recess 34 on the side opposite to the first current collector 81.

[0417] In some embodiments, the electrode terminal 30 has a terminal recess 34 on the side facing the first current collector 81, and another terminal recess 34 on the side of the electrode terminal 30 away from the first current collector 81; the corresponding portions of the bottom surfaces of the two terminal recesses 34 are welded to the first current collector 81.

[0418] In some embodiments, the bottom wall of the terminal recess 34 is provided with a second through hole 311, which can be used to inject electrolyte.

[0419] In some embodiments, the battery cell 7 further includes a cover plate 82, which is connected to the electrode terminal 30 and serves to separate the second through hole 311 from the external space of the battery cell 7.

[0420] In some embodiments, at least a portion of the cover plate 82 is accommodated in the terminal recess 34.

[0421] In some embodiments, the battery cell 7 further includes a sealing pin 83, which is inserted into the second through hole 311 and seals the second through hole 311.

[0422] In some embodiments, the first electrode tab 10a is a positive electrode tab 1111, and the positive electrode lead-out portion includes a cover plate 82 and an electrode terminal 30; alternatively, the first electrode tab 10a is a negative electrode tab 1211, and the negative electrode lead-out portion includes a cover plate 82 and an electrode terminal 30.

[0423] In some embodiments, a terminal recess 34 is formed on the terminal body 31.

[0424] In some embodiments, the battery cell 7 further includes a second current collector 84, a second tab 10b connected to the second current collector 84, and at least one of the sidewall 212 and the second wall 20a connected to the second current collector 84, so that the sidewall 212 is electrically connected to the first wall 211 and the second current collector 84.

[0425] In some examples, the second current collector 84 is connected to the second wall 20a, which is electrically connected to the side wall 212. The second tab 10b is electrically connected to the first wall 211 via the second current collector 84, the second wall 20a, and the side wall 212.

[0426] In other examples, the second current collector 84 is connected to the sidewall 212. The second tab 10b is electrically connected to the first wall 211 via the second current collector 84 and the sidewall 212. Optionally, the first wall 211 is insulated from the sidewall 212.

[0427] Before the battery cell 7 experiences thermal runaway and the pressure relief mechanism 50 is activated, the side wall 212 or the second wall 20a can bind the first wall 211 of the electrode terminal 30 through the second current collector 84, the electrode assembly 10 and the first current collector 81, thereby reducing the deformation of the first wall 211 during the process of increasing internal pressure in the battery cell 7.

[0428] In some embodiments, the second current collector 84 is connected to the second wall 20a. Optionally, the second wall 20a is welded to the side wall 212.

[0429] In some embodiments, the electrode assembly 10 includes a positive electrode sheet 11, the positive electrode sheet 11 includes a positive current collector 111 and a positive electrode film layer 112 disposed on at least one side of the positive current collector 111, the positive electrode film layer 112 includes a positive electrode active material, the positive electrode active material includes a layered transition metal oxide.

[0430] Layered transition metal oxides include those with the chemical formula Li a Ni b Co c M d O e A f The compound and its modified compounds contain at least one of the following: 0.8≤a≤1.2, 0.8≤b≤0.95, 0<c<1, 0<d<1, 1≤e≤2, 0≤f≤1, M includes at least one of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, and A includes at least one of N, F, S and Cl.

[0431] For example, b is 0.8, 0.82, 0.84, 0.85, 0.88, 0.9, 0.92, 0.94, or 0.95.

[0432] As an example, examples of layered transition metal oxides may include, but are not limited to, LiNi. 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 LiNi 0.9 Co 0.05 Mn 0.05 O2 (also known as Ni) 90 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.80 Co 0.15 Al 0.05 At least one of O2 and its modified compounds.

[0433] Battery cells with higher nickel content have advantages such as high energy density, good low-temperature performance, and good charge and discharge performance.

[0434] Specifically, the positive electrode film layer 112 has a higher nickel content, enabling it to store more electrical energy, thus significantly improving the energy density of the battery cell 7. With the increase in nickel content, the amount of cobalt used is relatively reduced. Cobalt is a scarce and expensive metal; reducing cobalt usage lowers the cost of the battery cell 7. The battery cell 7 with a higher nickel content has higher conductivity, meaning it can operate at higher power, supporting fast charging and high-current discharge. In low-temperature environments, the battery cell 7 with a higher nickel content exhibits relatively less capacity decay, maintaining high discharge efficiency and allowing electrical equipment to operate normally in low-temperature conditions.

[0435] However, the high-nickel content battery cell 7 has relatively poor thermal stability, and it generates more heat and experiences a higher temperature rise during thermal runaway. In this embodiment, a high-temperature resistant first insulating member 40 is provided between the first wall 211 and the electrode terminal 30. The first insulating member 40 can withstand the high temperature generated by the high-nickel battery cell 7 during thermal runaway, thereby suppressing the current between the electrode terminal 30 and the first wall 211 and reducing the continuous heat generation between the electrode terminal 30 and the first wall 211.

[0436] In this embodiment, b is set to less than or equal to 0.95, which can reduce the maximum temperature of the battery cell 7 during thermal runaway and reduce the risk of the first insulating member 40 losing excessive weight due to excessive temperature.

[0437] In some embodiments, 0.8 ≤ b ≤ 0.95, and optionally, 0.85 ≤ b ≤ 0.90.

[0438] In some embodiments, the battery cell 7 further includes an electrolyte contained within the housing 20. The electrolyte comprises a chain ester solvent, wherein the chain ester solvent comprises 25.5 wt% to 76.5 wt% by mass in the electrolyte.

[0439] For example, the mass percentage of the chain ester solvent in the electrolyte is 25.5 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt%, 30 wt%, 32 wt%, 35 wt%, 38 wt%, 40 wt%, 42 wt%, 45 wt%, 48 wt%, 50 wt%, 52 wt%, 55 wt%, 58 wt%, 60 wt%, 62 wt%, 65 wt%, 68 wt%, 70 wt%, 72 wt%, 75 wt%, 76.5 wt%, or any range of two of the above values.

[0440] In this embodiment, the mass percentage of the chain ester solvent is greater than or equal to 25.5 wt%, resulting in a relatively high electrolyte conductivity. This is beneficial for improving the liquid-phase transport capability of active ions, enhancing the fast charging and discharging capability of the battery cell 7, and thus improving the rate performance of the battery cell 7. The mass percentage of the chain ester solvent is also greater than or equal to 25.5 wt%, which also results in a relatively low viscosity of the electrolyte system, making it easier to flow and wet the electrode assembly 10. This further improves the fast charging and discharging capability of the battery cell 7, thereby enhancing its rate performance.

[0441] Chain-like ester solvents may decompose and generate gas during the cyclic charging and discharging of battery cell 7. In this embodiment, the mass percentage of chain-like ester solvents is set to less than or equal to 76.5 wt%, which can limit the internal pressure of battery cell 7, reduce the deformation of the outer casing 20, reduce the risk of battery cell 7 failure, and improve reliability.

[0442] In some embodiments, the chain ester solvent has a mass percentage content of 42.5 wt% to 70 wt% in the electrolyte, which can further balance the rate performance and reliability of the battery cell 7 and improve the cycle performance of the battery cell 7.

[0443] In some embodiments, the chain ester solvent includes at least one of chain carbonates and chain carboxylic esters.

[0444] In some embodiments, the chain ester solvent includes chain carbonates and chain carboxylic esters. The combined use of chain carboxylic esters and chain carbonates can improve the conductivity of the electrolyte, enhance the liquid phase transport kinetics of the electrolyte, and further improve the rate performance and reliability of the battery cell 7.

[0445] Figure 15 is a partial cross-sectional view of a battery cell provided in some embodiments of this application; Figure 16 is an enlarged view of Figure 15 at the boxed area.

[0446] Referring to Figures 15 and 16, at least a portion of the first insulating member 40 is located between the inner surface 2113 of the first wall 211 and the electrode terminal 30 in the thickness direction Z of the first wall 211, thereby reducing the risk of the electrode terminal 30 becoming conductive with the first wall 211 in the event of thermal runaway of the battery cell 7.

[0447] In some embodiments, at least a portion of the first insulating member 40 is bonded to the inner surface 2113 of the first wall 211.

[0448] In some embodiments, portions of the seal 60 and the first insulating member 40 are stacked in the thickness direction Z to improve the isolation effect and reduce the risk of the electrode terminal 30 contacting the first wall 211 in the event of thermal runaway of the battery cell 7.

[0449] In some embodiments, the second insulating portion 42 and the second sealing portion 62 at least partially overlap within the electrode lead-out hole 2111 in the radial direction of the electrode lead-out hole 2111.

[0450] The second insulating part 42 and the second sealing part 62 can provide double isolation in the radial direction of the electrode lead-out hole 2111, reducing the risk of the electrode terminal 30 contacting the first wall 211 in the event of thermal runaway of the battery cell 7.

[0451] In some embodiments, the first insulating member 40 further includes a third insulating portion 43. In the thickness direction Z, a portion of the third insulating portion 43 is stacked with a portion of the first sealing portion 61 between the first wall 211 and the second limiting portion 33.

[0452] In some embodiments, the end of the third insulating portion 43 facing the terminal body 31 is connected to the second insulating portion 42.

[0453] In some embodiments, the third insulating portion 43 is bonded to the inner surface 2113. At least a portion of the first sealing portion 61 is sandwiched between the third insulating portion 43 and the second limiting portion 33.

[0454] In some embodiments, in the direction from the terminal body 31 to the second limiting portion 33, the third insulating portion 43 protrudes from the end of the second limiting portion 33 away from the terminal body 31. The third insulating portion 43 can isolate the second limiting portion 33 from the first wall 211.

[0455] In some embodiments, in the thickness direction Z, the third insulating portion 43 covers the outer end of the first sealing portion 61 away from the terminal body 31 and the inner end of the third insulating member 80 near the terminal body 31.

[0456] In some embodiments, the first sealing portion 61 partially overlaps with the third insulating member 80 in the thickness direction Z.

[0457] In some embodiments, the first insulating portion 41 and the third insulating portion 43 are formed independently. Optionally, one of the first insulating portion 41 and the third insulating portion 43 is integrally formed with the second insulating portion 42.

[0458] Figure 17 is a partial cross-sectional view of a battery cell provided in some embodiments of this application; Figure 18 is an enlarged view of Figure 17 at the boxed area; Figure 19 is an enlarged view of Figure 18 at the boxed area.

[0459] Referring to Figures 17 to 19, in some embodiments, at least a portion of the second insulating member 70 is disposed between the first insulating member 40 and the first wall 211.

[0460] In some embodiments, the first insulating member 40 is attached to the surface of the electrode terminal 30.

[0461] In some embodiments, the first insulating member 40 includes a first insulating portion 41, which is attached to the surface of the first limiting portion 32.

[0462] Optionally, a portion of the first insulating portion 41 is attached to the surface of the first limiting portion 32 facing the first wall 211, and another portion of the first insulating portion 41 is attached to the outer peripheral surface of the first limiting portion 32.

[0463] In some embodiments, the first insulating member 40 includes a second insulating portion 42 connected to the first insulating portion 41, and the second insulating portion 42 is attached to the outer peripheral surface of the terminal body 31.

[0464] In some embodiments, the first insulating member 40 includes a third insulating portion 43, which is attached to the surface of the second limiting portion 33.

[0465] Optionally, a portion of the third insulating portion 43 is attached to the surface of the second limiting portion 33 facing the first wall 211, and another portion of the third insulating portion 43 is attached to the outer peripheral surface of the second limiting portion 33.

[0466] Figure 20 is a partial cross-sectional view of a battery cell provided in some other embodiments of this application; Figure 21 is an enlarged view of Figure 20 at the boxed area.

[0467] Referring to Figures 20 and 21, in some embodiments, a portion of the second insulating member 70 is disposed between the first insulating member 40 and the first wall 211, and another portion of the second insulating member 70 is disposed between the first insulating member 40 and the electrode terminal 30.

[0468] In some embodiments, at least a portion of the first insulating member 40 is embedded in the second insulating member 70.

[0469] Optionally, the first insulating member 40 is integrally embedded in the second insulating member 70.

[0470] Optionally, the first insulating member 40 includes a ceramic layer composed of alumina, titanium oxide, silicon oxide, zirconium oxide, or glass.

[0471] Optionally, the first insulating member 40 comprises thermosetting polyimide.

[0472] Figure 22 is a partial cross-sectional schematic diagram of a battery cell provided in some other embodiments of this application.

[0473] Referring to FIG22, in some embodiments, the second insulating member 70 may be omitted. The first insulating member 40 can provide insulation when the battery cell 7 is operating normally and can maintain the isolation between the electrode terminal 30 and the first wall 211 in the event of thermal runaway of the battery cell 7.

[0474] In some embodiments, the third insulating member 80 and the first insulating member 40 may be made of the same material to improve the high temperature resistance of the third insulating member 80.

[0475] Figure 23 is a partial cross-sectional view of a battery cell provided in some other embodiments of this application; Figure 24 is an enlarged view of Figure 23 at the boxed area.

[0476] Referring to Figures 23 and 24, in some embodiments, the first insulating member 40 and the second insulating member 70 at least partially overlap in the thickness direction Z.

[0477] In some embodiments, at least a portion of the first insulating member 40 is disposed between the second insulating member 70 and the first wall 211 in the thickness direction Z.

[0478] In some embodiments, the first insulating member 40 is annular. The first insulating member 40 is disposed around the terminal body 31. In other embodiments, there are multiple first insulating members 40, which are spaced apart circumferentially along the terminal body 31.

[0479] In some embodiments, the second insulating member 70 is provided with a fourth recess 73, and at least a portion of the first insulating member 40 is accommodated in the fourth recess 73.

[0480] In some embodiments, the first insulating member 40 may be a ceramic component. Exemplarily, the first insulating member 40 may be made of alumina, titanium oxide, silicon oxide, zirconium oxide, glass, etc.

[0481] Figure 25 is a partial cross-sectional view of a battery cell provided in some other embodiments of this application; Figure 26 is an enlarged view of Figure 25 at the boxed area.

[0482] In some embodiments, the battery cell further includes a fifth insulating member 87. At least a portion of the fifth insulating member 87 is disposed between the electrode terminal 30 and the first wall 211. For example, at least a portion of the fifth insulating member 87 is disposed between the second limiting portion 33 and the first wall 211.

[0483] In some embodiments, the thermal weight loss temperature of the fifth insulating member 87 is greater than or equal to 300°C.

[0484] In some embodiments, the material of the fifth insulating member 87 is the same as the material of the first insulating member 40.

[0485] In some embodiments, the fifth insulating member 87 may include a ceramic component. As an example, the fifth insulating member 87 may be made of alumina, titanium dioxide, silicon dioxide, zirconium oxide, glass, etc.

[0486] In some embodiments, the fifth insulating member 87 at least partially overlaps with the third insulating member 80 in the thickness direction Z.

[0487] In some embodiments, at least a portion of the fifth insulating member 87 is disposed between the third insulating member 80 and the second limiting portion 33 in the thickness direction Z.

[0488] In some embodiments, the fifth insulating member 87 is annular. The fifth insulating member 87 is disposed around the terminal body 31. In other embodiments, there are multiple fifth insulating members 87, which are spaced apart circumferentially along the terminal body 31. For example, the fifth insulating member 87 is a ceramic post.

[0489] In some embodiments, the third insulating member 80 has a fifth recess 80a on the side facing the second limiting portion 33, and the second limiting portion 33 has a sixth recess 331 on the side facing the third insulating member 80. A portion of the fifth insulating member 87 is accommodated in the fifth recess 80a, and another portion is accommodated in the sixth recess 331.

[0490] The fifth recess 80a and the sixth recess 331 can position the fifth insulating member 87.

[0491] Figure 27 is a partial cross-sectional schematic diagram of a battery cell provided in some other embodiments of this application.

[0492] Referring to FIG27, in some embodiments, the sidewall 212 is provided with an inwardly projecting protrusion 2121. In the thickness direction Z of the first wall 211, at least a portion of the protrusion 2121 is located between the end cap 22 and the second tab 10b.

[0493] For example, the protrusion 2121 can be a solid structure or a hollow structure.

[0494] The protrusion 2121 overlaps with the second tab 10b in the thickness direction Z. When the battery cell 7 is subjected to external impact, it can restrict the movement of the second tab 10b in the thickness direction Z and reduce the risk of failure of the connection between the second tab 10b and the second current collector 84.

[0495] In some embodiments, the second current collector 84 is connected to the protrusion 2121. As an example, the second current collector 84 may be welded to the protrusion 2121; alternatively, the second current collector 84 may also be press-fitted to the protrusion 2121.

[0496] For example, the second current collector 84 is connected to the side of the protrusion 2121 facing the second electrode 10b, or it can be connected to the side of the protrusion 2121 facing the end cap 22.

[0497] Connecting the second current collector 84 to the protrusion 2121 can shorten the conductive path between the second tab 10b and the first wall 211, reduce resistance, reduce heat generation, and improve the cycle performance of the battery cell 7.

[0498] In some embodiments, a portion of the second current collector 84 is located on the side of the protrusion 2121 facing the end cap 22 and is connected to the protrusion 2121. The second current collector 84 is connected to the protrusion 2121 from the outside of the protrusion 2121, which can reduce assembly difficulty.

[0499] In some embodiments, the second current collector 84 is welded to the protrusion 2121.

[0500] In some embodiments, a second recess 2122 is provided on the outer side of the sidewall 212, and the second recess 2122 corresponds to the position of the protrusion 2121. As an example, after the electrode assembly 10 is installed into the housing 21, the inwardly protruding protrusion 2121 is formed by pressing the sidewall 212 from the outside.

[0501] In some embodiments, the sidewall 212 further includes a crimping portion 2123, which extends from the end of the protrusion 2121 away from the first wall 211 and surrounds the end cap 22.

[0502] A portion of the crimping part 2123 is bent to form a flange structure, and a portion of the end cap 22 is located between the flange structure and the protrusion 2121 in the thickness direction Z. The protrusion 2121 and the flange structure can limit the end cap 22 to fix the end cap 22 in the thickness direction Z.

[0503] In some embodiments, the battery cell 7 further includes a fourth insulating member 85, which is disposed between the sidewall 212 and the end cap 22 and insulates the end cap 22 from the sidewall 212.

[0504] In some embodiments, a portion of the fourth insulating member 85 is located between the second current collector 84 and the end cap 22 to insulate the second current collector 84 from the end cap 22.

[0505] Figure 28 is a schematic diagram of the first insulating component and adhesive layer of a battery cell provided in some embodiments of this application.

[0506] Referring to Figures 12 and 28, in some embodiments, the battery cell 7 further includes an adhesive layer 86.

[0507] In some embodiments, the adhesive layer 86 adheres the first insulating member 40 to the surface of the first wall 211.

[0508] In other embodiments, adhesive layer 86 adheres the first insulating member 40 to the surface of electrode terminal 30.

[0509] In some other embodiments, adhesive layers 86 are provided on both sides of the first insulating member 40. The adhesive layer 86 on one side of the first insulating member 40 bonds the first insulating member 40 to the surface of the first wall 211, and the adhesive layer 86 on the other side of the first insulating member 40 bonds the first insulating member 40 to the surface of the first wall 211.

[0510] The adhesive layer 86 can fix the first insulating member 40 to reduce the risk of the first insulating member 40 shifting during the use of the battery cell 7.

[0511] In some embodiments, the thickness t5 of the first insulating member 40 is greater than or equal to the thickness t6 of the adhesive layer 86.

[0512] Compared to the adhesive layer 86, the first insulating member 40 can have a larger thickness to reduce the risk of the first insulating member 40 being cracked or punctured, and to improve the insulation reliability.

[0513] In some embodiments, the ratio of the thickness t5 of the first insulating member 40 to the thickness t6 of the adhesive layer 86 is 1-5.

[0514] t5 / t6 can be 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 or 5.

[0515] In this embodiment, limiting t5 / t6 to greater than or equal to 1 allows the first insulating member 40 to have a larger thickness, reducing the risk of the first insulating member 40 being cracked or punctured and improving insulation reliability. Limiting t5 / t6 to less than or equal to 5 allows the adhesive layer 86 to have higher adhesive strength, reducing the risk of the first insulating member 40 detaching.

[0516] In some embodiments, 5μm ≤ t5 ≤ 100μm. Optionally, t5 is 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, or 100μm.

[0517] In some embodiments, 20 μm ≤ t5 ≤ 60 μm. Optionally, 25 μm ≤ t5 ≤ 50 μm.

[0518] In some embodiments, 3μm≤t6≤80μm. Optionally, t6 is 3μm, 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm or 80μm.

[0519] In some embodiments, 15μm≤t6≤50μm.

[0520] In some embodiments, adhesive layer 86 comprises a thermosetting material. Optionally, adhesive layer 86 comprises a thermosetting phenolic resin.

[0521] Figure 29 is an exploded view of a battery cell provided in some other embodiments of this application; Figure 30 is a partial cross-sectional view of a battery cell provided in some other embodiments of this application.

[0522] Referring to Figures 29 and 30, in some embodiments, the battery cell 7 is a square-shell battery cell. Exemplarily, the sidewall 212 is a square tube.

[0523] In some embodiments, the housing 20 includes a housing 21 and an end cap 22. The housing 21 includes an integrally formed second wall 20a and a side wall 212. The end cap 22 is a first wall 211 and is sealed to the side wall 212.

[0524] In some embodiments, the second limiting part 33 is integrally formed with the terminal body 31, and the first limiting part 32 is riveted to the terminal body 31.

[0525] In some embodiments, the battery cell 7 may include an electrode lead-out portion 90 disposed on the end cap 22, the electrode lead-out portion 90 being electrically connected to the second tab 10b and the end cap 22. The electrode lead-out portion 90 and the electrode terminal 30 may serve as two electrodes of the battery cell 7.

[0526] In some embodiments, the second tab 10b can be a positive tab 1111, and the end cap 22 can be made of aluminum or aluminum alloy. Electrically connecting the second tab 10b to the end cap 22 can keep the end cap 22 at a high potential, reducing the risk of the end cap 22 being corroded by the electrolyte.

[0527] In other embodiments, the second tab 10b may be the negative tab 1211, and the end cap 22 may be made of steel.

[0528] Figure 31 is a simplified schematic diagram of a battery device provided in some other embodiments of this application.

[0529] Referring to FIG31, this application also provides a battery device 2, including a plurality of battery cells 7 of any of the above embodiments.

[0530] In some embodiments, the battery device 2 further includes a plurality of busbars 8 that electrically connect a plurality of battery cells 7.

[0531] In some embodiments, at least two battery cells 7 are connected in parallel.

[0532] For example, at least two battery cells 7 are connected in parallel to form a battery cell 7a, and multiple battery cells 7a are connected in series. The multiple battery cells 7 of the battery device 2 form a multi-parallel series structure. The multi-parallel series structure can improve reliability. If a battery cell 7 fails due to an accident (such as thermal runaway), the battery cells 7 connected in parallel with that battery cell 7 can still operate normally, reducing the risk of complete circuit failure.

[0533] When a battery cell 7 experiences thermal runaway, the normal battery cells 7 connected in parallel with the thermally runaway battery cell 7 may be electrically connected to the first wall 211 and the electrode terminal 30 of the thermally runaway battery cell 7, respectively. The first insulating member 40 can suppress the current between the electrode terminal 30 and the first wall 211, reduce the continuous heat generation between the electrode terminal 30 and the first wall 211, reduce the thermal impact on other surrounding battery cells 7, lower the risk of thermal runaway in other battery cells 7, and improve reliability.

[0534] According to some embodiments of this application, this application also provides an electrical device, including a battery cell 7 of any of the above embodiments, wherein the battery cell 7 is used to provide electrical energy to the electrical device. The electrical device can be any of the aforementioned devices or systems that utilize the battery cell 7.

[0535] Referring to Figures 4 to 14, an embodiment of this application provides a cylindrical battery cell, which includes a housing 20, electrode terminals 30, electrode assembly 10, a first insulating member 40, a second insulating member 70, a third insulating member 80, and a sealing member 60.

[0536] The housing 20 includes a housing 21 and an end cap 22. The housing 21 includes an integrally formed side wall 212 and a first wall 211. The side wall 212 surrounds the electrode assembly 10. The first wall 211 and the end cap 22 are opposite to each other, and the end cap 22 is sealed to the side wall 212.

[0537] The electrode assembly 10 is housed within the housing 20. The electrode assembly 10 includes a first tab 10a and a second tab 10b, the first tab 10a being electrically connected to the electrode terminal 30, and the second tab 10b being electrically connected to the first wall 211.

[0538] The first wall 211 is provided with an electrode lead-out hole 2111. The electrode terminal 30 includes a terminal body 31, a first limiting portion 32, and a second limiting portion 33. At least a portion of the terminal body 31 is accommodated in the electrode lead-out hole 2111. The first limiting portion 32 is connected to the terminal body 31, and at least a portion of the first limiting portion 32 protrudes from the outer peripheral surface of the terminal body 31. The second limiting portion 33 is connected to the terminal body 31, and at least a portion of the second limiting portion 33 protrudes from the outer peripheral surface of the terminal body 31. In the thickness direction Z of the first wall 211, the first limiting portion 32 and the second limiting portion 33 are respectively located on both sides of the first wall 211.

[0539] A second insulating member 70 surrounds the terminal body 31, and at least a portion of the second insulating member 70 is disposed between the first limiting portion 32 and the first wall 211. A sealing member 60 surrounds the terminal body 31, and at least a portion of the sealing member 60 is disposed between the second limiting portion 33 and the first wall 211. At least a portion of a third insulating member 80 surrounds the outside of the sealing member 60 and is located between the second limiting portion 33 and the first wall 211.

[0540] The first insulating member 40 is bonded to the outer surface 2112 of the first wall 211, and at least a portion of the second insulating member 70 is sandwiched between the electrode terminal 30 and the first insulating member 40.

[0541] The thermal weight loss temperature of the first insulating component 40 is greater than or equal to 300℃.

[0542] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0543] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features. However, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A single battery cell, comprising: The outer casing includes a first wall and a receiving cavity, wherein the first wall is provided with an electrode lead-out hole communicating with the receiving cavity; Electrode terminals are located at the electrode lead-out holes; An electrode assembly is housed within the receiving cavity. The electrode assembly includes a first electrode tab and a second electrode tab with opposite polarities. The first electrode tab is electrically connected to the electrode terminal, and the second electrode tab is electrically connected to the first wall. A first insulating member is at least partially fixed between the electrode terminal and the first wall to insulate at least a portion of the electrode terminal from the first wall, wherein the thermal weight loss temperature of the first insulating member is greater than or equal to 300°C.

2. The battery cell according to claim 1, wherein, The thermal weight loss temperature of the first insulating component is greater than or equal to 350°C, and optionally, the thermal weight loss temperature of the first insulating component is greater than or equal to 500°C.

3. The battery cell according to claim 1 or 2, wherein, The material of the first insulating component includes thermosetting materials.

4. The battery cell according to any one of claims 1-3, wherein, The material of the first insulating component includes one or more thermosetting polyimides and their derivatives.

5. The battery cell according to claim 4, wherein, The material of the first insulating component includes one or more of bismaleimide, ethynyl-terminated polyimide, and norbornene-terminated polyimide.

6. The battery cell according to any one of claims 1-5, wherein, The first insulating member is bonded to at least one of the electrode terminal and the first wall.

7. The battery cell according to claim 6 further includes an adhesive layer; The adhesive layer bonds the first insulating member to the surface of the first wall, and / or the adhesive layer bonds the first insulating member to the surface of the electrode terminal.

8. The battery cell according to claim 7, wherein, The thickness of the first insulating member is greater than or equal to the thickness of the adhesive layer.

9. The battery cell according to claim 8, wherein, The ratio of the thickness of the first insulating member to the thickness of the adhesive layer is 1-5.

10. The battery cell according to any one of claims 6-9, wherein, The first insulating component is bonded to the first wall.

11. The battery cell according to any one of claims 1-10, wherein, In the thickness direction of the first wall, at least a portion of the first insulating member is located between the outer surface of the first wall and the electrode terminal; and / or In the thickness direction of the first wall, at least a portion of the first insulating member is located between the inner surface of the first wall and the electrode terminal.

12. The battery cell according to claim 11, wherein, The first insulating member includes a first insulating portion and a second insulating portion connected to the first insulating portion. The first insulating portion is disposed on the outer surface of the first wall, and the second insulating portion is disposed on the hole wall surface of the electrode lead-out hole.

13. The battery cell according to any one of claims 1-12, further comprising a second insulating member; At least a portion of the second insulating member is disposed between the first insulating member and the first wall; and / or, at least a portion of the second insulating member is disposed between the first insulating member and the electrode terminal.

14. The battery cell according to claim 13, wherein, The compressive modulus of the second insulating member is less than that of the first insulating member.

15. The battery cell according to claim 13 or 14, wherein, The material of the second insulating component includes thermoplastic materials.

16. The battery cell according to any one of claims 13-15, wherein, In the thickness direction of the first wall, at least a portion of the first insulating member and at least a portion of the second insulating member are stacked between the first wall and the electrode terminal.

17. The battery cell according to claim 16, wherein, In the thickness direction of the first wall, at least a portion of the second insulating member is disposed between the first insulating member and the electrode terminal.

18. The battery cell according to claim 17, wherein, The electrode terminal includes a terminal body, a first limiting portion and a second limiting portion. At least a portion of the terminal body is accommodated in the electrode lead-out hole. Both the first limiting portion and the second limiting portion are connected to the terminal body. At least a portion of the first limiting portion protrudes from the outer peripheral surface of the terminal body, and at least a portion of the second limiting portion protrudes from the outer peripheral surface of the terminal body. At least a portion of the first insulating member is attached to the surface of the first wall facing the first limiting portion. In the thickness direction of the first wall, the first limiting part and the second limiting part are respectively located on both sides of the first wall, and at least a portion of the second insulating member is disposed between the first limiting part and the first insulating member.

19. The battery cell according to claim 18, wherein, The electrode terminal is riveted to the first wall; the first limiting portion is configured to be formed after the electrode terminal passes through the electrode lead-out hole.

20. The battery cell according to any one of claims 16-19, wherein, In the thickness direction of the first wall, the minimum thickness of the portion of the first insulating member located between the first wall and the electrode terminal is t1, and the minimum thickness of the portion of the second insulating member located between the first wall and the electrode terminal is t2, where t2 is greater than t1.

21. The battery cell according to any one of claims 1-20, further comprising a pressure relief mechanism disposed in the housing.

22. The battery cell according to claim 21, wherein, The pressure relief mechanism includes a pressure relief section and a weak section provided along the outer periphery of the pressure relief section; The area of ​​the pressure relief section is larger than the area of ​​the electrode lead-out hole.

23. The battery cell according to claim 21 or 22, wherein, The housing includes a second wall, and the pressure relief mechanism is disposed on the second wall.

24. The battery cell according to claim 23, wherein, The pressure relief mechanism includes a pressure relief section and a weak section provided along the outer periphery of the pressure relief section; The area enclosed by the outer contour of the projection of the second wall along its own thickness direction is S1, and the area of ​​the projection of the pressure relief part in the thickness direction of the second wall is S2. 0.1≤S2 / S1≤0.

8.

25. The battery cell according to claim 24, wherein, 0.3≤S2 / S1≤0.

7.

26. The battery cell according to any one of claims 23-25, wherein, The battery cell is a cylindrical battery cell, and the first wall and the second wall are arranged opposite each other along the axial direction of the cylindrical battery cell; The pressure relief mechanism includes a pressure relief section and a weak section arranged along the outer periphery of the pressure relief section, wherein the pressure relief section is circular; The diameter φ1 of the pressure relief section and the diameter φ2 of the cylindrical battery cell satisfy the following relationship: 0.35≤φ1 / φ2≤0.

85.

27. The battery cell according to any one of claims 23-26, wherein, The thickness of the first wall is greater than the thickness of the second wall.

28. The battery cell according to any one of claims 23-27, wherein, The first wall and the second wall are located on both sides of the electrode assembly, respectively; The housing also includes a sidewall that surrounds the electrode assembly and connects the first wall and the second wall.

29. The battery cell according to claim 28, wherein, The thickness of the first wall is greater than the thickness of the side wall.

30. The battery cell according to claim 28 or 29, wherein, The housing includes a shell and an end cap. The shell includes an integrally formed first wall and a side wall. The end cap is the second wall and is sealed to the side wall.

31. The battery cell according to any one of claims 28-30, wherein, The electrode assembly has a first through hole at its center; Along the extending direction of the first through hole, the first through hole is disposed between the electrode terminal and the pressure relief mechanism.

32. The battery cell according to any one of claims 28-31, wherein, The first electrode tab is disposed at one end of the electrode assembly facing the first wall, and the second electrode tab is disposed at one end of the electrode assembly facing the second wall; The battery cell further includes a first current collector and a second current collector. The first current collector is connected to the first tab and the electrode terminal. The second tab is connected to the second current collector. At least one of the side wall and the second wall is connected to the second current collector, so that the side wall is electrically connected to the first wall and the second current collector.

33. The battery cell according to claim 32, wherein, The second current collection component is connected to the second wall.

34. The battery cell according to any one of claims 1-33, wherein, The electrode terminal includes a terminal body and a first limiting portion. At least a portion of the terminal body is accommodated in the electrode lead-out hole. The first limiting portion is connected to the terminal body, and at least a portion of the first limiting portion protrudes from the outer peripheral surface of the terminal body. In the thickness direction of the first wall, the first limiting portion at least partially overlaps with the first wall, and at least a portion of the first insulating member is located between the first wall and the first limiting portion.

35. The battery cell according to claim 34, wherein, The electrode terminal further includes a second limiting portion connected to the terminal body. At least a portion of the second limiting portion protrudes from the outer peripheral surface of the terminal body. In the thickness direction of the first wall, the first limiting portion and the second limiting portion are respectively located on both sides of the first wall. The battery cell includes a seal, and at least a portion of the seal is disposed between the second limiting portion and the first wall in the thickness direction of the first wall. The thermal weight loss temperature of the seal is greater than or equal to 200°C.

36. The battery cell according to claim 35, wherein, The seal comprises a thermosetting material.

37. The battery cell according to claim 35 or 36, wherein, The portion of the sealing member and the portion of the first insulating member are stacked in the thickness direction of the first wall to separate the hole wall surface of the electrode lead-out hole from the terminal body.

38. The battery cell according to any one of claims 35-37, wherein, The sealing element includes a first sealing portion and a second sealing portion connected together, at least a portion of the first sealing portion being located between the second limiting portion and the first wall, and at least a portion of the second sealing portion being located inside the electrode lead-out hole; The first insulating member includes a first insulating portion and a second insulating portion connected together. At least a portion of the first insulating portion is located between the first limiting portion and the first wall. At least a portion of the second insulating portion is located within the electrode lead-out hole. In the radial direction of the electrode lead-out hole, the second insulating portion and the second sealing portion at least partially overlap within the electrode lead-out hole.

39. The battery cell according to any one of claims 1-38, wherein, The electrode assembly includes a positive electrode sheet, the positive electrode sheet includes a positive current collector and a positive electrode film layer disposed on at least one side of the positive current collector, the positive electrode film layer includes a positive electrode active material, and the positive electrode active material includes a layered transition metal oxide; The layered transition metal oxide includes the chemical formula Li a Ni b Co c M d O e A f The compound and its modified compounds contain at least one of the following: 0.8≤a≤1.2, 0.8≤b≤0.95, 0<c<1, 0<d<1, 1≤e≤2, 0≤f≤1, M includes at least one of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, and A includes at least one of N, F, S and Cl.

40. The battery cell according to any one of claims 1-39, further comprising an electrolyte contained within the casing; The electrolyte comprises a chain ester solvent, wherein the chain ester solvent comprises 25.5 wt% to 76.5 wt% by mass in the electrolyte.

41. The battery cell according to claim 40, wherein, The chain ester solvent has a mass percentage of 42.5 wt% to 70 wt% in the electrolyte.

42. The battery cell according to any one of claims 1-41, wherein, The thermal conductivity of the first insulating component is less than that of the first wall, and the thermal conductivity of the first insulating component is less than that of the electrode terminal.

43. The battery cell according to claim 42, wherein, The thermal conductivity of the first wall is less than that of the electrode terminal.

44. The battery cell according to any one of claims 1-43, wherein, The battery cell is a cylindrical battery cell with a diameter greater than or equal to 35 mm and less than or equal to 70 mm.

45. A battery device comprising a plurality of battery cells according to any one of claims 1-44.

46. ​​The battery device according to claim 45, wherein, At least two of the battery cells are connected in parallel.

47. An electrical appliance comprising a battery device according to claim 45 or 46, the battery device being used to provide electrical energy.

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