Cylindrical battery monomer, battery and power utilization device

Abstract

The embodiment of the invention provides a cylindrical battery monomer, a battery and a power utilization device. And the capacity of the cylindrical battery monomer is greater than or equal to 20Ah. The cylindrical battery cell includes a housing and an electrode assembly housed within the housing. The electrode assembly comprises a first pole piece and a second pole piece which are opposite in polarity, the first pole piece and the second pole piece are wound in the winding direction, the first pole piece comprises a first current collector and a first film layer, the first current collector comprises a first coating area and a first tab, the surface of the first coating area is coated with the first film layer, and the first tab is coated with the second film layer. The first tab extends from the first coating area along one axial end of the cylindrical battery monomer, and the surface of the first tab is not coated with the first film layer. The cylindrical battery monomer comprises a first electrode leading-out part, and the first tab is electrically connected to the first electrode leading-out part. In the winding direction, the length of the connecting position of the first tab and the first coating area is L1, the length of the first coating area is L0, and L1 / L0 is larger than or equal to 0.8 and smaller than or equal to 1.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, and more particularly, to a cylindrical battery cell, a battery, and an electric device. BACKGROUND

[0002] Battery cells, especially cylindrical battery cells, are widely used in electronic devices, such as mobile phones, notebook computers, electric cars, electric vehicles, electric aircraft, electric ships, electric toy cars, electric toy ships, electric toy aircraft, electric tools, and the like.

[0003] With the development of battery technology, users have higher requirements for the capacity of cylindrical battery cells. Due to the increase in capacity, the current of the cylindrical battery cell increases when charging, which can increase the heat generation of the cylindrical battery cell and affect the cycle performance of the cylindrical battery cell. SUMMARY

[0004] The present application provides a cylindrical battery cell, a battery, and an electric device, which can improve the cycle performance.

[0005] In a first aspect, the embodiments of the present application provide a cylindrical battery cell with a capacity greater than or equal to 20 Ah. The cylindrical battery cell includes a housing and an electrode assembly contained in the housing. The electrode assembly includes first and second polar opposite electrode tabs, which are wound in a winding direction. The first electrode tab includes a first current collector and a first film layer. The first current collector includes a first coated area and a first tab. The surface of the first coated area is coated with the first film layer. The first tab extends from the first coated area along one end of the cylindrical battery cell in the axial direction, and the surface of the first tab is not coated with the first film layer. The cylindrical battery cell includes a first electrode lead-out portion, and the first tab is electrically connected to the first electrode lead-out portion. In the winding direction, the length of the connection position between the first tab and the first coated area is L1, the length of the first coated area is L0, and 0.8≤L1 / L0≤1.

[0006] By limiting L1 / L0 to be greater than or equal to 0.8, the overcurrent area of the connection position between the first coated area and the first tab can be increased, the impedance can be reduced, the heat generation of the connection position between the first coated area and the first tab can be reduced, the temperature rise of the first current collector and the first film layer can be reduced, the risk of ion precipitation can be reduced, the cycle performance of the cylindrical battery cell can be improved, the risk of thermal runaway can be reduced, and the reliability of the cylindrical battery cell can be improved. By limiting L1 / L0 to be less than or equal to 1 in the embodiments of the present application, the redundancy of the first tab can be reduced, the space can be saved, and the impact of lengthening the first tab on the energy density of the cylindrical battery cell can be reduced.

[0007] In some embodiments, 0.95≤L1 / L0≤1, which can balance the cycle performance and energy density of the cylindrical battery cell to a certain extent.

[0008] In some embodiments, 3000mm≤L0≤9000mm; optionally, 4500mm≤L0≤7000mm.

[0009] L0 is positively correlated with the length of the first tab. In the embodiments of the present application, L0 is limited to be greater than or equal to 3000mm, which can improve the capacity of the cylindrical battery cell. By using a first tab with a larger length, the length of the first tab can also be correspondingly increased, thereby improving the overcurrent capacity, reducing the impedance, reducing the temperature rise of the first current collector and the first film layer, and reducing the risk of ion precipitation, and improving the cycle performance of the cylindrical battery cell. When the diameter of the cylindrical battery cell is constant, the longer the first current collector, the higher the weight proportion of the first current collector in the cylindrical battery cell. In the embodiments of the present application, L0 is limited to be less than or equal to 9000mm, which can limit the space and weight occupied by the first current collector and reduce the loss of energy density of the cylindrical battery cell.

[0010] In some embodiments, 2400mm≤L1≤9000mm; optionally, 3600mm≤L1≤7000mm.

[0011] In some embodiments, the thickness of the first tab is equal to the thickness of the first coating area. By using a first tab and a first coating area with the same thickness, the forming process of the first tab can be simplified.

[0012] In some embodiments, the sum of the thickness of the first film layer and the thickness of the first coating area is D1, the thickness of the first coating area is T1, and 0.17≤T1 / D1≤0.35.

[0013] In the embodiments of the present application, T1 / D1 is limited to be greater than or equal to 0.17 to increase the overcurrent area of the first coating area, thereby reducing the heat generation of the first coating area during charging and discharging, reducing the temperature rise of the first film layer and the first coating area, improving the cycle performance of the cylindrical battery cell, and reducing the risk of thermal runaway. In the embodiments of the present application, T1 / D1 is limited to be less than or equal to 0.35 to limit the thickness proportion of the first coating area in the first tab and reduce the loss of capacity of the first tab. In the embodiments of the present application, T1 / D1 is limited to be 0.17-0.35, which can balance the cycle performance and energy density of the cylindrical battery cell to a certain extent.

[0014] In some embodiments, 9 pm≤T1≤17 pm, and optionally, 11 pm≤T1≤15 pm. Defining T1 to be greater than or equal to 9 pm can make the first coating region have a larger flow area, thereby reducing the impedance, reducing the heat generation of the first coating region during charging and discharging, reducing the temperature rise of the first film layer and the first coating region, reducing ion precipitation (e.g., lithium precipitation), improving the cycle performance of the cylindrical battery cell, and reducing the risk of thermal runaway. Defining T1 to be greater than or equal to 17 pm can limit the thickness ratio of the first coating region in the first tab, thereby reducing the loss of capacity of the first tab.

[0015] In some embodiments, the sum of the thickness of the first film layer and the thickness of the first coating region is D1, the thickness of the first film layer is T2, and 0.67≤T2 / D1≤0.81. Defining T2 / D1 to be greater than or equal to 0.67 can increase the thickness ratio of the first film layer in the first tab, thereby increasing the capacity of the first tab and the energy density of the cylindrical battery cell. Defining T2 / D1 to be less than or equal to 0.81 can limit the thickness ratio of the first film layer and the first coating region, so that the first coating region can have a larger thickness, thereby reducing the impedance, reducing the heat generation of the first coating region during charging and discharging, reducing the temperature rise of the first film layer and the first coating region, reducing ion precipitation, improving the cycle performance of the cylindrical battery cell, and reducing the risk of thermal runaway. The embodiments of the present application define T2 / D1 to be 0.67-0.81, which can balance the cycle performance and the energy density of the cylindrical battery cell to a certain extent.

[0016] In some embodiments, the capacity of the cylindrical battery cell is 25 Ah-50 Ah. The cylindrical battery cell having a capacity greater than or equal to 25 Ah can be conducive to improving the energy density when a plurality of cylindrical battery cells are assembled into a group. Defining the capacity of the cylindrical battery cell to be less than or equal to 50 Ah can limit the charging current of the cylindrical battery cell, thereby reducing the heat generation, reducing the temperature rise of the first film layer and the first current collector, and improving the cycle performance of the battery cell.

[0017] In some embodiments, the connection position of the first tab and the first coating region is continuously arranged along the winding direction, which can increase the flow area between the first tab and the first coating region, reduce the heat generation of the first tab and the first coating region, reduce the temperature rise of the first film layer, and improve the cycle performance of the cylindrical battery cell.

[0018] In some embodiments, the first tab is continuously arranged along the winding direction as a whole, which can improve the flow capacity of the first tab, improve the current consistency, and reduce the heat generation.

[0019] In some embodiments, the first tab includes a transition portion and a plurality of first sub-tabs spaced apart along the winding direction, the transition portion is connected to the first coating region, the first sub-tabs are connected to one end of the transition portion away from the first coating region, and the connection position of the transition portion and the first coating region is continuously arranged along the winding direction.

[0020] The plurality of first sub-tab can be bent inwardly in a radial direction of the cylindrical battery cell when under pressure, so that the bent portions of some of the first sub-tab are stacked in an axial direction and form a multi-layer structure. The multi-layer structure can improve the overcurrent capacity, reduce the impedance, reduce the heat generation, and improve the cycle performance of the cylindrical battery cell. The plurality of first sub-tab are unconstrained with respect to each other in the winding direction, which facilitates the directional bending of the first sub-tab and helps to improve the morphology of the multi-layer structure.

[0021] In some embodiments, the sum of the lengths of the connection positions of the plurality of first sub-tab and the transition portion in the winding direction is L2, and the length of the connection position of the transition portion and the first coating area is L1. L2 and L1 satisfy: 0.6≤L2 / L1≤0.95. Defining L2 / L1 to be 0.6-0.95 can increase the overcurrent area of the connection position of the first sub-tab and the transition portion, reduce the impedance, reduce the heat generation of the connection position of the first sub-tab and the transition portion, thereby reducing the temperature rise of the first current collector and the first film layer, reducing the risk of ion (e.g., lithium ion) precipitation, improving the cycle performance of the cylindrical battery cell, reducing the risk of thermal runaway, and improving the reliability of the cylindrical battery cell.

[0022] In some embodiments, an end of the first tab away from the first coating area is bent and forms a first stacking portion, the first stacking portion has a multi-layer structure in the axial direction of the cylindrical battery cell, and the first stacking portion is electrically connected to the first electrode lead-out portion. The multi-layer structure between the first stacking portion can transmit current, and electrically connecting the first stacking portion with the multi-layer structure to the first electrode lead-out portion can improve the overcurrent capacity, reduce the impedance, reduce the heat generation, and improve the cycle performance of the cylindrical battery cell.

[0023] In some embodiments, the cylindrical battery cell includes a first current collecting member, the first current collecting member is at least partially located between the first stacking portion and the first electrode lead-out portion, and the first current collecting member is welded to the first stacking portion and the first electrode lead-out portion, respectively. Welding the first stacking portion with the multi-layer structure to the first current collecting member can not only reduce the risk of false welding, but also increase the welding area of the first tab and the first current collecting member, thereby improving the overcurrent capacity.

[0024] In some embodiments, the first electrode lead-out portion includes an electrode terminal which is insulatedly arranged on the shell, at least a portion of the electrode terminal protrudes from the wall portion of the shell, and the first tab is electrically connected to the electrode terminal. By protruding at least a portion of the electrode terminal, the electrode terminal can be easily connected to the external busbar component, and the exposed area of the electrode terminal can be increased, thereby improving the heat dissipation efficiency of the electrode terminal, reducing the temperature rise of the first tab, and improving the cycle performance of the cylindrical battery cell.

[0025] In some embodiments, the electrode terminal has a thermal conductivity greater than that of the shell. The electrode terminal is electrically connected to the first tab, and the electrode terminal has better thermal conductivity than the shell. Therefore, the electrode terminal can quickly conduct the heat of the first tab out, thereby slowing the temperature rise of the first tab, reducing the thermal impact on the first film layer, and improving the cycle performance of the cylindrical battery cell.

[0026] In some embodiments, the first tab is a positive tab, and the first current collector is made of aluminum or an aluminum alloy. Aluminum and aluminum alloys have good electrical conductivity and thermal conductivity. Using an aluminum first current collector can reduce impedance, reduce heat generation, and improve the cycle performance of the cylindrical battery cell.

[0027] In some embodiments, the second tab includes a second current collector and a second film layer. The second current collector includes a second coated area and a second tab. The surface of the second coated area is coated with the second film layer. The second tab extends from one end of the second coated area in the axial direction, and the surface of the second tab is not coated with the second film layer. In the axial direction, the first tab and the second tab are respectively located at two ends of the electrode assembly. The cylindrical battery cell includes a second electrode lead-out portion, and the second tab is electrically connected to the second electrode lead-out portion. By respectively arranging the first tab and the second tab at two ends of the electrode assembly, more space can be provided for the first tab and the second tab, so that the first tab and the second tab can have a larger length, improve the overcurrent capacity, reduce the impedance, and improve the cycle performance of the cylindrical battery cell.

[0028] In some embodiments, in the winding direction, the length of the second coated area is L3, and the length of the connection position of the second tab and the second coated area is L4. 0.8≤L4 / L3≤1; optionally, 0.95≤L4 / L3≤1.

[0029] In some embodiments, L4 / L3 is greater than or equal to 0.8, which can increase the overcurrent area of the connection position of the second coated area and the second tab, reduce the impedance, reduce the heat generation of the connection position of the second coated area and the second tab, thereby reducing the temperature rise of the second current collector and the second film layer, reducing the risk of ion precipitation, improving the cycle performance of the cylindrical battery cell, reducing the risk of thermal runaway, and improving the reliability of the cylindrical battery cell. In some embodiments, L4 / L3 is less than or equal to 1, which can reduce the redundancy of the second tab, save space, and reduce the impact of lengthening the second tab on the energy density of the cylindrical battery cell.

[0030] In some embodiments, the first tab is a positive tab, and the second tab is a negative tab. The first current collector is made of aluminum, and the second current collector is made of copper.

[0031] In some embodiments, the first coating region has a thickness greater than the thickness of the second coating region, and the first tab has a thickness greater than the thickness of the second tab. Because the electrical conductivity of copper is higher than that of aluminum, setting the thickness of the aluminum first coating region to be greater than the thickness of the copper second coating region can reduce the difference in electrical conductivity between the first coating region and the second coating region, improve current uniformity, reduce the temperature difference between the first coating region and the second coating region, and improve the cycle performance of the cylindrical battery cell. Similarly, setting the thickness of the aluminum first tab to be greater than the thickness of the copper second tab can reduce the difference in electrical conductivity between the first tab and the second tab, improve current uniformity, reduce the temperature difference between the first tab and the second tab, and improve the cycle performance of the cylindrical battery cell.

[0032] In some embodiments, the electrode assembly further includes a separator, the separator being wound along the winding direction and separating the first tab and the second tab. The separator includes a base and a plurality of support portions, the base having two first surfaces oppositely arranged along the thickness direction of the base, and the plurality of support portions being protruded from at least one of the first surfaces to form a gap between the first tab and the second tab.

[0033] In the embodiments of the present application, the cylindrical battery cell has a high capacity. As the capacity increases, the electrode assembly generates a greater expansion force during charging. During the cycle of the cylindrical battery cell, the gap provides space for the expansion of the tabs, reduces the pressure between the first tab and the second tab, thereby reducing the compression of the electrolyte in the internal pores of the first film layer and the internal pores of the second film layer, reducing the concentration difference of the electrolyte in different regions of the tabs, and improving the cycle performance of the cylindrical battery cell with a large capacity. The gap can reduce the expansion amount of the electrode assembly, thereby reducing the compression of the shell, reducing the risk of deformation and cracking of the shell, and improving the reliability of the cylindrical battery cell. By providing the gap, the increase in the expansion force caused by increasing the capacity of the cylindrical battery cell can be reduced.

[0034] In some embodiments, the plurality of support portions includes a first support portion and a second support portion, the first support portion protruding from the first surface to a height greater than the height to which the second support portion protrudes from the first surface. The first support portion has a greater height, which can support the first tab or the second tab to form a larger gap, thereby providing more space for the expansion of the tabs. The second support portion has a smaller height and occupies less space. As the tabs expand, the gap gradually decreases. The second support portion can be compressed after the tabs expand to a certain extent, which can reduce the pressure on the tabs in the early stage of expansion. When the second support portion is compressed, the second support portion can slow down the expansion of the tabs to some extent, reduce the electrolyte squeezed out by the tabs, and improve the cycle performance of the cylindrical battery cell.

[0035] In some embodiments, the support portion includes organic particles disposed on the base portion. The organic particles can serve a support function to form the gap. When the cylindrical battery cell experiences thermal runaway, the organic particles can form a gel film structure at high temperature, thereby reducing the diffusion channel of active ions, delaying the time of thermal spread, and thus improving the reliability of the cylindrical battery cell.

[0036] In some embodiments, the base portion includes a base film and an inorganic particle layer disposed on the base film, and the organic particles at least partially protrude from the inorganic particle layer. The inorganic particle layer includes a plurality of inorganic particles, and gaps are formed between the inorganic particles and the organic particles, which are sufficient and unevenly distributed, thereby improving the air permeability of the separator and the cycle performance and reliability of the cylindrical battery cell.

[0037] In some embodiments, the plurality of organic particles includes first organic particles and second organic particles, and the number average particle size of the first organic particles is greater than the number average particle size of the second organic particles. The first organic particles with a larger number average particle size can support the first or second electrode tab to form a larger gap, thereby providing more space for the expansion of the electrode tab. The second organic particles with a smaller number average particle size can be compressed after the electrode tab expands to a certain extent, which can reduce the pressure on the electrode tab in the initial stage of expansion. When the second organic particles are compressed, the second organic particles can slow down the expansion of the electrode tab to some extent, reduce the electrolyte squeezed out by the electrode tab, and improve the cycle performance of the cylindrical battery cell.

[0038] In some embodiments, the plurality of support portions includes first support portions and second support portions, and the height of the first support portions protruding from the first surface is greater than the height of the second support portions protruding from the first surface. The plurality of organic particles includes first organic particles and second organic particles, and the first support portions include the first organic particles and the second support portions include the second organic particles. By providing the first organic particles and the second organic particles with different number average particle sizes, the first support portions and the second support portions with different heights can be formed. The first support portions have a larger height, which can support the first or second electrode tab to form a larger gap, thereby providing more space for the expansion of the electrode tab. The second support portions can be compressed after the electrode tab expands to a certain extent, which can reduce the pressure on the electrode tab in the initial stage of expansion. When the second support portions are compressed, the second support portions can slow down the expansion of the electrode tab to some extent, reduce the electrolyte squeezed out by the electrode tab, and improve the cycle performance of the cylindrical battery cell.

[0039] In some embodiments, the radial dimension of at least part of the gap is 5-60 μm. The embodiments of the present application limit the radial dimension of the gap to be greater than or equal to 5 μm, which provides space for the expansion of the pole piece, reduces the expansion force, improves the cycle performance of the cylindrical battery cell, and reduces the risk of deformation and cracking of the shell. The embodiments of the present application limit the radial dimension of the gap to be less than or equal to 50 μm, which shortens the ion migration path between the first pole piece and the second pole piece, reduces the internal resistance of the cylindrical battery cell, reduces heat generation, and reduces the impact of the gap on the energy density.

[0040] In some embodiments, the spacer is provided with a plurality of support portions on both sides. The gap includes a first gap formed between the first pole piece and the spacer, and a second gap formed between the second pole piece and the spacer. By providing a plurality of support portions on both sides of the spacer, the gap can be increased to provide more space for the expansion of the pole piece.

[0041] In some embodiments, the gap extends in the winding direction and has a winding start end and a winding end. The radial dimension of the part of the gap near the winding start end is greater than or equal to the radial dimension of the part of the gap near the winding end. The part of the gap near the winding start end has a larger radial dimension to provide more expansion space for the pole piece in the middle of the electrode assembly, reduce the risk of the middle of the electrode assembly collapsing due to expansion, and improve the cycle performance of the cylindrical battery cell.

[0042] In some embodiments, the radial dimension of at least part of the gap gradually decreases along the winding direction to provide more expansion space for the pole piece in the middle of the electrode assembly, reduce the risk of the middle of the electrode assembly collapsing due to expansion, and improve the cycle performance of the cylindrical battery cell.

[0043] In some embodiments, the gap includes a middle region and two end regions arranged in the axial direction, the middle region being located between the two end regions, and the radial dimension of the middle region being smaller than the radial dimension of the end regions. The end regions have a larger radial dimension to facilitate the entry of electrolyte into the gap, improve the wettability of the pole piece by the electrolyte, and improve the cycle performance of the cylindrical battery cell.

[0044] In some embodiments, the radial dimension of the gap gradually decreases in the direction from the end region to the middle region, which reduces the abrupt change in the radial dimension of the gap, reduces the stress concentration of the second pole piece, and improves the cycle performance of the cylindrical battery cell.

[0045] In some embodiments, in the radial direction of the cylindrical battery cell, a portion of the plurality of support portions is located between the first tab and the base. The first tab generates heat when current passes through, and the support portions can separate at least part of the first tab from the base, thereby reducing the amount of heat conducted to the base, reducing the deformation of the base due to high temperature, reducing the risk of the first tab and the second tab being in contact, and improving the reliability of the cylindrical battery cell.

[0046] In some embodiments, the electrode assembly further comprises a separator, which is wound along the winding direction and separates the first tab and the second tab. The separator comprises a base and a plurality of support portions, the base has two first surfaces oppositely arranged along the thickness direction of the base, and the plurality of support portions protrude from at least one of the first surfaces to form a gap between the first tab and the second tab.

[0047] In the embodiments of the present application, the cylindrical battery cell has a higher capacity; as the capacity increases, the electrode assembly will generate greater swelling force when charging. During the cycle of the cylindrical battery cell, the gap can provide space for the expansion of the tabs, reduce the pressure between the first tab and the second tab, thereby reducing the compression of the electrolyte in the internal pores of the first membrane layer and the internal pores of the second membrane layer, reducing the concentration difference of the electrolyte in different regions of the tabs, and improving the cycle performance of the cylindrical battery cell with a larger capacity. The gap can reduce the swelling amount of the electrode assembly, thereby reducing the compression of the shell, reducing the risk of deformation and cracking of the shell, and improving the reliability of the cylindrical battery cell. By providing a gap, the increase in swelling force caused by increasing the capacity of the cylindrical battery cell can be reduced.

[0048] In some embodiments, the plurality of support portions comprises a first support portion and a second support portion, the height of the first support portion protruding from the first surface is greater than the height of the second support portion protruding from the first surface. The first support portion has a greater height, which can support the first tab or the second tab to form a larger gap, thereby providing more space for the expansion of the tabs. The second support portion has a smaller height and occupies less space. As the tabs expand, the gap gradually decreases; the second support portion can be compressed after the tabs expand to a certain extent, which can reduce the pressure on the tabs in the early stage of expansion. When the second support portion is compressed, the second support portion can slow down the expansion of the tabs to some extent, reduce the electrolyte squeezed out by the tabs, and improve the cycle performance of the cylindrical battery cell.

[0049] In some embodiments, the support portion comprises an organic particle arranged on the base. The organic particle can support the formation of a gap. When the cylindrical battery cell experiences thermal runaway, the organic particle can form a gel film structure at high temperature, thereby reducing the diffusion channel of active ions and delaying the time of heat spread, thereby improving the reliability of the cylindrical battery cell.

[0050] In some embodiments, the base includes a base film and an inorganic particle layer disposed on the base film, the organic particles at least partially protrude from the inorganic particle layer. The inorganic particle layer includes a plurality of inorganic particles, and gaps are formed between the inorganic particles and the organic particles, which are sufficient and unevenly distributed, thereby improving the air permeability of the separator and the cycle performance and reliability of the cylindrical battery cell.

[0051] In some embodiments, the plurality of organic particles includes first organic particles and second organic particles, and the first organic particles have a number average particle size greater than the number average particle size of the second organic particles. The first organic particles with a larger number average particle size can support the first or second electrode tab to form a larger gap, thereby providing more space for the expansion of the electrode tab. The second organic particles with a smaller number average particle size can be compressed after the electrode tab expands to a certain extent, thereby reducing the pressure on the electrode tab in the initial stage of expansion. When the second organic particles are compressed, the second organic particles can slow down the expansion of the electrode tab to some extent, reduce the electrolyte squeezed out by the electrode tab, and improve the cycle performance of the cylindrical battery cell.

[0052] In some embodiments, the plurality of support portions includes first support portions and second support portions, and the height of the first support portions protruding from the first surface is greater than the height of the second support portions protruding from the first surface. The plurality of organic particles includes first organic particles and second organic particles, and the first support portions include the first organic particles and the second support portions include the second organic particles. By providing the first organic particles and the second organic particles with different number average particle sizes, the first support portions and the second support portions with different heights can be formed. The first support portions have a larger height, which can support the first or second electrode tab to form a larger gap, thereby providing more space for the expansion of the electrode tab. The second support portions can be compressed after the electrode tab expands to a certain extent, thereby reducing the pressure on the electrode tab in the initial stage of expansion. When the second support portions are compressed, the second support portions can slow down the expansion of the electrode tab to some extent, reduce the electrolyte squeezed out by the electrode tab, and improve the cycle performance of the cylindrical battery cell.

[0053] In some embodiments, the radial dimension of at least part of the gap is 5 μm-60 μm. The embodiments of the present application limit the radial dimension of the gap to be greater than or equal to 5 μm, which can provide space for the expansion of the electrode tab, reduce the expansion force, improve the cycle performance of the cylindrical battery cell, and reduce the risk of deformation and cracking of the shell. The embodiments of the present application limit the radial dimension of the gap to be less than or equal to 50 μm, which shortens the ion migration path between the first electrode tab and the second electrode tab, reduces the internal resistance of the cylindrical battery cell, reduces heat generation, and reduces the impact of the gap on the energy density.

[0054] In some embodiments, the spacer has a plurality of support portions on both sides. The gap includes a first gap formed between the first tab and the spacer, and a second gap formed between the second tab and the spacer. By providing a plurality of support portions on both sides of the spacer, the gap can be increased, providing more space for the expansion of the tabs.

[0055] In some embodiments, the gap extends along the winding direction, and has a winding start end and a winding end end. A portion of the gap near the winding start end has a radial dimension that is greater than or equal to a radial dimension of a portion of the gap near the winding end end. The portion of the gap near the winding start end has a greater radial dimension to provide more space for the expansion of the tabs in the middle of the electrode assembly, reduce the risk of the middle of the electrode assembly collapsing due to expansion, and improve the cycle performance of the cylindrical battery cell.

[0056] In some embodiments, the radial dimension of at least part of the gap gradually decreases along the winding direction to provide more space for the expansion of the tabs in the middle of the electrode assembly, reduce the risk of the middle of the electrode assembly collapsing due to expansion, and improve the cycle performance of the cylindrical battery cell.

[0057] In some embodiments, the gap includes a middle region and two end regions arranged along the axial direction, the middle region being located between the two end regions, and the radial dimension of the middle region being smaller than the radial dimension of the end regions. The end regions have a larger radial dimension to facilitate the entry of electrolyte into the gap, improve the wettability of the tabs by the electrolyte, and improve the cycle performance of the cylindrical battery cell.

[0058] In some embodiments, the radial dimension of the gap gradually decreases in a direction from the end region to the middle region to reduce the abrupt change in the radial dimension of the gap, reduce stress concentration of the second tab, and improve the cycle performance of the cylindrical battery cell.

[0059] In some embodiments, in the radial direction of the cylindrical battery cell, a portion of the plurality of support portions is located between the first tab and the base. The first tab generates heat when current passes through, and the support portions can separate at least part of the first tab from the base, thereby reducing the amount of heat conducted to the base, reducing the deformation of the base due to high temperature, reducing the risk of the first tab and the second tab being in conduction, and improving the reliability of the cylindrical battery cell.

[0060] In some embodiments, the shell has a melting point greater than or equal to 1050℃. When the cylindrical battery cell is in thermal runaway, a large amount of heat and gas is generated inside the electrode assembly, which can be discharged through the pressure relief mechanism of the cylindrical battery cell. The first tab has a large length, which can slow down the discharge of heat and gas to some extent, so that the temperature inside the cylindrical battery cell is higher; the shell has a high melting point, which can withstand high temperature, and the use of a shell with a high melting point can reduce the risk of the shell being melted through, realize directional pressure relief of the cylindrical battery cell, and reduce the risk of heat spread.

[0061] In some embodiments, the shell has a tensile strength greater than or equal to 300MPa. When the cylindrical battery cell is in thermal runaway, a large amount of heat and gas is generated inside the electrode assembly, which can be discharged through the pressure relief mechanism of the cylindrical battery cell. The first tab has a large length, which can slow down the discharge of heat and gas to some extent, so that the pressure inside the cylindrical battery cell is higher; the use of a shell with a higher tensile strength can reduce the risk of the shell being cracked, realize directional pressure relief of the cylindrical battery cell, and reduce the risk of heat spread.

[0062] In some embodiments, the shell is a steel shell. The steel shell has a high melting point and strength, which is not easy to break when the cylindrical battery cell is in thermal runaway, thereby improving the reliability of the cylindrical battery cell. During the cycle process of the cylindrical battery cell, the electrode assembly will swell; the steel shell has high strength and deforms less under the swelling force of the electrode assembly, so the steel shell can effectively limit the deformation of the electrode assembly.

[0063] In some embodiments, the shell includes a shell body and an end cover, the shell body includes an integrally formed side wall and an end wall, the side wall surrounds the electrode assembly, the end wall and the end cover are opposite along the axial direction of the cylindrical battery cell, and the end cover is sealingly connected to the side wall.

[0064] In some embodiments, the second tab includes a second tab. The first electrode lead-out portion includes an electrode terminal insulatively provided on the end wall, the first tab is electrically connected to the electrode terminal, and the second tab is electrically connected to the end wall. The electrode terminal and the end wall can serve as two exposed electrodes of the cylindrical battery cell, and the electrode terminal and the end wall are located on the same side, which is conducive to assembling a plurality of cylindrical battery cells into a group and simplifying the battery structure.

[0065] In some embodiments, the cylindrical battery cell further includes a first current collecting member, the first current collecting member is located on the side of the first tab facing the end wall and connected to the first tab. The electrode terminal abuts against and is connected to the surface of the first current collecting member facing the end wall.

[0066] In some embodiments, the electrode terminal is provided with a terminal recess on the side facing the first current collecting member, and / or the electrode terminal is provided with a terminal recess on the side facing away from the first current collecting member. The bottom wall of the terminal recess is welded to the first current collecting member. By providing the terminal recess, the thickness of the bottom wall of the terminal recess can be reduced, the power required for welding the electrode terminal to the first current collecting member from the outside can be reduced, the risk of particles generated by welding falling into the shell can be reduced, and the reliability of the cylindrical battery cell can be improved.

[0067] In some embodiments, the first tab is located at the end of the first tab facing the end wall, and the second tab is located at the end of the second tab facing the end cover. The cylindrical battery cell further comprises a second current collecting member connected to the second tab; the second current collecting member is connected to at least one of the end cover and the side wall.

[0068] In some embodiments, the side wall is provided with a protrusion protruding inwardly, at least part of the protrusion is located between the end cover and the second tab in the axial direction. The second current collecting member is connected to the protrusion. The protrusion overlaps the second tab in the axial direction, which can limit the movement of the second tab in the axial direction when the cylindrical battery cell is subjected to external impact, and reduce the risk of failure of the connection between the second tab and the second current collecting member. Connecting the second current collecting member to the protrusion can shorten the conductive path between the second tab and the end wall, reduce the resistance, reduce the heat generation, and improve the cycle performance of the cylindrical battery cell.

[0069] In some embodiments, part of the second current collecting member is located on the side of the protrusion facing the end cover and connected to the protrusion. The second current collecting member can be connected to the protrusion from the outside of the protrusion, which can reduce the assembly difficulty.

[0070] In some embodiments, the height of the shell is 1.3 to 4 times the diameter of the shell. When the shell meets the above size requirements, the structural stability of the shell can be higher, and the use reliability of the cylindrical battery cell can be improved.

[0071] In some embodiments, the height of the shell is 50 mm to 150 mm.

[0072] In some embodiments, the diameter of the shell is 45 mm to 80 mm.

[0073] In some embodiments, the height of the shell is 50 mm to 150 mm.

[0074] In some embodiments, the diameter of the shell is 45 mm to 80 mm. BRIEF DESCRIPTION OF DRAWINGS

[0075] 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.

[0076] Figure 1 This application provides structural schematic diagrams of vehicles for some embodiments;

[0077] Figure 2 Explosion diagrams of batteries provided for some embodiments of this application;

[0078] Figure 3 for Figure 2 The diagram shows the structure of the battery module.

[0079] Figure 4 This is a schematic diagram of the structure of a cylindrical battery cell in some embodiments of this application;

[0080] Figure 5 for Figure 4 An exploded view of a cylindrical battery cell;

[0081] Figure 6 This is a schematic diagram of the electrode assembly of a cylindrical battery cell provided in some embodiments of this application;

[0082] Figure 7 for Figure 6 A cross-sectional view along the AA direction;

[0083] Figure 8 A partial structural schematic diagram of the electrode assembly of a cylindrical battery cell provided in some embodiments of this application;

[0084] Figure 9 This is a schematic diagram of the first electrode of a cylindrical battery cell in a flattened state, provided in some embodiments of this application.

[0085] Figure 10 for Figure 9 A cross-sectional schematic diagram of the first pole piece shown;

[0086] Figure 11 A schematic diagram of the second electrode of a cylindrical battery cell in a flattened state, provided in some embodiments of this application;

[0087] Figure 12 for Figure 11 A cross-sectional schematic diagram of the second pole piece shown;

[0088] Figure 13 A schematic diagram of the first electrode of a cylindrical battery cell in a flattened state, provided in some other embodiments of this application;

[0089] Figure 14 A schematic view of a first pole piece of a cylindrical battery cell in a flattened state, provided for some embodiments of the present application;

[0090] Figure 15 A schematic view of a first pole piece of a cylindrical battery cell in a flattened state, provided for some embodiments of the present application;

[0091] Figure 16 A schematic view of a first pole piece of a cylindrical battery cell in a flattened state, provided for some embodiments of the present application;

[0092] Figure 17 A schematic view of a cross-section of an electrode assembly of a cylindrical battery cell, provided for some embodiments of the present application;

[0093] Figure 18 A schematic view of a separator of an electrode assembly of a cylindrical battery cell, provided for some embodiments of the present application; Figure 17 A zoomed-in schematic view at the dashed box;

[0094] Figure 19 A schematic view of a separator of an electrode assembly of a cylindrical battery cell, provided for some embodiments of the present application;

[0095] Figure 20 A schematic view of a partial cross-section of an electrode assembly of a cylindrical battery cell, provided for some embodiments of the present application;

[0096] Figure 21 A schematic view of a separator of an electrode assembly of a cylindrical battery cell, provided for some embodiments of the present application;

[0097] Figure 22 A schematic view of a partial cross-section of an electrode assembly of a cylindrical battery cell, provided for some embodiments of the present application;

[0098] Figure 23 A schematic view of a partial cross-section of an electrode assembly of a cylindrical battery cell, provided for some embodiments of the present application;

[0099] Figure 24 A schematic view of a cross-section of a cylindrical battery cell, provided for some embodiments of the present application;

[0100] Figure 25 A schematic view of a cross-section of a cylindrical battery cell, provided for some embodiments of the present application; Figure 24 A zoomed-in schematic view at the circle box;

[0101] Figure 26 A schematic view of a partial cross-section of a cylindrical battery cell, provided for some embodiments of the present application.

[0102] In the drawings, the drawings are not drawn to scale.

[0103] The reference signs are explained as follows:

[0104] 1, vehicle; 2, battery; 3, controller; 4, motor; 5, case; 5a, first case portion; 5b, second case portion; 5c, accommodation space; 6, battery module; 7, cylindrical battery cell; 7a, first electrode lead-out portion; 7b, second electrode lead-out portion;

[0105] 10, electrode assembly;

[0106] 11, first tab; 111, first current collector; 1111, first coated region; 1112, first tab; 1112a, first lamination portion; 1112b, transition portion; 1112c, connection portion; 1112d, first sub-tab; 1112e, tab section; 112, first film layer;

[0107] 12, second tab; 121, second current collector; 1211, second coated region; 1212, second tab; 122, second film layer;

[0108] 13, separator; 131, base portion; 1311, base film; 1312, inorganic particle layer; 131a, first surface; 132, support portion; 132a, first support portion; 132b, second support portion;

[0109] 20, housing; 21, case; 211, end wall; 212, side wall; 2121, protrusion; 2122, crimp portion; 2123, recess; 22, end cap;

[0110] 30, electrode terminal; 31, terminal recess; 32, through-hole;

[0111] 40, first current collecting member; 50, cover plate; 60, second current collecting member; 70, insulating member;

[0112] C1, middle region; C2, end region; C3, transition region;

[0113] P, organic particle; P1, first organic particle; P2, second organic particle;

[0114] E1, winding start end; E2, winding end end; E3, first winding start end; E4, first winding end end; E5, second winding start end; E6, second winding end end; E7, first end; E8, second end;

[0115] G, gap; G1, first gap; G2, second gap;

[0116] J, notch; V, winding direction; Z, axial direction. DETAILED DESCRIPTION

[0117] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0118] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs; the terms used in the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application; the terms "include" and "have" and any variations thereof in the specification and claims of the present application and the above description of drawings are intended to cover non-exclusive inclusion. The terms "first", "second" and the like in the specification and claims of the present application and the above description of drawings are used to distinguish different objects, not to describe a particular order or primary and secondary relationship.

[0119] In the present application, the phrase "embodiments" means that the specific features, structures or characteristics described in connection with the embodiments can be included in at least one embodiment of the present application. The phrase appears at various places in the specification does not necessarily all refer to the same embodiments, nor are they necessarily mutually exclusive or alternative embodiments to each other.

[0120] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mount", "connect", "connection", "attach" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral connection; it can be direct connection, or indirect connection through intermediate medium, or internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0121] In the present application, the term "and / or" is only a description of the association relationship between the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone. In addition, the character " / " in the present application generally represents an "or" relationship between the front and rear associated objects.

[0122] In the embodiments of the present application, the same reference signs represent the same components, and for the sake of brevity, detailed description of the same components is omitted in different embodiments. It should be understood that the thickness, length and width of various components in the embodiments of the present application shown in the drawings, and the overall thickness, length and width of the integrated device are only exemplary and should not constitute any limitation on the present application.

[0123] "plurality" appearing in this application refers to two or more (including two).

[0124] The cylindrical battery cell can be a cylindrical secondary battery, which refers to a battery cell that can be activated by charging after discharging to continue to be used.

[0125] The battery can refer to a single physical module including one or more cylindrical battery cells to provide higher voltage and capacity.

[0126] The cylindrical battery cell generally includes an electrode assembly and a housing for accommodating the electrode assembly. The electrode assembly generally includes a positive electrode sheet, a negative electrode sheet, and a separator that separates the positive electrode sheet and the negative electrode sheet.

[0127] During the charging and discharging of the cylindrical battery cell, the positive electrode sheet and the negative electrode sheet generate heat under the action of current, thereby causing the temperature of the cylindrical battery cell to rise. In particular, as the capacity of the cylindrical battery cell increases, and the user's requirement for charging speed gradually increases, the current of the cylindrical battery cell during charging is also increasing. As the current increases, the heat generation of the positive electrode sheet and the negative electrode sheet also increases, which causes the local temperature of the cylindrical battery cell to rise greatly, resulting in cycle decay of the cylindrical battery cell due to temperature rise, affecting the cycle performance and reliability performance of the cylindrical battery cell.

[0128] In view of this, the embodiments of the present application provide a technical solution, which increases the length of the coating area of the electrode sheet and the connection position of the tab to improve the overcurrent capacity of the electrode sheet, reduce the heat generation of the electrode sheet, reduce the temperature rise of the cylindrical battery cell, and improve the cycle performance and reliability performance of the cylindrical battery cell.

[0129] The cylindrical battery cell described in the embodiments of the present application is suitable for a battery and a power consumption device using the battery.

[0130] The power consumption device can be a device using a battery as a power source or various energy storage systems using a battery as an energy storage element. The power consumption device can be, but is not limited to, a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, an electric vehicle, an electric car, a ship, a spacecraft, etc. Among them, the electric toy can include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric plane toys, etc. The spacecraft can include airplanes, rockets, space shuttles, and spaceships, etc.

[0131] The following embodiments take a vehicle as an example for convenience of description.

[0132] Figure 1 The following embodiments take a vehicle as an example for convenience of description.

[0133] AsFigure 1 As shown, the vehicle 1 is provided with a battery 2, which can be arranged at the bottom, head or tail of the vehicle 1. The battery 2 can be used for power supply of the vehicle 1, for example, the battery 2 can be used as the operating power source of the vehicle 1.

[0134] The vehicle 1 can also include a controller 3 and a motor 4, the controller 3 is used to control the battery 2 to supply power to the motor 4, for example, for the power demand of the vehicle 1 during starting, navigation and driving.

[0135] In some embodiments of the present application, the battery 2 can not only be used as the operating power source of the vehicle 1, but also be used as the driving power source of the vehicle 1, instead of or partially instead of fuel or natural gas to provide driving power for the vehicle 1.

[0136] Figure 2 The explosion schematic diagram of the battery provided in some embodiments of the present application is shown. As shown, the battery 2 includes a box body 5 and a cylindrical battery cell (not shown), and the cylindrical battery cell is contained in the box body 5. Figure 2 Figure 2 The box body 5 is used to contain the cylindrical battery cell, and the box body 5 can have various structures. In some embodiments, the box body 5 can include a first box body part 5a and a second box body part 5b, the first box body part 5a and the second box body part 5b are mutually covered, and the first box body part 5a and the second box body part 5b jointly define a containing space 5c for containing the cylindrical battery cell. The second box body part 5b can be a hollow structure with one end open, and the first box body part 5a is a plate-like structure, which is covered on the open side of the second box body part 5b to form the box body 5 with the containing space 5c; or the first box body part 5a and the second box body part 5b can both be a hollow structure with one side open, and the open side of the first box body part 5a is covered on the open side of the second box body part 5b to form the box body 5 with the containing space 5c. Of course, the first box body part 5a and the second box body part 5b can have various shapes, such as cylinder, cuboid, etc.

[0137] In order to improve the sealing performance of the first box body part 5a and the second box body part 5b after being connected, a sealing member such as sealing glue, sealing ring, etc. can be arranged between the first box body part 5a and the second box body part 5b.

[0138] Suppose the first box body part 5a is covered on the top of the second box body part 5b, the first box body part 5a can also be called an upper box cover, and the second box body part 5b can also be called a lower box body.

[0139] Suppose the first box body part 5a is covered on the top of the second box body part 5b, the first box body part 5a can also be called an upper box cover, and the second box body part 5b can also be called a lower box body.

[0140] ​In the battery 2, the cylindrical battery cell can be one or multiple. If the cylindrical battery cell is multiple, the multiple cylindrical battery cells can be connected in series, in parallel, or in a mixed connection. The mixed connection means that the multiple cylindrical battery cells are connected in series and in parallel. The multiple cylindrical battery cells can be directly connected in series, in parallel, or in a mixed connection, and the whole of the multiple cylindrical battery cells is accommodated in the box 5. Alternatively, the multiple cylindrical battery cells can be connected in series, in parallel, or in a mixed connection to form a battery module 6, and the multiple battery modules 6 are connected in series, in parallel, or in a mixed connection to form a whole, which is accommodated in the box 5.

[0141] The cylindrical battery cell can be the smallest unit of the battery.

[0142] In some embodiments, the box 5 can be part of the chassis structure of the vehicle. For example, part of the box 5 can be at least part of the floor of the vehicle, or part of the box 5 can be at least part of the cross beam and the longitudinal beam of the vehicle.

[0143] In some embodiments, the battery 2 can be an energy storage device. The energy storage device includes an energy storage container, an energy storage cabinet, etc.

[0144] Figure 3 For Figure 2 the structure of the battery module is shown.

[0145] In some embodiments, as Figure 3 shown, the cylindrical battery cell 7 is multiple, and the multiple cylindrical battery cells 7 are connected in series, in parallel, or in a mixed connection to form a battery module 6. The multiple battery modules 6 are connected in series, in parallel, or in a mixed connection to form a whole, which is accommodated in the box.

[0146] The multiple cylindrical battery cells 7 in the battery module 6 can be electrically connected through a busbar component to realize the parallel connection, the series connection, or the mixed connection of the multiple cylindrical battery cells 7 in the battery module 6. The busbar component can be one or multiple, and each busbar component is used to electrically connect at least two cylindrical battery cells 7.

[0147] The cylindrical battery cell 7 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 hydrogen battery cell, a nickel cadmium battery cell, a lead-acid battery cell, etc.

[0148] Referring to Figures 4 to 12 , the embodiments of the present application provide a cylindrical battery cell 7, which includes a shell 20 and an electrode assembly 10, and the electrode assembly 10 is accommodated in the shell 20.

[0149] The shell 20 is a hollow structure, and an accommodation space for accommodating the electrode assembly 10 and the electrolyte is formed in the shell 20. The shell 20 of the cylindrical battery cell 7 can be a cylindrical shell.

[0150] As an example, the housing 20 includes a shell 21 having an opening and an end cap 22 for covering the opening.

[0151] The shell 21 is a component for cooperating with the end cap 22 to form an internal cavity of the cylindrical battery cell 7, which can be used to accommodate the electrode assembly 10, electrolyte, and other components.

[0152] The shell 21 and the end cap 22 can be separate components. As an example, the shell 21 can be provided with an opening, and the end cap 22 can be used to cover the opening to form the internal cavity of the cylindrical battery cell 7.

[0153] The shell 21 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc.

[0154] The end cap 22 can be shaped to fit the shell 21. The material of the end cap 22 can be the same as or different from that of the shell 21. Optionally, the end cap 22 can be made of a material with certain hardness and strength (such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.), so that the end cap 22 is less likely to deform when subjected to extrusion or impact, and the cylindrical battery cell 7 can have higher structural strength and improved reliability.

[0155] The end cap 22 can be connected to the shell 21 by welding, bonding, clamping, or other means.

[0156] The shell 21 can be open at one end or both ends. In some examples, the shell 21 can be open at one side, and the end cap 22 can be provided as one and cover the shell 21. In other examples, the shell 21 can be open at both ends, and the end cap 22 can be provided as two and cover the two openings of the shell 21.

[0157] In some embodiments, the shell 21 includes an integral side wall 212 and an end wall 211, the end wall 211 and the end cap 22 are opposite along the axial direction Z of the cylindrical battery cell 7, and the end cap 22 is sealingly connected to the side wall 212.

[0158] In some embodiments, the electrode assembly 10 is a component that undergoes electrochemical reactions in the cylindrical battery cell 7.

[0159] In some embodiments, the electrode assembly 10 includes first and second polar plates 11 and 12 with opposite polarities. One of the first and second polar plates 11 and 12 is a positive polar plate, and the other is a negative polar plate.

[0160] In some embodiments, the first tab 11 includes a first current collector 111 and a first film layer 112 disposed on at least one surface of the first current collector 111. The second tab 12 includes a second current collector 121 and a second film layer 122 disposed on at least one surface of the first current collector 111.

[0161] As an example, the first current collector 111 has two surfaces opposite in its own thickness direction, and the first film layer 112 is disposed on either or both of the two opposite surfaces of the first current collector 111. The second current collector 121 has two surfaces opposite in its own thickness direction, and the second film layer 122 is disposed on either or both of the two opposite surfaces of the second current collector 121.

[0162] In some examples, the first tab 11 is a positive tab, and the second tab 12 is a negative tab. Correspondingly, the first current collector 111 is a positive current collector, the second current collector 121 is a negative current collector, the first film layer 112 is a positive film layer, and the second film layer 122 is a negative film layer. In other examples, the first tab 11 is a negative tab, and the second tab 12 is a positive tab. Correspondingly, the first current collector 111 is a negative current collector, the second current collector 121 is a positive current collector, the first film layer 112 is a negative film layer, and the second film layer 122 is a positive film layer.

[0163] As an example, the positive current collector can be a metal foil or a composite current collector. For example, as a metal foil, silver surface treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon, carbon, nickel, or titanium, etc. can be used. The composite current collector can include a high molecular 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 high molecular material base material (such as a base material of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0164] As an example, the positive electrode film layer includes a positive electrode active material, which can include at least one of lithium-containing phosphates, lithium transition metal oxides, and modified compounds thereof. However, the present application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials can also be used. These positive electrode active materials can be used alone or in combination of two or more. Among them, examples of the lithium-containing phosphates can include, but are not limited to, at least one of lithium iron phosphate (e.g., LiFeP04(also referred to as LFP)), a composite of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnP04), a composite of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite of lithium manganese iron phosphate and carbon. Examples of the lithium transition metal oxides can include, but are not limited to, at least one of lithium cobalt oxide (e.g., LiCo02), lithium nickel oxide (e.g., LiNi02), lithium manganese oxide (e.g., LiMn02, LiMn204), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (e.g., LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2(also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2(also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2(also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2(also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (e.g., LiNi 0.80 Co 0.15 Al 0.05 O2), and modified compounds thereof.

[0165] As an example, the negative current collector can employ a metal foil, a foamed metal, a foamed carbon, or a composite current collector. For example, as the metal foil, silver surface-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, a carbon electrode, or the like can be employed. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or the like. The composite current collector can include a polymer material base layer 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, or the like) on a polymer material base material (such as a base material of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, or the like).

[0166] As an example, the negative electrode film layer includes a negative electrode active material. For example, the negative electrode active material can include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, a silicon-based material, a tin-based material, lithium titanate, and the like. The silicon-based material can be selected from at least one of elemental silicon, a silicon oxide compound, a silicon-carbon composite, a silicon-nitrogen composite, and a silicon alloy. The tin-based material can be selected from at least one of elemental tin, a tin oxide compound, and a tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery negative electrode active material can also be used. These negative electrode active materials can be used alone only one or two or more can be used in combination.

[0167] In some embodiments, the material of the positive current collector can be aluminum, and the material of the negative current collector can be copper.

[0168] In some embodiments, the electrode assembly 10 further includes a separator 13 disposed between the positive electrode sheet and the negative electrode sheet. The separator 13 can function to prevent short-circuiting of the positive and negative electrodes while allowing the passage of active ions.

[0169] In some embodiments, the cylindrical battery cell 7 further includes an electrolyte that functions to conduct ions between the positive electrode sheet and the negative electrode sheet. The electrolyte can be in a liquid state, a gel state, or a solid state.

[0170] In some embodiments, the liquid electrolyte includes an electrolyte salt and a solvent.

[0171] As an example, the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonylimide, lithium bistrifluoromethylsulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoroboric oxalate, lithium difluoroboric bisoxalate, lithium difluorophosphoric bisoxalate, and lithium tetrafluorophosphoric oxalate.

[0172] As an example, the solvent can 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, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, butyl sulfone, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent can also be selected from an ether-based solvent. The ether-based solvent can 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 a crown ether.

[0173] In some embodiments, the gel-state electrolyte includes a polymer as a backbone network of the electrolyte, in combination with an ionic liquid-lithium salt.

[0174] In some embodiments, the solid-state electrolyte includes a polymer solid-state electrolyte, an inorganic solid-state electrolyte, a composite solid-state electrolyte.

[0175] As an example, the polymer solid-state electrolyte can be a polyether (polyethylene oxide), a polysiloxane, a polycarbonate, a polyacrylonitrile, a polyvinylidene fluoride, a polymethyl methacrylate, a single-ion polymer, a polyionic liquid-lithium salt, a cellulose, or the like.

[0176] As an example, the inorganic solid-state electrolyte can be one or more of an oxide solid electrolyte (crystalline perovskite, sodium superionic conductor, garnet, amorphous LiPON thin film), a sulfide solid electrolyte (crystalline lithium superionic conductor (lithium germanium phosphorous sulfide, argyrodite), amorphous sulfide), and a halide solid electrolyte, a nitride solid electrolyte, and a hydride solid electrolyte.

[0177] As an example, the composite solid-state electrolyte is formed by adding an inorganic solid-state electrolyte filler to a polymer solid-state electrolyte.

[0178] In some embodiments, the first electrode tab 11, the second electrode tab 12, and the separator 13 are wound. The electrode assembly 10 is a wound structure. As an example, the first electrode tab 11, the separator 13, and the second electrode tab 12 are wound into a cylindrical wound structure.

[0179] In some embodiments, the cylindrical battery cell 7 further includes a first electrode lead-out portion 7a and a second electrode lead-out portion 7b, the first electrode lead-out portion 7a being electrically connected to the first electrode tab 11, and the second electrode lead-out portion 7b being electrically connected to the second electrode tab 12.

[0180] The first electrode lead-out portion 7a and the second electrode lead-out portion 7b are insulated from each other.

[0181] The first electrode lead-out portion 7a and the second electrode lead-out portion 7b are used to connect with external circuits to realize charging or discharging of the cylindrical battery cell 7. Exemplarily, when a plurality of cylindrical battery cells 7 are assembled into a group, the first electrode lead-out portion 7a and the second electrode lead-out portion 7b are used to connect with busbar components.

[0182] The first electrode lead-out portion 7a can include an electrode terminal 30 arranged on the outer shell 20. The electrode terminal 30 is separately formed from the outer shell 20 and assembled together during the production of the cylindrical battery cell 7. Exemplarily, the electrode terminal 30 is arranged on the end cover 22 or the shell 21 in an insulating manner.

[0183] Alternatively, the first electrode lead-out portion 7a can also be a part of the outer shell 20. For example, the first electrode lead-out portion 7a can be the end cover 22 of the outer shell 20, or the first electrode lead-out portion 7a can be the end wall 211 of the shell 21 opposite to the end cover 22.

[0184] The second electrode lead-out portion 7b can be an electrode terminal 30 arranged on the outer shell 20. Alternatively, the second electrode lead-out portion 7b can be a part of the outer shell 20. For example, the second electrode lead-out portion 7b can be the end cover 22 of the outer shell 20, or the second electrode lead-out portion 7b can be the end wall 211 of the shell 21 opposite to the end cover 22.

[0185] In some embodiments, the first electrode lead-out portion 7a is the electrode terminal 30, the second electrode lead-out portion 7b is the end wall 211 of the shell 21, and the electrode terminal 30 is arranged on the end wall 211 in an insulating manner. In other examples, the second electrode lead-out portion 7b is the electrode terminal 30, the first electrode lead-out portion 7a is the end wall 211 of the shell 21, and the electrode terminal 30 is arranged on the end wall 211 in an insulating manner.

[0186] In some embodiments, the cylindrical battery cell 7 has a capacity greater than or equal to 20 Ah. The cylindrical battery cell 7 includes an outer shell 20 and an electrode assembly 10 accommodated in the outer shell 20. The electrode assembly 10 includes first and second electrode sheets 11 and 12 having opposite polarities. The first and second electrode sheets 11 and 12 are wound along a winding direction V. The first electrode sheet 11 includes a first current collector 111 and a first film layer 112, the first current collector 111 includes a first coated area 1111 and a first tab 1112, a surface of the first coated area 1111 is coated with the first film layer 112, and the first tab 1112 extends from one end of the first coated area 1111 along an axial direction Z of the cylindrical battery cell 7 and a surface of the first tab 1112 is not coated with the first film layer 112. The cylindrical battery cell 7 includes a first electrode lead-out portion 7a, and the first tab 1112 is electrically connected to the first electrode lead-out portion 7a. Along the winding direction V, a length of a connection position of the first tab 1112 to the first coated area 1111 is L1, a length of the first coated area 1111 is L0, and 0.8≤L1 / L0≤1.

[0187] As an example, the length of the first film layer 112 is equal to the length of the first coating area 1111 along the winding direction V.

[0188] As an example, after the first tab 11 is flattened, the first film layer 112 and the first coating area 1111 can both be rectangular; after the first tab 11 is flattened, L0 can be equal to the length of the first coating area 1111, and L1 can be equal to the length of the connection position of the first tab 1112 and the first coating area 1111.

[0189] As an example, the capacity can be 20 Ah, 22 Ah, 25 Ah, 28 Ah, 30 Ah, 35 Ah, 40 Ah, 45 Ah, 50 Ah, 55 Ah, or 60 Ah.

[0190] As an example, the capacity can be the rated capacity of the cylindrical battery cell 7. The rated capacity can be obtained from the manufacturer or seller on the label, packaging, user manual, instruction manual, advertisement, marketing, or other support documents of these products so that the user can use it. The rated capacity can include a number, or other words, phrases, combinations of alphanumeric characters, icons, or signs indicating to the user how the cylindrical battery cell 7 works.

[0191] In the first tab 11, one surface of the first coating area 1111 can be coated with the first film layer 112, or both surfaces of the first coating area 1111 can be coated with the first film layer 112. Both surfaces of the first tab 1112 are not coated with the first film layer 112.

[0192] As an example, L1 / L0 is 0.8, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, or 1.

[0193] The thickness of the first tab 1112 can be the same as or different from the thickness of the first coating area 1111.

[0194] In the winding direction V, the first tab 1112 can be a continuous structure or a discontinuous structure. As an example, the first tab 1112 can also be divided into a plurality of tab segments, and the sum of the lengths of the connection positions of the plurality of tab segments and the first coating area 1111 is L1.

[0195] The cylindrical battery cell 7 has a capacity greater than or equal to 20 Ah, which is beneficial to improve the energy density when a plurality of cylindrical battery cells 7 are assembled into a group.

[0196] During the charging or discharging process, the current is transmitted between the first coating area 1111 and the first tab 1112. For a cylindrical battery cell 7 with a larger capacity, the current flowing through the connection position of the first coating area 1111 and the first tab 1112 is larger. The connection position of the first coating area 1111 and the first tab 1112 is close to the first film layer 112. Therefore, the heat generated at the connection position of the first coating area 1111 and the first tab 1112 under the action of the current is more likely to affect the first film layer 112.

[0197] In the embodiments of the present application, L1 / L0 is greater than or equal to 0.8. The overcurrent area of the connection position of the first coating area 1111 and the first tab 1112 can be increased, the impedance can be reduced, the heat generated at the connection position of the first coating area 1111 and the first tab 1112 can be reduced, the temperature rise of the first current collector 111 and the first film layer 112 can be reduced, the risk of ion (e.g., lithium ion) precipitation can be reduced, the cycle performance of the cylindrical battery cell 7 can be improved, the risk of thermal runaway can be reduced, and the reliability of the cylindrical battery cell 7 can be improved. In the embodiments of the present application, L1 / L0 is less than or equal to 1. The redundancy of the first tab 1112 can be reduced, the space can be saved, and the influence of lengthening the first tab 1112 on the energy density of the cylindrical battery cell 7 can be reduced.

[0198] In some embodiments, 0.95≤L1 / L0≤1. The cycle performance and the energy density of the cylindrical battery cell 7 can be considered to some extent.

[0199] In some embodiments, 3000mm≤L0≤9000mm. For example, L0 is 3000mm, 3500mm, 4000mm, 4500mm, 5000mm, 5500mm, 6000mm, 6500mm, 7000mm, 7500mm, 8000mm, 8500mm, or 9000mm.

[0200] L0 is positively correlated with the length of the first tab 11. In the embodiments of the present application, L0 is greater than or equal to 3000mm. The capacity of the cylindrical battery cell 7 can be improved. The first tab 11 with a larger length can also correspondingly increase the length of the first tab 1112, thereby improving the overcurrent capacity, reducing the impedance, reducing the temperature rise of the first current collector 111 and the first film layer 112, and reducing the risk of ion precipitation, and improving the cycle performance of the cylindrical battery cell 7. When the diameter of the cylindrical battery cell 7 is constant, the longer the first current collector 111 is, the higher the weight proportion of the first current collector 111 in the cylindrical battery cell 7 is. In the embodiments of the present application, L0 is less than or equal to 9000mm. The space and weight occupied by the first current collector 111 can be limited, and the loss of the energy density of the cylindrical battery cell 7 can be reduced.

[0201] As an example, 4500 mm ≤ L0 ≤ 7000 mm. Defining the length of the first coating area 1111 to be within the range of 4500 mm-7000 mm can balance the cycle performance and the energy density of the cylindrical battery cell 7 to a certain extent.

[0202] In some embodiments, 2400 mm ≤ L1 ≤ 9000 mm. Defining L1 to be greater than or equal to 2400 mm can improve the overcurrent capacity, reduce the impedance, reduce the temperature rise of the first current collector 111 and the first film layer 112, and reduce the risk of ion precipitation, thereby improving the cycle performance of the cylindrical battery cell 7. Defining L1 to be less than or equal to 9000 mm can limit the space and weight occupied by the first current collector 111, and reduce the loss of the energy density of the cylindrical battery cell 7.

[0203] As an example, L1 is 2400 mm, 2700 mm, 3000 mm, 3500 mm, 4000 mm, 4500 mm, 5000 mm, 5500 mm, 6000 mm, 6500 mm, 7000 mm, 7500 mm, 8000 mm, 8500 mm, or 9000 mm.

[0204] In some embodiments, 3600 mm ≤ L1 ≤ 7000 mm.

[0205] In some embodiments, the diameter of the cylindrical battery cell 7 is 40 mm-100 mm, and L0 is 3000 mm-9000 mm. By using a first tab 11 with a larger length, the thickness of the first tab 11, i.e., the thickness of the first film layer 112, can be reduced, the impedance can be reduced, the rate of ion precipitation or intercalation can be improved, and the fast charging capability of the cylindrical battery cell 7 can be improved.

[0206] In some embodiments, the thickness of the first tab 1112 is equal to the thickness of the first coating area 1111. Using the first tab 1112 and the first coating area 1111 with the same thickness can simplify the forming process of the first tab 11.

[0207] In some embodiments, the first tab 1112 and the first coating area 1111 are integrally formed.

[0208] In some embodiments, the sum of the thickness of the first film layer 112 and the thickness of the first coating area 1111 is D1, the thickness of the first coating area 1111 is T1, and 0.17 ≤ T1 / D1 ≤ 0.35.

[0209] As an example, the first coating area 1111 is provided with the first film layer 112 on both sides, and T1 can be the thickness of the first film layer 112 on one side of the first coating area 1111.

[0210] As an example, T1 / D1 can be 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, or 0.35.

[0211] The greater T1 / D1 is, the greater the flow area of the first coating area 1111 is, the lower the impedance of the first coating area 1111 is, the less heat the first coating area 1111 generates during charging and discharging, and the lower the temperature rise of the first coating area 1111 is. The smaller T1 / D1 is, the greater the thickness ratio of the first film layer 112 to the first coating area 1111 is, and the higher the capacity of the first film layer 112 is.

[0212] Embodiments of the present application limit T1 / D1 to be greater than or equal to 0.17 to increase the flow area of the first coating area 1111 or reduce the thickness of the first film layer 112 (reducing the thickness of the first film layer 112 can reduce the capacity of the first film layer 112, and in turn reduce the current flowing through the first coating area 1111 during charging or discharging), thereby reducing the heat generated by the first coating area 1111 during charging and discharging, reducing the temperature rise of the first film layer 112 and the first coating area 1111, improving the cycle performance of the cylindrical battery cell 7, and reducing the risk of thermal runaway. Embodiments of the present application limit T1 / D1 to be less than or equal to 0.35 to limit the thickness ratio of the first coating area 1111 in the first tab 11, and reduce the loss of capacity of the first tab 11. Embodiments of the present application limit T1 / D1 to be 0.17-0.35, which can balance the cycle performance and energy density of the cylindrical battery cell 7 to a certain extent.

[0213] In some embodiments, 9 pm ≤ T1 ≤ 17 pm. As an example, T1 is 9 pm, 10 pm, 11 pm, 12 pm, 13 pm, 14 pm, 15 pm, 16 pm, or 17 pm.

[0214] Limiting T1 to be greater than or equal to 9 pm can make the first coating area 1111 have a larger flow area, thereby reducing the impedance, reducing the heat generated by the first coating area 1111 during charging and discharging, reducing the temperature rise of the first film layer 112 and the first coating area 1111, reducing ion precipitation (such as lithium precipitation), improving the cycle performance of the cylindrical battery cell 7, and reducing the risk of thermal runaway. Limiting T1 to be greater than or equal to 17 pm limits the thickness ratio of the first coating area 1111 in the first tab 11, and reduces the loss of capacity of the first tab 11.

[0215] In some embodiments, 11 pm ≤ T1 ≤ 15 pm, which can further balance the cycle performance and energy density of the cylindrical battery cell 7.

[0216] In some embodiments, the sum of the thickness of the first film layer 112 and the thickness of the first coating area 1111 is D1, the thickness of the first film layer 112 is T2, and 0.67≤T2 / D1≤0.81.

[0217] As an example, D1=T1+T2.

[0218] As an example, the thickness of the first pole piece 11 is T1+2×T2.

[0219] As an example, T2 / D1 is 0.67, 0.68, 0.69, 0.70, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.80, or 0.81.

[0220] Defining T2 / D1 to be greater than or equal to 0.67 can increase the proportion of the thickness of the first film layer 112 in the first pole piece 11, improve the capacity of the first pole piece 11, and the energy density of the cylindrical battery cell 7. Defining T2 / D1 to be less than or equal to 0.81 can limit the thickness ratio of the first film layer 112 and the first coating area 1111, so that the first coating area 1111 can maintain a larger thickness, thereby reducing the impedance, reducing the heat generation of the first coating area 1111 during charging and discharging, reducing the temperature rise of the first film layer 112 and the first coating area 1111, reducing ion precipitation, improving the cycle performance of the cylindrical battery cell 7, and reducing the risk of thermal runaway. The embodiments of the present application limit T2 / D1 to 0.67-0.81, which can balance the cycle performance and energy density of the cylindrical battery cell 7 to some extent.

[0221] In addition, defining T2 / D1 to be less than or equal to 0.81 can also improve the rate of ion extraction or embedding, and improve the rapid charging capability of the cylindrical battery cell 7.

[0222] In some embodiments, the capacity of the cylindrical battery cell 7 is 25Ah-50Ah. As an example, the capacity of the cylindrical battery cell 7 is 25Ah, 26Ah, 28Ah, 30Ah, 32Ah, 34Ah, 35Ah, 36Ah, 38Ah, 40Ah, 42Ah, 44Ah, 45Ah, 46Ah, 48Ah, or 50Ah.

[0223] The cylindrical battery cell 7 has a capacity greater than or equal to 25Ah, which is beneficial to improve the energy density when multiple cylindrical battery cells 7 are assembled into a group. Defining the capacity C of the cylindrical battery cell 7 to be less than or equal to 50Ah can limit the charging current of the cylindrical battery cell 7, reduce heat generation, reduce the temperature rise of the first film layer 112 and the first current collector 111, and improve the cycle performance of the cylindrical battery cell 7.

[0224] In some embodiments, the cylindrical battery cell 7 has a rapid charging capability.

[0225] The capacity of the cylindrical battery cell 7 is C Ah. The cylindrical battery cell 7 can be charged at 2C rate, 3C rate or 4C rate at a partial stage of charging. As an example, the cylindrical battery cell 7 is charged at 2C rate, i.e. at a constant current of 2 x C A.

[0226] For example, the capacity of the cylindrical battery cell 7 is 25 Ah (i.e. C is 25); at 30°C, the cylindrical battery cell 7 can be charged at a current of 25 A, 50 A or 75 A during charging from 10% SOC to 80% SOC.

[0227] SOC refers to the state of charge of the battery cell.

[0228] As an example, the cylindrical battery cell is charged at 25°C at a constant current of 0.33C to 4.25V, and then charged at a constant voltage of 4.25V until the charging current decays to 0.05C, at which time the cylindrical battery cell is at 100% SOC. The cylindrical battery cell 7 is discharged at a rate of 0.33C to 2.5V, at which time the cylindrical battery cell is at 0% SOC.

[0229] The discharge capacity A0 is recorded in Ah; according to the charged capacity, the state of charge of the cylindrical battery cell can be determined, for example, when the cylindrical battery cell is charged from 0% SOC to 0.1A0, the cylindrical battery cell is at 10% SOC.

[0230] In some embodiments, the connection position of the first tab 1112 and the first coating area 1111 is continuously arranged along the winding direction V, which can increase the flow area between the first tab 1112 and the first coating area 1111, reduce the heat generation of the first coating area 1111 and the first tab 1112, reduce the temperature rise of the first film layer 112, and improve the cycle performance of the cylindrical battery cell 7.

[0231] In some embodiments, the first tab 1112 is continuously arranged as a whole along the winding direction V, which can improve the flow capacity of the first tab 1112, improve the current consistency, and reduce the heat generation.

[0232] In some embodiments, the minimum length of the first tab 1112 along the winding direction V is greater than or equal to 0.8 x L0, which can increase the flow area of each region of the first tab 1112, reduce the impedance, reduce the heat generation of the first tab 1112, reduce the temperature rise of the first film layer 112, and improve the cycle performance of the cylindrical battery cell 7.

[0233] In some embodiments, the first tab 1112 is rectangular after being flattened.

[0234] In some embodiments, the first tab 1112 is bent away from the end of the first coating area 1111 and forms a first laminated portion 1112a, the first laminated portion 1112a has a multi-layer structure in the axial direction Z of the cylindrical battery cell 7, and the first laminated portion 1112a is electrically connected to the first electrode lead-out portion 7a.

[0235] The multi-layer structure between the first laminated portion 1112a can transmit current. By electrically connecting the first laminated portion 1112a with the multi-layer structure to the first electrode lead-out portion 7a, the overcurrent capacity can be improved, the impedance can be reduced, the heat generation can be reduced, and the cycle performance of the cylindrical battery cell 7 can be improved.

[0236] In some embodiments, the cylindrical battery cell 7 includes a first current collecting member 40, the first current collecting member 40 is at least partially located between the first laminated portion 1112a and the first electrode lead-out portion 7a, and the first current collecting member 40 is welded to the first laminated portion 1112a and the first electrode lead-out portion 7a, respectively.

[0237] Welding the first laminated portion 1112a with the multi-layer structure to the first current collecting member 40 can not only reduce the risk of false welding, but also increase the welding area of the first tab 1112 and the first current collecting member 40, thereby improving the overcurrent capacity.

[0238] In some embodiments, in the axial direction Z, the first current collecting member 40 is located on the side of the first laminated portion 1112a facing the first electrode lead-out portion 7a.

[0239] In some embodiments, the first current collecting member 40, the first current collecting member 40, and the first electrode lead-out portion 7a are made of the same material.

[0240] In some embodiments, the first tab 1112 is wound in the winding direction V and forms a plurality of winding turns, and the end of at least part of the winding turns is bent towards the middle and forms the first laminated portion 1112a.

[0241] In some embodiments, the end region of the first tab 1112 away from the first coating area 1111 is bent by a rubbing process or a smoothing process, and forms the first laminated portion 1112a.

[0242] In some embodiments, the first electrode lead-out portion 7a includes an electrode terminal 30 which is insulatedly arranged on the shell 20, at least part of the electrode terminal 30 protrudes from the wall of the shell 20; and the first tab 1112 is electrically connected to the electrode terminal 30.

[0243] As an example, the wall can be an end wall 211 of the shell 21, or can be an end cover 22.

[0244] The at least partial protrusion of the electrode terminal 30 facilitates the connection of the electrode terminal 30 with the external busbar component, increases the exposed area of the electrode terminal 30, and improves the heat dissipation efficiency of the electrode terminal 30, thereby reducing the temperature rise of the first tab 1112 and improving the cycle performance of the cylindrical battery cell 7.

[0245] In some embodiments, the thermal conductivity of the electrode terminal 30 is greater than that of the shell 20. The electrode terminal 30 is electrically connected to the first tab 1112, and the electrode terminal 30 has better heat conduction capacity than the shell 20. Therefore, the electrode terminal 30 can quickly conduct the heat of the first tab 1112 out, thereby slowing down the temperature rise of the first tab 1112, reducing the thermal impact on the first film layer 112, and improving the cycle performance of the cylindrical battery cell 7.

[0246] In some embodiments, the thermal conductivity of the electrode terminal 30 is greater than or equal to 100 W / (m·K).

[0247] In some embodiments, the first tab 11 is a positive tab, and the first current collector 111 is made of aluminum or aluminum alloy. Aluminum and aluminum alloy have good electrical conductivity and thermal conductivity. The use of the aluminum first current collector 111 can reduce impedance, reduce heat generation, and improve the cycle performance of the cylindrical battery cell 7.

[0248] In some embodiments, the first current collector 111 is an aluminum foil.

[0249] In some embodiments, the electrode terminal 30 is made of aluminum or aluminum alloy.

[0250] In some embodiments, the first current collecting member 40 is made of aluminum or aluminum alloy.

[0251] In some embodiments, the second tab 12 includes a second current collector 121 and a second film layer 122. The second current collector 121 includes a second coated area 1211 and a second tab 1212. The surface of the second coated area 1211 is coated with the second film layer 122. The second tab 1212 extends from one end of the second coated area 1211 along the axial direction Z, and the surface of the second tab 1212 is not coated with the second film layer 122. In the axial direction Z, the first tab 1112 and the second tab 1212 are respectively located at two ends of the electrode assembly 10. The cylindrical battery cell 7 includes a second electrode lead-out portion 7b, and the second tab 1212 is electrically connected to the second electrode lead-out portion 7b.

[0252] The first tab 1112 and the second tab 1212 are respectively arranged at two ends of the electrode assembly 10, which provides more space for the first tab 1112 and the second tab 1212, so that the first tab 1112 and the second tab 1212 can have a larger length, improve the overcurrent capacity, reduce the impedance, and improve the cycle performance of the cylindrical battery cell 7.

[0253] In some embodiments, along the winding direction V, the length of the second coating area 1211 is L3, and the length of the connection position of the second tab 1212 and the second coating area 1211 is L4. 0.8≤L4 / L3≤1.

[0254] As an example, along the winding direction V, the length of the second film layer 122 is equal to the length of the second coating area 1211.

[0255] As an example, after the second tab 12 is flattened, both the second film layer 122 and the second coating area 1211 can be rectangular; after the second tab 12 is flattened, L3 can be equal to the length of the second coating area 1211, and L4 can be equal to the length of the connection position of the second tab 1212 and the second coating area 1211.

[0256] In the second tab 12, one surface of the second coating area 1211 can be coated with the second film layer 122, or both surfaces of the second coating area 1211 can be coated with the second film layer 122. Both surfaces of the second tab 1212 are not coated with the second film layer 122.

[0257] As an example, L4 / L3 is 0.8, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, or 1.

[0258] Along the winding direction V, the second tab 1212 can be a continuous structure or a discontinuous structure.

[0259] The embodiments of the present application limit L4 / L3 to be greater than or equal to 0.8, which can increase the flow area of the connection position of the second coating area 1211 and the second tab 1212, reduce the impedance, reduce the heat generation of the connection position of the second coating area 1211 and the second tab 1212, thereby reducing the temperature rise of the second current collector 121 and the second film layer 122, reducing the risk of ion (e.g., lithium ion) precipitation, improving the cycle performance of the cylindrical battery cell 7, reducing the risk of thermal runaway, and improving the reliability of the cylindrical battery cell 7. The embodiments of the present application limit L4 / L3 to be less than or equal to 1, which can reduce the redundancy of the second tab 1212, save space, and reduce the impact of lengthening the second tab 1212 on the energy density of the cylindrical battery cell 7.

[0260] In some embodiments, 0.95≤L4 / L3≤1, which can balance the cycle performance and energy density of the cylindrical battery cell 7 to some extent.

[0261] In some embodiments, 3000 mm ≤ L3 ≤ 9000 mm. As an example, L3 is 3000 mm, 3500 mm, 4000 mm, 4500 mm, 5000 mm, 5500 mm, 6000 mm, 6500 mm, 7000 mm, 7500 mm, 8000 mm, 8500 mm, or 9000 mm.

[0262] In some embodiments, 2400 mm ≤ L4 ≤ 9000 mm. As an example, L4 is 2400 mm, 2700 mm, 3000 mm, 3500 mm, 4000 mm, 4500 mm, 5000 mm, 5500 mm, 6000 mm, 6500 mm, 7000 mm, 7500 mm, 8000 mm, 8500 mm, or 9000 mm.

[0263] In some embodiments, the first tab 11 is a positive tab, and the second tab 12 is a negative tab. As an example, L3 is greater than L0, and the second film layer 122 is capable of providing an intercalation space for ions to be extracted from the first film layer 112, thereby reducing the risk of ion precipitation and improving the cycle performance and reliability of the cylindrical battery cell 7.

[0264] In some embodiments, the first tab 11 is a positive tab, and the second tab 12 is a negative tab. The first current collector 111 is made of aluminum, and the second current collector 121 is made of copper.

[0265] In some embodiments, the thickness T1 of the first coated area 1111 is greater than the thickness T3 of the second coated area 1211, and the thickness T4 of the first tab 1112 is greater than the thickness T5 of the second tab 1212.

[0266] Because the electrical conductivity of copper is higher than that of aluminum, setting the thickness of the aluminum first coated area 1111 to be greater than the thickness of the copper second coated area 1211 can reduce the difference in electrical conductivity between the first coated area 1111 and the second coated area 1211, improve current uniformity, reduce the temperature difference between the first coated area 1111 and the second coated area 1211, and improve the cycle performance of the cylindrical battery cell 7.

[0267] Similarly, setting the thickness of the aluminum first tab 1112 to be greater than the thickness of the copper second tab 1212 can reduce the difference in electrical conductivity between the first tab 1112 and the second tab 1212, improve current uniformity, reduce the temperature difference between the first tab 1112 and the second tab 1212, and improve the cycle performance of the cylindrical battery cell 7.

[0268] In some embodiments, t1 = t2, and t3 = t4.

[0269] In some embodiments, L1xt1>L4xt2. The thermal conductivity and electrical conductivity of copper are superior to that of aluminum. By setting the overcurrent area of the connection position of the first tab 1112 and the first coated area 1111 to be greater than the overcurrent area of the connection position of the second tab and the second coated area 1211, the temperature difference between the first current collector 111 and the second current collector 121 can be reduced.

[0270] In some embodiments, the melting point of the shell 20 is greater than or equal to 1050°C. Illustratively, the melting point of the shell 20 refers to the melting point under standard atmospheric pressure.

[0271] When the cylindrical battery cell 7 is in thermal runaway, a large amount of heat and gas will be generated inside the electrode assembly 10, which can be discharged through the pressure relief mechanism of the cylindrical battery cell 7. The first tab 1112 has a relatively large length, which will slow down the discharge of heat and gas to some extent, so that the temperature inside the cylindrical battery cell 7 is relatively high; the shell 20 has a relatively high melting point, which can withstand a relatively high temperature. By using a shell 20 with a high melting point, the risk of the shell 20 being melted through can be reduced, directional pressure relief of the cylindrical battery cell 7 can be achieved, and the risk of heat spreading can be reduced.

[0272] In some embodiments, the melting point of the shell 20 is greater than or equal to 1300°C, which can be greater than or equal to 1400°C.

[0273] In some embodiments, the tensile strength of the shell 20 is greater than or equal to 300MPa. As an example, the tensile strength of the shell 20 is 400MPa-1000MPa.

[0274] As an example, the tensile strength of the shell 20 can be measured in accordance with GB / T 228.1-2010 "Metallic Materials-Tensile Testing-Part 1: Method of Test at Room Temperature".

[0275] When the cylindrical battery cell 7 is in thermal runaway, a large amount of heat and gas will be generated inside the electrode assembly 10, which can be discharged through the pressure relief mechanism of the cylindrical battery cell 7. The first tab 1112 has a relatively large length, which will slow down the discharge of heat and gas to some extent, so that the pressure inside the cylindrical battery cell 7 is relatively high; by using a shell 20 with a relatively high tensile strength, the risk of the shell 20 being cracked can be reduced, directional pressure relief of the cylindrical battery cell 7 can be achieved, and the risk of heat spreading can be reduced.

[0276] In some embodiments, the shell 20 is a steel shell.

[0277] As an example, the shell 21 can be made of steel with a high melting point and high strength, such as low-carbon steel, medium-carbon steel, or stainless steel.

[0278] As an example, the end cover 22 can be made of steel with a high melting point and high strength, such as low-carbon steel, medium-carbon steel, or stainless steel.

[0279] The steel shell has a high melting point and strength, and is not easy to break when the cylindrical battery cell 7 is in thermal runaway, thereby improving the reliability of the cylindrical battery cell 7. During the cycle process of the cylindrical battery cell 7, the electrode assembly 10 will swell; the steel shell has high strength and is less deformed under the swelling force of the electrode assembly 10, so the steel shell can effectively limit the deformation of the electrode assembly 10.

[0280] Figure 13 A schematic view of the first pole piece of the cylindrical battery cell in a flattened state is provided for other embodiments of the present application.

[0281] Referring to Figure 13 In some embodiments, L1 < L0. The length of the first tab 1112 can be reduced to save the space and weight occupied by the first tab 1112 and improve the energy density of the cylindrical battery cell 7, on the premise that the overcurrent capacity of the connection position of the first tab 1112 and the first coated area 1111 meets the requirements.

[0282] In some embodiments, L1 / L0 is 0.8-0.98, which can be 0.90-0.95.

[0283] Figure 14 A schematic view of the first pole piece of the cylindrical battery cell in a flattened state is provided for other embodiments of the present application.

[0284] Referring to Figure 14 In some embodiments, L1 = L0.

[0285] In some embodiments, the first tab 1112 includes a transition portion 1112b and a connection portion 1112c, and the transition portion 1112b connects the first coated area 1111 and the connection portion 1112c; in the winding direction V, the length of the transition portion 1112b is greater than the length of the connection portion 1112c, and at least one end of the transition portion 1112b exceeds the connection portion 1112c.

[0286] Exemplarily, the length of the connection position of the transition portion 1112b and the first coated area 1111 in the winding direction V is L1; alternatively, the length of the transition portion 1112b in the winding direction V is equal to L1.

[0287] In some embodiments, in the axial direction Z, the end of the transition portion 1112b away from the first coated area 1111 does not exceed the separator 13.

[0288] In some embodiments, at least one end of the first tab 1112 is provided with a notch in the winding direction V to reduce the length of the connection portion 1112c in the winding direction V.

[0289] In some embodiments, the minimum length of the connecting portion 1112c along the winding direction V is greater than or equal to 0.8 x L1.

[0290] In some embodiments, the connecting portion 1112c is connected to the first current collecting member 40.

[0291] In some embodiments, the connecting portion 1112c is bent and forms a first stacking portion at an end away from the transition portion 1112b.

[0292] In some embodiments, both ends of the transition portion 1112b extend beyond the connecting portion 1112c along the winding direction V.

[0293] In some embodiments, the connecting portion 1112c is provided with a notch J at both sides along the winding direction V.

[0294] After the electrode assembly 10 is wound and formed, the middle part generally has a central hole. The central hole can serve as a passage for electrolyte flow, thereby improving the electrolyte's infiltration effect on the electrode assembly 10.

[0295] Providing the notch J at the inner side of the connecting portion 1112c can make the connecting portion 1112c be arranged outwardly, thereby reducing the risk of the connecting portion 1112c blocking the central hole during bending. Providing the notch J at the outer side of the connecting portion 1112c can reduce the risk of the sharp corner at the tail end of the connecting portion 1112c piercing other components.

[0296] In some embodiments, after the first tab 1112 is flattened, the connecting portion 1112c is trapezoidal; the length of the connecting portion 1112c gradually decreases in the direction away from the transition portion 1112b.

[0297] Figure 15 A schematic view of a first electrode tab of a cylindrical battery cell in a flattened state according to another embodiment of the present application.

[0298] Referring to Figure 15 In some embodiments, the first tab 1112 includes a transition portion 1112b and a plurality of first sub-tabs 1112d arranged at intervals along the winding direction V, the transition portion 1112b is connected to the first coating area 1111, the first sub-tabs 1112d are connected to an end of the transition portion 1112b away from the first coating area 1111, and the connection position of the transition portion 1112b to the first coating area 1111 is arranged continuously along the winding direction V.

[0299] The plurality of first sub-tab 1112d can be bent inwardly along the radial direction of the cylindrical battery cell 7 when under pressure, so that the bent portions of some of the first sub-tab 1112d are stacked in the axial direction Z and form a multi-layer structure. The multi-layer structure can improve the overcurrent capacity, reduce the impedance, reduce the heat generation, and improve the cycle performance of the cylindrical battery cell 7. The plurality of first sub-tab 1112d are unconstrained with respect to each other in the winding direction V, which facilitates the directional bending of the first sub-tab 1112d and helps to improve the morphology of the multi-layer structure.

[0300] In some embodiments, along the winding direction V, the sum of the lengths of the connection positions of the plurality of first sub-tab 1112d to the transition portion 1112b is L2, and the length of the connection position of the transition portion 1112b to the first coating area 1111 is L1. L2 and L1 satisfy: 0.6≤L2 / L1≤0.95.

[0301] Exemplarily, the length of the connection position of each first sub-tab 1112d to the transition portion 1112b is L21; the lengths L21 of the connection positions of the plurality of first sub-tab 1112d to the transition portion 1112b can be the same or different. In some examples, the lengths L21 of the connection positions of the plurality of first sub-tab 1112d to the transition portion 1112b are the same; in other examples, the lengths L21 of the connection positions of the plurality of first sub-tab 1112d to the transition portion 1112b gradually increase along the winding direction V.

[0302] Exemplarily, L2 / L1 is 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, or 0.95.

[0303] The embodiments of the present application limit L2 / L1 to 0.6-0.95, which can increase the overcurrent area of the connection position of the first sub-tab 1112d and the transition portion 1112b, reduce the impedance, reduce the heat generation of the connection position of the first sub-tab 1112d and the transition portion 1112b, thereby reducing the temperature rise of the first current collector 111 and the first film layer 112, reducing the risk of ion (e.g., lithium ion) precipitation, improving the cycle performance of the cylindrical battery cell 7, reducing the risk of thermal runaway, and improving the reliability of the cylindrical battery cell 7. Limiting L2 / L1 to less than or equal to 0.95 can reduce the difficulty of bending the first sub-tab 1112d and reduce the risk of tearing the first sub-tab 1112d, which helps to improve the morphology of the first tab 1112.

[0304] In some embodiments, L1=L0.

[0305] In some embodiments, the first sub-tab 1112d can be formed by a die-cutting process.

[0306] In some embodiments, the sum of the minimum dimensions of the plurality of first sub-tab 1112d along the winding direction V is greater than or equal to 0.8 x L1.

[0307] In some embodiments, after the first tab 1112 is flattened, the first sub-tab 1112d is trapezoidal and the transition portion 1112b is rectangular.

[0308] Figure 16 A schematic view of a first tab of a cylindrical battery cell in a flattened state is provided for some other embodiments of the present application.

[0309] Referring to Figure 16 In some embodiments, the first tab 1112 includes a plurality of tab segments 1112e, which are spaced apart along the winding direction V.

[0310] Exemplarily, the length of the connection position of each tab segment 1112e with the first coating region 1111 is L5. The lengths L5 of the plurality of tab segments 1112e can be the same or different.

[0311] The sum of the lengths of the connection positions of the plurality of tab segments 1112e with the first coating region 1111 is L1.

[0312] Figure 17 A cross-sectional schematic view of an electrode assembly of a cylindrical battery cell is provided for some embodiments of the present application. Figure 18 For Figure 17 An enlarged schematic view at the dashed box; Figure 19 A schematic view of a separator of an electrode assembly of a cylindrical battery cell is provided for some embodiments of the present application.

[0313] Referring to Figure 5 , Figures 17 to 19 In some embodiments, the electrode assembly 10 further includes a separator 13, which is wound along the winding direction V and separates the first tab 11 and the second tab 12. The separator 13 includes a base 131 having two first surfaces 131a oppositely arranged along the thickness direction thereof and a plurality of support portions 132 protruding from at least one first surface 131a to form a gap G between the first tab 11 and the second tab 12.

[0314] As an example, the plurality of support portions 132 are dispersedly arranged on the first surface 131a.

[0315] In some examples, one first surface 131a of the base 131 is provided with the plurality of support portions 132, which can be the first surface 131a of the base 131 inwardly along the radial direction of the cylindrical battery cell or the first surface 131a of the base 131 outwardly along the radial direction of the cylindrical battery cell.

[0316] In some examples, the two first surfaces 131a of the base 131 are each provided with a plurality of support portions 132.

[0317] As an example, the first film layer of the first electrode tab 11 can be in contact with the support portions 132 of the portion of the separator 13, and / or the second film layer of the second electrode tab 12 can be in contact with the support portions 132 of the portion of the separator 13.

[0318] As an example, the gap G can be a space between the first electrode tab 11 and the second electrode tab 12 that is not filled by the separator 13.

[0319] The support portions 132 can be rigid or flexible.

[0320] In the embodiments of the present application, the cylindrical battery cell has a high capacity; as the capacity increases, the electrode assembly 10 will generate a greater swelling force when charging. During the cycling process of the cylindrical battery cell 7, the gap G can provide space for the swelling of the electrode tabs, reduce the pressure between the first electrode tab 11 and the second electrode tab 12, thereby reducing the compression of the electrolyte in the internal pores of the first film layer and the internal pores of the second film layer, reducing the concentration difference of the electrolyte in different regions of the electrode tabs, and improving the cycling performance of the cylindrical battery cell 7 with a large capacity. The gap G can reduce the swelling amount of the electrode assembly 10, thereby reducing the compression of the shell 20, reducing the risk of deformation and cracking of the shell 20, and improving the reliability of the cylindrical battery cell 7. By providing the gap G, the increase in the swelling force caused by increasing the capacity of the cylindrical battery cell 7 can be reduced.

[0321] The gap G can also accommodate electrolyte to improve the wettability of the electrolyte on the first electrode tab and the second electrode tab, and improve the cycling performance of the cylindrical battery cell.

[0322] In addition, when ion precipitation occurs in the negative electrode tab during the cycling process, such as lithium precipitation, the gap G can provide space for the deformation of the separator 13, so that the separator 13 can release the pressure exerted by the lithium dendrites through deformation, thereby to some extent avoiding the separator 13 being pierced, reducing the risk of short circuit, and improving the reliability.

[0323] In some embodiments, the negative active material includes a carbon-based material. The carbon-based material has high cycling stability, which can improve the cycling performance of the cylindrical battery cell.

[0324] In some embodiments, the support portion 132 is configured to be compressible. During the cycling of the cylindrical battery cell 7, the support portion 132 can be compressed when pressed, thereby providing more expansion space for the electrode tab. The compressible support portion 132 can release stress by deforming under compression, to reduce the risk of the first electrode tab 11 or the second electrode tab 12 being pressed by the support portion 132, improving reliability.

[0325] In some embodiments, the plurality of support portions 132 includes a first support portion 132a and a second support portion 132b, the first support portion 132a protruding from the first surface 131a by a height H1 greater than a height H2 by which the second support portion 132b protrudes from the first surface 131a.

[0326] The first support portion 132a can be one or more. The second support portion 132b can be one or more. Alternatively, both the first support portion 132a and the second support portion 132b are a plurality.

[0327] The first support portion 132a has a greater height, which can support the first electrode tab 11 or the second electrode tab 12 to form a larger gap G, thereby providing more space for the expansion of the electrode tab. The second support portion 132b has a smaller height, which occupies less space. As the electrode tab expands, the gap G gradually decreases; the second support portion 132b can be pressed after the electrode tab expands to a certain extent, which can reduce the pressure on the electrode tab in the early stage of expansion. When the second support portion 132b is pressed, the second support portion 132b can slow down the expansion of the electrode tab to some extent, reduce the electrolyte squeezed out by the electrode tab, and improve the cycling performance of the cylindrical battery cell 7.

[0328] In some embodiments, the first support portion 132a is a plurality, and the second support portion 132b is a plurality.

[0329] In some embodiments, the height of the first support portion 132a is 1.1 to 15 times, and optionally 2 to 7 times, the height of the second support portion 132b.

[0330] In some embodiments, the support portion 132 includes organic particles P disposed on the base portion 131.

[0331] The support portion 132 is a plurality, and correspondingly, the organic particles P are a plurality.

[0332] The organic particles P can protrude from the base portion 131 as a whole. Alternatively, part of the organic particles is embedded in the base portion 131, and the other part protrudes from the base portion 131.

[0333] The organic particles P can play a supporting role to form the gap G. When the cylindrical battery cell 7 undergoes thermal runaway, the organic particles P can form a gel film structure at high temperature, thereby reducing the diffusion channel of active ions, delaying the time of thermal spread, and thus improving the reliability of the cylindrical battery cell 7.

[0334] Exemplarily, the organic particles P can be formed on the separator 13 by coating. The support portion 132 formed by coating the organic particles P can simplify the forming process.

[0335] In some embodiments, the plurality of organic particles P includes first organic particles P1 and second organic particles P2, and the number average particle size of the first organic particles P1 is greater than the number average particle size of the second organic particles P2.

[0336] It should be noted that the number average particle size of the organic particles is the arithmetic mean of the particle size of the organic particles counted by the number of the organic particles. The particle size of the organic particles can refer to the distance between the two most distant points on the organic particles.

[0337] The first organic particles P1 with a larger number average particle size can support the first or second electrode tab 11 or 12 to form a larger gap G, thereby providing more space for the expansion of the electrode tab. The second organic particles P2 with a smaller number average particle size can be compressed after the electrode tab expands to a certain extent, which can reduce the pressure on the electrode tab in the initial stage of expansion. When the second organic particles P2 are compressed, the second organic particles P2 can slow down the expansion of the electrode tab to a certain extent, reduce the electrolyte squeezed out by the electrode tab, and improve the cycle performance of the cylindrical battery cell 7.

[0338] In some embodiments, the plurality of support portions 132 includes first support portions 132a and second support portions 132b, and the height of the first support portions 132a protruding from the first surface 131a is greater than the height of the second support portions 132b protruding from the first surface 131a. The plurality of organic particles P includes first organic particles P1 and second organic particles P2; the first support portions 132a include the first organic particles P1, and the second support portions 132b include the second organic particles P2.

[0339] By setting the first organic particles P1 and the second organic particles P2 with different number average particle sizes, the first support portions 132a and the second support portions 132b with different heights can be formed. The first support portions 132a have a larger height, which can support the first or second electrode tab 11 or 12 to form a larger gap G, thereby providing more space for the expansion of the electrode tab. The second support portions 132b can be compressed after the electrode tab expands to a certain extent, which can reduce the pressure on the electrode tab in the initial stage of expansion. When the second support portions 132b are compressed, the second support portions 132b can slow down the expansion of the electrode tab to a certain extent, reduce the electrolyte squeezed out by the electrode tab, and improve the cycle performance of the cylindrical battery cell 7.

[0340] In some embodiments, the first organic particles P1 have a number average particle diameter of > 10 pm, and the second organic particles P2 have a number average particle diameter of 2 pm to 10 pm.

[0341] In some embodiments, the first organic particles P1 have a number average particle diameter of 12 pm to 25 pm. For example, the first organic particles P1 can have a number average particle diameter of 12 pm, 13 pm, 15 pm, 16 pm, 18 pm, 20 pm, 21 pm, 22 pm, 24 pm, or 25 pm.

[0342] In some embodiments, the second organic particles P2 have a number average particle diameter of 2 pm to 9 pm. For example, the first organic particles P1 can have a number average particle diameter of 2 pm, 2.5 pm, 3 pm, 4 pm, 5 pm, 5.5 pm, 6 pm, 7 pm, 8 pm, or 9 pm.

[0343] In some embodiments, the ratio of the number average particle diameter of the first organic particles P1 to the number average particle diameter of the second organic particles P2 is greater than or equal to 1.5.

[0344] In some embodiments, the first organic particles P1 are secondary particles.

[0345] In some embodiments, the second organic particles P2 are primary particles.

[0346] It should be noted that primary particles and secondary particles have meanings known in the art. Primary particles refer to particles that have not formed an agglomerated state. Secondary particles refer to agglomerated particles formed by the aggregation of two or more primary particles.

[0347] In some embodiments, the plurality of organic particles P includes first organic particles P1 that include one or more of a homopolymer or copolymer of a fluorine-containing alkenyl monomer unit, a homopolymer or copolymer of an alkenyl monomer unit, a homopolymer or copolymer of an unsaturated nitrile monomer unit, a homopolymer or copolymer of an alkylene oxide monomer unit, and a modified compound of each of the above homopolymers or copolymers.

[0348] In some embodiments, the fluorine-containing alkenyl monomer unit can be selected from one or more of difluoroethylene, vinylidene fluoride, trifluoroethylene, chlorotrifluoroethylene, tetrafluoroethylene, hexafluoropropylene.

[0349] In some embodiments, the alkenyl monomer unit can be selected from one or more of ethylene, propylene, butadiene, isoprene, and the like.

[0350] In some embodiments, the unsaturated nitrile monomer unit can be selected from one or more of acrylonitrile, methacrylonitrile, and the like.

[0351] In some embodiments, the alkylene oxide monomer units can be selected from one or more of ethylene oxide, propylene oxide, and the like.

[0352] In some embodiments, the first organic particles P1 include one or more of polytetrafluoroethylene, polychlorotrifluoroethylene, polyfluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyacrylonitrile, polyethylene oxide, copolymers of different fluorine-containing alkenyl monomer units, copolymers of fluorine-containing alkenyl monomer units and olefin-based monomer units, copolymers of fluorine-containing alkenyl monomer units and acrylic monomer units, copolymers of fluorine-containing alkenyl monomer units and acrylate monomer units, and modified compounds of each of the above homopolymers or copolymers.

[0353] In some embodiments, the first organic particles P1 can include one or more of a vinylidene fluoride-trifluoroethylene copolymer, a vinylidene fluoride-hexafluoropropylene copolymer, a vinylidene fluoride-trifluoroethylene-hexafluoropropylene copolymer, a vinylidene fluoride-hexafluoropropylene-acrylic acid copolymer, a vinylidene fluoride-hexafluoropropylene-acrylate copolymer, and modified compounds of the above copolymers.

[0354] In some embodiments, the plurality of organic particles P includes second organic particles P2 including one or more of a homopolymer or copolymer of acrylate monomer units, a homopolymer or copolymer of acrylic monomer units, a homopolymer or copolymer of styrene monomer units, a polyurethane-based compound, a rubber-based compound, and modified compounds of each of the above homopolymers or copolymers.

[0355] In some embodiments, the second organic particles P2 include one or more of a copolymer of acrylate monomer units and styrene monomer units, a copolymer of acrylic monomer units and styrene monomer units, a copolymer of acrylic monomer units-acrylate monomer units-styrene monomer units, a copolymer of styrene monomer units and unsaturated nitrile monomer units, a copolymer of styrene monomer units-olefin-based monomer units-unsaturated nitrile monomer units, and modified compounds of the above copolymers.

[0356] In some embodiments, the acrylate monomer units can be selected from one or more of methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, methyl methacrylate, butyl methacrylate, isooctyl methacrylate, and the like.

[0357] In some embodiments, the acrylic monomer units can be selected from one or more of acrylic acid, methacrylic acid, and the like.

[0358] In some embodiments, the styrene monomer units can be selected from one or more of styrene, methylstyrene, and the like.

[0359] In some embodiments, the unsaturated nitrile monomer units can be selected from one or more of acrylonitrile, methacrylonitrile, and the like.

[0360] In some embodiments, the second organic particles P2 can include one or more of butyl acrylate-styrene copolymer, butyl methacrylate-isooctyl methacrylate copolymer, isooctyl methacrylate-styrene copolymer, methacrylate-methacrylic acid-styrene copolymer, methyl acrylate-isooctyl methacrylate-styrene copolymer, butyl acrylate-isooctyl acrylate-styrene copolymer, butyl acrylate-isooctyl methacrylate-styrene copolymer, butyl methacrylate-isooctyl acrylate-styrene copolymer, butyl methacrylate-isooctyl methacrylate-styrene copolymer, styrene-acrylonitrile copolymer, styrene-butadiene-acrylonitrile copolymer, methyl acrylate-styrene-acrylonitrile copolymer, isooctyl methacrylate-styrene-acrylonitrile copolymer, styrene-vinyl acetate copolymer, styrene-vinyl acetate-pyrrolidone copolymer, and modified compounds of each of the above materials.

[0361] In some embodiments, the base 131 includes a base film 1311 and an inorganic particle layer 1312 disposed on the base film 1311, and the organic particles P at least partially protrude from the inorganic particle layer 1312.

[0362] The inorganic particle layer 1312 includes a plurality of inorganic particles, and sufficient and unevenly distributed voids are formed between the inorganic particles and the organic particles, which can improve the air permeability of the separator, and the cylindrical battery cell has better cycle performance and reliability.

[0363] In some embodiments, the inorganic particles can be coated on the base film 1311 first to form the inorganic particle layer 1312, and then the plurality of organic particles can be coated on the inorganic particle layer 1312. In other embodiments, the inorganic particles and the organic particles can be mixed together and then coated on the base film 1311.

[0364] In some examples, one surface of the base film 1311 is coated with a coating layer including the inorganic particle layer 1312 and the plurality of organic particles P, and the other surface of the base film 1311 can be uncoated or coated with the inorganic particle layer 1312. In other examples, both surfaces of the base film 1311 are coated with a coating layer including the inorganic particle layer 1312 and the organic particles P.

[0365] Sufficient and unevenly distributed voids are formed between the inorganic particles and the organic particles P, which can improve the air permeability of the separator 13, and the cylindrical battery cell 7 has better cycle performance and reliability. The organic particles P can support the first electrode sheet 11 or the second electrode sheet 12 to increase the gap G and provide space for the expansion of the electrode sheet.

[0366] In some embodiments, the inorganic particles can include one or more of boehmite (γ-AlOOH), aluminum oxide (Al2O3), barium sulfate (BaSO4), magnesium oxide (MgO), magnesium hydroxide (Mg(OH)2), silicon dioxide (SiO2), tin dioxide (SnO2), titanium oxide (TiO2), calcium oxide (CaO), zinc oxide (ZnO), zirconium oxide (ZrO2), yttrium oxide (Y2O3), nickel oxide (NiO), cerium oxide (CeO2), zirconium titanate (SrTiO3), barium titanate (BaTiO3), magnesium fluoride (MgF2).

[0367] In some embodiments, the volume average particle size Dv50 of the inorganic particles is ≤ 2.5 μm; for example, the particle size of the inorganic particles can be 0.5 μm-2.5 μm, 1.5 μm-2.5 μm, 0.3 μm-0.7 μm, etc.

[0368] In some embodiments, the surface of the base film 1311 facing the first electrode tab 11 is coated with a coating layer comprising the inorganic particle layer 1312 and a plurality of organic particles P, and / or, the surface of the base film 1311 facing the second electrode tab 12 is coated with a coating layer comprising the inorganic particle layer 1312 and a plurality of organic particles P.

[0369] In some embodiments, the gap G extends along the winding direction V of the electrode assembly 10, and the gap G has a winding starting end E1 and a winding ending end E2.

[0370] The gap G is wound into multiple turns along the winding direction V.

[0371] As an example, the first electrode tab 11 has a first winding starting end E3 and a first winding ending end E4, and the second electrode tab 12 has a second winding starting end E5 and a second winding ending end E6.

[0372] In some embodiments, the first electrode tab 11 is a positive electrode tab, and the second electrode tab 12 is a negative electrode tab. Along the winding direction V, the second winding ending end E6 exceeds the first winding ending end E4; along the opposite direction of the winding direction V, the second winding starting end E5 exceeds the first winding starting end E3. The second electrode tab 12 exceeds the first electrode tab 11 at both ends along the winding direction V, and the second electrode tab 12 can provide an insertion space for the active ions that are stripped out of the first electrode tab 11, thereby reducing the risk of ion stripping. In the radial direction of the cylindrical battery cell, the winding starting end E1 of the gap G corresponds to the first winding starting end E3, and the winding ending end E2 of the gap G corresponds to the first winding ending end E4.

[0373] In some embodiments, the radial dimension of at least part of the gap G is 5 μm-60 μm.

[0374] As an example, the radial dimension of the gap G can be the dimension of the gap G along the radial direction of the cylindrical battery cell. The radial dimensions W of the gap G at different positions can be the same or different.

[0375] Optionally, the radial dimension W of each part of the gap G is 5-60 μm.

[0376] Optionally, the radial dimension W of the gap G can be 5 μm, 6 μm, 8 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm or a range defined by any two of the above values.

[0377] As an example, the radial dimension of the gap G can be measured in the following way:

[0378] Discharge the cylindrical battery cell to the lower limit cut-off voltage (for example, 2.5 V);

[0379] Use CT (Computed Tomography) technology to obtain an image of the cross section of the electrode assembly using X-rays, the cross section being perpendicular to the axial direction of the cylindrical battery cell;

[0380] Based on the image, measure the distance D1 between the outer surface of the first electrode sheet of the 6th layer and the inner surface of the first electrode sheet of the 10th layer in the radial direction of the electrode assembly;

[0381] Disassemble the cylindrical battery cell and measure the thickness t1 of the first electrode sheet, the thickness t2 of the second electrode sheet and the thickness t3 of the separator.

[0382] There are 3 layers of first electrode sheets, 4 layers of second electrode sheets and 8 layers of separators between the outer surface of the first electrode sheet of the 6th layer and the inner surface of the first electrode sheet of the 10th layer, forming 8 layers of gaps between the outer surface of the first electrode sheet of the 6th layer and the inner surface of the first electrode sheet of the 10th layer. W = (D1-3xt1-4xt2-8xt3) / 8.

[0383] It is explained herein that the thickness t3 is measured at the part of the separator where no support part is provided, i.e. the thickness t3 is the thickness of the base part of the separator.

[0384] The embodiments of the present application limit the radial dimension W of the gap G to be greater than or equal to 5 μm, which provides space for the expansion of the electrode sheets, reduces the expansion force, improves the cycle performance of the cylindrical battery cell 7 and reduces the risk of deformation and cracking of the shell 20. The embodiments of the present application limit the radial dimension W of the gap G to be less than or equal to 50 μm, which shortens the ion migration path between the first electrode sheet 11 and the second electrode sheet 12, reduces the internal resistance of the cylindrical battery cell 7, reduces heat generation and reduces the impact of the gap G on the energy density.

[0385] Figure 20 A partial cross-sectional view of an electrode assembly of a cylindrical battery cell according to some embodiments of the present application. Figure 21 A schematic view of a separator of an electrode assembly of a cylindrical battery cell according to some embodiments of the present application.

[0386] Referring to Figure 20 and Figure 21 In some embodiments, the separator 13 is provided with a plurality of support portions 132 on both sides thereof. The gap G includes a first gap G1 formed between the first electrode tab 11 and the separator 13, and a second gap G2 formed between the second electrode tab 12 and the separator 13.

[0387] As an example, the first gap G1 has a radial dimension W1, and the second gap G2 has a radial dimension W2. The radial dimension W of the gap G is W1+W2.

[0388] In the thickness direction of the separator 13, the support portions 132 on both sides of the separator 13 can or can not overlap.

[0389] By providing a plurality of support portions 132 on both sides of the separator 13, the gap G can be increased, providing more space for the expansion of the electrode tab.

[0390] In some embodiments, the base film 1311 is provided with a coating layer containing inorganic particles 1312 and a plurality of organic particles P on both sides thereof.

[0391] Figure 22 A partial cross-sectional view of an electrode assembly of a cylindrical battery cell according to some embodiments of the present application. Figure 17 A circle of first electrode tabs, a circle of second electrode tabs, and a circle of separators are shown.

[0392] Referring to Figure 17 and Figure 22 In some embodiments, the radial dimension of the portion of the gap G near the winding start end E1 is greater than or equal to the radial dimension of the portion of the gap G near the winding end E2.

[0393] In embodiments of the present application, the radial dimensions of different portions of the gap G along the winding direction V are compared in the same cross-section perpendicular to the axial direction Z.

[0394] The "portion of the gap G near the winding start end E1" does not require that it extends from the winding start end E1. As an example, the "portion of the gap G near the winding start end E1" can extend from a position 1-5 turns away from the winding start end E1 in the winding direction V.

[0395] The portion of the gap G near the winding end E2 does not require extending to the winding end E2 along the winding direction V. As an example, the tail end of the portion of the gap G near the winding end E2 along the winding direction V can be 1-5 windings away from the winding end E2.

[0396] In embodiments of the present application, the portion of the gap G near the winding start E1 has a larger radial dimension to provide more expansion space for the jellyroll 10 middle section electrode tabs, reduce the risk of jellyroll 10 middle section collapse due to expansion, and improve the cycle performance of the cylindrical battery cell 7.

[0397] In some embodiments, the gap G extends along the winding direction V and is wound into n windings, each winding defined as a winding turn, and n≥20. The average of the radial dimensions of the 5th-9th winding turns is greater than the average of the radial dimensions of the n-9th to n-5th winding turns.

[0398] It is explained that n does not require being an integer, in other words, the 1st to n-1th winding turns are each an integer winding turn; the portion from the end of the n-1th winding turn to the winding end E2 can or can not be an integer winding turn, for example, 1 / 4 winding turn, 1 / 2 winding turn, or 3 / 4 winding turn.

[0399] In embodiments of the present application, the portion of the gap G near the winding start E1 has a larger radial dimension to provide more expansion space for the jellyroll 10 middle section electrode tabs, reduce the risk of jellyroll 10 middle section collapse due to expansion, and improve the cycle performance of the cylindrical battery cell 7.

[0400] In some embodiments, the radial dimension of at least part of the gap G gradually decreases along the winding direction V. The gradual change of the radial dimension of the gap G reduces the abrupt change of the radial dimension of the gap G, reduces the stress concentration of the second electrode tab 12, and improves the cycle performance of the cylindrical battery cell 7.

[0401] Figure 23 Partial cross-sectional views of electrode assemblies of cylindrical battery cells provided for other embodiments of the present application.

[0402] Reference is made to Figure 23 In some embodiments, the gap G includes a middle region C1 and two end regions C2 arranged along the axial direction Z, the middle region C1 is located between the two end regions C2, and the radial dimension of the middle region C1 is smaller than the radial dimension of the end region C2.

[0403] In embodiments of the present application, the radial dimension of the middle region C1 and the radial dimension of the end region C2 are compared in a cross section of a winding turn parallel to the axial direction Z.

[0404] The gap G has a first end E7 and a second end E8 arranged opposite along the axial direction Z; a dimension of the gap G along the axial direction Z is defined as L, that is, a distance between the first end E7 and the second end E8 along the axial direction Z is K.

[0405] The end region C2 is a region having a dimension along the axial direction Z. One end region C2 is a region extending to a length K1 from the first end E7 toward the second end E8, and the other end region C2 is a region extending to the length K1 from the second end E8 toward the first end E7; the middle region C1 includes a region extending to a length K2 from the middle section S toward the first end E7 and a region extending to the length K2 from the middle section S toward the second end E8. The middle section S is a section perpendicular to the axial direction Z; along the axial direction Z, a distance between the middle section S and the first end E7 is equal to a distance between the middle section S and the second end E8.

[0406] Exemplarily, K1 / K is 0.1-0.3, and can be 0.2. Exemplarily, K2 / K is 0.03-0.2, and can be 0.1.

[0407] Exemplarily, K1 can be 20 mm, and K2 can be 5 mm.

[0408] Exemplarily, a minimum radial dimension of the end region C2 is greater than a maximum radial dimension of the middle region C1.

[0409] In the embodiments of the present application, the end region C2 has a larger radial dimension, so as to facilitate the electrolyte to enter the gap G, improve the wettability of the electrolyte to the electrode sheet, and improve the cycle performance of the cylindrical battery cell 7.

[0410] In some embodiments, the radial dimension of the middle region is 5 μm-60 μm, and can be 10 μm-30 μm.

[0411] In some embodiments, the gap G further includes a transition region C3 connecting the middle region C1 and the end region C2.

[0412] In some embodiments, in a direction from the end region C2 to the middle region C1, the radial dimension of the gap G gradually decreases, so as to reduce the sudden change of the radial dimension of the gap G, reduce the stress concentration of the second electrode sheet 12, and improve the cycle performance of the cylindrical battery cell 7.

[0413] In some embodiments, in the radial direction of the cylindrical battery cell, a part of the plurality of support portions 132 is located between the first tab 1112 and the base 131.

[0414] The first tab 1112 generates heat when current passes through, and the support portion 132 can separate at least part of the first tab 1112 from the base portion 131, thereby reducing heat conduction to the base portion 131, reducing deformation of the base portion 131 due to high temperature, reducing the risk of conduction of the first and second tabs, and improving the reliability of the cylindrical battery cell.

[0415] In some embodiments, in the radial direction of the cylindrical battery cell, part of the plurality of support portions 132 is located between the second tab and the base portion 131.

[0416] Figure 24 A cross-sectional view of a cylindrical battery cell is provided for some embodiments of the present application; Figure 25 For Figure 24 An enlarged schematic view at the circular frame.

[0417] Referring to Figure 24 And Figure 25 In some embodiments, the shell 20 includes a housing 21 and an end cover 22, the housing 21 includes an integrally formed side wall 212 and an end wall 211, the side wall 212 surrounds the electrode assembly 10, the end wall 211 and the end cover 22 are opposite along the axial direction Z of the cylindrical battery cell 7, and the end cover 22 is sealingly connected to the side wall 212.

[0418] The end cover 22 can be insulated from the side wall 212 or can be electrically connected.

[0419] The housing 21 has an opening at an end away from the end wall 211, and the end cover 22 covers the opening of the housing 21.

[0420] In some embodiments, the first tab 1112 is included in the first tab 1112, and the second tab 1212 is included in the second tab 1212. The first electrode lead-out portion 7a includes an electrode terminal 30 insulated from the end wall 211, the first tab 1112 is electrically connected to the electrode terminal 30, and the second tab 1212 is electrically connected to the end wall 211.

[0421] As an example, the second tab 1212 is indirectly connected to the end wall 211 by the end cover 22, the side wall 212, or other components.

[0422] As an example, the end wall 211 can be the second electrode lead-out portion 7b.

[0423] The electrode terminal 30 and the end wall 211 can be two exposed electrodes of the cylindrical battery cell 7, and the electrode terminal 30 and the end wall 211 are located on the same side, which is conducive to assembling a plurality of cylindrical battery cells 7 into a group and simplifying the battery structure.

[0424] In some embodiments, the cylindrical battery cell 7 further comprises a first current collecting member 40 located on the side of the first tab 1112 facing the end wall 211 and connected to the first tab 1112. The electrode terminal 30 abuts against and is connected to the surface of the first current collecting member 40 facing the end wall 211.

[0425] The first current collecting member 40 can serve as an adapter to realize the electrical connection between the first tab 1112 and the electrode terminal 30.

[0426] In some embodiments, the first current collecting member 40 is in the shape of a circular ring.

[0427] In some embodiments, the side of the electrode terminal 30 facing away from the first current collecting member 40 is provided with a terminal recess 31. The bottom wall of the terminal recess 31 is welded to the first current collecting member 40.

[0428] By providing the terminal recess 31, the thickness of the bottom wall of the terminal recess 31 can be reduced, the power required for welding the electrode terminal 30 and the first current collecting member 40 from the outside can be reduced, the risk of particles generated by welding falling into the housing 20 can be reduced, and the reliability of the cylindrical battery cell 7 can be improved.

[0429] In some embodiments, the side of the terminal recess 31 facing the first current collecting member 40 is provided with a terminal recess 31, and the bottom wall of the terminal recess 31 is welded to the first current collecting member 40.

[0430] By providing the terminal recess 31, the thickness of the bottom wall of the terminal recess 31 can be reduced, the power required for welding the electrode terminal 30 and the first current collecting member 40 from the outside can be reduced, the risk of particles generated by welding falling into the housing 20 can be reduced, and the reliability of the cylindrical battery cell 7 can be improved. By providing the terminal recess 31 on the inner side of the electrode terminal 30, the internal space of the cylindrical battery cell 7 can also be increased.

[0431] In some embodiments, the side of the electrode terminal 30 facing the first current collecting member 40 is provided with one terminal recess 31, and the side of the electrode terminal 30 facing away from the first current collecting member 40 is provided with another terminal recess 31; the bottom surfaces of the two terminal recesses 31 are welded to the first current collecting member 40 at corresponding positions.

[0432] In some embodiments, the bottom wall of the terminal recess 31 is provided with a through hole 32, which can be used for injecting electrolyte.

[0433] In some embodiments, the cylindrical battery cell 7 further comprises a cover plate 50 connected to the electrode terminal 30 and used to separate the through hole 32 from the external space of the cylindrical battery cell 7.

[0434] In some embodiments, at least part of the cover plate 50 is accommodated in the terminal recess 31. In some embodiments, the first electrode lead-out portion 7a includes the cover plate 50 and the electrode terminal 30.

[0435] In some embodiments, the electrode terminal 30 is riveted to the end wall 211.

[0436] In some embodiments, the first tab 1112 is located at an end of the first tab 11 facing the end wall 211, and the second tab 1212 is located at an end of the second tab 12 facing the end cover 22. The cylindrical battery cell 7 further includes a second current collecting member 60 connected to the second tab 1212; the second current collecting member 60 is connected to at least one of the end cover 22 and the side wall 212.

[0437] In some examples, the second current collecting member 60 is connected to the end cover 22, and the end cover 22 is electrically connected to the side wall 212. The second tab 1212 is electrically connected to the end wall 211 through the second current collecting member 60, the end cover 22, and the side wall 212. Optionally, the end cover 22 is welded to the side wall 212.

[0438] In other examples, the second current collecting member 60 is connected to the side wall 212. The second tab 1212 is electrically connected to the end wall 211 through the second current collecting member 60 and the side wall 212. Optionally, the end cover 22 is insulated from the side wall 212.

[0439] In some embodiments, the height of the shell 20 is 1.3 to 4 times the diameter of the shell 20.

[0440] Exemplarily, the height of the shell 20 can be the dimension of the shell 20 along the axial direction Z.

[0441] Optionally, the height of the shell 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 shell 20.

[0442] When the shell 20 satisfies the above size requirements, the structural stability of the shell 20 can be higher, and the use reliability of the cylindrical battery cell 7 can be improved.

[0443] In some embodiments, the height of the shell 20 is 1.5 to 2.5 times the diameter of the shell 20.

[0444] In some embodiments, the height of the shell 20 is 50mm to 150mm. For example, the height of the shell 20 is 50mm, 55mm, 60mm, 65mm, 70mm, 75mm, 80mm, 85mm, 90mm, 95mm, 100mm, 105mm, 110mm, 115mm, 120mm, 125mm, 130mm, 135mm, 140mm, 145mm or 150mm.

[0445] Optionally, the height of the shell 20 is 60mm-100mm.

[0446] The shell 20 has a large height to improve the capacity of the cylindrical battery cell 7.

[0447] In some embodiments, the diameter of the shell 20 is 45mm to 80mm. For example, the diameter of the shell 20 is 45mm, 50mm, 55mm, 60mm, 65mm, 70mm, 75mm or 80mm.

[0448] Optionally, the diameter of the shell 20 is 45mm to 60mm.

[0449] The shell 20 has a large diameter to improve the capacity of the cylindrical battery cell 7.

[0450] Figure 26 A partial cross-sectional view of a cylindrical battery cell is provided for some other embodiments of the present application.

[0451] Referring to Figure 26 In some embodiments, the side wall 212 is provided with a protrusion 2121 protruding inwardly. In the axial direction Z, at least part of the protrusion 2121 is located between the end cover 22 and the second tab 1212.

[0452] Exemplarily, the protrusion 2121 can be a solid structure or a hollow structure.

[0453] The protrusion 2121 overlaps with the second tab 1212 in the axial direction Z, which can limit the movement of the second tab 1212 in the axial direction Z when the cylindrical battery cell 7 is subjected to external impact, and reduce the risk of disconnection of the second tab 1212 from the second current collecting member 60.

[0454] In some embodiments, the second current collecting member 60 is connected to the protrusion 2121. Exemplarily, the second current collecting member 60 can be welded to the protrusion 2121; alternatively, the second current collecting member 60 can also be crimped to the protrusion 2121.

[0455] Exemplarily, the second current collecting member 60 is connected to the side of the protrusion 2121 facing the second tab 1212, or to the side of the protrusion 2121 facing the end cover 22.

[0456] Connecting the second current collecting member 60 to the protrusion 2121 can shorten the conductive path between the second tab 1212 and the end wall 211, reduce the resistance, reduce the heat generation, and improve the cycle performance of the cylindrical battery cell 7.

[0457] In some embodiments, a portion of the second current collecting member 60 is located on the side of the protrusion 2121 facing the end cover 22 and is connected to the protrusion 2121. The second current collecting member 60 is connected to the protrusion 2121 from the outside of the protrusion 2121, which can reduce the assembly difficulty.

[0458] In some embodiments, the second current collecting member 60 is welded to the protrusion 2121.

[0459] In some embodiments, the outer side of the side wall 212 is provided with a recess 2123, and the recess 2123 is in position correspondence with the protrusion 2121. As an example, after the electrode assembly is installed into the shell, the protrusion 2121 is formed by extruding the side wall 212 from the outside.

[0460] In some embodiments, the side wall 212 further includes a crimping portion 2122, which extends from one end of the protrusion 2121 away from the end wall and is arranged around the end cover 22.

[0461] A portion of the crimping portion 2122 is arranged in a bent manner and forms a flange structure, and a portion of the end cover 22 is located between the flange structure and the protrusion 2121 in the axial direction Z. The protrusion 2121 and the flange structure can limit the end cover 22 to achieve the fixation of the end cover 22 in the axial direction Z.

[0462] In some embodiments, the cylindrical battery cell 7 further includes an insulating member 70 arranged between the side wall 212 and the end cover 22 and insulating the end cover 22 from the side wall 212.

[0463] In some embodiments, a portion of the insulating member 70 is located between the second current collecting member 60 and the end cover 22 to insulate the second current collecting member 60 from the end cover 22.

[0464] According to some embodiments of the present application, the present application also provides a battery including a plurality of cylindrical battery cells 7 of any of the above embodiments.

[0465] According to some embodiments of the present application, the present application also provides an electric device including the cylindrical battery cell 7 of any of the above embodiments, which is used to provide electric energy for the electric device. The electric device can be any of the devices or systems mentioned above which can use the cylindrical battery cell 7.

[0466] Reference Figures 4 to 12The cylindrical battery cell 7 has a capacity greater than or equal to 20 Ah. The cylindrical battery cell 7 includes a housing 20, an electrode assembly 10, an electrode terminal 30, a first current collecting member 40, and a second current collecting member 60.

[0467] The housing 20 includes a shell 21 and an end cap 22. The shell 21 includes an integrally formed side wall 212 and an end wall 211. The end wall 211 and the end cap 22 are opposite along an axial direction Z of the cylindrical battery cell 7. The end cap 22 is welded to the side wall 212.

[0468] The electrode terminal 30 is insulatively disposed on the end wall 211. The electrode assembly 10 is accommodated in the housing 20.

[0469] The electrode assembly 10 includes a first electrode tab 11, a second electrode tab 12, and a separator 13 for separating the first electrode tab 11 and the second electrode tab 12. The first electrode tab 11, the separator 13, and the second electrode tab 12 are wound in a winding direction V.

[0470] The first electrode tab 11 includes a first current collector 111 and a first film layer 112. The first current collector 111 includes a first coated region 1111 and a first tab 1112. The first coated region 1111 has a surface coated with the first film layer 112. The first tab 1112 extends from the first coated region 1111 in one end of the axial direction Z of the cylindrical battery cell 7. The first tab 1112 has a surface not coated with the first film layer 112.

[0471] The second electrode tab 12 includes a second current collector 121 and a second film layer 122. The second current collector 121 includes a second coated region 1211 and a second tab 1212. The second coated region 1211 has a surface coated with the second film layer 122. The second tab 1212 extends from the second coated region 1211 in one end of the axial direction Z of the cylindrical battery cell 7. The second tab 1212 has a surface not coated with the second film layer 122.

[0472] The first tab 1112 and the second tab 1212 are respectively located at both ends of the electrode assembly 10 in the axial direction Z. The first current collecting member 40 is welded to the electrode terminal 30 and the first tab 1112, respectively. The second current collecting member 60 is welded to the second tab 1212 and electrically connected to the end wall 211.

[0473] In the winding direction V, the length of a connection position of the first tab 1112 to the first coated region 1111 is L1, and the length of the first coated region 1111 is L0. 0.8≤L1 / L0≤1.

[0474] In the winding direction V, the length of a connection position of the second tab 1212 to the second coated region 1211 is L4, and the length of the second coated region 1211 is L3. 0.8≤L4 / L3≤1.

[0475] 4500mm ≤ L0≤ 7000mm, 4500mm ≤ L3≤ 7000mm.

[0476] Embodiments

[0477] The embodiments disclosed herein are described more particularly below with reference to the following examples, which are merely illustrative and are not intended to be limiting on the scope of the embodiments disclosed herein. Unless otherwise indicated, all parts, percentages, and ratios reported herein are based on mass, and all reagents used in the examples are commercially available or synthesized according to conventional methods and used without further purification, and the instruments used in the examples are commercially available.

[0478] Example 1

[0479] 1. Preparation of the positive electrode sheet

[0480] The positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer, the positive electrode film layer is located on both sides of the positive electrode current collector, the positive electrode current collector is an aluminum foil, and the positive electrode film layer is a film layer formed by uniformly coating a positive electrode slurry (the solvent is N-methyl pyrrolidone NMP) on the surface of the positive electrode current collector aluminum foil, and then drying and cold pressing, the positive electrode film layer comprises positive electrode active material, conductive agent carbon black (Super P), and binder polyvinylidene fluoride (PVDF) in a weight ratio of 97:1:2.

[0481] The positive electrode active material comprises a layered transition metal oxide with a molecular formula of LiNi 0.9 Co 0.05 Mn 0.05 O2.

[0482] The positive electrode current collector comprises a positive electrode coating area coated with the positive electrode film layer and a positive electrode tab not coated with the positive electrode film layer, the length LX0 of the positive electrode coating area is 5100 mm, and the length LX1 of the connection position of the positive electrode tab and the positive electrode coating area is 5100 mm.

[0483] 2. Preparation of the negative electrode sheet

[0484] The negative electrode sheet comprises a negative electrode current collector and a negative electrode film layer, the negative electrode film layer is located on both sides of the negative electrode current collector, the negative electrode current collector is a copper foil, and the negative electrode film layer is a film layer formed by uniformly coating a negative electrode slurry (the solvent is deionized water) on the surface of the negative electrode current collector copper foil, and then drying and cold pressing, the negative electrode film layer comprises silicon-based material (specifically silicon carbide), graphite, conductive agent carbon black, conductive agent carbon nanotube, and binder polyacrylic acid in a weight ratio of 4.6:90.4:1.9:0.1:3.

[0485] The negative current collector comprises a negative coating area coated with a negative film layer and a negative tab without the negative film layer; the length LX3 of the negative coating area is 5250 mm, and the length LX4 of the connection position of the negative tab and the negative coating area is 5250 mm.

[0486] 3. Preparation of the spacer

[0487] A PE (polyethylene) base film is provided, and the thickness of the base film is 7 μm.

[0488] 4. Preparation of the electrolyte

[0489] The electrolyte comprises an organic solvent and a lithium salt; the organic solvent is obtained by mixing ethylene carbonate (EC), methyl ethyl carbonate (EMC) and diethyl carbonate (DEC) in a volume ratio of 1:1:1, and then the fully dried lithium salt LiPF6 is dissolved in the mixed organic solvent to prepare the electrolyte with a lithium salt concentration of 1 mol / L.

[0490] 5. Preparation of the cylindrical battery cell

[0491] The above positive sheet, the spacer and the negative sheet are stacked in sequence, and the spacer is arranged between the positive sheet and the negative sheet to play a role of isolation; the positive sheet, the spacer and the negative sheet are wound to obtain an electrode assembly; the positive tab and the negative tab are subjected to rubbing treatment; the electrode assembly is placed in a cylindrical shell, and after drying, the electrolyte is injected; and after vacuum packaging, standing, formation and shaping, a cylindrical battery cell is obtained.

[0492] The electrode assembly has a cylindrical structure, and the shell has a cylindrical structure; the diameter of the cylindrical battery cell is 46 mm, and the height is 95 mm.

[0493] Example 2

[0494] The battery cell is prepared by using a method similar to that of Example 1, and the length of the connection position of the positive tab and the positive coating area is adjusted to 4845 mm.

[0495] Example 3

[0496] The battery cell is prepared by using a method similar to that of Example 1, and the length of the connection position of the positive tab and the positive coating area is adjusted to 4080 mm.

[0497] Example 4

[0498] The battery cell is prepared by using a method similar to that of Example 1, and the length of the connection position of the negative tab and the negative coating area is adjusted to 4200 mm.

[0499] Example 5

[0500] A battery cell was prepared in a similar manner to Example 1, except that the length of the connection position of the positive tab and the positive coating area was adjusted to 4080 mm, and the length of the connection position of the negative tab and the negative coating area was adjusted to 3675 mm.

[0501] Example 6

[0502] A battery cell was prepared in a similar manner to Example 1, except that the length of the connection position of the positive tab and the positive coating area was adjusted to 3570 mm, and the length of the connection position of the negative tab and the negative coating area was adjusted to 4200 mm.

[0503] Example 7

[0504] A battery cell was prepared in a similar manner to Example 1, except that the length of the connection position of the positive tab and the positive coating area was adjusted to 4080 mm, and the length of the connection position of the negative tab and the negative coating area was adjusted to 3675 mm.

[0505] Comparative Example 1

[0506] A battery cell was prepared in a similar manner to Example 1, except that the length of the connection position of the positive tab and the positive coating area was adjusted to 3060 mm, and the length of the connection position of the negative tab and the negative coating area was adjusted to 3150 mm.

[0507] Performance test

[0508] 1. First week discharge capacity test

[0509] The cylindrical battery cell of each example and comparative example was tested in the following manner, respectively.

[0510] Fresh cylindrical battery cell was charged to 4.25 V at 0.33 C constant current at 25 °C, and then continued to charge at 4.25 V constant voltage until the charge current decayed to 0.05 C, and then rested for 30 min; then discharged to 2.5 V at 0.33 C constant current, and the first week discharge capacity was recorded, in units of Ah.

[0511] 2. Cycle test of cylindrical battery cell

[0512] The cylindrical battery cell of each example and comparative example was tested in the following manner, respectively.

[0513] The cylindrical battery cell prepared above was charged at 25 °C to 4.25 V at 0.5 C and discharged to 2.5 V at 0.5 C, which was one charge-discharge cycle, and the first discharge capacity was recorded as Co; the above charge-discharge cycle steps were repeated until the cycle capacity retention rate (i.e., the discharge capacity decayed to 80% of Co) was 80%, and the cycle number was recorded. The more the cycle number, the better the cycle performance of the cylindrical battery cell.

[0514] 3. Lithium precipitation area test of cylindrical battery cell

[0515] The cylindrical battery cell of each example and comparative example was tested in the following manner, respectively.

[0516] After the cylindrical battery cell was cycled for 50 cycles according to the following charge-discharge strategy, the negative electrode sheet in the cylindrical battery cell was disassembled, unfolded, and the lithium precipitation area (gray-white area) was observed and the lithium precipitation area was measured, and the lithium precipitation degree was as follows:

[0517] No lithium precipitation: lithium precipitation area < 0.05%.

[0518] Mild lithium precipitation: lithium precipitation area < 2%.

[0519] Severe lithium precipitation: lithium precipitation area > 2%.

[0520] The cylindrical battery cell was charged at an external environment temperature of 30 °C, and the charging steps included the following steps:

[0521] Charged from 0% SOC to 30% SOC at 3.0 C constant current;

[0522] Charged from 30% SOC to 35% SOC at 2.8 C constant current;

[0523] Charged from 35% SOC to 40% SOC at 2.6 C constant current;

[0524] Charged from 40% SOC to 45% SOC at 2.4 C constant current;

[0525] Charged from 45% SOC to 50% SOC at 2.2 C constant current;

[0526] Charged from 50% SOC to 55% SOC at 2.0 C constant current;

[0527] Charged from 55% SOC to 60% SOC at 1.8 C constant current;

[0528] Charged from 60% SOC to 65% SOC at 1.6 C constant current;

[0529] Charged from 65% SOC to 70% SOC at 1.4 C constant current;

[0530] Charge from 70% SOC to 75% SOC at 1.3C constant current;

[0531] Charge from 75% SOC to 80% SOC at 1.2C constant current;

[0532] Charge from 80% SOC to 85% SOC at 0.8C constant current;

[0533] Charge from 85% SOC to 90% SOC at 0.6C constant current;

[0534] Charge from 90% SOC to 95% SOC at 0.4C constant current;

[0535] Charge from 95% SOC to 98% SOC at 0.33C constant current;

[0536] Charge from 98% SOC to 100% SOC at 0.3C constant current.

[0537] The cut-off voltage of the last charging step in the above charging steps is 4.25V.

[0538] The discharge strategy is as follows: discharge to the cut-off voltage 2.5V at 0.33C constant current.

[0539] 4. DC internal resistance DCR test of cylindrical battery monomer

[0540] The method can be referred to in GB / T 31467 "Performance Test Specification for High Power Lithium Ion Power Battery for HEV".

[0541] For example, at 25℃, charge the cylindrical battery monomer to 4.25V at 0.33C constant current, and continue to charge at 4.25V constant voltage until the charging current decays to 0.05C, and stand for 30min; then discharge to 2.5V at 0.33C constant current, and record the discharge capacity A0, unit Ah; then charge the cylindrical battery monomer to 4.25V at 0.33C constant current, and charge at constant voltage to 0.05C, and stand for 30min; then discharge 0.5A0 at 0.33C constant current, so that the cylindrical battery monomer is at 50% SOC.

[0542] After the battery monomer is placed at 25℃ for 2h, discharge at a constant current of 2C for 10s, record ΔU discharge, ΔI discharge, and calculate the discharge DCR data of the cylindrical battery monomer through the following formula.

[0543] R discharge = ΔU discharge / ΔI discharge,

[0544] Wherein, ΔU discharge represents the voltage change within 10s of discharging start, and ΔI discharge represents the current value within 10s of discharging start.

[0545] In this specification, each example and each comparative example can prepare four identical cylindrical battery monomers, and four tests are respectively carried out.

[0546] The test results are shown in Table 1.

[0547] Table 1

[0548]

[0549] With reference to Examples 1-5, 7 and Comparative Example 1, limiting LX1 / LX0 to 0.8-1 can increase the flow area of the connection position of the positive electrode coating area and the positive electrode tab, reduce the direct current resistance, reduce the risk of lithium precipitation, improve the cycle performance of the cylindrical battery monomer, reduce the risk of thermal runaway, and improve the reliability of the cylindrical battery monomer.

[0550] With reference to Examples 1-6 and Comparative Example 1, limiting LX4 / LX3 to 0.8-1 can increase the flow area of the connection position of the negative electrode coating area and the negative electrode tab, reduce the direct current resistance, reduce the risk of lithium precipitation, improve the cycle performance of the cylindrical battery monomer, reduce the risk of thermal runaway, and improve the reliability of the cylindrical battery monomer.

[0551] With reference to Examples 1-5 and Comparative Example 1, limiting LX1 / LX0 to 0.8-1 and limiting LX4 / LX3 to 0.8-1 can further reduce the direct current resistance, reduce the risk of lithium precipitation, improve the cycle performance of the cylindrical battery monomer, reduce the risk of thermal runaway, and improve the reliability of the cylindrical battery monomer.

[0552] With reference to Example 1-7, the cylindrical battery monomer is not prone to lithium precipitation or has a relatively mild lithium precipitation during rapid charging. The cylindrical battery monomer of the present application has good rapid charging capacity.

[0553] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0554] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features, but these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A cylindrical battery cell, characterized by, The cylindrical battery cell has a capacity greater than or equal to 20 Ah, and includes a housing and an electrode assembly accommodated in the housing; The electrode assembly includes first and second polar plates of opposite polarity, which are wound in a winding direction, the first polar plate including a first current collector and a first film layer, the first current collector including a first coated region and a first tab, a surface of the first coated region being coated with the first film layer, the first tab extending from one end of the first coated region in an axial direction of the cylindrical battery cell, and a surface of the first tab being uncoated with the first film layer; The cylindrical battery cell includes a first electrode lead-out portion, and the first tab is electrically connected to the first electrode lead-out portion; In the winding direction, a length of a connection position of the first tab and the first coated region is L1, a length of the first coated region is L0, and 0.8≤L1 / L0≤1.

2. The cylindrical battery cell according to claim 1, characterized in that, 0.95≤L1 / L0≤1.

3. The cylindrical battery cell of claim 1, wherein, 3000mm≤L0≤9000mm.

4. The cylindrical battery cell of claim 1, wherein, 2400mm≤L1≤9000mm.

5. The cylindrical battery cell of claim 1, wherein, The thickness of the first tab is equal to the thickness of the first coated region.

6. The cylindrical battery cell of claim 1, wherein, A sum of the thickness of the first film layer and the thickness of the first coated region is D1, the thickness of the first coated region is T1, and 0.17≤T1 / D1≤0.

35.

7. The cylindrical battery cell of claim 6, wherein, 9μm≤T1≤17μm.

8. The cylindrical battery cell of claim 1, wherein, A sum of the thickness of the first film layer and the thickness of the first coated region is D1, the thickness of the first film layer is T2, and 0.67≤T2 / D1≤0.

81.

9. The cylindrical battery cell of claim 1, wherein, The cylindrical battery cell has a capacity of 25 Ah-50 Ah.

10. The cylindrical battery cell of claim 1, wherein, The connection position of the first tab and the first coated region is continuously provided in the winding direction.

11. The cylindrical battery cell of claim 10, wherein, The first tab is continuously provided in the winding direction as a whole.

12. The cylindrical battery cell of claim 10, wherein, The first tab includes a transition portion and a plurality of first sub-tabs which are spaced apart in the winding direction, the transition portion being connected to the first coated region, the first sub-tabs being connected to one end of the transition portion away from the first coated region, and the connection position of the transition portion and the first coated region being continuously provided in the winding direction.

13. The cylindrical battery cell of claim 12, wherein, In the winding direction, a sum of lengths of connection positions of the plurality of first sub-tabs and the transition portion is L2, and a length of the connection position of the transition portion and the first coated region is L1; L2 and L1 satisfy: 0.6≤L2 / L1≤0.

95.

14. The cylindrical battery cell of claim 1, wherein, One end of the first tab away from the first coated region is bent and forms a first layer-stacking portion, the first layer-stacking portion having a multi-layer structure in the axial direction of the cylindrical battery cell, and the first layer-stacking portion being electrically connected to the first electrode lead-out portion.

15. The cylindrical battery cell of claim 14, wherein, The cylindrical battery cell includes a first current collection member, which is at least partially located between the first layer-stacking portion and the first electrode lead-out portion, and is respectively welded to the first layer-stacking portion and the first electrode lead-out portion.

16. The cylindrical battery cell of claim 1, wherein, The first electrode lead-out portion includes an electrode terminal which is insulatively provided to the housing, at least a portion of the electrode terminal being protrudingly provided to a wall portion of the housing, and the first tab being electrically connected to the electrode terminal.

17. The cylindrical battery cell of claim 16, wherein, The thermal conductivity of the electrode terminal is greater than the thermal conductivity of the shell.

18. The cylindrical battery cell of claim 1, wherein, The first pole piece is a positive pole piece, and the material of the first current collector is aluminum or an aluminum alloy.

19. The cylindrical battery cell of any one of claims 1-18, wherein, The second pole piece comprises a second current collector and a second film layer, the second current collector comprises a second coated area and a second tab, the surface of the second coated area is coated with the second film layer, the second tab extends from one end of the second coated area along the axial direction, and the surface of the second tab is not coated with the second film layer. In the axial direction, the first tab and the second tab are respectively located at two ends of the electrode assembly; the cylindrical battery monomer comprises a second electrode lead-out part, and the second tab is electrically connected to the second electrode lead-out part.

20. The cylindrical battery cell of claim 19, wherein, In the winding direction, the length of the second coated area is L3, and the length of the connection position of the second tab and the second coated area is L4. 0.8≤L4 / L3≤1.

21. The cylindrical battery cell of claim 19, wherein, The first pole piece is a positive pole piece, and the second pole piece is a negative pole piece. The material of the first current collector is aluminum, and the material of the second current collector is copper.

22. The cylindrical battery cell of claim 21, wherein, The thickness of the first coated area is greater than the thickness of the second coated area, and the thickness of the first tab is greater than the thickness of the second tab.

23. The cylindrical battery cell of claim 1, wherein, The electrode assembly further comprises a separator, the separator is wound along the winding direction, and the first pole piece and the second pole piece are separated by the separator. The separator comprises a base and a plurality of support portions, the base has two first surfaces oppositely arranged along the thickness direction of the base, and the plurality of support portions are protruded from at least one of the first surfaces to form a gap between the first pole piece and the second pole piece.

24. The cylindrical battery cell of claim 23, wherein, The plurality of support portions comprise a first support portion and a second support portion, the height of the first support portion protruding from the first surface is greater than the height of the second support portion protruding from the first surface.

25. The cylindrical battery cell of claim 23, wherein, The support portion comprises organic particles arranged on the base.

26. The cylindrical battery cell of claim 25, wherein, The base comprises a base film and an inorganic particle layer arranged on the base film, and the organic particles at least partially protrude from the inorganic particle layer.

27. The cylindrical battery cell of claim 25, wherein, The plurality of organic particles comprise first organic particles and second organic particles, and the number average particle size of the first organic particles is greater than the number average particle size of the second organic particles.

28. The cylindrical battery cell of claim 25, wherein, The plurality of support portions comprise a first support portion and a second support portion, the height of the first support portion protruding from the first surface is greater than the height of the second support portion protruding from the first surface. The plurality of organic particles comprise first organic particles and second organic particles; the first support portion comprises the first organic particles, and the second support portion comprises the second organic particles.

29. The cylindrical battery cell of claim 23, wherein, The radial dimension of at least part of the gap is 5-60 μm.

30. The cylindrical battery cell of claim 23, wherein, Both sides of the separator are provided with a plurality of support portions. The gap comprises a first gap and a second gap, the first gap is formed between the first pole piece and the separator, and the second gap is formed between the second pole piece and the separator.

31. The cylindrical battery cell of claim 23, wherein, The gap extends along the winding direction, and the gap has a winding starting end and a winding ending end. The radial dimension of the part of the gap close to the winding starting end is greater than or equal to the radial dimension of the part of the gap close to the winding ending end.

32. The cylindrical battery cell of claim 23, wherein, A radial dimension of at least part of the gap gradually decreases along the winding direction.

33. The cylindrical battery cell of claim 23, wherein, The gap comprises a middle region and two end regions arranged along the axial direction, the middle region being located between the two end regions, and a radial dimension of the middle region is smaller than that of the end regions.

34. The cylindrical battery cell of claim 33, wherein, A radial dimension of the gap gradually decreases in a direction from the end region to the middle region.

35. The cylindrical battery cell of claim 23, wherein, In a radial direction of the cylindrical battery cell, a part of the plurality of support portions is located between the first tab and the base.

36. The cylindrical battery cell of claim 1, wherein, The shell has a melting point greater than or equal to 1050°C; and / or The shell has a tensile strength greater than or equal to 300 MPa.

37. The cylindrical battery cell of claim 1, wherein, The shell is a steel shell.

38. The cylindrical battery cell of claim 1, wherein, The shell comprises a shell body and an end cover, the shell body comprising an integrally formed side wall and an end wall, the side wall surrounding the electrode assembly, the end wall and the end cover being opposite along an axial direction of the cylindrical battery cell, and the end cover being sealingly connected to the side wall.

39. The cylindrical battery cell of claim 38, wherein, The second tab comprises a second tab; The first electrode lead-out portion comprises an electrode terminal insulatively provided on the end wall, the first tab being electrically connected to the electrode terminal, and the second tab being electrically connected to the end wall.

40. The cylindrical battery cell of claim 39, wherein, The cylindrical battery cell further comprises a first current collecting member, the first current collecting member being located on a side of the first tab facing the end wall and connected to the first tab. The electrode terminal abuts against and is connected to a surface of the first current collecting member facing the end wall.

41. The cylindrical battery cell of claim 40, wherein, The electrode terminal is provided with a terminal recess on a side facing the first current collecting member, and / or the electrode terminal is provided with a terminal recess on a side facing away from the first current collecting member. A bottom wall of the terminal recess is welded to the first current collecting member.

42. The cylindrical battery cell of any one of claims 39-41, wherein, The first tab is located at an end of the first tab facing the end wall, and the second tab is located at an end of the second tab facing the end cover. The cylindrical battery cell further comprises a second current collecting member connected to the second tab; and the second current collecting member is connected to at least one of the end cover and the side wall.

43. The cylindrical battery cell of claim 42, wherein, The side wall is provided with a protrusion protruding inwardly, at least part of the protrusion being located between the end cover and the second tab in the axial direction. The second current collecting member is connected to the protrusion.

44. The cylindrical battery cell of claim 43, wherein, A part of the second current collecting member is located on a side of the protrusion facing the end cover and connected to the protrusion.

45. The cylindrical battery cell of claim 1, wherein, A height of the shell is 1.3 to 4 times a diameter of the shell.

46. The cylindrical battery cell of claim 1, wherein, The height of the shell is 50 mm to 150 mm; and / or The diameter of the shell is 45 mm to 80 mm.

47. A battery, comprising: The battery cell according to any one of claims 1-46.

48. An electrical device, comprising: The battery according to claim 47 is used to provide electrical energy.

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