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 an electrode assembly, a housing, electrode terminals, and a first insulating member. The housing includes a first end wall, a side wall, and a receiving cavity. The first end wall has an electrode lead-out hole communicating with the receiving cavity, and the side wall is connected to the first end wall. The electrode terminals are disposed in the electrode lead-out hole and are insulated from the first end wall. The electrode assembly is housed within the receiving cavity, and the side wall surrounds the electrode assembly. The electrode assembly includes a first tab and a second tab with opposite polarities. The first tab is electrically connected to the electrode terminal, and the second tab is electrically connected to the first end wall and the side wall. The thermal decomposition temperature of the first insulating member is greater than or equal to 300°C. At least a portion of the first insulating member is disposed between the first end wall and the first tab, and / or, at least a portion of the first insulating member is disposed between the side wall and the first tab.

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, including an electrode assembly, a housing, electrode terminals, and a first insulating member. The housing includes a first end wall, a side wall, and a receiving cavity. The first end wall has an electrode lead-out hole communicating with the receiving cavity, and the side wall is connected to the first end wall. The electrode terminals are disposed in the electrode lead-out hole and are insulated from the first end wall. The electrode assembly is housed within the receiving cavity, and the side wall surrounds the electrode assembly. The electrode assembly includes an electrode body and a first tab and a second tab extending from the electrode body. The first tab and the second tab have opposite polarities. The first tab is disposed at the end of the electrode assembly facing the first end wall and is electrically connected to the electrode terminal. The second tab is electrically connected to the first end wall and the side wall. The thermal weight loss temperature of the first insulating member is greater than or equal to 300°C. At least a portion of the first insulating member is disposed between the first end wall and the first tab, and / or, at least a portion of the first insulating member is disposed between the side wall and the first tab.

[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 within the casing and isolate the first tab from the first end wall or from the side wall, reducing the risk of the side wall or first end wall conducting to the electrode terminal through the first tab. Correspondingly, even if the electrode terminal and first end wall are electrically connected to other battery cells or an external power source, the first insulating member can suppress the current between the electrode terminal and the first end wall, reducing continuous heat generation between the electrode terminal and the first end 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; 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 the sidewall or first endwall becoming conductive with the electrode terminal through the first tab, reduce the continuous heat generation of the electrode terminal and the first endwall, 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. The first insulating member containing a thermosetting material is less likely to soften at high temperatures, which can reduce the deformation of the first insulating member under internal pressure, reduce the risk of failure of the first insulating member, and thus improve insulation performance.

[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 fixed to at least one of the first end wall, side wall, electrode body, and first tab. Fixing the first insulating member to at least one of the first end wall, side wall, electrode body, and first tab can improve the stability of the first insulating member, reduce the displacement of the first insulating member within the casing when the battery cell is subjected to external impact, and reduce the risk of insulation failure.

[0013] In some embodiments, the battery cell further includes an adhesive layer. The adhesive layer bonds the first insulating member to at least one of the first end wall, side wall, electrode body, and first tab. 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, at least a portion of the first insulating member is located between the sidewall and the first tab.

[0016] In the event of thermal runaway of a battery cell, the first insulating member is less prone to weight loss or has minimal weight loss. It can separate the first tab from the sidewall, reducing the risk of the electrode terminal becoming connected to the first end wall through the first tab and sidewall. Even if the electrode terminal and the first end wall are electrically connected to other battery cells or an external power source, the first insulating member can suppress the current between the electrode terminal and the first end wall, reduce the continuous heat generation between the electrode terminal and the first end wall, reduce the thermal impact on other surrounding battery cells, reduce the risk of thermal runaway in other battery cells, and improve reliability.

[0017] In some embodiments, a first insulating member is disposed around the first tab to isolate the outer peripheral surface of the first tab from the sidewall, reducing the risk of the first tab becoming conductive with the second tab through the sidewall and improving reliability. During thermal runaway of a battery cell, the first insulating member is less prone to weight loss or experiences minimal weight loss, thus separating the first tab from the sidewall and reducing the risk of the electrode terminals becoming conductive with the first end wall through the first tab and sidewall.

[0018] In some embodiments, the first tab is a cylindrical structure, and the circumferential angle of the first insulating member is greater than 360 degrees, so as to improve the insulation effect and reduce the risk of the outer peripheral surface of the first tab being exposed.

[0019] In some embodiments, the outer peripheral surface of the electrode body is closer to the sidewall than the outer peripheral surface of the first electrode tab, so that a space is formed between the outer peripheral surface of the first electrode tab and the sidewall to accommodate at least a portion of the first insulating member. This application can reserve a larger space between the outer peripheral surface of the first electrode tab and the sidewall, thereby allowing the first insulating member to have a greater thickness, reducing the risk of failure of the first insulating member, and improving reliability.

[0020] In some embodiments, the first insulating member protrudes from the first tab along the direction of the electrode assembly toward the first end wall; or, the end of the first insulating member facing the first end wall is flush with the end of the first tab facing the first end wall. The first insulating member can separate the end of the first tab facing the first end wall from the sidewall, thereby reducing the risk of short circuit. In the event of thermal runaway of a single battery cell, the first insulating member can also reduce the risk of conductivity between the first tab and the first end wall.

[0021] In some embodiments, the battery cell further includes a first current collector, which includes a tab connection portion connected to a first tab and a terminal connection portion connected to an electrode terminal, the tab connection portion surrounding the terminal connection portion. A first insulating member protrudes from the tab connection portion along the direction of the electrode assembly toward the first end wall. The tab connection portion is closer to the side wall than the terminal connection portion. The protrusion of the first insulating member from the tab connection portion can separate the tab connection portion from the side wall, thereby reducing the risk of short circuit. In the event of thermal runaway of the battery cell, the first insulating member is less prone to weight loss or experiences minimal weight loss, thereby reducing the risk of the first current collector portion conducting between the side wall and the electrode terminal.

[0022] In some embodiments, a portion of the first insulating member is located between the sidewall and the electrode body.

[0023] In the event of thermal runaway in a battery cell, the separator may melt and fail. This embodiment of the application places a heat-resistant first insulating member between the sidewall and the electrode body. This reduces the risk of the remaining portion of the electrode body becoming conductive with the sidewall during thermal runaway, thereby reducing the risk of the first end wall becoming conductive with the electrode terminal through the sidewall, the remaining portion of the electrode body, and the first tab. This suppresses the current between the electrode terminal and the first end wall, reduces the continuous heat generation between the electrode terminal and the first end wall, minimizes the thermal impact on other surrounding battery cells, reduces the risk of thermal runaway in other battery cells, and improves reliability.

[0024] In some embodiments, the first insulating member includes a first insulating portion and a second insulating portion connected to the first insulating portion, wherein at least a portion of the first insulating portion is located between a sidewall and a first tab, and at least a portion of the second insulating portion is located between a first endwall and a first tab.

[0025] When a battery cell experiences thermal runaway, the first insulating component is less prone to weight loss or experiences minimal weight loss at high temperatures. The first insulating portion can separate the first tab from the sidewall, and the second insulating portion can separate the first tab from the first endwall, thereby reducing the risk of the sidewall and the first endwall becoming conductive through the first tab to the electrode terminal. Even if the electrode terminal and the first endwall are electrically connected to other battery cells or an external power source, the first insulating component can suppress the current between the electrode terminal and the first endwall, reduce the continuous heat generation between the electrode terminal and the first endwall, reduce the thermal impact on other surrounding battery cells, reduce the risk of thermal runaway in other battery cells, and improve reliability.

[0026] In some embodiments, the first insulating portion is attached to the inner surface of the sidewall, and the second insulating portion is attached to the inner surface of the first endwall. The embodiments of this application can improve the stability of the first insulating member, reduce the displacement of the first insulating portion relative to the sidewall during thermal runaway of the battery cell, and reduce the displacement of the second insulating portion relative to the sidewall during thermal runaway of the battery cell, thereby improving the insulation effect and reducing the risk of the first tab and the first endwall becoming conductive during thermal runaway of the battery cell.

[0027] In some embodiments, the battery cell further includes a second insulating member. At least a portion of the second insulating member surrounds the first tab and is located between the first insulating member and the first tab; and / or, at least a portion of the second insulating member surrounds the first tab and is located between the sidewall and the first insulating member. By providing the first insulating member and the second insulating member, a double-layer insulation structure can be formed between the first tab and the sidewall, thereby further improving the insulation effect and reducing the risk of the first tab and the sidewall conducting electricity during thermal runaway of the battery cell.

[0028] In some embodiments, at least a portion of the first insulating member is attached to the inner surface of the sidewall. At least a portion of the second insulating member surrounds the first tab and is located between the first insulating member and the first tab. The second insulating member can separate the first tab from the first insulating member, thereby reducing the risk of the first insulating member being cracked or scratched by the first tab during use of the battery cell.

[0029] In some embodiments, the tensile modulus of the second insulating member is less than that of the first insulating member. When the second insulating member is wrapped around the outside of the first tab, it can be stretched and tightened to close and restrain the first tab. The second insulating member has a smaller tensile modulus, which allows it to release stress through tensile deformation, reducing the deformation of the first tab under the restraint of the second insulating member. The first insulating member is attached to the sidewall and can have a larger tensile modulus. When the electrode assembly expands, the first insulating member can restrain the sidewall, reducing sidewall deformation and improving the morphology of the battery cell.

[0030] In some embodiments, a portion of the second insulating member is disposed between the first tab and the first end wall. The second insulating member can isolate at least a portion of the first tab from the first end wall, thereby reducing the risk of the first tab contacting the first end wall, thus reducing the risk of short circuit and improving reliability.

[0031] In some embodiments, the thermal weight loss temperature of the first insulating member is greater than that of the second insulating member. During thermal runaway of a single battery cell, the second insulating member can soften and lose weight under high temperature, thereby adhering to metal particles near the first tab, reducing the impact of the metal particles on the first insulating member, and lowering the risk of failure of the first insulating member.

[0032] In some embodiments, the battery cell further includes a third insulating member disposed between the electrode body and the sidewall. The third insulating member can separate the electrode body from the sidewall to reduce the risk of short circuit.

[0033] In some embodiments, a third insulating member is fixed to the outer peripheral surface of the electrode body. The electrode body includes a wound-mounted spacer, and the third insulating member is connected to the outer surface of the spacer. The third insulating member can protect the spacer from the outside to reduce the risk of the spacer being punctured. The third insulating member can also restrain the spacer to reduce the risk of the spacer coming apart. The third insulating member can also constrain the electrode body from the outside to reduce the expansion and deformation of the electrode body.

[0034] In some embodiments, the thermal decomposition temperature of the third insulating member is greater than or equal to 300°C. 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 thermal decomposition temperature of the third insulating member is 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 third insulating member to remain within the casing and separate the remaining portion of the electrode body from the sidewalls, reducing the risk of the sidewalls conducting through the remaining portion of the electrode body and the first tab to the electrode terminals. This, in turn, suppresses the current between the electrode terminals and the first end wall, reduces the continuous heat generation between the electrode terminals and the first end wall, minimizes the thermal impact on other surrounding battery cells, reduces the risk of thermal runaway in other battery cells, and improves reliability.

[0035] In some embodiments, at least a portion of the first insulating member is disposed between the sidewall and the third insulating member. By providing the first and third insulating members, a double-layer insulation structure can be formed between the electrode body and the sidewall, thereby further improving the insulation effect and reducing the risk of conduction between the electrode body and the sidewall during thermal runaway of the battery cell.

[0036] In some embodiments, a first insulating member protrudes from a third insulating member along the direction from the first end wall toward the electrode assembly. Both ends of the first insulating member protrude from the third insulating member. The first insulating member can separate the portion of the electrode assembly protruding from the third insulating member from the sidewall, thereby reducing the risk of residual portions of the electrode body contacting the sidewall in the event of thermal runaway of a single battery cell, and improving reliability.

[0037] In some embodiments, the first insulating member is located on one side of the third insulating member along the direction from the electrode assembly to the first end wall. This application embodiment utilizes the first and third insulating members together to achieve insulation, thereby saving space and weight occupied by the first insulating member and increasing the energy density of the battery cell.

[0038] In some embodiments, a first gap is provided between the first insulating member and the third insulating member along the direction of the electrode assembly pointing towards the first end wall. During the operation of the battery cell, the electrode body will expand. By providing a first gap between the first insulating member and the second insulating member, the risk of contact and compression between the first insulating member and the third insulating member can be reduced when the electrode assembly expands and deforms, thereby reducing the risk of cracking of the first insulating member and improving insulation reliability.

[0039] In some embodiments, the dimension D3 of the first gap is 0.5mm-5mm along the direction of the electrode assembly pointing towards the first end wall.

[0040] In this embodiment, D3 is defined as greater than or equal to 0.5 mm to reduce the risk of overlap between the first and second insulating components due to assembly errors. Defining D3 as greater than or equal to 0.5 mm also reduces the risk of contact and compression between the first and third insulating components when the electrode assembly expands and deforms. Defining D3 as less than or equal to 5 mm reduces the risk of continuity between the residual portion of the electrode body and the sidewalls in the event of thermal runaway of a single battery cell.

[0041] In some embodiments, a second tab is disposed at the end of the electrode assembly facing away from the first end wall, and at least a portion of the first insulating member is located between the side wall and the second tab. The first insulating member protrudes from the second tab in the direction from the first end wall toward the electrode assembly; alternatively, the end of the first insulating member facing away from the first end wall is flush with the end of the second tab facing away from the first end wall. Embodiments of this application can increase the insulation range of the first insulating member to separate the remaining portion of the electrode assembly from the side wall after thermal runaway of a single battery cell, reducing the risk that the remaining portion of the electrode assembly will conduct electricity between the side wall and the electrode terminals.

[0042] In some embodiments, at least a portion of the first insulating member is located between the first end wall and the first tab.

[0043] When a battery cell experiences thermal runaway, the first insulating component is less prone to weight loss or experiences minimal weight loss at high temperatures. The first insulating component can separate the first tab from the first end wall, thereby reducing the risk of the first end wall conducting through the first tab to the electrode terminal. Even if the electrode terminal and the first end wall are electrically connected to other battery cells or an external power source, the first insulating component can suppress the current between the electrode terminal and the first end wall, reduce the continuous heat generation between the electrode terminal and the first end wall, reduce the thermal impact on other surrounding battery cells, reduce the risk of thermal runaway in other battery cells, and improve reliability.

[0044] In some embodiments, the battery cell further includes a fourth insulating member; at least a portion of the fourth insulating member is disposed between the first end wall and the first tab to separate the first end wall from the first tab, thereby reducing the risk of the first end wall and the first tab becoming conductive and improving reliability.

[0045] In some embodiments, at least a portion of the first insulating member is disposed between the first end wall and the fourth insulating member; and / or, at least a portion of the first insulating member is disposed between the first tab and the fourth insulating member. By providing the first insulating member and the fourth insulating member, a double-layer insulation structure can be formed between the first tab and the first end wall, thereby further improving the insulation effect and reducing the risk of the first tab and the first end wall conducting during thermal runaway of the battery cell.

[0046] In some embodiments, the battery cell further includes a first current collector located between a first end wall and a first tab, the first current collector connecting the electrode terminal and the first tab. A portion of a first insulating member is disposed between the first current collector and the first end wall. In the event of thermal runaway in the battery cell, the first insulating member can isolate the first current collector from the first end wall, thereby reducing the risk of the first end wall becoming conductive to the electrode terminal through the first current collector.

[0047] In some embodiments, the housing further includes a second end wall, which is disposed opposite to the first end wall, and a side wall connects the first end wall and the second end wall. A second tab is disposed at one end of the electrode assembly facing the second end wall. Distributing the first tab and the second tab at opposite ends of the electrode assembly reduces the risk of short circuits between the first tab and the second tab, provides more space for the first tab and the second tab, and improves the current-carrying capacity of the first tab and the second tab.

[0048] In some embodiments, the battery cell further includes a pressure relief mechanism disposed on the second end wall. In the event of thermal runaway of the battery cell, the pressure relief mechanism can release the internal temperature and pressure of the battery cell, thereby reducing the risk of battery cell explosion. After the pressure relief mechanism is activated, the temperature of the casing gradually decreases, thereby shortening the time the first insulating member is exposed to the high-temperature environment, reducing the weight loss of the first insulating member, and lowering the risk of failure of the first insulating member.

[0049] In some embodiments, the minimum distance between the first insulating member and the second end wall along the direction from the first end wall to the second end wall is D1, and the total dimension of the electrode body is D2, where 0 ≤ D1 / D2 ≤ 0.25. During thermal runaway of the battery cell, at least a portion of the second tab and a portion of the electrode body near the second end wall are discharged to the outside of the casing via a pressure relief mechanism under high temperature and pressure. After the battery cell is depressurized, a portion of the electrode body near the first end wall remains inside the casing. Limiting D1 / D2 to less than or equal to 0.25 allows the first insulating member to separate the remaining portion of the electrode body from the sidewall during thermal runaway of the battery cell, reducing the risk of the remaining portion of the electrode body conducting through the first tab and the sidewall, and improving reliability.

[0050] 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 end 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 end wall is S2. 0.1≤S2 / S1≤0.8.

[0051] 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 end wall, lowers the risk of weak points breaking during normal use of the battery cell, and improves the reliability of the battery cell.

[0052] In some embodiments, 0.3 ≤ S2 / S1 ≤ 0.7 can further improve the reliability of the battery cell.

[0053] In some embodiments, the battery cell is a cylindrical battery cell, and the first end wall and the second end wall are disposed opposite to each other along the axial direction of the cylindrical battery cell. The pressure relief mechanism includes a pressure relief part and a weak part disposed 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.

[0054] 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 end wall, lowers the risk of weak points breaking during normal use of the battery cell, and improves the reliability of the battery cell.

[0055] In some embodiments, the thickness of the second end wall is less than the thickness of the first end wall. Compared to the second end wall, the first end wall deforms less, thereby reducing the deformation or displacement of the first tab under the influence of the first end wall and the electrode terminal, reducing the risk of the first tab compressing the first insulating member, and thus reducing the risk of the first insulating member being cracked, improving the insulation effect, and increasing the reliability of the battery cell. Compared to the first end wall, the second end wall is more likely to bulge outward, which can increase the gas flow channel on the inner side of the second end wall and improve the gas emission efficiency.

[0056] In some embodiments, a first through-hole is provided at the center of the electrode assembly. The first through-hole is located between the electrode terminal and the pressure relief mechanism along its extending direction. During thermal runaway of the battery cell, gas between the electrode assembly and the first end wall can flow through the first through-hole to the pressure relief mechanism, thereby reducing the pressure on the first end wall and the electrode terminal, reducing the deformation or displacement of the first tab under the influence of the electrode terminal, reducing the risk of the first tab crushing the first insulating member, and further reducing the risk of the first insulating member being cracked, improving insulation performance, and enhancing the reliability of the battery cell.

[0057] In some embodiments, the battery cell further includes a second current collector. The second current collector is connected to the second end wall and the second tab, and the second end wall is electrically connected to the side wall; or, the second current collector is connected to the side wall and the second tab.

[0058] In some embodiments, the battery cell further includes a pressure relief mechanism disposed on the second end wall. At least a portion of the second current collector is located between the pressure relief mechanism and the second tab. In the event of thermal runaway of the battery cell, high-temperature gas is discharged to the outside of the casing through the pressure relief channel formed by the pressure relief mechanism. At least a portion of the second current collector is opposite to the pressure relief mechanism. In the event of thermal runaway of the battery cell, the second current collector can deform or even melt under the action of high-temperature gas, thereby reducing the risk of the second current collector conducting through the sidewall and residual portions of the electrode body, and improving the reliability of the battery cell.

[0059] In some embodiments, the housing includes a shell and an end cap. The shell includes an integrally formed first end wall and a side wall, and the end cap is a second end wall, which is sealed to the side wall. A first insulating member is spaced apart from the end cap to reduce interference between the first insulating member and the connection between the end cap and the shell during assembly of the shell and the end cap, improve the connection strength between the end cap and the shell, and reduce the risk of the first insulating member being damaged by pressure.

[0060] In some embodiments, the electrode terminal includes a terminal body and a first limiting portion, at least a portion of the terminal body being received in an electrode lead-out hole, the first limiting portion being connected to the terminal body, and at least a portion of the first limiting portion protruding from the outer peripheral surface of the terminal body. The battery cell also includes a seal, wherein the first limiting portion is located inside the first end wall in the thickness direction of the first end wall, and at least a portion of the seal is disposed between the first end wall and the first limiting portion. The thermal decomposition temperature of the seal is greater than or equal to 200°C.

[0061] The seal is less likely to lose weight or loses little weight during thermal runaway of a battery cell, thus allowing the seal to remain between the first end wall and the electrode terminal, reducing the risk of direct contact between the electrode terminal and the first end wall.

[0062] 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.

[0063] 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 and experience a higher temperature rise. This application's embodiment includes a high-temperature-resistant first insulating component within the casing. This first insulating component can withstand the high temperatures generated by the high-nickel battery cell during thermal runaway, thereby reducing the risk of electrical connection between the first end wall and the first electrode tab, suppressing the current between the electrode terminals and the first end wall, and reducing continuous heat generation between the electrode terminals and the first end wall.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] In some embodiments, at least two battery cells are connected in parallel. Multiple battery cells in the battery device form a multi-parallel series structure. This multi-parallel series structure improves reliability; if one battery cell fails unexpectedly, the battery cells connected in parallel with it can still function normally, reducing the risk of complete circuit failure. In the event of thermal runaway in one battery cell, the normal battery cells connected in parallel with the thermally runaway battery cell may be electrically connected to the first end wall and electrode terminal of the thermally runaway battery cell, respectively. The first insulating member can insulate the first tab from the first end wall, suppressing the current between the electrode terminal and the first end wall, reducing the continuous heat generation between the electrode terminal and the first end wall, reducing the thermal impact on other surrounding battery cells, lowering the risk of thermal runaway in other battery cells, and improving reliability.

[0071] 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

[0072] 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.

[0073] Figure 1 is a structural schematic diagram of a vehicle provided in some embodiments of this application;

[0074] Figure 2 is a schematic diagram of a battery device provided in some embodiments of this application;

[0075] Figure 3 is a schematic diagram of the battery module shown in Figure 2;

[0076] Figure 4 is a schematic diagram of the structure of a single battery cell in some embodiments of this application;

[0077] Figure 5 is a schematic diagram of the explosion of the battery cell shown in Figure 4;

[0078] Figure 6 is a cross-sectional schematic diagram of the electrode assembly of a battery cell provided in some embodiments of this application;

[0079] 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;

[0080] 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;

[0081] Figure 9 is a cross-sectional schematic diagram of a battery cell provided in some embodiments of this application;

[0082] Figure 10 is an enlarged view of Figure 9 at box A;

[0083] Figure 11 is an enlarged view of Figure 10 at the circular frame;

[0084] Figure 12 is an enlarged view of Figure 9 at point B in the circular frame;

[0085] Figure 13 is an enlarged view of the area in box C of Figure 9;

[0086] Figure 14 is a partial cross-sectional view of a battery cell provided in some other embodiments of this application;

[0087] Figure 15 shows an enlarged view of the area within the box in Figure 14.

[0088] Figure 16 is a partial cross-sectional schematic diagram of a battery cell provided in some other embodiments of this application;

[0089] Figure 17 is an enlarged view of Figure 17 at the boxed area;

[0090] Figure 18 is an enlarged view of Figure 16 at the circular frame;

[0091] Figure 19 is a schematic diagram of the electrode assembly, first insulating member, and third insulating member of a battery cell provided in some embodiments of this application;

[0092] Figure 20 is a partial cross-sectional schematic diagram of a battery cell provided in some other embodiments of this application;

[0093] Figure 21 is a schematic diagram of the first insulating member and adhesive layer of a battery cell provided in some embodiments of this application;

[0094] Figure 22 is an exploded schematic diagram of a battery cell provided in some other embodiments of this application;

[0095] Figure 23 is a simplified schematic diagram of a battery device provided in some other embodiments of this application.

[0096] The reference numerals in the attached drawings are explained as follows: 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; 10. Electrode assembly; 10a. First tab; 10b. Second tab; 10c. Electrode body; 10d. First through hole; 10e. First end face; 10f. Second end face; 10g. Outer peripheral surface of the first tab; 10i. Outer peripheral surface of the electrode body; 11. Positive electrode sheet; 111. Positive current collector; 1111. Positive electrode body region; 1112. Positive electrode blank region; 112. Positive electrode film; 12. Negative electrode sheet; 121. Negative electrode current collector; 1211. Negative electrode body region; 1212. Negative electrode blank region; 122. Negative electrode film; 13. Separator; 131. Winding start end; 132. Winding end. 20. Outer shell; 20a. Second end wall; 20b. Receiving cavity; 21. Housing; 211. First end wall; 2111. Electrode lead-out hole; 212. Side wall; 2121. Protrusion; 2122. Second recess; 2123. Press-fit part; 212a. First sub-wall; 212b. Second sub-wall; 22. End cap; 30. Electrode terminal; 31. Terminal body; 311. Second through hole; 32. First limiting part; 33. Second limiting part; 34. Terminal recess; 40. First insulating member; 40a. Head end; 40b. Tail end; 41. First insulating part; 42. Second insulating part; 50. Second insulating member; 51. Third insulating part; 52. Fourth insulating part; 60. Third insulating member; 70. Pressure relief mechanism; 71. Pressure relief part; 72. Weak part; 73. First recess; 80. Seal; 81. First current collector; 811. Electrode connection part; 811a. Outer peripheral surface of electrode connection part; 812. Terminal connection part; 82. Cover plate; 83. Sealing nail; 84. Second current collector; 85. Fifth insulating member; 86. Adhesive layer; 87. Sixth insulating member; 88. Electrode lead-out part; 90. Fourth insulating member; G1. First gap; G2. Second gap; V. Winding direction; Z. Thickness direction. Detailed Implementation

[0097] 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.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] In this application, "multiple" means two or more (including two).

[0104] 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.

[0105] 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.

[0106] A battery cell typically includes a casing, an electrode assembly housed within the casing, and a positive and negative electrode lead disposed on the casing. The electrode assembly typically includes a positive tab and a negative tab, with the positive electrode lead electrically connected to the positive tab and the negative electrode lead electrically connected to the negative tab. The positive and negative electrode leads are used for electrical connection to an external circuit to enable charging or discharging of the battery cell.

[0107] 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.

[0108] When a battery cell in a battery pack experiences thermal runaway due to an accident (such as an internal short circuit), that cell may remain at a high temperature for a period of time. At this high temperature, the internal insulation components of the casing may fail, and the tabs (positive or negative) may simultaneously connect to both the casing and the electrode terminals. Since the tabs have low resistance, when the casing and electrode terminals are connected via the tabs, current from other battery cells or from an external power source may continuously flow between the electrode terminals and the casing, causing continuous localized heat generation in that battery cell. This can trigger abnormal temperature increases and thermal runaway in other normal battery cells, leading to heat propagation.

[0109] 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.

[0110] In view of this, the present application provides a battery cell that, by providing an insulating component with a high thermal runaway temperature inside the casing, reduces the risk of the tab simultaneously conducting with 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.

[0111] 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.

[0112] For ease of explanation, the following embodiments use a vehicle as an example of electrical equipment.

[0113] Figure 1 is a schematic diagram of the structure of a vehicle provided in some embodiments of this application.

[0114] 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.

[0115] 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.

[0116] 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.

[0117] Figure 2 is a schematic diagram of a battery device provided in some embodiments of this application.

[0118] In some embodiments, the battery device 2 may include one or more battery cell assemblies for providing voltage and capacity.

[0119] 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.

[0120] 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.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] In some embodiments, the housing 5 is used to house individual battery cells, and the housing 5 can have various structures.

[0126] 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.

[0127] 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.

[0128] 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.

[0129] In some embodiments, the battery device 2 may be an energy storage device.

[0130] 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.

[0131] In some embodiments, the energy storage device includes an energy storage container, an energy storage cabinet, etc.

[0132] Figure 3 is a schematic diagram of the battery module shown in Figure 2.

[0133] 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.

[0134] 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.

[0135] 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.

[0136] 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.

[0137] 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).

[0138] The outer shell 20 may be a hollow structure, with an internal cavity 20b for accommodating the electrode assembly 10 and the electrolyte.

[0139] 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.

[0140] 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;

[0141] 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.

[0142] 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.

[0143] 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.

[0144] 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.

[0145] The end cap 22 is connected to the housing 21 by welding, bonding, snap-fitting or other means.

[0146] 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.

[0147] 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.

[0148] 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.

[0149] 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.

[0150] 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.

[0151] 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.

[0152] 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.).

[0153] 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 battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium phosphate may 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 may 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 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1Mn 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.

[0154] In some embodiments, the negative electrode 12 may include a negative current collector 121.

[0155] 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.).

[0156] 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.

[0157] 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.

[0158] 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.

[0159] In some embodiments, the positive current collector 111 may be made of aluminum, and the negative current collector 121 may be made of copper.

[0160] 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.

[0161] 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.

[0162] Inorganic particle coating, organic particle coating, or organic / inorganic composite coating can also be applied to the surface of the separator.

[0163] 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.

[0164] 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.

[0165] In some embodiments, the battery cell 7 further includes an electrolyte that 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, or solid.

[0166] In some embodiments, the liquid electrolyte includes an electrolyte salt and a solvent.

[0167] 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.

[0168] 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.

[0169] 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.

[0170] 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.

[0171] In some embodiments, the solid electrolyte includes a polymer solid electrolyte, an inorganic solid electrolyte, and a composite solid electrolyte.

[0172] 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.

[0173] 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.

[0174] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0175] In some embodiments, the electrode assembly 10 can be a wound structure, a stacked structure, or a hybrid structure of wound and stacked.

[0176] 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.

[0177] In some embodiments, the electrode assembly 10 has a stacked structure.

[0178] 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.

[0179] As an example, both the positive electrode 11 and the negative electrode 12 are folded to form multiple stacked folded segments.

[0180] As an example, multiple separators 13 can be provided, respectively disposed between any adjacent positive electrode 11 or negative electrode 12.

[0181] 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.

[0182] In some embodiments, the electrode assembly 10 may be cylindrical, flat, or polygonal in shape.

[0183] In some embodiments, the positive current collector 111 includes a positive electrode body region 1111 and a positive electrode blank region 1112, the positive electrode body region 1111 is covered by a positive electrode film layer 112, and the positive electrode blank region 1112 is not covered by a positive electrode film layer 112.

[0184] In some embodiments, the negative electrode current collector 121 includes a negative electrode main region 1211 and a negative electrode blank region 1212. The negative electrode main region 1211 is covered with a negative electrode film layer 122, and the negative electrode blank region 1212 is not covered with a positive electrode film layer 112.

[0185] 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 positive electrode body region 1111, a negative electrode film 122, a negative electrode body region 1211, and a separator 13. At least a portion of the positive electrode blank region 1112 protrudes to the outside of the separator 13, and at least a portion of the negative electrode blank region 1212 protrudes to the outside of the separator 13.

[0186] In some embodiments, the electrode assembly 10 includes a first tab 10a and a second tab 10b extending from the electrode body 10c. One of the first tab 10a and the second tab 10b is a positive tab, and the other is a negative tab.

[0187] In some examples, the portion of the positive blank area 1112 that protrudes to the outside of the separator 13 constitutes a positive tab, and the portion of the negative blank area 1212 that protrudes to the outside of the separator 13 constitutes a negative tab.

[0188] The first tab 10a and the second tab 10b 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.

[0189] In some embodiments, the electrode assembly 10 has a wound structure. The positive electrode blank area 1112 is wound multiple turns along the winding direction V. Optionally, the end of the positive electrode blank area 1112 is bent by a flattening or smoothing process to form a positive electrode tab. The positive electrode tab has a multi-layer structure stacked along the winding axis of the electrode assembly 10. Optionally, the positive electrode tab is cylindrical.

[0190] In some embodiments, the electrode assembly 10 has a wound structure. The negative electrode blank area 1212 is wound multiple turns along the winding direction V. Optionally, the end of the negative electrode blank area 1212 is bent by a flattening or smoothing process to form a negative electrode tab. The negative electrode tab has a multi-layer structure stacked along the winding axis of the electrode assembly 10. Optionally, the negative electrode tab is cylindrical.

[0191] 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 9 at the circular frame B; Figure 13 is an enlarged schematic diagram of Figure 9 at the box C.

[0192] Referring to Figures 4 to 13, this application embodiment provides a battery cell 7, which includes an electrode assembly 10, a housing 20, electrode terminals 30, and a first insulating member 40. The housing 20 includes a first end wall 211, a side wall 212, and a receiving cavity 20b. The first end wall 211 has an electrode lead-out hole 2111 communicating with the receiving cavity 20b, and the side wall 212 is connected to the first end wall 211. The electrode terminals 30 are disposed in the electrode lead-out hole 2111. The electrode terminals 30 are insulated from the first end wall 211. The electrode assembly 10 is received within the receiving cavity 20b. The side wall 212 surrounds the electrode assembly 10. The electrode assembly 10 includes an electrode body 10c and a first tab 10a and a second tab 10b extending from the electrode body 10c. The first tab 10a and the second tab 10b have opposite polarities. The first tab 10a is disposed at the end of the electrode assembly 10 facing the first end wall 211 and is electrically connected to the electrode terminal 30. The second tab 10b is electrically connected to the first end wall 211 and the side wall 212. The thermal weight loss temperature of the first insulating member 40 is greater than or equal to 300°C.

[0193] At least a portion of the first insulating member 40 is disposed between the first end wall 211 and the first tab 10a, and / or at least a portion of the first insulating member 40 is disposed between the side wall 212 and the first tab 10a.

[0194] As an example, the first end wall 211 can be an end cap 22 or a wall of the housing 21.

[0195] As an example, in the thickness direction Z of the first end wall 211, at least a portion of the first insulating member 40 is disposed between the first end wall 211 and the first tab 10a. As an example, in the thickness direction of the side wall 212, at least a portion of the first insulating member 40 is disposed between the side wall 212 and the first tab 10a.

[0196] One of the first electrode tab 10a and the second electrode tab 10b is a positive electrode tab, and the other is a negative electrode tab. 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, and the electrode terminal 30 is a positive terminal; in other examples, the first electrode tab 10a is a negative electrode tab, and the electrode terminal 30 is a negative terminal.

[0197] The second tab 10b can be disposed at the end of the electrode assembly 10 facing the first end wall 211, or at the end of the electrode assembly 10 facing away from the first end wall 211.

[0198] In some examples, the electrode body 10c includes a first end face 10e and a second end face 10f disposed opposite to each other. The first end face 10e is located on the side of the electrode body 10c facing the first end wall 211, and the second end face 10f is located on the side of the electrode body 10c away from the first end wall 211. As an example, the two opposite ends of the spacer 13 form the first end face 10e and the second end face 10f, respectively.

[0199] The first electrode tab 10a protrudes from the first end face 10e. Optionally, the second electrode tab 10b protrudes from the first end face 10e; alternatively, the second electrode tab 10b protrudes from the second end face 10f.

[0200] 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.

[0201] In some examples, the second tab 10b can be directly connected to the first end wall 211, or it can be indirectly connected to the first end wall 211 through other conductive structures.

[0202] In some examples, the second tab 10b can be directly connected to the sidewall 212, or it can be indirectly connected to the sidewall 212 through other conductive structures.

[0203] In some examples, the second tab 10b can be electrically connected to the first end wall 211 via the side wall 212; in other examples, the second tab 10b can be electrically connected to the side wall 212 via the first end wall 211.

[0204] Electrode lead-out hole 2111 penetrates the first end wall 211. As an example, along the thickness direction Z of the first end wall 211, the electrode lead-out hole 2111 penetrates the first end wall 211, and the projection of the electrode terminal 30 at least partially overlaps with the projection of the electrode lead-out hole 2111.

[0205] 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.

[0206] In some examples, at least a portion of the electrode terminal 30 is located outside the first end wall 211 and covers the electrode lead-out hole 2111. Optionally, the electrode terminal 30 may be entirely located outside the first end wall 211; alternatively, the electrode terminal 30 passes through the electrode lead-out hole 2111, with a portion of the electrode terminal 30 located outside the first end wall 211 and a portion of the electrode terminal 30 located inside the first end wall 211.

[0207] The side wall 212 is electrically connected to the first end wall 211.

[0208] In some examples, the sidewall 212 and the first endwall 211 may be integrally formed. In other examples, the sidewall 212 and the first endwall 211 may also be formed independently and joined together by bonding, snap-fitting, welding or other means.

[0209] 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.

[0210] 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.

[0211] For example, the thermogravimetric temperature of the first insulating component 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 component 40 can be measured with reference to GB / T27761-2011 Test Method for Weight Loss and Residual Weight of Thermogravimetric Analyzer.

[0212] In some examples, at least a portion of the first insulating member 40 is disposed between the first end wall 211 and the first tab 10a. In other examples, at least a portion of the first insulating member 40 is disposed between the side wall 212 and the first tab 10a. In still other examples, a portion of the first insulating member 40 is disposed between the first end wall 211 and the first tab 10a, and another portion of the first insulating member 40 is disposed between the side wall 212 and the first tab 10a.

[0213] When the battery cell 7 is working normally, the first insulating member 40 can isolate the first tab 10a from the side wall 212 or the first tab 10a from the first end wall 211, thereby reducing the risk of the first tab 10a and the second tab 10b becoming conductive and improving reliability.

[0214] 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 weight loss temperature of the first insulating member 40 is greater than or equal to 300°C, making it less prone to weight loss or experiencing minimal weight loss during thermal runaway of the battery cell 7. This allows the first insulating member 40 to remain within the housing 20 and to separate the first tab 10a from the first end wall 211 or from the side wall 212, reducing the risk of the side wall 212 or the first end wall 211 becoming conductive with the electrode terminal 30 through the first tab 10a. Correspondingly, even if the electrode terminal 30 and the first end 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 end wall 211, reducing the continuous heat generation between the electrode terminal 30 and the first end wall 211, reducing the thermal impact on other surrounding battery cells 7, lowering the risk of thermal runaway in other battery cells 7, and improving reliability.

[0215] For example, when the first end wall 211 and electrode terminal 30 of the normal battery cell 7 are electrically connected to the first end wall 211 and electrode terminal 30 of the thermally runaway battery cell 7, the first insulating member 40 can reduce the risk of circuit continuity between the two battery cells 7, reduce the continuous heat generation of the electrode terminal 30 and the first end wall 211 of the thermally runaway battery cell 7, reduce the thermal impact on other surrounding battery cells 7, reduce the risk of thermal runaway in other battery cells 7, and improve reliability.

[0216] The first end 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 is convenient to connect the busbar to the first end wall 211 or the busbar to the electrode terminal 30, thus simplifying the structure of the battery device.

[0217] 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 the side wall 212 or the first end wall 211 being connected to the electrode terminal 30 through the first tab 10a, reduce the continuous heat generation of the electrode terminal 30 and the first end wall 211, reduce the thermal impact on other battery cells 7 in the vicinity, reduce the risk of thermal runaway of other battery cells 7, and improve reliability.

[0218] 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 the side wall 212 or the first end wall 211 being connected to the electrode terminal 30 through the first tab 10a, reduce the continuous heat generation of the electrode terminal 30 and the first end wall 211, reduce the thermal impact on other battery cells 7 in the vicinity, reduce the risk of thermal runaway of other battery cells 7, and improve reliability.

[0219] In some embodiments, the thermal weight loss temperature of the first insulating member 40 is greater than or equal to 550°C.

[0220] In some embodiments, the material of the first insulating member 40 includes a thermosetting material.

[0221] 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. 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 internal pressure, lowering the risk of failure and thus improving insulation performance.

[0222] In some embodiments, the thermosetting material may include at least one of thermosetting polyimide, thermosetting phenolic resin, or other high-temperature resistant thermosetting materials.

[0223] In some embodiments, the material of the first insulating member 40 includes one or more thermosetting polyimides and their derivatives.

[0224] 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.

[0225] 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.

[0226] 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 prone to cracking under the internal pressure of the battery cell 7, thereby reducing the risk of insulation failure.

[0227] 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.

[0228] Thermosetting polyimide has good corrosion resistance. During the 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.

[0229] In some embodiments, the material of the first insulating member 40 includes one or more of bismaleimide, ethynyl-terminated polyimide, and norbornene-terminated polyimide.

[0230] Bismaleimide, ethynyl-terminated polyimide, and norbornene-terminated polyimide have advantages such as excellent high temperature resistance, high mechanical strength, and strong chemical corrosion resistance.

[0231] 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.

[0232] 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.

[0233] 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.

[0234] 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.

[0235] In some embodiments, the first insulating member 40 is fixed to at least one of the first end wall 211, the side wall 212, the electrode body 10c, and the first tab 10a.

[0236] As an example, the first insulating member 40 may be fixed to at least one of the first end wall 211, side wall 212, electrode body 10c and first tab 10a by bonding, pressing or other means.

[0237] Fixing the first insulating member 40 to at least one of the first end wall 211, side wall 212, electrode body 10c and first tab 10a can improve the stability of the first insulating member 40, reduce the displacement of the first insulating member 40 in the housing 20 when the battery cell 7 is subjected to external impact, and reduce the risk of insulation failure.

[0238] In some embodiments, the first insulating member 40 includes an insulating coating.

[0239] In some embodiments, the first insulating member 40 is bonded to at least one of the first end wall 211, the side wall 212, the electrode body 10c, and the first tab 10a.

[0240] In some examples, the first insulating member 40 is bonded to the sidewall 212. The first insulating member 40 can be directly bonded to the sidewall 212; for example, an adhesive insulating material (e.g., a thermosetting material) can be directly coated onto the surface of the sidewall 212, and the insulating material, after curing, forms the first insulating member 40. The first insulating member 40 can also be bonded to the sidewall 212 using other materials; for example, an adhesive can be coated onto the surface of the first insulating member 40 and then bonded to the sidewall 212 using the adhesive, which, after curing, forms an adhesive layer.

[0241] In some examples, the first insulating member 40 may be directly bonded to the first end wall 211, or it may be bonded to the first end wall 211 by an adhesive.

[0242] In some examples, the first insulating member 40 can be directly bonded to the electrode body 10c, or it can be bonded to the electrode body 10c by adhesive.

[0243] In some examples, the first insulating member 40 can be directly bonded to the first tab 10a, or it can be bonded to the first tab 10a by adhesive.

[0244] In some embodiments, the first insulating member 40 is fixed to at least two of the first end wall 211, the side wall 212, the electrode body 10c, and the first tab 10a.

[0245] For example, the first insulating member 40 is fixed to the first end wall 211 and the side wall 212. Alternatively, the first insulating member 40 is bonded to the first end wall 211 and the side wall 212.

[0246] For example, the first insulating member 40 is fixed to the electrode body 10c and the first tab 10a. Alternatively, the first insulating member 40 is bonded to the electrode body 10c and the first tab 10a.

[0247] By bonding the first insulating member 40 to at least one of the first end wall 211, side wall 212, electrode body 10c and first tab 10a, the stability of the first insulating member 40 can be improved, and the displacement of the first insulating member 40 can be reduced when the battery cell 7 is subjected to external impact, thereby reducing the risk of insulation failure.

[0248] In some embodiments, at least a portion of the first insulating member 40 is located between the sidewall 212 and the first tab 10a.

[0249] The first insulating member 40 can be integrally disposed between the side wall 212 and the first electrode tab 10a, or it can be partially disposed between the side wall 212 and the first electrode tab 10a.

[0250] As an example, the first insulating member 40 can be fixed to the side wall 212, fixed to the first tab 10a, or non-fixedly disposed between the side wall 212 and the first tab 10a.

[0251] In the event of thermal runaway of a battery cell 7, the first insulating member 40 is less prone to weight loss or experiences minimal weight loss. It can separate the first tab 10a from the side wall 212, reducing the risk of the electrode terminal 30 becoming conductive with the first end wall 211 through the first tab 10a and the side wall 212. Even if the electrode terminal 30 and the first end 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 end wall 211, reducing the continuous heat generation between the electrode terminal 30 and the first end wall 211, reducing the thermal impact on other surrounding battery cells 7, lowering the risk of thermal runaway in other battery cells 7, and improving reliability.

[0252] In some embodiments, the minimum distance between the first tab 10a and the sidewall 212 is less than the minimum distance between the first tab 10a and the first endwall 211. A larger distance can be maintained between the first tab 10a and the first endwall 211 to allow for the installation of other components. A smaller distance can be maintained between the first tab 10a and the sidewall 212, allowing the first tab 10a to have a larger current-carrying area and improving its current-carrying capacity. The first insulating member 40 can separate the first tab 10a from the sidewall 212, thereby reducing the risk of short circuits caused by increasing the size of the first tab 10a.

[0253] In some embodiments, the first insulating member 40 is disposed around the first tab 10a to isolate the outer peripheral surface 10g of the first tab from the sidewall 212, reducing the risk of the first tab 10a conducting with the second tab 10b through the sidewall 212 and improving reliability. In the event of thermal runaway of the battery cell 7, the first insulating member 40 is less prone to weight loss or experiences minimal weight loss, thus separating the first tab 10a from the sidewall 212 and reducing the risk of the electrode terminal 30 conducting with the first end wall 211 through the first tab 10a and the sidewall 212.

[0254] In some embodiments, the first tab 10a has a cylindrical structure. Exemplarily, the battery cell 7 is a cylindrical battery cell, and the electrode body 10c is cylindrical. The surface of the first tab 10a away from the electrode body 10c may be an annular surface.

[0255] In some embodiments, the circumferential angle of the first insulating member 40 may be greater than or equal to 360°. The first insulating member 40 wraps around the first tab 10a at least once.

[0256] In some embodiments, the outer peripheral surface 10i of the electrode body is closer to the sidewall 212 than the outer peripheral surface 10g of the first electrode tab, so that a space is formed between the outer peripheral surface 10g of the first electrode tab and the sidewall 212 to accommodate at least a portion of the first insulating member 40.

[0257] The embodiments of this application can reserve a larger space between the outer peripheral surface 10g of the first electrode tab and the side wall 212, thereby allowing the first insulating member 40 to have a larger thickness, reducing the risk of failure of the first insulating member 40 and improving reliability.

[0258] In some embodiments, the outer peripheral surface 10i of the electrode body is a cylindrical surface, and the outer peripheral surface 10g of the first electrode tab may also be a cylindrical surface. The diameter of the outer peripheral surface 10i of the electrode body is larger than the diameter of the outer peripheral surface 10g of the first electrode tab.

[0259] In some embodiments, the end of the first insulating member 40 facing the first end wall 211 is flush with the end of the first tab 10a facing the first end wall 211. The first insulating member 40 can separate the end of the first tab 10a facing the first end wall 211 from the side wall 212, thereby reducing the risk of short circuit. In the event of thermal runaway of the battery cell 7, the first insulating member 40 can also reduce the risk of conduction between the first tab 10a and the first end wall 211.

[0260] In some embodiments, along the direction of the electrode assembly 10 toward the first end wall 211, the first insulating member 40 protrudes from the first tab 10a, which can separate the end of the first tab 10a facing the first end wall 211 from the side wall 212, thereby reducing the risk of short circuit. The first insulating member 40 protruding from the first tab 10a can increase the insulation area. In the event of thermal runaway, the first insulating member 40 can block metal particles, reducing the risk that metal particles will cross the first insulating member 40 and conduct electricity between the first tab 10a and the side wall 212.

[0261] 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.

[0262] In some embodiments, the first current collector 81 is located on the side of the first tab 10a facing the first end 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 end wall 211. 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.

[0263] In some embodiments, the first current collector 81 includes a tab connection portion 811 connected to the first tab 10a and a terminal connection portion 812 connected to the electrode terminal 30, with the tab connection portion 811 surrounding the terminal connection portion 812.

[0264] As an example, the terminal connection portion 812 may be the portion of the first current collector 81 that abuts against the electrode terminal 30.

[0265] In some embodiments, along the direction of the electrode assembly 10 toward the first end wall 211, the first insulating member 40 protrudes from the tab connection portion 811.

[0266] Compared to the terminal connection portion 812, the tab connection portion 811 is closer to the side wall 212. The first insulating member 40 protrudes from the tab connection portion 811, which can separate the tab connection portion 811 from the side wall 212, thereby reducing the risk of short circuit. In the event of thermal runaway of the battery cell 7, the first insulating member 40 is less likely to lose weight or loses less weight, thereby reducing the risk that the first current collector 81 will conduct electricity between the side wall 212 and the electrode terminal 30.

[0267] In some embodiments, the first tab 10a is welded to the tab connection portion 811, and the electrode terminal 30 is welded to the terminal connection portion 812.

[0268] 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 terminal connection portion 812.

[0269] 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.

[0270] By providing the terminal recess 34, the thickness of the bottom wall of the terminal recess 34 can be reduced, the power required for welding the electrode terminal 30 to the terminal connection part 812 from the outside can be reduced, the risk of welding particles falling into the housing 20 can be reduced, and the reliability of the battery cell 7 can be improved.

[0271] In some embodiments, the electrode terminal 30 has a terminal recess 34 on the side opposite to the first current collector 81.

[0272] 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.

[0273] 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.

[0274] 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.

[0275] In some embodiments, at least a portion of the cover plate 82 is accommodated in the terminal recess 34.

[0276] In some embodiments, the first electrode tab 10a is a positive electrode tab, 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, and the negative electrode lead-out portion includes a cover plate 82 and an electrode terminal 30.

[0277] 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.

[0278] In some embodiments, a portion of the first insulating member 40 is located between the sidewall 212 and the electrode body 10c.

[0279] In the event of thermal runaway of battery cell 7, the separator 13 may melt and fail. In this embodiment, a heat-resistant first insulating member 40 is disposed between the sidewall 212 and the electrode body 10c. This reduces the risk that the remaining portion of the electrode body 10c will conduct through the sidewall 212 during thermal runaway, thereby reducing the risk that the first end wall 211 will conduct through the sidewall 212, the remaining portion of the electrode body 10c, and the first tab 10a to the electrode terminal 30. This suppresses the current between the electrode terminal 30 and the first end wall 211, reduces the continuous heat generation between the electrode terminal 30 and the first end wall 211, reduces the thermal impact on other surrounding battery cells 7, lowers the risk of thermal runaway in other battery cells 7, and improves reliability.

[0280] In some embodiments, a second tab 10b is disposed at one end of the electrode assembly 10 facing away from the first end wall 211, and at least a portion of the first insulating member 40 is located between the side wall 212 and the second tab 10b. The first insulating member 40 protrudes from the second tab 10b in the direction from the first end wall 211 to the electrode assembly 10; or, the end of the first insulating member 40 facing away from the first end wall 211 is flush with the end of the second tab 10b facing away from the first end wall 211.

[0281] The embodiments of this application can increase the insulation range of the first insulating member 40 so as to separate the remaining part of the electrode assembly 10 from the sidewall 212 after the battery cell 7 thermally runs away, thereby reducing the risk that the remaining part of the electrode assembly 10 will conduct electricity between the sidewall 212 and the electrode terminal 30.

[0282] In some embodiments, the battery cell 7 further includes a second insulating member 50. At least a portion of the second insulating member 50 is disposed between the first tab 10a and the sidewall 212. The second insulating member 50 can insulate at least a portion of the first tab 10a from the sidewall 212.

[0283] The second insulating member 50 may be entirely disposed between the first tab 10a and the side wall 212, or it may be partially disposed between the first tab 10a and the side wall 212. In some examples, a portion of the second insulating member 50 is also disposed between the first tab 10a and the first end wall 211.

[0284] The second insulating member 50 can be independently disposed between the first electrode tab 10a and the side wall 212, or it can be fixed to the first electrode tab 10a or the side wall 212.

[0285] The thermal weight loss temperature of the second insulating member 50 may be higher than, equal to or lower than the thermal weight loss temperature of the first insulating member 40.

[0286] The material of the second insulating member 50 may be the same as or different from the material of the first insulating member 40.

[0287] In some examples, the second insulating member 50 may be disposed along the outer periphery of the first tab 10a. For example, the angle of the second insulating member 50 around the first tab 10a is greater than or equal to 180°.

[0288] In some embodiments, at least a portion of the second insulating member 50 surrounds the first tab 10a to increase the insulating area and improve the insulating effect.

[0289] In some embodiments, at least a portion of the second insulating member 50 surrounds the first tab 10a and is located between the first insulating member 40 and the first tab 10a. In other embodiments, at least a portion of the second insulating member 50 surrounds the first tab 10a and is located between the sidewall 212 and the first insulating member 40. In still other embodiments, a portion of the second insulating member 50 surrounds the first tab 10a and is located between the first insulating member 40 and the first tab 10a, and a portion of the second insulating member 50 surrounds the first tab 10a and is located between the sidewall 212 and the first insulating member 40.

[0290] By setting the first insulating member 40 and the second insulating member 50, a double-layer insulating structure can be formed between the first tab 10a and the side wall 212, thereby further improving the insulation effect and reducing the risk of the first tab 10a and the side wall 212 conducting when the battery cell 7 experiences thermal runaway.

[0291] In some embodiments, at least a portion of the first insulating member 40 is attached to the inner surface of the sidewall 212. Exemplarily, the first insulating member 40 is bonded to the inner surface of the sidewall 212.

[0292] Attaching the first insulating member 40 to the inner surface of the sidewall 212 can improve the stability of the first insulating member 40, reduce the displacement of the first insulating member 40 relative to the sidewall 212 when the battery cell 7 experiences thermal runaway, improve the insulation effect, and reduce the risk of the first tab 10a and the sidewall 212 becoming conductive when the battery cell 7 experiences thermal runaway.

[0293] In addition, during the assembly of the battery cell 7, the side wall 212 and the first insulating component 40 can be supplied as a single piece, thereby simplifying the assembly process.

[0294] In some embodiments, at least a portion of the second insulating member 50 surrounds the first tab 10a and is located between the first insulating member 40 and the first tab 10a.

[0295] The tensile modulus of the second insulating member 50 may be less than, greater than or equal to the tensile modulus of the first insulating member 40.

[0296] The second insulating member 50 can separate the first tab 10a from the first insulating member 40, thereby reducing the risk of the first insulating member 40 being cracked or scratched by the first tab 10a during the use of the battery cell 7.

[0297] In some embodiments, the tensile modulus of the second insulating member 50 is less than that of the first insulating member 40.

[0298] As an example, the tensile modulus of the second insulating member 50 and the tensile modulus of the first insulating member 40 can be measured with reference to GB / T 1040.1-2018 Determination of tensile properties of plastics - Part 1: General Rules.

[0299] When the second insulating member 50 is wrapped around the outside of the first tab 10a, the second insulating member 50 can be stretched and tightened to close and bind the first tab 10a. The second insulating member 50 has a small tensile modulus, which can release stress through tensile deformation and reduce excessive deformation of the first tab 10a under the binding of the second insulating member 50. The first insulating member 40 is attached to the sidewall 212 and can have a large tensile modulus. When the electrode assembly 10 expands, the first insulating member 40 can bind the sidewall 212, reduce the deformation of the sidewall 212, and improve the morphology of the battery cell 7.

[0300] In some embodiments, the first tab 10a is cylindrical. The second insulating member 50 surrounds the first tab 10a at an angle greater than or equal to 360°. Optionally, the surround angle of the second insulating member 50 is greater than 360°.

[0301] In some embodiments, the second insulating member 50 may be bonded to the outer peripheral surface 10g of the first electrode tab.

[0302] In some embodiments, a portion of the second insulating member 50 is disposed between the first tab 10a and the first end wall 211.

[0303] The second insulating member 50 can isolate at least a portion of the first tab 10a from the first end wall 211, thereby reducing the risk of the first tab 10a contacting the first end wall 211, thus reducing the risk of short circuit and improving reliability.

[0304] In some embodiments, the second insulating member 50 includes a third insulating portion 51 and a fourth insulating portion 52, the fourth insulating portion 52 being connected to the third insulating portion 51. At least a portion of the third insulating portion 51 is disposed between the sidewall 212 and the first tab 10a, and at least a portion of the fourth insulating portion 52 is disposed between the first endwall 211 and the first tab 10a.

[0305] In some embodiments, the fourth insulating portion 52 is connected to the end of the third insulating portion 51 facing the first end wall 211 and is bent relative to the third insulating portion 51.

[0306] In some embodiments, a portion of the third insulating portion 51 is located between the sidewall 212 and the electrode body 10c.

[0307] In some embodiments, at least a portion of the tab connection 811 is located between the fourth insulating portion 52 and the first tab 10a. The fourth insulating portion 52 can separate at least a portion of the tab connection 811 from the first end wall 211 to reduce the risk of short circuit.

[0308] In some embodiments, the fourth insulating portion 52 is bonded to the tab connection portion 811.

[0309] In some embodiments, the third insulating portion 51 may be a cylindrical structure. The fourth insulating portion 52 may be an annular structure. As an example, the second insulating member 50 can be independently fitted onto the first tab 10a without the need for the first tab 10a to be bonded.

[0310] In some embodiments, the thermal weight loss temperature of the first insulating member 40 is greater than that of the second insulating member 50.

[0311] When the battery cell 7 experiences thermal runaway, the second insulating component 50 can soften and lose weight under high temperature, thereby adhering to metal particles near the first tab 10a, reducing the impact of metal particles on the first insulating component 40, and lowering the risk of failure of the first insulating component 40.

[0312] In some embodiments, the material of the second insulating member 50 includes a thermoplastic material.

[0313] Thermoplastic materials have advantages such as ease of molding, good flexibility, high chemical stability, and excellent electrical insulation. The second insulating member 50 containing thermoplastic material is easy to mold, and its shape can be adapted to the first tab 10a. When subjected to external force, the second insulating member 50 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.

[0314] In some embodiments, the battery cell 7 further includes a third insulating member 60 disposed between the electrode body 10c and the sidewall 212.

[0315] The thermal weight loss temperature of the third insulating member 60 may be higher than, equal to or lower than the thermal weight loss temperature of the first insulating member 40.

[0316] The material of the third insulating member 60 may be the same as or different from the material of the first insulating member 40.

[0317] The third insulating member 60 may be integrally disposed between the electrode body 10c and the side wall 212. Alternatively, a portion of the third insulating member 60 may be disposed between the electrode body 10c and the side wall 212.

[0318] In the thickness direction of the third insulating member 60, the third insulating member 60 may overlap with the first insulating member 40 or may not overlap.

[0319] The third insulating member 60 can separate the electrode body 10c from the side wall 212 to reduce the risk of short circuit.

[0320] For example, during the production of the battery cell 7, metal particles may remain inside the casing 20 due to process reasons. These metal particles may puncture the separator 13 of the electrode body 10c, causing a short circuit risk. The third insulating member 60 can separate the electrode body 10c from the side wall 212 to reduce the short circuit risk.

[0321] In some embodiments, the third insulating member 60 is disposed along the outer periphery of the electrode body 10c. Optionally, the angle of the third insulating member 60 around the electrode body 10c is greater than or equal to 90°.

[0322] In some embodiments, the third insulating member 60 is fixed to the outer peripheral surface 10i of the electrode body to reduce the risk of displacement of the third insulating member 60 when the battery cell 7 is subjected to external impact, thereby improving the stability of the third insulating member 60.

[0323] As an example, the third insulating member 60 is bonded to the outer peripheral surface 10i of the electrode body.

[0324] In some embodiments, the electrode body 10c includes a wound insulating member 13, and a third insulating member 60 is connected to the outer surface of the insulating member 13.

[0325] The third insulating member 60 can protect the isolator 13 from the outside to reduce the risk of the isolator 13 being punctured. The third insulating member 60 can also restrain the isolator 13 to reduce the risk of the isolator 13 coming apart.

[0326] The third insulating member 60 can also constrain the electrode body 10c from the outside, reducing the expansion and deformation of the electrode body 10c.

[0327] In some embodiments, the spacer 13 has a winding start end 131 and a winding end end 132. A third insulating member 60 extends continuously along the winding direction V, with a portion of the third insulating member 60 located on one side of the winding end end 132 and another portion located on the other side of the winding end end 132. The third insulating member 60 may cover the winding end end 132 of the spacer 13 to reduce the risk of the spacer 13 unraveling.

[0328] In some embodiments, the thermal weight loss temperature of the third insulating member 60 is greater than or equal to 300°C.

[0329] As an example, the thermal decomposition temperature of the third insulating member 60 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.

[0330] For example, the thermogravimetric temperature of the third insulating component 60 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 third insulating component 60 can be measured with reference to GB / T27761-2011 Test Method for Weight Loss and Residual Weight of Thermogravimetric Analyzer.

[0331] 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 third insulating member 60 is greater than or equal to 300°C, making it less prone to weight loss or experiencing minimal weight loss during thermal runaway of the battery cell 7. This allows the third insulating member 60 to remain within the casing 20 and separate the remaining portion of the electrode body 10c from the side wall 212, reducing the risk of the side wall 212 conducting through the remaining portion of the electrode body 10c and the first tab 10a to the electrode terminal 30. This, in turn, suppresses the current between the electrode terminal 30 and the first end wall 211, reduces the continuous heat generation between the electrode terminal 30 and the first end wall 211, reduces the thermal impact on other surrounding battery cells 7, lowers the risk of thermal runaway in other battery cells 7, and improves reliability.

[0332] In some embodiments, at least a portion of the first insulating member 40 is disposed between the sidewall 212 and the third insulating member 60.

[0333] By setting the first insulating member 40 and the third insulating member 60, a double-layer insulating structure can be formed between the electrode body 10c and the side wall 212, thereby further improving the insulation effect and reducing the risk of the electrode body 10c and the side wall 212 conducting when the battery cell 7 experiences thermal runaway.

[0334] For example, since the first insulating member 40 has high heat resistance, the third insulating member 60 can also be made of a material with a low thermal weight loss temperature.

[0335] In some embodiments, the first insulating member 40 protrudes from the third insulating member 60 in the direction from the first end wall 211 toward the electrode assembly 10.

[0336] Both ends of the first insulating member 40 protrude from the third insulating member 60. The first insulating member 40 can separate the part of the electrode assembly 10 that protrudes from the third insulating member 60 from the side wall 212, so as to reduce the risk of the residual part of the electrode body 10c contacting the side wall 212 in the event of thermal runaway of the battery cell 7, thereby improving reliability.

[0337] In some embodiments, along the direction of the first end wall 211 pointing towards the electrode assembly 10, the electrode body 10c protrudes from the third insulating member 60, and the first insulating member 40 protrudes from the electrode body 10c. The first end face 10e of the electrode body 10c is spaced apart from the third insulating member 60.

[0338] Along the direction from the electrode assembly 10 to the first end wall 211, the electrode body 10c protrudes from the third insulating member 60, and the first insulating member 40 protrudes from the electrode body 10c. The second end face 10f of the electrode body 10c is spaced apart from the third insulating member 60.

[0339] In some embodiments, the second insulating member 50 is located on one side of the third insulating member 60 along the direction of the electrode assembly 10 toward the first end wall 211.

[0340] In some embodiments, a second gap G2 is provided between the second insulating member 50 and the third insulating member 60 along the direction of the electrode assembly 10 pointing towards the first end wall 211, which can reduce the risk of overlap between the second insulating member 50 and the third insulating member 60. The electrode assembly 10 may expand during operation. If the third insulating member 60 and the second insulating member 50 overlap radially in the battery cell 7, it may cause localized stress concentration, affecting the cycle performance of the electrode assembly 10.

[0341] In some embodiments, the size D4 of the second gap G2 is 0.5mm-10mm along the direction of the electrode assembly 10 pointing to the first end wall 211.

[0342] Optionally, along the direction of the electrode assembly 10 pointing to the first end wall 211, the size D4 of the second gap G2 is 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, 8mm, 8.5mm, 9mm, 9.5mm, or 10mm.

[0343] In some embodiments, the first insulating member 40 covers the second gap G2 from the outside to separate the sidewall 212 from the electrode body 10c.

[0344] In some embodiments, the housing 20 further includes a second end wall 20a, which is disposed opposite to the first end wall 211, and a side wall 212 connects the first end wall 211 and the second end wall 20a.

[0345] In some examples, one of the second end wall 20a and the first end wall 211 is integrally formed with the side wall 212, while the other is formed independently of the side wall 212.

[0346] For example, the sidewall 212 and the second endwall 20a can be formed independently and connected as a whole by bonding, snap-fitting, welding or other means. The sidewall 212 and the second endwall 20a can be electrically connected or insulated connected.

[0347] In some embodiments, a second tab 10b is disposed at one end of the electrode assembly 10 facing the second end wall 20a. Exemplarily, the second tab 10b protrudes from the second end face 10f of the electrode body 10c.

[0348] By placing the first tab 10a and the second tab 10b at opposite ends of the electrode assembly 10, the risk of short circuit between the first tab 10a and the second tab 10b can be reduced, and more space can be provided for the first tab 10a and the second tab 10b, thereby improving the current carrying capacity of the first tab 10a and the second tab 10b.

[0349] In some embodiments, the battery cell 7 further includes a pressure relief mechanism 70 disposed on the housing 20.

[0350] The pressure relief mechanism 70 can be installed on the first end wall 211, the side wall 212, or the second end wall 20a.

[0351] As an example, the pressure relief mechanism 70 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 performs its action or a weak structure provided in the pressure relief mechanism 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.

[0352] 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.

[0353] In the event of thermal runaway of the battery cell 7, the pressure relief mechanism 70 can release the temperature and pressure inside the battery cell 7, thereby reducing the risk of the battery cell 7 exploding.

[0354] After the pressure relief mechanism 70 is activated, the temperature of the outer casing 20 gradually decreases, thereby shortening the time that the first insulating component 40 is in the high-temperature environment, reducing the weight loss of the first insulating component 40, and reducing the risk of failure of the first insulating component 40.

[0355] In some embodiments, the pressure relief mechanism 70 is disposed on the second end wall 20a.

[0356] When the battery cell 7 experiences thermal runaway, high-temperature substances (such as high-temperature gases, particles, debris, etc.) will be released outward through the pressure relief channel formed by the pressure relief mechanism 70. By placing the pressure relief mechanism 70 on the second end wall 20a, the thermal shock to the first insulating member 40 can be reduced, thereby lowering the risk of deformation and failure of the first insulating member 40.

[0357] During the release of high-temperature gas, some of the heat will be conducted to the second end wall 20a. The second end wall 20a is far from the first tab 10a, which can reduce the heat conducted to the part of the first insulating member 40 near the first tab 10a, 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.

[0358] By placing the pressure relief mechanism 70 on the second end 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 end wall 211 and the electrode terminal 30.

[0359] In some embodiments, the pressure relief mechanism 70 includes a pressure relief portion 71 and a weak portion 72 disposed along the outer periphery of the pressure relief portion 71.

[0360] The portion that is cracked, broken, torn, or opened. For example, the strength of the pressure relief mechanism 70 is less than the strength of the portion of the pressure relief mechanism 70 near the weak point 72.

[0361] In some examples, this application may create grooves, notches, through holes, or other structures in a predetermined area of ​​the pressure relief mechanism 70 to reduce the local strength of the pressure relief mechanism 70, thereby forming a weak portion 72 in the pressure relief mechanism 70. For example, a thinning process may be performed on a predetermined area of ​​the pressure relief mechanism 70, and the thinned portion of the pressure relief mechanism 70 forms the weak portion 72. In other examples, the predetermined area of ​​the pressure relief mechanism 70 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 72.

[0362] The weak part 72 can rupture when the internal pressure or temperature of the battery cell 7 reaches a threshold; the pressure relief part 71 can be the part of the pressure relief mechanism 70 used to form a pressure relief channel when the weak part 72 ruptures.

[0363] In some examples, the weak portion 72 may surround the pressure relief portion 71. In the event of thermal runaway of the battery cell 7, the weak portion 72 ruptures at least partially; for example, the weak portion 72 ruptures completely, and the pressure relief portion 71 detaches from the casing 20, thereby forming a pressure relief channel; for example, the weak portion 72 ruptures partially, and the pressure relief portion 71 flips outward under the internal pressure of the battery cell 7 to form a pressure relief channel.

[0364] In other examples, the weak portion 72 may also partially surround the pressure relief portion 71. The line connecting the two ends of the weak portion 72 and the weak portion 72 together define the pressure relief portion 71. During thermal runaway of the battery cell 7, the weak portion 72 ruptures, and the pressure relief portion 71 can, under the internal pressure of the battery cell 7, rotate outward about the line connecting the two ends of the weak portion 72 as an axis to form a pressure relief channel. Optionally, with the center of the pressure relief portion 71 as the center, the line connecting one end of the weak portion 72 to the center is L1, and the line connecting the other end of the weak portion 72 to the center is L2. The angle α between L1 and L2 is greater than or equal to 180°, and angle α is opposite to the weak portion 72. Optionally, α is greater than or equal to 270°.

[0365] In some embodiments, the area of ​​the pressure relief portion 71 is larger than the area of ​​the electrode lead-out hole 2111.

[0366] 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 71 can be the area of ​​the smallest cross-section of the pressure relief part 71 perpendicular to its own thickness direction.

[0367] Compared to the electrode lead-out hole 2111, the pressure relief section 71 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 71, 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 end wall 211 and minimizes deformation of the portion of the first end wall 211 near the electrode lead-out hole 2111.

[0368] In some embodiments, the pressure relief part 71 is circular, and the diameter φ1 of the pressure relief part 71 satisfies: 20mm≤φ1≤35mm. Optionally, 22mm≤φ1≤32mm.

[0369] 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.

[0370] In some embodiments, the area enclosed by the outer contour of the projection of the second end wall 20a along its own thickness direction is S1, and the area of ​​the pressure relief part 71 projected onto the second end wall 20a in the thickness direction is S2. 0.1≤S2 / S1≤0.8.

[0371] As an example, S2 / S1 can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7 or 0.8.

[0372] In this embodiment, limiting S2 / S1 to greater than or equal to 0.1 allows the pressure relief mechanism 70 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 in the first insulating member 40, lowers the risk of insulation failure, and improves the reliability of the battery cell 7.

[0373] Limiting S2 / S1 to less than or equal to 0.8 can restrict the range of the weak part 72, reduce the impact of the weak part 72 on the strength of the second end wall 20a, reduce the risk of the weak part 72 breaking during normal use of the battery cell 7, and improve the reliability of the battery cell 7.

[0374] In some embodiments, 0.3 ≤ S2 / S1 ≤ 0.7 can further improve the reliability of the battery cell 7.

[0375] In some embodiments, the pressure relief mechanism 70 is integrally formed with the second end wall 20a. Exemplarily, the second end wall 20a has a first recess 73, and the weak portion 72 includes the bottom wall of the first recess 73. The first recess 73 surrounds the pressure relief portion 71.

[0376] 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.

[0377] In some examples, at least a portion of the first insulating member 40 is disposed between the first tab 10a and the first end wall 211 along the axial direction of the cylindrical battery cell. As an example, the thickness direction Z of the first end wall is parallel to the axial direction of the cylindrical battery cell.

[0378] In some examples, at least a portion of the first insulating member 40 is disposed between the first tab 10a and the sidewall 212 in the radial direction of the cylindrical battery cell.

[0379] In some embodiments, the first end wall 211 and the second end wall 20a are disposed opposite to each other along the axial direction of the cylindrical battery cell. The pressure relief mechanism 70 includes a pressure relief portion 71 and a weak portion 72 disposed along the outer periphery of the pressure relief portion 71, the pressure relief portion 71 being circular. The diameter φ1 of the pressure relief portion 71 and the diameter φ2 of the cylindrical battery cell satisfy the following relationship: 0.35≤φ1 / φ2≤0.85.

[0380] 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.

[0381] In this embodiment, limiting φ1 / φ2 to greater than or equal to 0.35 allows the pressure relief mechanism 70 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.

[0382] Limiting φ1 / φ2 to less than or equal to 0.85 can restrict the range of the weak part 72, reduce the impact of the weak part 72 on the strength of the second end wall 20a, reduce the risk of the weak part 72 breaking during normal use of the battery cell 7, and improve the reliability of the battery cell 7.

[0383] 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.

[0384] As an example, the diameter φ2 of the cylindrical battery cell is 35mm, 40mm, 45mm, 50mm, 55mm, 60mm, 65mm or 70mm.

[0385] 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.

[0386] Optionally, the diameter φ2 of the cylindrical battery cell is 45mm to 60mm.

[0387] 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.

[0388] Optionally, the height of the housing 20 is 60mm-100mm.

[0389] 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.

[0390] 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.

[0391] 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.

[0392] In some embodiments, the height of the housing 20 is 1.5 to 2.5 times the diameter of the housing 20.

[0393] In some embodiments, the thickness t2 of the second end wall 20a is less than the thickness t1 of the first end wall 211.

[0394] In the event of thermal runaway of the battery cell 7, the deformation of the first end wall 211 is smaller than that of the second end wall 20a. This reduces the deformation or displacement of the first tab 10a under the influence of the first end wall 211 and the electrode terminal 30, lowering the risk of the first tab 10a compressing the first insulating member 40, thereby reducing the risk of the first insulating member 40 being crushed, improving the insulation effect, and enhancing the reliability of the battery cell 7. Compared to the first end wall 211, the second end wall 20a is more likely to bulge outwards, which can increase the gas flow channel inside the second end wall 20a and improve the gas emission efficiency.

[0395] In some embodiments, t1 / t2 ≥ 1.5.

[0396] In some embodiments, 0.5mm ≤ t1 ≤ 2mm. Optionally, 0.5mm ≤ t1 ≤ 1.5mm. Optionally, t1 can be 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, or 2.0mm.

[0397] In some embodiments, 0.3mm ≤ t2 ≤ 1.8mm. Optionally, 0.4mm ≤ t2 ≤ 1.3mm. Optionally, t2 can be 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, or 1.8mm.

[0398] In some embodiments, the thickness of the sidewall 212 is less than the thickness of the first endwall 211. During thermal runaway of the battery cell 7, the deformation of the thicker first endwall 211 is smaller, thereby reducing the deformation or displacement of the first tab 10a under the influence of the first endwall 211 and the electrode terminal 30. This reduces the risk of the first tab 10a compressing the first insulating member 40, further reducing the risk of the first insulating member 40 being crushed, improving insulation performance, and enhancing the reliability of the battery cell 7. During thermal runaway of the battery cell 7, the thinner sidewall 212 can bulge outwards, increasing the gap between the sidewall 212 and the electrode body 10c, which facilitates gas escape.

[0399] In some embodiments, the sidewall 212 is made of steel.

[0400] In some embodiments, the thickness of the sidewall 212 is 0.3 mm to 1.5 mm.

[0401] 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.

[0402] In the embodiments of this application, the thickness of the first end wall 211, the thickness of the side wall 212, and the thickness of the second end wall have meanings known in the art and can be detected using equipment and methods known in the art, such as a micrometer or vernier caliper.

[0403] As an example, the material of sidewall 212 includes stainless steel.

[0404] In some embodiments, the thickness of the sidewall 212 is 0.3 mm to 1.2 mm.

[0405] 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.

[0406] In some embodiments, the material of the first end wall 211 is the same as the material of the side wall 212.

[0407] In some embodiments, the electrode assembly 10 has a first through hole 10d at its center.

[0408] In some examples, the electrode assembly 10 is a wound structure, and a first through-hole 10d is formed at the winding center of the electrode assembly 10. Optionally, the extending direction of the first through-hole 10d is parallel to the winding axis of the electrode assembly 10.

[0409] In some embodiments, the first through hole 10d is disposed between the electrode terminal 30 and the pressure relief mechanism 70 along the extending direction of the first through hole 10d.

[0410] When the battery cell 7 experiences thermal runaway, the gas between the electrode assembly 10 and the first end wall 211 can flow to the pressure relief mechanism 70 through the first through hole 10d, thereby reducing the pressure on the first end wall 211 and the electrode terminal 30, reducing the deformation or displacement of the first tab 10a driven by the electrode terminal 30, reducing the risk of the first tab 10a squeezing the first insulating member 40, thereby reducing the risk of the first insulating member 40 being crushed, improving the insulation effect, and improving the reliability of the battery cell 7.

[0411] In some embodiments, the extension direction of the first through hole 10d is parallel to the thickness direction Z of the first end wall 211.

[0412] In some embodiments, the minimum distance between the first insulating member 40 and the second end wall 20a along the direction from the first end wall 211 to the second end wall 20a is D1, and the total size of the electrode body 10c is D2, where 0≤D1 / D2≤0.25.

[0413] As an example, D1 / D2 can be 0, 0.01, 0.02, 0.03, 0.05, 0.06, 0.08, 0.1, 0.11, 0.12, 0.13, 0.15, 0.16, 0.18, 0.2, 0.21, 0.22, 0.23, or 0.25.

[0414] In the event of thermal runaway of battery cell 7, at least a portion of the second tab 10b and a portion of the electrode body 10c near the second end wall 20a will be discharged to the outside of housing 20 via pressure relief mechanism 70 under high temperature and pressure. After the pressure relief of battery cell 7, a portion of the electrode body 10c near the first end wall 211 may remain inside housing 20.

[0415] In this embodiment, D1 / D2 is limited to less than or equal to 0.25. This allows the first insulating member 40 to separate the remaining portion of the electrode body 10c from the sidewall 212 in the event of thermal runaway of the battery cell 7, thereby reducing the risk that the remaining portion of the electrode body 10c will conduct the first tab 10a and the sidewall 212 and improving reliability.

[0416] In some embodiments, D1 / D2 is greater than 0. The first insulating member 40 is spaced a certain distance from the second end wall 20a.

[0417] During the release of high-temperature gas, some of the heat will be conducted to the second end wall 20a. The second end wall 20a is spaced apart from the first insulating member 40, which can reduce the heat conducted to 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.

[0418] In some embodiments, 0.01 ≤ D1 / D2 ≤ 0.2.

[0419] 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 side wall 212 and the second end wall 20a connected to the second current collector 84, so that the side wall 212 is electrically connected to the first end wall 211 and the second current collector 84.

[0420] In some embodiments, the second current collector 84 is connected to the second end wall 20a and the second tab 10b, and the second end wall 20a is electrically connected to the side wall 212. The second tab 10b is electrically connected to the first end wall 211 through the second current collector 84, the second end wall 20a, and the side wall 212.

[0421] In some embodiments, the battery cell 7 further includes a pressure relief mechanism 70 disposed on the second end wall 20a. At least a portion of the second current collector 84 is located between the pressure relief mechanism 70 and the second tab 10b.

[0422] In the event of thermal runaway of the battery cell 7, the high-temperature gas is discharged to the outside of the casing 21 through the pressure relief channel formed by the pressure relief mechanism 70. At least a portion of the second current collector 84 is opposite to the pressure relief mechanism 70. In the event of thermal runaway of the battery cell 7, the second current collector 84 can deform or even melt under the action of the high-temperature gas, thereby reducing the risk that the second current collector 84 will conduct electricity to the side wall 212 and the residual part of the electrode body 10c, and improving the reliability of the battery cell 7.

[0423] In some embodiments, the housing 20 includes a housing 21 and an end cap 22. The housing 21 includes an integrally formed first end wall 211 and a side wall 212. The end cap 22 is a second end wall 20a and is sealed to the side wall 212.

[0424] The end cap 22 can be insulated from the side wall 212 or electrically connected.

[0425] The end of the housing 21 away from the first end wall 211 has an opening, and the end cap 22 covers the opening of the housing 21.

[0426] The first end wall 211 and the side wall 212 are integrally formed, and the connection strength between the first end wall 211 and the side wall 212 is high. When the battery cell 7 experiences thermal runaway, the side wall 212 can bind the first end wall 211, reduce the deformation of the first end wall 211, thereby reducing the deformation or displacement of the first tab 10a under the action of the first end wall 211 and the electrode terminal 30, reducing the risk of the first tab 10a squeezing the first insulating member 40, thereby reducing the risk of the first insulating member 40 being crushed, improving the insulation effect, and improving the reliability of the battery cell 7.

[0427] In some embodiments, the housing 21 is made of steel. The electrode terminals 30 are made of aluminum or an aluminum alloy.

[0428] In some embodiments, the end cap 22 is made of steel.

[0429] In some embodiments, the first insulating member 40 is spaced apart from the end cap 22 to reduce interference between the first insulating member 40 and the end cap 21 during the assembly of the housing 21 and the end cap 22, thereby increasing the connection strength between the end cap 22 and the housing 21 and reducing the risk of the first insulating member 40 being crushed.

[0430] In some embodiments, the end cap 22 is welded to the side wall 212.

[0431] 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.

[0432] 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.

[0433] In some embodiments, a terminal recess 34 is formed on the terminal body 31.

[0434] In some embodiments, the first limiting portion 32 is located inside the first end wall 211 in the thickness direction Z.

[0435] In the thickness direction Z of the first end wall 211, the first limiting portion 32 at least partially overlaps with the first end wall 211.

[0436] The first end wall 211 and the first limiting part 32 can limit each other in the thickness direction Z to reduce the risk of the electrode terminal 30 detaching from the housing 20 through the electrode lead-out hole 2111.

[0437] In some embodiments, the battery cell 7 further includes a seal 80, at least a portion of which is disposed between the first end wall 211 and the first limiting portion 32.

[0438] The first limiting part 32 and the first end wall 211 can clamp the sealing member 80 in the thickness direction Z to achieve the sealing of the electrode lead-out hole 2111.

[0439] In some embodiments, the thermal weight loss temperature of the seal 80 is greater than or equal to 200°C. As an example, the thermal weight loss temperature of the seal 80 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.

[0440] For example, the thermogravimetric temperature of the seal 80 can be the 5% thermogravimetric temperature. The thermogravimetric temperature of the seal 80 can be measured with reference to GB / T27761-2011 Test Method for Weight Loss and Residual Weight by Thermogravimetric Analyzer.

[0441] The seal 80 is less likely to lose weight or loses less weight when the battery cell 7 experiences thermal runaway, thus enabling the seal 80 to remain between the first end wall 211 and the electrode terminal 30, reducing the risk of direct contact between the electrode terminal 30 and the first end wall 211.

[0442] In the event of thermal runaway of the battery cell 7, the seal 80 and the electrode terminal 30 can limit the displacement of the first tab 10a to maintain a certain distance between the first tab 10a and the first end wall 211, reducing the risk of contact between the first tab 10a and the first end wall 211. Therefore, in some embodiments, the first insulating member 40 may not be provided between the first end wall 211 and the first tab 10a.

[0443] In some embodiments, the seal 80 is electrically insulating. Exemplarily, the seal 80 is made of an insulating material. After thermal runaway of the battery cell 7, the seal 80 can suppress the current between the first limiting portion 32 and the first end wall 211, reducing the continuous heat generation between the electrode terminal 30 and the first end wall 211, lowering the risk of thermal runaway in other battery cells 7, and improving reliability.

[0444] In some embodiments, the thermal weight loss temperature of the seal 80 is lower than that of the first insulating member 40. To achieve a seal, the seal 80 is typically in a compressed state; even if the weight loss rate of the seal 80 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 first limiting portion 32 and the first end wall 211, reducing the risk of direct contact between the first limiting portion 32 and the first end wall 211.

[0445] In some embodiments, the seal 80 comprises a thermosetting material. The seal 80 comprising a thermosetting material can maintain good stability at high temperatures and can isolate the first limiting portion 32 from the first end wall 211 in the event of thermal runaway of the battery cell 7.

[0446] In some embodiments, the material of the seal 80 includes fluororubber. Optionally, the material of the seal 80 includes thermosetting fluororubber.

[0447] In some embodiments, the electrode terminal 30 further includes a second limiting portion 33. 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. The second limiting portion 33 is located outside the first end wall 211. To improve the stability of the electrode terminal 30, the second limiting portion 33 and the first limiting portion 32 can clamp the first end wall 211 from both sides.

[0448] 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.

[0449] In some embodiments, the battery cell 7 further includes a fifth insulating member 85, at least a portion of which is disposed between the second limiting portion 33 and the first end wall 211. Optionally, the thermal decomposition temperature of the fifth insulating member 85 is greater than 300°C.

[0450] In some embodiments, the second limiting part 33 and the terminal body 31 are integrally formed.

[0451] In some embodiments, the electrode terminal 30 is riveted to the first end wall 211.

[0452] In some examples, the second limiting portion 33 is configured to be formed after the electrode terminal 30 passes through the electrode lead-out hole 2111. For example, when assembling the first end 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 pressed to form a flanged structure, which can serve as the second limiting portion 33.

[0453] In other examples, the first limiting portion 32 is configured to be formed after the electrode terminal 30 passes through the electrode lead-out hole 2111.

[0454] In some embodiments, the battery cell 7 includes a fourth insulating member 90. At least a portion of the fourth insulating member 90 is disposed between the first end wall 211 and the first tab 10a to separate the first end wall 211 from the first tab 10a, thereby reducing the risk of conduction between the first end wall 211 and the first tab 10a and improving reliability.

[0455] The thermal weight loss temperature of the fourth insulating component 90 can be greater than, less than or equal to the thermal weight loss temperature of the first insulating component 40.

[0456] The material of the fourth insulating member 90 may be the same as or different from that of the first insulating member 40.

[0457] In some embodiments, at least a portion of the fourth insulating member 90 is located between the first limiting portion 32 and the first end wall 211 in the thickness direction Z of the first end wall 211, so as to reduce the risk of the first limiting portion 32 and the first end wall 211 becoming connected.

[0458] When the battery cell 7 is operating normally, the fourth insulating member 90 can separate the first limiting part 32 from the first end 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 fourth insulating member 90 melts at high temperature, the seal 80 can remain between the first limiting part 32 and the first end wall 211, reducing the risk of contact between the first limiting part 32 and the first end wall 211 and suppressing the current between the electrode terminal 30 and the first end wall 211.

[0459] In some embodiments, the material of the fourth insulating member 90 includes a thermoplastic material. Optionally, the material of the fourth insulating member 90 is plastic. Optionally, the material of the fourth insulating member 90 may be polypropylene.

[0460] In some embodiments, a fourth insulating member 90 is disposed around the terminal body 31.

[0461] In some embodiments, the outer periphery of the fourth insulating member 90 extends beyond the first tab 10a in a direction away from the terminal body 31.

[0462] In some embodiments, a portion of the first insulating member 40 is located between the sidewall 212 and the fourth insulating member 90. The first insulating member 40 may fill the gap between the sidewall 212 and the fourth insulating member 90, reducing the risk of metallic impurities making the first tab 10a connected to the sidewall 212 and the first end wall 211 connected through the gap.

[0463] 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.

[0464] 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.

[0465] For example, b is 0.8, 0.82, 0.84, 0.85, 0.88, 0.9, 0.92, 0.94, or 0.95.

[0466] 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.

[0467] Battery cells with higher nickel content have advantages such as high energy density, good low-temperature performance, and good charge and discharge performance.

[0468] 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.

[0469] However, the high-nickel battery cell 7 has relatively poor thermal stability, and generates more heat and a higher temperature rise during thermal runaway. In this embodiment, a high-temperature resistant first insulating member 40 is provided inside the casing 20. The first insulating member 40 can withstand the high temperature generated by the high-nickel battery cell 7 during thermal runaway, thereby reducing the risk of electrical connection between the first end wall 211 and the first tab 10a, suppressing the current between the electrode terminal 30 and the first end wall 211, and reducing the continuous heat generation between the electrode terminal 30 and the first end wall 211.

[0470] In this embodiment, the value 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.

[0471] In some embodiments, 0.8 ≤ b ≤ 0.95, and optionally, 0.85 ≤ b ≤ 0.90.

[0472] 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.

[0473] 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.

[0474] 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.

[0475] 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.

[0476] 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.

[0477] In some embodiments, the chain ester solvent includes at least one of chain carbonates and chain carboxylic esters.

[0478] 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.

[0479] Figure 14 is a partial cross-sectional view of a battery cell provided in some other embodiments of this application; Figure 15 is an enlarged schematic diagram of Figure 14 at the box.

[0480] Referring to Figures 14 and 15, in some embodiments, at least a portion of the first insulating member 40 is located between the first end wall 211 and the first tab 10a.

[0481] For example, in the thickness direction Z of the first end wall 211, the first insulating member 40 may be entirely located between the first end wall 211 and the first tab 10a, or it may be only partially located between the first end wall 211 and the first tab 10a.

[0482] As an example, the first insulating member 40 can be fixed to the first end wall 211, or to the first tab 10a, or to the first current collector 81, or it can be non-fixedly disposed between the side wall 212 and the first tab 10a.

[0483] When a battery cell 7 experiences thermal runaway, the first insulating member 40 is less prone to weight loss or experiences minimal weight loss at high temperatures. The first insulating member 40 can separate the first tab 10a from the first end wall 211, thereby reducing the risk of the first end wall 211 conducting through the first tab 10a to the electrode terminal 30. Even if the electrode terminal 30 and the first end 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 end wall 211, reduce the continuous heat generation between the electrode terminal 30 and the first end 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.

[0484] In some embodiments, the battery cell 7 further includes a fourth insulating member 90; at least a portion of the fourth insulating member 90 is disposed between the first end wall 211 and the first tab 10a.

[0485] The fourth insulating member 90 can separate at least a portion of the first tab 10a from the first end wall 211, thereby reducing the risk of short circuit.

[0486] In some embodiments, at least a portion of the first insulating member 40 is disposed between the first end wall 211 and the fourth insulating member 90.

[0487] The first insulating member 40 may be fixedly connected to the fourth insulating member 90, or it may not be fixedly connected to the fourth insulating member 90. Optionally, the opposite two side surfaces of the first insulating member 40 are respectively connected to the first end wall 211 and the fourth insulating member 90.

[0488] In other embodiments, at least a portion of the first insulating member 40 is disposed between the first tab 10a and the fourth insulating member 90. Optionally, the first insulating member 40 is fixed to at least one of the first tab 10a, the fourth insulating member 90, and the first current collector 81.

[0489] In some other embodiments, a portion of the first insulating member 40 is disposed between the first end wall 211 and the fourth insulating member 90, and a portion of the first insulating member 40 is disposed between the first tab 10a and the fourth insulating member 90.

[0490] By setting the first insulating member 40 and the fourth insulating member 90, a double-layer insulating structure can be formed between the first tab 10a and the first end wall 211, thereby further improving the insulation effect and reducing the risk of the first tab 10a and the first end wall 211 conducting when the battery cell 7 experiences thermal runaway.

[0491] In some embodiments, the battery cell 7 further includes a first current collector 81, which is located between the first end wall 211 and the first tab 10a. The first current collector 81 connects the electrode terminal 30 and the first tab 10a, and a portion of the first insulating member 40 is disposed between the first current collector 81 and the first end wall 211.

[0492] When thermal runaway occurs in the battery cell 7, the first insulating member 40 can separate the first current collector 81 from the first end wall 211, thereby reducing the risk that the first end wall 211 will be connected to the electrode terminal 30 through the first current collector 81.

[0493] In some embodiments, a portion of the fourth insulating member 90 is disposed between the first current collector 81 and the first end wall 211.

[0494] In some embodiments, a portion of the first insulating member 40 is located between the sidewall and the first current collector 81.

[0495] In some embodiments, at least a portion of the first insulating member 40 is located between the tab connection portion 811 and the first end wall 211 in the thickness direction Z of the first end wall 211.

[0496] In some embodiments, the outer peripheral surface 10g of the first electrode tab is closer to the sidewall 212 than the outer peripheral surface 811a of the electrode tab connection portion.

[0497] For example, the first tab 10a is cylindrical and protrudes from the tab connection portion 811 in the radial direction of the first tab 10a. The first insulating member 40 separates the portion of the first tab 10a protruding from the tab connection portion 811 from the first end wall 211.

[0498] In some embodiments, in the thickness direction Z of the first end wall 211, the first insulating member 40 separates the tab connection portion 811 from the first end wall 211. In the thickness direction Z of the first end wall 211, the projection of the tab connection portion 811 lies within the projection of the first insulating member 40.

[0499] In some embodiments, a portion of the first insulating member 40 is located between the first limiting portion 32 and the first end wall 211 in the thickness direction Z of the first end wall 211. Optionally, the first insulating member 40 and the seal 80 at least partially overlap in the thickness direction Z of the first end wall 211, and the first insulating member 40 and the seal 80 together separate the first limiting portion 32 from the first end wall 211.

[0500] In some embodiments, at least a portion of the first insulating member 40 is bonded to the inner surface of the first end wall 211.

[0501] In some embodiments, at least a portion of the fourth insulating portion 52 is disposed between the fourth insulating member 90 and the first current collector 81.

[0502] Between the first end wall 211 and the first tab 10a, the first insulating member 40, the fourth insulating member 90 and the second insulating member 50 form a three-layer insulating structure.

[0503] In some embodiments, the fourth insulating portion 52 is bonded to the first current collector 81.

[0504] In some embodiments, in the thickness direction Z of the first end wall 211, the second insulating member 50 covers the outer peripheral surface 10g of the first electrode tab, the outer peripheral surface 811a of the electrode tab connection portion, and the outer peripheral surface 10i of the electrode body.

[0505] 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. At least a portion of the first insulating portion 41 is located between the side wall 212 and the first tab 10a, and at least a portion of the second insulating portion 42 is located between the first end wall 211 and the first tab 10a.

[0506] When a battery cell 7 experiences thermal runaway, the first insulating member 40 is less prone to weight loss or experiences minimal weight loss at high temperatures. The first insulating part 41 can separate the first tab 10a from the side wall 212, and the second insulating part 42 can separate the first tab 10a from the first end wall 211. This reduces the risk of the side wall 212 and the electrode terminal 30 being connected through the first tab 10a, as well as the risk of the first end wall 211 and the electrode terminal 30 being connected through the first tab 10a. Even if the electrode terminal 30 and the first end 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 end wall 211, reduce the continuous heat generation between the electrode terminal 30 and the first end 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.

[0507] In some embodiments, the first insulating portion 41 may be fixed to at least one of the side wall 212, the electrode body 10c, and the first tab 10a.

[0508] In some embodiments, the second insulating portion 42 is fixed to at least one of the first end wall 211, the fourth insulating member 90, the first current collector 81, and the first tab 10a.

[0509] In some embodiments, at least a portion of the third insulating portion 51 is disposed between the first tab 10a and the first insulating portion 41, and at least a portion of the fourth insulating portion 52 is disposed between the second insulating portion 42 and the first tab 10a. In other embodiments, at least a portion of the third insulating portion 51 is disposed between the sidewall 212 and the first insulating portion 41, and at least a portion of the fourth insulating portion 52 is disposed between the second insulating portion 42 and the first endwall 211.

[0510] In some embodiments, the first insulating portion 41 is attached to the inner surface of the sidewall 212, and the second insulating portion 42 is attached to the inner surface of the first endwall 211. Exemplarily, the first insulating portion 41 is bonded to the inner surface of the sidewall 212, and the second insulating portion 42 is bonded to the inner surface of the first endwall 211.

[0511] The embodiments of this application can improve the stability of the first insulating member 40, reduce the displacement of the first insulating part 41 relative to the side wall 212 when the battery cell 7 is thermally runaway, and reduce the displacement of the second insulating part 42 relative to the side wall 212 when the battery cell 7 is thermally runaway, thereby improving the insulation effect and reducing the risk of the first tab 10a and the first end wall 211 becoming conductive when the battery cell 7 is thermally runaway.

[0512] In some embodiments, at least a portion of the fourth insulating member 90 is disposed between the second insulating portion 42 and the fourth insulating portion 52 in the thickness direction Z of the first end wall 211.

[0513] In some embodiments, a portion of the first insulating portion 41 is disposed between the sidewall 212 and the electrode body 10c. The first insulating portion 41 protrudes from the electrode body 10c in the direction from the first end wall 211 to the electrode assembly 10; the first insulating portion 41 protrudes from the electrode body 10c in the direction from the electrode assembly 10 to the first end wall 211.

[0514] Figure 16 is a partial cross-sectional view of a battery cell provided in some other embodiments of this application; Figure 17 is an enlarged view of Figure 17 at the box; Figure 18 is an enlarged view of Figure 16 at the circle; Figure 19 is a schematic diagram of the electrode assembly, the first insulating member, and the third insulating member of a battery cell provided in some embodiments of this application.

[0515] Referring to Figures 16 to 19, in some embodiments, the first tab 10a is a cylindrical structure, which can be gathered and bound by the first insulating member 40. Exemplarily, the first insulating member 40 is wound at least once around the outer periphery of the first tab 10a.

[0516] In some embodiments, the first tab 10a has a cylindrical structure and the first insulating member 40 has a circumferential angle greater than 360 degrees to improve the insulation effect and reduce the risk of the outer peripheral surface 10g of the first tab being exposed.

[0517] In some examples, the first insulating member 40 has a beginning end 40a and a end end 40b; along the winding direction of the first insulating member 40, the end end 40b of the first insulating member 40 extends beyond the beginning end 40a, such that the first insulating member 40 covers a portion of the beginning end 40a. Exemplarily, in FIG19, the beginning end 40a is covered and is shown in dashed lines.

[0518] In some embodiments, the second insulating member may be omitted. Alternatively, the second insulating member may also be attached to the housing 20; for example, a third insulating portion may be attached to the inner surface of the sidewall 212, and a fourth insulating portion may be attached to the inner surface of the first endwall 211.

[0519] In some embodiments, the first insulating portion 41 may not protrude from the electrode body 10c in the direction of the first end wall 211 pointing toward the electrode assembly 10.

[0520] In some embodiments, along the direction from the first end wall 211 to the second end wall 20a, the portion of the first insulating member 40 located between the side wall 212 and the electrode body 10c has a dimension of D5, and the total dimension of the electrode body 10c is D2. 0.01≤D5 / D2≤0.25.

[0521] The embodiments of this application can save the space and weight occupied by the first insulating member 40 and increase the energy density of the battery cell 7.

[0522] In some embodiments, the first insulating member 40 is located on one side of the third insulating member 60 along the direction of the electrode assembly 10 toward the first end wall 211.

[0523] As an example, in the radial direction of the battery cell 7, the first insulating member 40 and the third insulating member 60 may or may not overlap.

[0524] In this embodiment, insulation is achieved by using the first insulating member 40 and the third insulating member 60 together, thereby saving the space and weight occupied by the first insulating member 40 and increasing the energy density of the battery cell 7.

[0525] In some embodiments, the thermal decomposition temperature of the third insulating member 60 is greater than or equal to 300°C. Optionally, the first insulating member 40 and the third insulating member 60 are made of the same material.

[0526] In some embodiments, a first gap G1 is provided between the first insulating member 40 and the third insulating member 60 in the direction of the electrode assembly 10 pointing to the first end wall 211.

[0527] During the operation of the battery cell 7, the electrode body 10c will expand. By leaving a first gap G1 between the first insulating member 40 and the second insulating member 50, the risk of contact and compression between the first insulating member 40 and the third insulating member 60 can be reduced when the electrode assembly 10 expands and deforms, thereby reducing the risk of cracking of the first insulating member 40 and improving insulation reliability.

[0528] In some embodiments, the size D3 of the first gap G1 is 0.5mm-5mm along the direction from the electrode assembly 10 to the first end wall 211.

[0529] As an example, D3 can be 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm, 1.2mm, 1.4mm, 1.5mm, 1.6mm, 1.8mm, 2.0mm, 2.2mm, 2.5mm, 2.8mm, 3.0mm, 3.2mm, 3.5mm, 3.8mm, 4.0mm, 4.2mm, 4.5mm, 4.8mm, or 5.0mm.

[0530] In this embodiment, D3 is defined as greater than or equal to 0.5 mm to reduce the risk of overlap between the first insulating member 40 and the second insulating member 50 due to assembly errors. Defining D3 as greater than or equal to 0.5 mm also reduces the risk of contact and compression between the first insulating member 40 and the third insulating member 60 when the electrode assembly 10 expands and deforms. Defining D3 as less than or equal to 5 mm reduces the risk of the residual portion of the electrode body 10c becoming conductive with the sidewall 212 in the event of thermal runaway of the battery cell 7.

[0531] In some embodiments, 1mm ≤ D3 ≤ 3mm.

[0532] In some embodiments, a first gap G1 is formed between a first insulating portion 41 and a third insulating member 60.

[0533] In some embodiments, the second insulating portion 42 is disposed around the electrode terminal 30. Optionally, the second insulating portion 42 is disposed at a distance from the first limiting portion 32 in the radial direction of the electrode terminal 30.

[0534] In some embodiments, at least a portion of the second insulating portion 42 is located between the fourth insulating member 90 and the first current collector 81. Optionally, the second insulating portion 42 is bonded to the first current collector 81.

[0535] Figure 20 is a partial cross-sectional schematic diagram of a battery cell provided in some other embodiments of this application.

[0536] Referring to FIG20, in some embodiments, the second current collector 84 is connected to the sidewall 212 and the second tab 10b.

[0537] In some embodiments, the second current collector 84 is directly connected to the sidewall 212. For example, the second current collector 84 is welded to the sidewall 212.

[0538] In some embodiments, the sidewall 212 is provided with an inwardly projecting protrusion 2121. At least a portion of the protrusion 2121 is located between the end cap 22 and the second tab 10b in the thickness direction of the end cap 22.

[0539] For example, the thickness direction of the end cap 22 is parallel to the thickness direction Z of the first end wall.

[0540] For example, the protrusion 2121 can be a solid structure or a hollow structure.

[0541] The protrusion 2121 overlaps with the second tab 10b in the thickness direction of the end cover 22. When the battery cell 7 is subjected to external impact, it can restrict the movement of the second tab 10b in the thickness direction of the end cover 22 and reduce the risk of failure of the connection between the second tab 10b and the second current collector 84.

[0542] 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.

[0543] 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.

[0544] Connecting the second current collector 84 to the protrusion 2121 can shorten the conductive path between the second tab 10b and the first end wall 211, reduce resistance, reduce heat generation, and improve the cycle performance of the battery cell 7.

[0545] 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.

[0546] In some embodiments, the second current collector 84 is welded to the protrusion 2121.

[0547] 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.

[0548] 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 endwall 211 and surrounds the end cap 22.

[0549] 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 of the end cap 22. The protrusion 2121 and the flange structure can limit the end cap 22 to fix the end cap 22 in the thickness direction Z.

[0550] In some embodiments, the battery cell 7 further includes a sixth insulating member 87, which is disposed between the sidewall 212 and the end cap 22 and insulates the end cap 22 from the sidewall 212.

[0551] In some embodiments, a portion of the sixth insulating member 87 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.

[0552] In some embodiments, the end cap 22 can serve as a pressure relief mechanism as a whole. When the battery cell 7 experiences thermal runaway, under the internal pressure of the battery cell 7, the crimping portion 2123 flips outward to disengage the end cap 22 from the side wall 212, forming a pressure relief channel.

[0553] In some embodiments, the first insulating member 40 is spaced apart from the protrusion 2121 along the direction from the electrode assembly 10 to the end cap 22.

[0554] Figure 21 is a schematic diagram of the first insulating member and adhesive layer of a battery cell provided in some embodiments of this application.

[0555] Referring to Figures 10 to 18 and Figure 21, in some embodiments, the battery cell 7 further includes an adhesive layer 86. The adhesive layer 86 bonds the first insulating member 40 to at least one of the first end wall 211, the side wall 212, the electrode body 10c, and the first tab 10a.

[0556] 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.

[0557] In some embodiments, the thickness t3 of the first insulating member 40 is greater than or equal to the thickness t4 of the adhesive layer 86.

[0558] 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.

[0559] In some embodiments, the ratio of the thickness t3 of the first insulating member 40 to the thickness t4 of the adhesive layer 86 is 1-5. As an example, t3 / t4 can be 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 or 5.

[0560] In this embodiment, limiting t3 / t4 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 t3 / t4 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.

[0561] In some embodiments, 5μm≤t3≤100μm. Optionally, t3 is 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, or 100μm.

[0562] In some embodiments, 20 μm ≤ t3 ≤ 60 μm. Optionally, 25 μm ≤ t3 ≤ 50 μm.

[0563] In some embodiments, 3μm≤t4≤80μm. Optionally, t4 is 3μm, 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm or 80μm.

[0564] In some embodiments, 15μm≤t4≤50μm.

[0565] In some embodiments, the adhesive layer 86 comprises a thermosetting material. Optionally, the adhesive layer 86 comprises a thermosetting phenolic resin.

[0566] Figure 22 is an exploded schematic diagram of a battery cell provided in some other embodiments of this application.

[0567] Referring to Figure 22, in some embodiments, the battery cell 7 is a square-shell battery cell. Exemplarily, the sidewall 212 is a square tube.

[0568] In some embodiments, the housing 20 includes a housing 21 and an end cap 22. The housing 21 includes an integrally formed second end wall 20a and a side wall 212. The end cap 22 is a first end wall 211 and is sealed to the side wall 212.

[0569] In some embodiments, the battery cell 7 may include an electrode lead-out portion 88 disposed on the end cap 22, the electrode lead-out portion 88 being electrically connected to the second tab 10b and the end cap 22. The electrode lead-out portion 88 and the electrode terminal 30 may serve as two electrodes of the battery cell 7.

[0570] In some embodiments, the second tab 10b can be a positive tab, the end cap 22 can be made of aluminum or aluminum alloy, and the housing 21 can be made of aluminum or aluminum alloy. Electrically connecting the second tab 10b to the end cap 22 can bring the end cap 22 and the housing 21 to a high potential, reducing the risk of the end cap 22 being corroded by the electrolyte.

[0571] In other embodiments, the second tab 10b may be a negative tab, the end cap 22 may be made of steel, and the housing 21 may be made of steel.

[0572] In some embodiments, the first insulating member 40 may be attached to the inner surface of the sidewall 212.

[0573] In some embodiments, the first insulating member 40 may include an insulating coating.

[0574] In some embodiments, the sidewall 212 includes two first sub-walls 212a and two second sub-walls 212b, which are alternately arranged circumferentially along the electrode assembly 10. Optionally, at least a portion of the first insulating member 40 may be disposed on the inner surface of the first sub-wall 212a. Optionally, a portion of the first insulating member 40 may be disposed on the inner surface of the first sub-wall 212a, and another portion of the first insulating member 40 may be disposed on the inner surface of the second sub-wall 212b.

[0575] In some embodiments, the area of ​​the first sub-wall 212a is greater than the area of ​​the second sub-wall 212b.

[0576] Figure 23 is a simplified schematic diagram of a battery device provided in some other embodiments of this application.

[0577] Referring to FIG23, this application also provides a battery device 2, including a plurality of battery cells 7 of any of the above embodiments.

[0578] In some embodiments, the battery device 2 further includes a plurality of busbars 8 that electrically connect a plurality of battery cells 7.

[0579] In some embodiments, at least two battery cells 7 are connected in parallel.

[0580] 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.

[0581] 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 end wall 211 and the electrode terminal 30 of the thermally runaway battery cell 7, respectively. The first insulating member 40 can insulate the first tab 10a from the first end wall 211, suppress the current between the electrode terminal 30 and the first end wall 211, reduce the continuous heat generation between the electrode terminal 30 and the first end wall 211, 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.

[0582] According to some embodiments of this application, this application also provides an electrical device, including a battery cell from any of the above embodiments, wherein the battery cell is used to provide electrical energy to the electrical device. The electrical device can be any of the aforementioned devices or systems that utilize battery cells.

[0583] Referring to Figures 4 to 13, an embodiment of this application provides a cylindrical battery cell, which includes an electrode assembly 10, a housing 20, electrode terminals 30, a first insulating member 40, a second insulating member 50, a third insulating member 60, a first current collector 81, a second current collector 84, and a pressure relief mechanism 70.

[0584] The outer casing 20 includes a housing 21 and an end cap 22. The housing 21 includes an integrally formed first end wall 211 and a side wall 212. The end cap 22 is sealed to the side wall 212 and surrounds the housing 21 to form a receiving cavity 20b.

[0585] The first end wall 211 is provided with an electrode lead-out hole 2111 that communicates with the receiving cavity 20b. The electrode terminal 30 is provided in the electrode lead-out hole 2111 and is insulated from the first end wall 211.

[0586] The electrode assembly 10 includes an electrode body 10c and a first tab 10a and a second tab 10b extending from the electrode body 10c. The first tab 10a and the second tab 10b have opposite polarities. The first tab 10a is disposed at one end of the electrode assembly 10 facing the first end wall 211 and at the other end of the electrode assembly 10 facing the end cap 22.

[0587] The first current collector 81 connects the electrode terminal 30 and the first tab 10a, and the second current collector 84 connects the end cap 22 and the second tab 10b. The end cap 22 is electrically connected to the side wall 212.

[0588] The first insulating member 40 is attached to the inner surface of the sidewall 212 and surrounds the electrode assembly 10. A portion of the first insulating member 40 is disposed between the sidewall 212 and the first tab 10a, and another portion of the first insulating member 40 is disposed between the sidewall 212 and the electrode body 10c.

[0589] The second insulating member 50 is disposed around the first electrode tab 10a. A portion of the second insulating member 50 is located between the first electrode tab 10a and the first insulating member 40, and another portion of the second insulating member 50 is located between the first electrode tab 10a and the first end wall 211.

[0590] The third insulating member 60 is disposed around the electrode body 10c and attached to the outer peripheral surface 10i of the electrode body. Along the axial direction of the cylindrical battery cell, the third insulating member 60 and the second insulating member 50 are spaced apart.

[0591] The thermal weight loss temperature of the first insulating member 40 is greater than or equal to 300°C. Optionally, the material of the first insulating member 40 includes polyimide.

[0592] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0593] 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 housing includes a first end wall, a side wall, and a receiving cavity. The first end wall is provided with an electrode lead-out hole communicating with the receiving cavity, and the side wall is connected to the first end wall. An electrode terminal is provided at the electrode lead-out hole, and the electrode terminal is insulated from the first end wall; An electrode assembly is housed within the receiving cavity, and the sidewall surrounds the electrode assembly. The electrode assembly includes an electrode body and a first electrode tab and a second electrode tab extending from the electrode body. The first electrode tab and the second electrode tab have opposite polarities. The first electrode tab is disposed at one end of the electrode assembly facing the first endwall and is electrically connected to the electrode terminal. The second electrode tab is electrically connected to the first endwall and the sidewall. A first insulating member, wherein the thermal weight loss temperature of the first insulating member is greater than or equal to 300°C, and at least a portion of the first insulating member is disposed between the first end wall and the first tab, and / or, at least a portion of the first insulating member is disposed between the side wall and the first tab.

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 fixed to at least one of the first end wall, the side wall, the electrode body, and the first electrode tab.

7. The battery cell according to claim 6 further includes an adhesive layer; the adhesive layer adheres the first insulating member to at least one of the first end wall, the side wall, the electrode body, and the first tab.

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 any one of claims 1-8, wherein, At least a portion of the first insulating member is located between the sidewall and the first tab.

10. The battery cell according to claim 9, wherein, The first insulating member is arranged around the first electrode tab.

11. The battery cell according to claim 10, wherein, The first tab is a cylindrical structure, and the circumferential angle of the first insulating member is greater than 360 degrees.

12. The battery cell according to any one of claims 9-11, wherein, The outer peripheral surface of the electrode body is closer to the sidewall than the outer peripheral surface of the first electrode tab, so that a space is formed between the outer peripheral surface of the first electrode tab and the sidewall to accommodate at least a portion of the first insulating member.

13. The battery cell according to any one of claims 9-12, wherein, Along the direction of the electrode assembly pointing towards the first end wall, the first insulating member protrudes from the first tab; or The end of the first insulating member facing the first end wall is flush with the end of the first electrode facing the first end wall.

14. The battery cell according to claim 13, further comprising a first current collector, the first current collector comprising a tab connection portion connected to the first tab and a terminal connection portion connected to the electrode terminal, the tab connection portion surrounding the terminal connection portion; Along the direction of the electrode assembly toward the first end wall, the first insulating member protrudes from the tab connection portion.

15. The battery cell according to any one of claims 9-14, wherein, A portion of the first insulating member is located between the sidewall and the electrode body.

16. The battery cell according to any one of claims 9-15, wherein, The first insulating member includes a first insulating portion and a second insulating portion connected to the first insulating portion, at least a portion of the first insulating portion being located between the sidewall and the first tab, and at least a portion of the second insulating portion being located between the first endwall and the first tab.

17. The battery cell according to claim 16, wherein, The first insulating portion is attached to the inner surface of the sidewall, and the second insulating portion is attached to the inner surface of the first endwall.

18. The battery cell according to any one of claims 9-17, further comprising a second insulating member; At least a portion of the second insulating member surrounds the first electrode tab and is located between the first insulating member and the first electrode tab; and / or, at least a portion of the second insulating member surrounds the first electrode tab and is located between the sidewall and the first insulating member.

19. The battery cell according to claim 18, wherein, At least a portion of the first insulating member is attached to the inner surface of the sidewall; At least a portion of the second insulating member surrounds the first tab and is located between the first insulating member and the first tab.

20. The battery cell according to claim 19, wherein, The tensile modulus of the second insulating member is less than that of the first insulating member.

21. The battery cell according to any one of claims 18-20, wherein, A portion of the second insulating member is disposed between the first tab and the first end wall.

22. The battery cell according to any one of claims 18-21, wherein, The thermal weight loss temperature of the first insulating component is greater than that of the second insulating component.

23. The battery cell according to any one of claims 1-22 further includes a third insulating member disposed between the electrode body and the sidewall.

24. The battery cell according to claim 23, wherein, The third insulating component is fixed to the outer peripheral surface of the electrode body; The electrode body includes a wound insulating member, and the third insulating member is connected to the outer surface of the insulating member. surface.

25. The battery cell according to claim 23 or 24, wherein, The thermal weight loss temperature of the third insulating component is greater than or equal to 300°C.

26. The battery cell according to any one of claims 23-25, wherein, At least a portion of the first insulating member is disposed between the sidewall and the third insulating member.

27. The battery cell according to claim 26, wherein, Along the direction from the first end wall toward the electrode assembly, the first insulating member protrudes from the third insulating member; Along the direction of the electrode assembly toward the first end wall, the first insulating member protrudes from the third insulating member.

28. The battery cell according to any one of claims 23-25, wherein, Along the direction of the electrode assembly toward the first end wall, the first insulating member is located on one side of the third insulating member.

29. The battery cell according to claim 28, wherein, A first gap is provided between the first insulating member and the third insulating member in the direction of the electrode assembly pointing towards the first end wall.

30. The battery cell according to claim 29, wherein, Along the direction of the electrode assembly pointing towards the first end wall, the size of the first gap is 0.5mm-5mm.

31. The battery cell according to any one of claims 1-30, wherein, The second electrode tab is disposed at one end of the electrode assembly facing away from the first end wall, and at least a portion of the first insulating member is located between the side wall and the second electrode tab; Along the direction from the first end wall toward the electrode assembly, the first insulating member protrudes from the second tab; or, the end of the first insulating member facing away from the first end wall is flush with the end of the second tab facing away from the first end wall.

32. The battery cell according to any one of claims 1-31, wherein, At least a portion of the first insulating member is located between the first end wall and the first tab.

33. The battery cell according to claim 32 further includes a fourth insulating member; at least a portion of the fourth insulating member is disposed between the first end wall and the first tab.

34. The battery cell according to claim 33, wherein, At least a portion of the first insulating member is disposed between the first end wall and the fourth insulating member; and / or At least a portion of the first insulating member is disposed between the first tab and the fourth insulating member.

35. The battery cell according to any one of claims 32-34, further comprising a first current collector, the first current collector being located between the first end wall and the first tab, the first current collector being connected to the electrode terminal and the first tab; A portion of the first insulating member is disposed between the first current collecting member and the first end wall.

36. The battery cell according to any one of claims 1-35, wherein, The outer casing further includes a second end wall, which is disposed opposite to the first end wall, and the side wall connects the first end wall and the second end wall; The second electrode tab is disposed at one end of the electrode assembly facing the second end wall.

37. The battery cell according to claim 36 further includes a pressure relief mechanism, the pressure relief mechanism being disposed on the second end wall.

38. The battery cell according to claim 37, wherein, Along the direction from the first end wall to the second end wall, the minimum distance between the first insulating member and the second end wall is D1, and the total size of the electrode body is D2, 0≤D1 / D2≤0.

25.

39. The battery cell according to claim 37 or 38, 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 end 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 end wall is S2. 0.1≤S2 / S1≤0.

8.

40. The battery cell according to claim 39, wherein, 0.3≤S2 / S1≤0.

7.

41. The battery cell according to any one of claims 37-40, wherein, The battery cell is a cylindrical battery cell, and the first end wall and the second end 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.

42. The battery cell according to any one of claims 37-41, wherein, The thickness of the second end wall is less than the thickness of the first end wall.

43. The battery cell according to any one of claims 37-42, 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.

44. The battery cell according to any one of claims 36-43, further comprising a second current collector; The second current collector is connected to the second end wall and the second electrode tab, and the second end wall is electrically connected to the side wall; or, the second current collector is connected to the side wall and the second electrode tab.

45. The battery cell according to claim 44 further includes a pressure relief mechanism, the pressure relief mechanism being disposed on the second end wall; At least a portion of the second current collector is located between the pressure relief mechanism and the second electrode tab.

46. ​​The battery cell according to any one of claims 36-45, wherein, The outer casing includes a housing and an end cap. The housing includes an integrally formed first end wall and a side wall. The end cap is the second end wall and is sealed to the side wall. The first insulating member is spaced apart from the end cap.

47. The battery cell according to any one of claims 1-46, 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. The battery cell further includes a sealing element. In the thickness direction of the first end wall, the first limiting portion is located inside the first end wall, and at least a portion of the sealing element is disposed on the first end wall and the first limiting portion. Between departments; The thermal weight loss temperature of the seal is greater than or equal to 200°C.

48. The battery cell according to any one of claims 1-47, 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.

49. The battery cell according to any one of claims 1-48, 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.

50. The battery cell according to claim 49, wherein, The chain ester solvent has a mass percentage of 42.5 wt% to 70 wt% in the electrolyte.

51. The battery cell according to any one of claims 1-50, 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.

52. A battery device comprising a plurality of battery cells according to any one of claims 1-51.

53. The battery device according to claim 52, wherein, At least two of the battery cells are connected in parallel.

54. An electrical appliance comprising a battery device according to claim 52 or 53, the battery device being used to provide electrical energy.

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