Cylindrical battery cell, battery device and power utilization device

Abstract

The utility model discloses a cylindrical battery monomer, a battery device and a power utilization device. The cylindrical battery cell includes a housing and an electrode assembly. The shell has an accommodating cavity. The electrode assembly is accommodated in the accommodating cavity. The electrode assembly comprises a positive plate, a negative plate and a separator, wherein the separator is used for separating the positive plate from the negative plate. The positive plate comprises a positive main body part provided with a positive active material layer; and the negative plate comprises a negative main body part provided with a negative active material layer. The electrode assembly has a cross section perpendicular to the axial direction, a virtual straight line extending in the radial direction of the cylindrical battery monomer is arranged in the cross section, the number of times that the virtual straight line intersects with the positive electrode main body part is N1, the number of times that the virtual straight line intersects with the negative electrode main body part is N2, and the number of times that the virtual straight line intersects with the separator is N3. The thickness of the positive electrode main body part is T1, the thickness of the negative electrode main body part is T2, and the thickness of the separator is T3. And the radial size of the accommodating cavity is D. 0.65 < = (N1 * T1 + N2 * T2 + N3 * T3) / D < = 0.95.

Description

Technical Field

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

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

[0003] As the demand for energy density increases, the diameter of cylindrical battery cells is gradually increasing. However, with the increase in the diameter of cylindrical battery cells, the expansion force during cycling also increases, and this expansion force affects the cycle performance of the cylindrical battery cells. How to improve the cycle performance of large-diameter cylindrical battery cells is an important research direction in the field of battery technology. Utility Model Content

[0004] This application provides a cylindrical battery cell, a battery device, and an electrical device that can improve cycle performance.

[0005] In a first aspect, this application provides a cylindrical battery cell, comprising a casing and an electrode assembly. The casing has a receiving cavity; the outer diameter of the casing is ≥40mm. The electrode assembly is received within the receiving cavity. The electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator, which are wound together, with the separator separating the positive and negative electrode sheets. The positive electrode sheet includes a positive electrode body portion and a positive electrode tab portion disposed along the axial direction of the cylindrical battery cell. At least a portion of the positive electrode body portion has a positive active material layer, and at least a portion of the positive electrode tab portion does not have a positive active material layer. The negative electrode sheet includes a negative electrode body portion and a negative electrode tab portion disposed along the axial direction. At least a portion of the negative electrode body portion has a negative active material layer, and at least a portion of the negative electrode tab portion does not have a negative active material layer. The electrode assembly has a cross-section perpendicular to the axial direction. Within this cross-section, there is a virtual straight line extending radially along the cylindrical battery cell. The virtual straight line intersects the positive electrode body N1 times, the negative electrode body N2 times, and the separator N3 times. The thickness of the positive electrode body is T1, the thickness of the negative electrode body is T2, and the thickness of the separator is T3. The radial dimension of the receiving cavity is D. 0.65≤(N1×T1+N2×T2+N3×T3) / D≤0.95.

[0006] Limiting (N1×T1+N2×T2+N3×T3) / D to less than or equal to 0.95 creates a gap between the positive and negative electrode substrates. During cycling of the cylindrical battery cell, this gap provides space for the expansion of the negative electrode active material layer, reducing the pressure between the positive and negative electrode substrates. This alleviates the compression of the electrolyte within the internal pores of both the positive and negative electrode active material layers, reducing electrolyte concentration differences across regions of the electrode and improving the cycling performance of cylindrical battery cells with larger diameters. The gap also reduces the expansion of the electrode assembly, thereby reducing the compression on the casing, lowering the risk of casing deformation and cracking, and improving the reliability of the cylindrical battery cell. Limiting (N1×T1+N2×T2+N3×T3) / D to greater than or equal to 0.65 shortens the ion migration path between the positive and negative electrode substrates, reduces the internal resistance of the cylindrical battery cell, decreases heat generation, and reduces the impact of the gap on energy density. In this embodiment, (N1×T1+N2×T2+N3×T3) / D is set to 0.65-0.95, which can balance the reliability and energy density of cylindrical battery cells to a certain extent.

[0007] In some embodiments, 0.70≤(N1×T1+N2×T2+N3×T3) / D≤0.90 can further balance the reliability and energy density of cylindrical battery cells and improve the cycle performance of cylindrical battery cells.

[0008] In some embodiments, N3 > N2 > N1. In the direction parallel to the virtual line, the negative electrode body has more layers than the positive electrode body. The negative electrode body can receive ions extracted from the positive electrode body, thereby reducing the risk of ion extraction and improving the reliability of the cylindrical battery cell. In the direction parallel to the virtual line, the separator has more layers to insulate the negative electrode body from the positive electrode body, reducing the risk of short circuits.

[0009] In some embodiments, 0.65 ≤ T1 / T2 ≤ 0.95. Given a fixed T1, limiting T1 / T2 to greater than or equal to 0.65 restricts the upper limit of the negative electrode body thickness, reducing the migration path of ions within the negative electrode body during charging and improving fast-charging and cycle performance. Given a fixed T1, limiting T1 / T2 to less than or equal to 0.95 restricts the lower limit of the negative electrode body thickness, reducing the compaction density of the negative electrode active material layer, decreasing the expansion of the negative electrode active material layer during charging, improving the cycle performance of the cylindrical battery cell, and reducing the risk of casing deformation and cracking.

[0010] In some embodiments, T1 is 80μm-150μm, T2 is 100μm-180μm, and T3 is 7μm-20μm.

[0011] In some embodiments, D is 35mm-80mm. The housing cavity has a large diameter, which provides more space for the electrode assembly and electrolyte, thereby increasing the capacity of the cylindrical battery cell.

[0012] In some embodiments, the electrode assembly has a central hole in the middle. The central hole provides space for the expansion of the negative electrode active material layer, thereby reducing the squeezing effect on the casing, reducing the risk of casing deformation and cracking, and improving the reliability of the cylindrical battery cell.

[0013] In some embodiments, a gap is provided between the positive electrode body portion and the negative electrode body portion.

[0014] During the cycling process of a cylindrical battery cell, the gap provides space for the expansion of the negative electrode active material layer, reducing the pressure between the positive and negative electrode main bodies. This alleviates the compression of the electrolyte within the internal pores of both the positive and negative electrode active material layers, reducing electrolyte concentration differences across different regions of the electrode and improving the cycling performance of cylindrical battery cells with larger diameters. The gap also reduces the expansion of the electrode assembly, thereby reducing the compression effect on the casing, lowering the risk of casing deformation and cracking, and improving the reliability of the cylindrical battery cell. By incorporating a gap, the increase in expansion force caused by increasing the diameter of the cylindrical battery cell can be reduced, thus increasing the capacity of the cylindrical battery cell.

[0015] In some embodiments, the gap includes a first gap and a second gap. The first gap is formed between the positive electrode body and the separator, and the second gap is formed between the negative electrode body and the separator. Both the first gap and the second gap can provide space for the expansion of the negative electrode active material layer, thereby reducing the squeezing effect on the casing, reducing the risk of casing deformation and cracking, and improving the reliability of the cylindrical battery cell.

[0016] In some embodiments, at least a portion of the gap has a radial dimension of 5 μm-60 μm.

[0017] Limiting the radial dimension W of the gap to greater than or equal to 5 μm provides space for the expansion of the negative electrode active material layer, reduces expansion force, improves the cycle performance of the cylindrical battery cell, and reduces the risk of casing deformation and cracking. In this embodiment, the radial dimension W of the gap is limited to less than or equal to 60 μm to shorten the ion migration path between the positive and negative electrode active material layers, reduce the internal resistance of the cylindrical battery cell, reduce heat generation, and minimize the impact of the gap on energy density.

[0018] In some embodiments, the gap extends along the winding direction of the electrode assembly and has a winding start end and a winding end.

[0019] In some embodiments, two gaps are provided, one on each side of the positive electrode body. By providing two gaps, the expansion of the electrode assembly can be further reduced, thereby reducing the squeezing effect on the casing, lowering the risk of casing deformation and cracking, and improving the reliability of the cylindrical battery cell.

[0020] In some embodiments, the radial dimension of the portion of the gap near the winding end is larger than the radial dimension of the portion of the gap near the winding start end. During the cycling process of the cylindrical battery cell, the expansion of the negative electrode body gradually accumulates radially from the inside to the outside; the portion of the gap near the winding end has a larger radial dimension to provide more expansion space for the negative electrode body, absorb the accumulated expansion of the negative electrode body, thereby reducing the interaction force between the electrode assembly and the casing, reducing the deformation of the casing, reducing the risk of casing cracking, and improving reliability.

[0021] In some embodiments, the gap is wound along the winding direction to form m windings, where m ≥ 20 and m is a natural number; the innermost winding is the first winding. The radial dimension of the k-th winding is smaller than the radial dimension of the (k+10)-th winding, where k is a natural number and 5 ≤ k ≤ m - 15. The (k+10)-th winding is positioned further outward than the k-th winding, and its radial dimension is larger than that of the k-th winding. The (k+10)-th winding can provide more expansion space for the inner negative electrode body, absorbing the accumulated expansion of the negative electrode body, thereby reducing the interaction force between the electrode assembly and the housing, reducing the deformation of the housing, reducing the risk of housing cracking, and improving reliability.

[0022] In some embodiments, the gap is wound along the winding direction to form m winding turns, where m ≥ 20, and m is a natural number. The innermost winding turn is the first winding turn. The average radial dimension of the (m-9)th to (m-5)th winding turns is greater than the average radial dimension of the 5th to 9th winding turns. The portion of the gap near the winding end has a larger radial dimension to provide more expansion space for the negative electrode body, absorb the accumulated expansion of the negative electrode body, thereby reducing the interaction force between the electrode assembly and the housing, reducing the deformation of the housing, reducing the risk of housing cracking, and improving reliability.

[0023] In some embodiments, the electrode assembly includes a central region and two end regions arranged axially along the cylindrical cell, with the central region located between the two end regions; the radial dimension of the portion of the gap located in the central region is smaller than the radial dimension of the portion of the gap located in the end regions. The gap has a larger radial dimension in the end regions to facilitate the entry of electrolyte into the gap, improve the electrolyte's wetting effect on the electrode, and enhance the cycle performance of the cylindrical cell.

[0024] In some embodiments, the radial dimension of the gap decreases in the direction from the two end regions to the middle region, so as to reduce the abrupt change in the radial dimension of the gap, reduce the stress concentration of the negative electrode, and improve the cycle performance of the cylindrical battery cell.

[0025] In some embodiments, the housing includes sidewalls surrounding the electrode assembly, the sidewalls being made of steel and having a thickness of 0.3 mm to 1.5 mm, optionally 0.3 mm to 1.2 mm. Limiting (N1×T1+N2×T2+N3×T3) / D to less than or equal to 0.95 reduces the expansion force exerted by the electrode assembly on the sidewalls; therefore, the steel sidewalls can have a thickness of less than or equal to 1.5 mm, thereby increasing the energy density of the cylindrical battery cell. A steel sidewall thickness greater than or equal to 0.3 mm reduces the risk of deformation and breakage of the sidewalls under the expansion force of the electrode assembly, improving the reliability of the cylindrical battery cell.

[0026] In some embodiments, the negative electrode active material layer includes a negative electrode active material, which includes a silicon-based material. The introduction of the silicon-based material can increase the capacity of the negative electrode active material and improve the energy density of the cylindrical battery cell. The gap formed between the positive electrode body and the negative electrode body provides space for the expansion of the silicon-based material, thereby reducing the influence of the silicon-based material on the expansion force.

[0027] In some embodiments, the silicon content of the silicon element in the negative electrode active material layer is 2% to 19% by mass, optionally 6% to 13%. Limiting the silicon content in the negative electrode active material layer to greater than or equal to 2% increases the capacity of the negative electrode sheet and improves the energy density of the cylindrical battery cell. The gap between the positive electrode body and the negative electrode body provides space for the expansion of the negative electrode active material layer, thereby reducing the influence of the silicon-based material on the expansion force. In this application embodiment, the silicon content in the negative electrode active material layer is limited to less than or equal to 19% by mass to limit the deformation of the cylindrical battery cell and improve its cycle performance.

[0028] In some embodiments, the areal density of the negative electrode is greater than or equal to 3.2 mAh / cm³. 2 The areal density of the negative electrode is related to its expansion. In this embodiment, by limiting (N1×T1+N2×T2+N3×T3) / D to 0.65-0.95, the influence of increasing the areal density of the negative electrode on the expansion force can be reduced, thereby increasing the capacity of the negative electrode and improving the energy density of the cylindrical battery cell.

[0029] In some embodiments, the areal density of the negative electrode is 3.3 mAh / cm³. 2 Up to 11.5mAh / cm 2This can balance the capacity and expansion of the negative electrode to a certain extent, while taking into account the energy density and cycle performance of the cylindrical battery cell.

[0030] In some embodiments, the areal density of the negative electrode is 3.96 mAh / cm³. 2 Up to 7.56mAh / cm 2 This can further balance the energy density and cycle performance of cylindrical battery cells.

[0031] In some embodiments, at least one of the positive electrode body portion, the negative electrode body portion, and the insulating member includes a base portion and a plurality of support portions, the support portions being protruding from the base portion.

[0032] Multiple protruding support portions support at least one of the positive and negative electrode main bodies, creating a gap between them. During cycling of the cylindrical battery cell, this gap provides space for the expansion of the negative electrode active material layer, reducing the pressure between the positive and negative electrode main bodies. This alleviates the compression of the electrolyte within the internal pores of both the positive and negative electrode active material layers, reducing electrolyte concentration differences across different regions of the electrode and improving the cycling performance of cylindrical battery cells with larger diameters. The gap also reduces the expansion of the electrode assembly, thereby reducing the compression on the casing, lowering the risk of casing deformation and cracking, and improving the reliability of the cylindrical battery cell.

[0033] In some embodiments, the support portion is configured to be compressible. During the cycling of the cylindrical battery cell, the support portion can be compressed under pressure, thereby providing more expansion space for the negative electrode body. The compressible support portion can release stress through compression deformation, reducing the risk of damage to the positive or negative electrode body by the support portion and improving reliability.

[0034] In some embodiments, the positive electrode body includes a base portion and a plurality of support portions. The base portion of the positive electrode body is a first base portion, and the plurality of support portions of the positive electrode body protrude from the first base portion. The plurality of support portions of the positive electrode body includes a first support portion and a second support portion. On the same side of the positive electrode body, the height of the first support portion protruding from the first base portion is greater than the height of the second support portion protruding from the first base portion.

[0035] The first support section has a greater height, which can support the negative electrode body to create a larger gap, thus providing more space for the expansion of the negative electrode body. The second support section is smaller in height and occupies less space. As the negative electrode body expands, the gap gradually decreases; the second support section can be compressed only after the negative electrode body has expanded to a certain extent, thus reducing the pressure on the negative electrode body in the initial stage of expansion. When the second support section is compressed, it can slow down the expansion of the negative electrode body to a certain extent, reduce the amount of electrolyte squeezed out, and improve the cycle performance of the cylindrical battery cell.

[0036] In some embodiments, the negative electrode body includes a base portion and a plurality of support portions. The base portion of the negative electrode body is a second base portion, and the plurality of support portions of the negative electrode body protrude from the second base portion. The plurality of support portions of the negative electrode body includes a third support portion and a fourth support portion. On the same side of the negative electrode body, the height of the third support portion protruding from the second base portion is greater than the height of the fourth support portion protruding from the second base portion.

[0037] The third support section has a greater height, which can support the positive electrode body to form a larger gap, thus providing more space for the expansion of the negative electrode body. The fourth support section is smaller in height and occupies less space. As the negative electrode body expands, the gap gradually decreases; the fourth support section can be compressed only after the negative electrode body has expanded to a certain extent, thus reducing the pressure on the negative electrode body in the initial stage of expansion. When the fourth support section is compressed, it can slow down the expansion of the negative electrode body to a certain extent, reduce the extruded electrolyte, and improve the cycle performance of the cylindrical battery cell.

[0038] In some embodiments, the isolation member includes a base portion and a plurality of support portions. The base portion of the isolation member is a third base portion, and the plurality of support portions of the isolation member protrude from the third base portion. The plurality of support portions of the isolation member include a fifth support portion and a sixth support portion. On the same side of the isolation member, the height of the fifth support portion protruding from the third base portion is greater than the height of the sixth support portion protruding from the third base portion.

[0039] The fifth support section has a relatively large height, which can support either the positive or negative electrode main body to create a larger gap, thus providing more space for the expansion of the negative electrode main body. The sixth support section is smaller in height and occupies less space. As the negative electrode main body expands, the gap gradually decreases; the sixth support section can be compressed only after the negative electrode main body has expanded to a certain extent, thus reducing the pressure on the negative electrode main body in the initial stage of expansion. When the sixth support section is compressed, it can slow down the expansion of the negative electrode main body to a certain extent, reduce the extruded electrolyte, and improve the cycle performance of the cylindrical battery cell.

[0040] In some embodiments, at least one of the positive electrode body, the negative electrode body, and the separator includes a plurality of organic particles. The support portion includes organic particles. The organic particles can act as supports to form gaps. In the event of thermal runaway in a cylindrical battery cell, the organic particles can form a gel film structure at high temperatures, thereby reducing the diffusion channels of active ions, delaying the time of heat propagation, and thus improving the reliability of the cylindrical battery cell.

[0041] In some embodiments, the plurality of organic particles include a first organic particle and a second organic particle, wherein the number-average particle size of the first organic particle is greater than the number-average particle size of the second organic particle.

[0042] The first organic particles, with a larger number-average particle size, can support the positive or negative electrode body to create larger gaps, thus providing more space for the expansion of the negative electrode body. The second organic particles, with a smaller number-average particle size, can be compressed after the negative electrode body has expanded to a certain extent, thereby reducing the pressure on the negative electrode body during the initial expansion phase. When the second organic particles are compressed, they can, to some extent, slow down the expansion of the negative electrode body, reduce the amount of electrolyte squeezed out, and improve the cycle performance of the cylindrical battery cell.

[0043] In some embodiments, the positive electrode body includes a base portion and a plurality of support portions. The base portion of the positive electrode body is a first base portion, and the plurality of support portions of the positive electrode body protrude from the first base portion. The plurality of support portions of the positive electrode body includes a first support portion and a second support portion. On the same side of the positive electrode body, the height of the first support portion protruding from the first base portion is greater than the height of the second support portion protruding from the first base portion. The plurality of organic particles include first organic particles and second organic particles. The first support portion includes the first organic particles, and the second support portion includes the second organic particles. By providing the first organic particles and the second organic particles, first support portions and second support portions with different heights can be formed.

[0044] In some embodiments, the negative electrode main body includes a base portion and a plurality of support portions. The base portion of the negative electrode main body is a second base portion, and the plurality of support portions of the negative electrode main body protrude from the second base portion. The plurality of support portions of the negative electrode main body includes a third support portion and a fourth support portion. On the same side of the negative electrode main body, the height of the third support portion protruding from the second base portion is greater than the height of the fourth support portion protruding from the second base portion. The plurality of organic particles include first organic particles and second organic particles. The third support portion includes the first organic particles, and the fourth support portion includes the second organic particles. By providing the first organic particles and the second organic particles, the third support portion and the fourth support portion can be formed with different heights.

[0045] In some embodiments, the spacer includes a base portion and a plurality of support portions. The base portion of the spacer is a third base portion, and the plurality of support portions of the spacer include a fifth support portion and a sixth support portion. On the same side of the spacer, the fifth support portion protrudes from the third base portion at a greater height than the sixth support portion protrudes from the third base portion. The plurality of organic particles include a first organic particle and a second organic particle. The fifth support portion includes the first organic particle, and the sixth support portion includes the second organic particle.

[0046] By incorporating first and second organic particles with different number-average particle sizes, fifth and sixth support sections with varying heights can be formed. The fifth support section has a greater height, enabling it to support either the positive or negative electrode main body and create a larger gap, thus providing more space for the expansion of the negative electrode main body. The sixth support section can be compressed only after the negative electrode main body has expanded to a certain extent, thereby reducing the pressure on the negative electrode main body during the initial expansion phase. When compressed, the sixth support section can, to some extent, slow down the expansion of the negative electrode main body, reduce the extruded electrolyte, and improve the cycle performance of the cylindrical battery cell.

[0047] In some embodiments, the plurality of organic particles include a first organic particle, the first organic particle comprising one or more of the following: a homopolymer or copolymer of fluorinated alkenyl monomer units, a homopolymer or copolymer of olefinic monomer units, a homopolymer or copolymer of unsaturated nitrile monomer units, a homopolymer or copolymer of epoxide monomer units, and a modified compound of the above homopolymers or copolymers.

[0048] In some embodiments, the first organic particle includes one or more of the following: polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride, polyethylene, polypropylene, polyacrylonitrile, polyethylene oxide, copolymers of different fluorinated alkenyl monomer units, copolymers of fluorinated alkenyl monomer units and olefin monomer units, copolymers of fluorinated alkenyl monomer units and acrylic monomer units, copolymers of fluorinated alkenyl monomer units and acrylate monomer units, and modified compounds of the above homopolymers or copolymers.

[0049] In some embodiments, the plurality of organic particles include second organic particles, which include one or more of the following: homopolymers or copolymers of acrylate monomer units, homopolymers or copolymers of acrylate monomer units, homopolymers or copolymers of styrene monomer units, polyurethane compounds, rubber compounds, and modified compounds of the above homopolymers or copolymers.

[0050] In some embodiments, the second organic particle comprises one or more of the following: a copolymer of acrylate monomer units and styrene monomer units, a copolymer of acrylate monomer units and styrene monomer units, a copolymer of acrylate 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 monomer units-unsaturated nitrile monomer units, and a modified compound of the above copolymers.

[0051] In some embodiments, the separator includes a base portion and a plurality of support portions. The base portion of the separator is a third base portion, and the plurality of support portions of the separator protrude from the third base portion. The support portions of the separator include organic particles. The organic particles can support the positive electrode body portion or the negative electrode body portion to increase the gap and provide space for the expansion of the negative electrode body portion.

[0052] In some embodiments, the third substrate includes a base film and an inorganic particle layer disposed on the base film. Organic particles of the separator are disposed on the inorganic particle layer and at least partially protrude from it. Sufficient and unevenly distributed voids are formed between the inorganic and organic particles, improving the permeability of the separator and enabling the cylindrical battery cell to have better cycle performance and reliability. The organic particles can support the positive or negative electrode body portion to increase the gap and provide space for the expansion of the negative electrode body portion.

[0053] In some embodiments, the positive electrode body has a plurality of support portions on the side facing the separator, and the separator has a plurality of support portions on the side facing the positive electrode body. The plurality of support portions of the positive electrode body facing the separator and the plurality of support portions of the separator facing the positive electrode sheet are at least partially opposite to each other. By arranging the plurality of support portions of the positive electrode body and the plurality of support portions of the separator facing each other, the plurality of support portions of the positive electrode body and the plurality of support portions of the separator can at least partially abut against each other, thereby increasing the gap and providing more space for the expansion of the negative electrode active material layer.

[0054] In some embodiments, the negative electrode main body has a plurality of support portions on the side facing the insulating member, and the insulating member has a plurality of support portions on the side facing the negative electrode main body. The plurality of support portions of the negative electrode main body facing the insulating member and the plurality of support portions of the insulating member facing the negative electrode main body are at least partially opposite each other. By arranging the plurality of support portions of the negative electrode main body and the plurality of support portions of the insulating member facing each other, the plurality of support portions of the negative electrode main body and the plurality of support portions of the insulating member can at least partially abut against each other, thereby increasing the gap and providing more space for the expansion of the negative electrode main body.

[0055] In some embodiments, the negative electrode main body has a plurality of support portions on the side facing the positive electrode main body, and the positive electrode main body has a plurality of support portions on the side facing the negative electrode main body. At least a portion of the plurality of support portions facing the positive electrode main body are arranged opposite to the plurality of support portions facing the negative electrode main body. By arranging the plurality of support portions of the negative electrode main body and the plurality of support portions of the positive electrode main body facing each other, the plurality of support portions of the negative electrode main body and the plurality of support portions of the positive electrode main body can support each other, thereby increasing the gap and providing more space for the expansion of the negative electrode main body.

[0056] In some embodiments, a first recess is provided on the surface of the positive electrode body opposite to the separator. By providing the first recess, the gap between the positive electrode body and the negative electrode body can be increased. During the cycling process of the cylindrical battery cell, the first recess provides space for the expansion of the negative electrode active material layer, reducing the pressure between the positive and negative electrode bodies, thereby alleviating the compression of the electrolyte in the internal pores of the positive and negative electrode active material layers, reducing the concentration difference of the electrolyte in different regions inside the electrode, and improving the cycling performance of cylindrical battery cells with larger diameters. The first recess can reduce the expansion of the electrode assembly, thereby reducing the compression effect on the casing, lowering the risk of casing deformation and cracking, and improving the reliability of the cylindrical battery cell.

[0057] In some embodiments, the first recess is formed in the positive electrode active material layer.

[0058] In some embodiments, the first recess extends axially through the positive electrode body portion to increase the gap between the positive electrode body portion and the negative electrode body portion.

[0059] In some embodiments, there are multiple first recesses. At least a portion of the multiple first recesses is disposed on the inner side of the positive electrode body portion. The inner side of the positive electrode body portion has a large curvature. By disposing the first recesses on the inner side of the positive electrode body portion, stress can be relieved, and the risk of positive electrode active material in the positive electrode active material layer falling off can be reduced.

[0060] In some embodiments, the positive electrode body includes a plurality of first recesses spaced apart along the winding direction. The plurality of first recesses can provide space for expansion of different regions of the negative electrode active material layer, reducing the pressure between the positive electrode body and the negative electrode body.

[0061] In some embodiments, a second recess is provided on the surface of the negative electrode body opposite to the separator. By providing the second recess, the gap between the positive and negative electrode bodies can be increased. During the cycling process of the cylindrical battery cell, the second recess provides space for the expansion of the negative electrode active material layer, reducing the pressure between the positive and negative electrode bodies. This alleviates the compression of the electrolyte within the internal pores of the positive and negative electrode active material layers, reduces the concentration difference of the electrolyte in different regions within the electrode, and improves the cycling performance of cylindrical battery cells with larger diameters. The second recess can reduce the expansion of the electrode assembly, thereby reducing the compression effect on the casing, lowering the risk of casing deformation and cracking, and improving the reliability of the cylindrical battery cell.

[0062] In some embodiments, a second recess is formed in the negative electrode active material layer. The second recess can provide space for the expansion of the negative electrode active material layer.

[0063] In some embodiments, the second recess extends axially through the negative electrode body portion to increase the gap between the positive electrode body portion and the negative electrode body portion.

[0064] In some embodiments, there are multiple second recesses; at least a portion of the multiple second recesses are disposed on the inner side of the negative electrode body portion. The inner side of the negative electrode body portion has a large curvature. By disposing the second recesses on the inner side of the negative electrode body portion, stress can be released, reducing the risk of negative electrode active material falling off from the negative electrode active material layer.

[0065] In some embodiments, the negative electrode body portion includes a plurality of second recesses spaced apart along the winding direction. The plurality of second recesses can provide space for expansion of different regions of the negative electrode active material layer, reducing the pressure between the positive electrode body portion and the negative electrode body portion.

[0066] In some embodiments, one of the positive electrode tab and the negative electrode tab is a first electrode tab, and the other is a second electrode tab. A cylindrical battery cell includes a first electrode lead and a second electrode lead, the first electrode lead being electrically connected to the first electrode tab, and the second electrode lead being electrically connected to the second electrode tab. Axially, the first electrode lead and the second electrode lead are located on the same side of the electrode assembly. When multiple cylindrical battery cells are assembled into a group, the first electrode leads and second electrode leads of the multiple cylindrical battery cells can be arranged on the same side, facilitating the connection between the current collector and the first and second electrode leads, and simplifying the battery structure.

[0067] In some embodiments, the housing includes a casing and an end cap. The casing includes a sidewall and an end wall. The sidewall surrounds the electrode assembly. The end wall and the end cap are axially opposed to each other along the cylindrical cell. The end cap is sealed to the sidewall.

[0068] In some embodiments, the sidewalls and endwalls are integrally formed.

[0069] In some embodiments, one of the positive electrode tab and the negative electrode tab is a first electrode tab, and the other is a second electrode tab. The cylindrical battery cell also includes electrode terminals insulated from the end wall, with the first electrode tab electrically connected to the electrode terminals and the second electrode tab electrically connected to the end wall.

[0070] In some embodiments, the cylindrical battery cell further includes a first current collector, which 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 connects to the surface of the first current collector facing the end wall. The first current collector can act as a connector to achieve electrical connection between the first tab and the electrode terminal.

[0071] In some embodiments, the electrode terminal has a terminal recess on the side facing the first current collector, and / or the electrode terminal has a terminal recess on the side away from the first current collector. The bottom wall of the terminal recess is welded to the first current collector.

[0072] By setting the terminal recess, the thickness of the bottom wall of the terminal recess can be reduced, the power required to weld the electrode terminal to the first current collector from the outside can be reduced, the risk of welding particles falling into the casing can be reduced, and the reliability of the cylindrical battery cell can be improved.

[0073] In some embodiments, both the first electrode tab and the second electrode tab are located at the end of the electrode assembly facing the end wall. The first electrode tab and the second electrode tab can share space in the axial direction, thereby improving space utilization and increasing energy density.

[0074] In some embodiments, a first tab is located at one end of the electrode assembly facing the end wall, and a second tab is located at one end of the electrode assembly facing the end cap. The cylindrical battery cell also includes a second current collector connected to the second tab; the second current collector is connected to at least one of the end cap and the side wall.

[0075] In some embodiments, the sidewall has an inwardly protruding protrusion. A second current collector is connected to the protrusion. The protrusion overlaps with the second tab in the axial direction, which can limit the axial movement of the second tab when the cylindrical battery cell is subjected to external impact, reducing the risk of connection failure between the second tab and the second current collector.

[0076] In some embodiments, a portion of the second current collector is located on the side of the protrusion facing the end cap and is connected to the protrusion. The second current collector connects to the protrusion from the outside, which can reduce assembly difficulty.

[0077] In some embodiments, the height of the housing is 1.3 to 4 times the diameter of the housing. When the housing meets the above dimensional requirements, the structural stability of the housing is high, which can improve the reliability of the cylindrical battery cell.

[0078] In some embodiments, the height of the housing is 50 mm to 150 mm.

[0079] In some embodiments, the diameter of the housing is 45 mm to 80 mm.

[0080] Secondly, this application provides a battery device comprising a plurality of cylindrical battery cells provided in any of the embodiments of the first aspect.

[0081] Thirdly, this application provides an electrical device, including the battery device provided in any embodiment of the second aspect, the battery device being used to provide electrical energy. Attached Figure Description

[0082] The features, advantages, and technical effects of exemplary embodiments of this application will now be described with reference to the accompanying drawings.

[0083] Figure 1 This application provides structural schematic diagrams of vehicles for some embodiments;

[0084] Figure 2 Schematic diagram of a battery device provided for some embodiments of this application;

[0085] Figure 3 for Figure 2 The diagram shows the structure of the battery module.

[0086] Figure 4 This is a schematic diagram of the structure of a cylindrical battery cell in some embodiments of this application;

[0087] Figure 5 for Figure 4 An exploded view of a cylindrical battery cell;

[0088] Figure 6 A cross-sectional schematic diagram of a cylindrical battery cell provided in some embodiments of this application;

[0089] Figure 7 A partial cross-sectional schematic diagram of the electrode assembly of a cylindrical battery cell provided in some embodiments of this application;

[0090] Figure 8 This is a schematic diagram of the positive electrode sheet of a cylindrical battery cell provided in some embodiments of this application in an unfolded state;

[0091] Figure 9 for Figure 8 A cross-sectional schematic diagram of the positive electrode plate shown;

[0092] Figure 10 This is a schematic diagram of the negative electrode sheet of a cylindrical battery cell provided in some embodiments of this application in an unfolded state;

[0093] Figure 11 for Figure 10 A cross-sectional schematic diagram of the negative electrode sheet shown;

[0094] Figure 12 A cross-sectional schematic diagram of the separator for a cylindrical battery cell provided in some embodiments of this application;

[0095] Figure 13 A partial cross-sectional view of the electrode assembly of a cylindrical battery cell provided for other embodiments of this application;

[0096] Figure 14 A partial cross-sectional view of the electrode assembly of a cylindrical battery cell provided for other embodiments of this application;

[0097] Figure 15 A cross-sectional schematic diagram of the electrode assembly of a cylindrical battery cell provided in some embodiments of this application;

[0098] Figure 16 for Figure 15 Enlarged illustration within the dashed box;

[0099] Figure 17 A schematic diagram of the separator for the electrode assembly of a cylindrical battery cell provided in some embodiments of this application;

[0100] Figure 18 A partial cross-sectional schematic diagram of the electrode assembly of a cylindrical battery cell provided in other embodiments of this application;

[0101] Figure 19 A schematic diagram of the separator for the electrode assembly of a cylindrical battery cell provided in other embodiments of this application;

[0102] Figure 20 A partial cross-sectional schematic diagram of the electrode assembly of a cylindrical battery cell provided in some embodiments of this application;

[0103] Figure 21 A schematic diagram of the positive electrode sheet of an electrode assembly provided in some embodiments of this application after being flattened;

[0104] Figure 22 A cross-sectional schematic diagram of the positive electrode sheet of an electrode assembly provided in some embodiments of this application;

[0105] Figure 23 A cross-sectional schematic diagram of the negative electrode sheet of an electrode assembly provided in some embodiments of this application;

[0106] Figure 24A cross-sectional schematic diagram of the positive electrode sheet provided for other embodiments of this application;

[0107] Figure 25 A cross-sectional schematic diagram of the negative electrode sheet provided in other embodiments of this application;

[0108] Figure 26 A partial cross-sectional view of the electrode assembly of a cylindrical battery cell provided for other embodiments of this application;

[0109] Figure 27 A partial cross-sectional view of the electrode assembly of a cylindrical battery cell provided for other embodiments of this application;

[0110] Figure 28 A partial cross-sectional schematic diagram of the electrode assembly of a cylindrical battery cell provided in other embodiments of this application;

[0111] Figure 29 A schematic diagram of the positive electrode sheet of a cylindrical battery cell in an unfolded state, provided in some other embodiments of this application;

[0112] Figure 30 A schematic diagram of the negative electrode sheet of a cylindrical battery cell in an unfolded state, provided in some other embodiments of this application;

[0113] Figure 31 for Figure 4 A cross-sectional schematic diagram of the battery cell shown.

[0114] Figure 32 for Figure 31 Enlarged view of the area within the circle;

[0115] Figure 33 A partial cross-sectional schematic diagram of a cylindrical battery cell provided for other embodiments of this application;

[0116] Figure 34 This is a partial cross-sectional schematic diagram of a cylindrical battery cell provided for other embodiments of this application.

[0117] The annotations in the attached figures are explained as follows:

[0118] 1. Vehicle; 2. Battery unit; 3. Controller; 4. Motor; 5. Housing; 5a. First housing; 5b. Second housing; 6. Battery module; 7. Cylindrical battery cell; 7a. First electrode lead-out; 7b. Second electrode lead-out;

[0119] 10. Electrode assembly; 10a. Electrode body; 10b. Central hole; 10c. First electrode tab; 10d. Second electrode tab;

[0120] 11. Positive electrode sheet; 111. Positive electrode body portion; 1111. First substrate portion; 1111a. First surface; 1112. Positive electrode protrusion; 1113. Positive electrode recess; 1114. First recess; 112. Positive electrode tab portion; 11a. Positive electrode current collector; 11b. Positive electrode active material layer; 11c. Positive electrode particle coating;

[0121] 12. Negative electrode sheet; 121. Negative electrode body portion; 1211. Second substrate portion; 1211a. Second surface; 1212. Negative electrode protrusion; 1213. Negative electrode recess; 1214. Second recess; 122. Negative electrode tab portion; 12a. Negative electrode current collector; 12b. Negative electrode active material layer; 12c. Negative electrode particle coating;

[0122] 13. Separator; 131. Third substrate; 1311. Base film; 1312. Inorganic particle layer; 131a. Third surface;

[0123] 14. Support section; 141. First support section; 142. Second support section; 143. Third support section; 144. Fourth support section; 145. Fifth support section; 146. Sixth support section;

[0124] 20. Outer shell; 20a. Receiving cavity; 21. Shell; 211. End wall; 212. Side wall; 2121. Protrusion; 2122. Recess; 2123. Press-fit part; 22. End cap;

[0125] 30. Electrode terminal; 31. Terminal recess; 32. Through hole; 40. First current collector; 50. Cover plate; 60. Second current collector; 70. Insulating component;

[0126] C1, central region; C2, end region; C3, transition region;

[0127] E1, winding start end; E2, winding end end; E3, positive electrode winding start end; E4, positive electrode winding end end; E5, negative electrode winding start end; E6, negative electrode winding end end; E7, first end; E8, second end;

[0128] G, gap; G1, first gap; G2, second gap;

[0129] P, organic particle; P1, first organic particle; P2, second organic particle;

[0130] S, mid-section;

[0131] V, winding direction;

[0132] X1, central axis; X2, virtual line;

[0133] W, radial dimension; Z, axial dimension. Detailed Implementation

[0134] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0135] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0136] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0137] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0138] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0139] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0140] In this application, "multiple" means two or more (including two).

[0141] Cylindrical battery cells can be cylindrical secondary batteries. Secondary batteries are battery cells that can be recharged after discharge to activate the active materials and continue to be used.

[0142] A battery device can refer to a single physical module comprising one or more cylindrical battery cells to provide higher voltage and capacity.

[0143] A cylindrical battery cell typically includes an electrode assembly and a housing for containing the electrode assembly. The electrode assembly typically includes a positive electrode, a negative electrode, and a separator that separates the positive and negative electrodes.

[0144] During the cyclic charging and discharging process of a cylindrical battery cell, the negative electrode expands due to ion insertion. As the diameter of the cylindrical battery cell increases, the expansion of the negative electrode accumulates and may generate greater expansion force. This increases the pressure between the positive and negative electrodes, causing the electrolyte in the pores inside the positive active material layer of the positive electrode and the pores inside the negative active material layer of the negative electrode to be squeezed out, affecting the cycle performance of the cylindrical battery cell.

[0145] In addition, in large-diameter cylindrical battery cells, both the positive and negative electrodes are wound with more turns. This may lead to more uneven volume changes in the cylindrical battery cell, greater internal pressure, and thus significant deformation of the outer casing, or even the risk of casing rupture, affecting the reliability of the cylindrical battery cell.

[0146] In view of this, the present application provides a technical solution that reduces expansion force, reduces shell deformation, improves the cycle performance of cylindrical battery cells, and enhances the reliability of cylindrical battery cells by rationally designing the positive electrode, negative electrode and separator, while also taking into account the energy density of cylindrical battery cells to a certain extent.

[0147] The battery cells described in this application are applicable to battery devices and electrical devices that use battery devices. Electrical devices can be equipment that uses battery devices as a power source or various energy storage systems that use battery devices as energy storage elements. Electrical devices can be, but are not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0148] For ease of explanation, the following embodiments will use a vehicle as an example of an electrical device.

[0149] Figure 1 The diagram shows the structural features of a vehicle provided in some embodiments of this application.

[0150] like Figure 1 As shown, a battery device 2 is installed inside the vehicle 1. The battery device 2 can be located at the bottom, front, or rear of the vehicle 1. The battery device 2 can be used to power the vehicle 1; for example, the battery device 2 can serve as the operating power source for the vehicle 1.

[0151] The vehicle 1 may also include a controller 3 and a motor 4. The controller 3 is used to control the battery device 2 to supply power to the motor 4, for example, for the power needs of the vehicle 1 during starting, navigation and driving.

[0152] In some embodiments of this application, the battery device 2 can not only serve as the operating power source for the vehicle 1, but also as the driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0153] Figure 2 A schematic diagram of a battery device provided for some embodiments of this application.

[0154] In some embodiments, the battery device 2 may include one or more battery cell assemblies for providing voltage and capacity.

[0155] A battery cell assembly may include multiple cylindrical battery cells, which are connected in series, parallel, or mixed connection via a busbar. Mixed connection refers to multiple cylindrical battery cells being connected in both series and parallel connections.

[0156] Cylindrical battery cells can be rechargeable battery cells, which are battery cells that can be recharged after being discharged to activate the active materials and continue to be used.

[0157] As an example, cylindrical battery cells can be lithium-ion battery cells, sodium-ion battery cells, sodium-lithium-ion battery cells, lithium metal battery cells, sodium metal battery cells, lithium-sulfur battery cells, magnesium-ion battery cells, nickel-metal hydride battery cells, nickel-cadmium battery cells, lead-acid battery cells, etc.

[0158] In some embodiments, the battery cell assembly is typically formed by arranging multiple cylindrical battery cells; as an example, the battery cell assembly can be a battery module 6, which is formed by arranging and fixing multiple cylindrical battery cells into a single module. As an example, the battery module 6 can be formed by binding multiple cylindrical battery cells together with cable ties.

[0159] In some embodiments, the battery device 2 may be a battery pack, which includes a housing 5 and one or more battery cell assemblies housed within the housing 5. As an example, the battery cell assembly may be a battery module 6, which can be housed within the housing by securing the battery module 6 to the housing. Alternatively, the battery cell assembly may be housed within the housing by directly securing multiple cylindrical battery cells to the housing.

[0160] In some embodiments, the housing 5 is used to house cylindrical battery cells, and the housing 5 can have various structures.

[0161] In some embodiments, the housing 5 may include a first housing 5a and a second housing 5b. The first housing 5a and the second housing 5b are fastened together to form a closed space inside the housing 5 to house the battery cell assembly. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first housing may be a top cover or a bottom plate.

[0162] In some embodiments, the housing 5 may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are respectively connected to the frame, forming an enclosed space inside the housing to accommodate individual battery cells. As an example, the frame may include multiple side beams.

[0163] In some embodiments, the housing 5 may be part of the vehicle's chassis structure. For example, a portion of the housing 5 may be at least a portion of the vehicle's floor, or a portion of the housing 5 may be at least a portion of the vehicle's crossbeams and longitudinal beams.

[0164] In some embodiments, the battery device 2 may be an energy storage device.

[0165] Energy storage devices can be used in energy storage power stations, wind power generation systems, solar power generation systems, mobile power systems, or temporary power supply systems. Energy storage devices can store electrical energy as needed and output it when appropriate. For example, energy storage devices can store electrical energy during off-peak hours and provide power to relevant users or electrical equipment during peak hours.

[0166] In some embodiments, the energy storage device includes an energy storage container, an energy storage cabinet, etc.

[0167] Figure 3 for Figure 2 The diagram shows the structure of the battery module.

[0168] In some embodiments, such as Figure 3 As shown, there are multiple cylindrical battery cells 7. These multiple cylindrical battery cells 7 are first connected in series, parallel, or in a mixed manner to form a battery module 6. The multiple battery modules 6 are then connected in series, parallel, or in a mixed manner to form a whole, which is housed in the casing.

[0169] Multiple cylindrical battery cells 7 in battery module 6 can be electrically connected through busbars to achieve parallel, series, or mixed connection of multiple cylindrical battery cells 7 in battery module 6. There can be one or more busbars, each used to electrically connect at least two cylindrical battery cells 7.

[0170] Figure 4 This is a schematic diagram of the structure of a cylindrical battery cell in some embodiments of this application; Figure 5 for Figure 4 An exploded view of a cylindrical battery cell; Figure 6 A cross-sectional schematic diagram of a cylindrical battery cell provided in some embodiments of this application;

[0171] Figure 7 A partial cross-sectional schematic diagram of the electrode assembly of a cylindrical battery cell provided in some embodiments of this application; Figure 8 This is a schematic diagram of the positive electrode sheet of a cylindrical battery cell provided in some embodiments of this application in an unfolded state; Figure 9 for Figure 8 A cross-sectional schematic diagram of the positive electrode plate shown; Figure 10 This is a schematic diagram of the negative electrode sheet of a cylindrical battery cell provided in some embodiments of this application in an unfolded state; Figure 11 for Figure 10 A cross-sectional schematic diagram of the negative electrode sheet shown; Figure 12 This is a cross-sectional schematic diagram of the separator of a cylindrical battery cell provided in some embodiments of this application.

[0172] Reference Figures 4 to 12 This application provides a cylindrical battery cell 7, which includes a housing 20 and an electrode assembly 10, with at least a portion of the electrode assembly 10 housed within the housing 20.

[0173] The outer casing 20 may be a hollow structure, with an internal space for accommodating the electrode assembly 10 and the electrolyte. For example, the outer casing 20 of the cylindrical battery cell 7 is a cylindrical casing.

[0174] In some embodiments, the housing 20 may be a metal housing, such as a steel housing, an aluminum housing, a composite metal housing (e.g., a copper-aluminum composite housing), or other metal housings. Alternatively, the housing 20 may also be a non-metallic housing, such as a plastic housing (e.g., polypropylene).

[0175] In some embodiments, the housing 20 includes a housing 21 and an end cap 22, the housing 21 having an opening, and the end cap 22 being connected to the housing 21 and covering the opening;

[0176] The housing 21 is a component used to fit the end cap 22 to form the internal cavity of the cylindrical battery cell. The formed internal cavity can be used to accommodate the electrode assembly 10, the electrolyte, and other components.

[0177] The housing 21 and the end cap 22 can be separate components. For example, an opening can be provided on the housing 21, and the end cap 22 can be used to close the opening to form an internal cavity for the battery cell.

[0178] The shell 21 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc.

[0179] The shape of the end cap 22 can be adapted to the shape of the housing 21 to fit the housing 21. The material of the end cap 22 can be the same as or different from the material of the housing 21. Optionally, the end cap 22 can be made of a material with a certain hardness and strength (such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.), so that the end cap 22 is not easily deformed when subjected to compression and impact, so that the battery cell can have higher structural strength and improve reliability.

[0180] The end cap 22 is connected to the housing 21 by welding, bonding, snap-fitting or other means.

[0181] The housing 21 may be open at one end or open at both ends. In some examples, the housing 21 may be a structure with an opening on one side, and one end cap 22 is provided to cover the housing 21. In other examples, the housing 21 may also be a structure with openings on both sides, and two end caps 22 are provided, with the two end caps 22 respectively covering the two openings of the housing 21.

[0182] In some embodiments, the housing 21 includes a sidewall 212 and an endwall 211, the endwall 211 and the end cap 22 being opposite each other along the axial direction Z of the cylindrical battery cell 7, and the end cap 22 being sealed to the sidewall 212.

[0183] Electrode assembly 10 is the component in the cylindrical battery cell 7 where the electrochemical reaction takes place. Electrode assembly 10 can be entirely housed within housing 20 or partially housed within housing 20. For example, a portion of the tabs of electrode assembly 10 can extend outside housing 20.

[0184] Optionally, the electrode assembly 10 is entirely housed within the housing 20.

[0185] In some embodiments, the sidewall 212 and the endwall 211 are integrally formed.

[0186] In some embodiments, the diameter of the cylindrical battery cell 7 is greater than or equal to 40 mm. Larger diameter cylindrical battery cells 7 have higher capacity, which is beneficial for increasing energy density when multiple cylindrical battery cells 7 are assembled into a group.

[0187] In some embodiments, the outer diameter of the housing 20 is greater than or equal to 40 mm. The outer diameter of the housing 20 may be the outer diameter of the housing 20.

[0188] The outer casing 20 has a larger diameter to increase its internal space and improve the capacity of the cylindrical battery cell 7.

[0189] In some embodiments, the electrode assembly 10 includes a positive electrode 11 and a negative electrode 12. During the charging and discharging process of the cylindrical battery cell 7, active ions (e.g., lithium ions) are inserted and extracted back and forth between the positive electrode 11 and the negative electrode 12.

[0190] In some embodiments, the positive electrode 11 may include a positive current collector 11a and a positive active material layer 11b disposed on at least one surface of the positive current collector 11a.

[0191] As an example, the positive current collector 11a has two surfaces opposite each other in its own thickness direction, and the positive active material layer 11b is disposed on either or both of the two opposite surfaces of the positive current collector 11a.

[0192] As an example, the positive current collector 11a can be made of metal foil, conductive polymer material, carbon material, or composite current collector. For example, as a metal foil, pure metal, alloy, or surface-treated metal can be used, including but not limited to stainless steel, copper, aluminum, nickel, nickel alloy, titanium, or silver. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0193] As an example, the positive electrode active material layer 11b includes a positive electrode active material, which may include at least one of the following materials: lithium phosphate, lithium transition metal oxide, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium phosphate may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.8 Co 0.15 Al 0.05 At least one of O2 and its modified compounds. Modified compounds refer to substances obtained by modification methods such as doping or coating based on the above-mentioned substances.

[0194] In some embodiments, the negative electrode 12 may include a negative electrode current collector 12a and a negative electrode active material layer 12b disposed on at least one surface of the negative electrode current collector 12a.

[0195] As an example, the negative electrode current collector 12a has two surfaces opposite each other in its own thickness direction, and the negative electrode active material layer 12b is disposed on either or both of the two opposite surfaces of the negative electrode current collector 12a.

[0196] As an example, the negative electrode current collector 12a can be made of metal foil, conductive polymer material, carbon material, or composite current collector. For example, as a metal foil, pure metal, alloy, or surface-treated metal can be used, including but not limited to stainless steel, copper, aluminum, nickel, nickel alloy, titanium, or silver. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0197] As an example, the negative electrode active material may be a negative electrode active material known in the art for use in cylindrical battery cells. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for cylindrical battery cells may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0198] In some embodiments, the positive current collector 11a may be made of aluminum, and the negative current collector 12a may be made of copper.

[0199] In some embodiments, the electrode assembly 10 further includes a separator 13 disposed between the positive electrode 11 and the negative electrode 12. The separator 13 serves to prevent short circuits between the positive and negative electrodes while allowing active ions to pass through.

[0200] In some embodiments, the separator 13 is a separator membrane. The separator membrane of this application can be any known porous structure separator membrane with good chemical and mechanical stability.

[0201] As an example, the main material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different. The separator 13 can be a single component located between the positive electrode 11 and the negative electrode 12, or it can be attached to the surface of the positive electrode 11 or the surface of the negative electrode 12. An inorganic particle coating, an organic particle coating, or an organic / inorganic composite coating can also be applied to the surface of the separator.

[0202] In some embodiments, the cylindrical battery cell 7 further includes an electrolyte, which acts as a conductor of ions between the positive electrode 11 and the negative electrode 12. The electrolyte used in this application can be selected according to requirements. The electrolyte can be liquid, gel, or solid.

[0203] In some embodiments, the liquid electrolyte includes an electrolyte salt and a solvent.

[0204] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0205] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent may also be an ether solvent. Ether solvents may include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ethers.

[0206] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain properties of cylindrical battery cells, such as additives that improve the overcharge / fast charge performance of cylindrical battery cells, additives that improve the high-temperature performance of cylindrical battery cells, additives that improve the low-temperature performance of cylindrical battery cells, etc.

[0207] In some embodiments, the gel electrolyte comprises a polymer as a backbone network and can be used in conjunction with an ionic liquid-lithium salt.

[0208] In some embodiments, the solid electrolyte includes a polymer solid electrolyte, an inorganic solid electrolyte, and a composite solid electrolyte.

[0209] As an example, the polymers of polymeric solid electrolytes may include polyethers (polyoxyethylene), polysiloxanes, polycarbonates, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, monoionic polymers, polyionic liquids, cellulose, etc.

[0210] As an example, inorganic solid electrolytes can be one or more of the following: oxide solid electrolytes (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous LiPON thin film), sulfide solid electrolytes (crystalline lithium superconducting ion conductor (lithium germanium phosphorus sulfide, silver sulfide germanium ore), amorphous sulfides), halide solid electrolytes, nitride solid electrolytes, and hydride solid electrolytes.

[0211] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0212] In some embodiments, the positive electrode 11, the negative electrode 12, and the separator 13 are wound together.

[0213] The electrode assembly 10 has a wound structure. For example, the positive electrode 11, the separator 13, and the negative electrode 12 are wound into a cylindrical wound structure.

[0214] In some embodiments, the cylindrical battery cell 7 includes a housing 20 and an electrode assembly 10. The housing 20 has a receiving cavity; the outer diameter of the housing 20 is ≥40mm. The electrode assembly 10 is received within the receiving cavity. The electrode assembly 10 includes a positive electrode 11, a negative electrode 12, and a separator 13, which are wound together. The separator 13 is used to isolate the positive electrode 11 and the negative electrode 12. The positive electrode 11 includes a positive electrode body portion 111 and a positive electrode tab portion 112 disposed along the axial direction Z of the cylindrical battery cell 7. At least a portion of the positive electrode body portion 111 is provided with a positive electrode active material layer 11b, and at least a portion of the positive electrode tab portion 112 is not provided with a positive electrode active material layer 11b. The negative electrode 12 includes a negative electrode body portion 121 and a negative electrode tab portion 122 disposed along the Z-axis. At least a portion of the negative electrode body portion 121 is provided with a negative electrode active material layer 12b, and at least a portion of the negative electrode tab portion 122 is not provided with a negative electrode active material layer 12b.

[0215] As an example, the positive electrode active material layer 11b can be entirely disposed on the positive electrode body portion 111, or it can be partially disposed on the positive electrode body portion 111 and partially disposed on the positive electrode tab portion 112. Optionally, the positive electrode body portion 111 includes the positive electrode active material layer 11b and the portion of the positive electrode current collector 11a covered by the positive electrode active material layer 11b. The positive electrode tab portion 112 includes the portion of the positive electrode current collector 11a not covered by the positive electrode active material layer 11b.

[0216] As an example, the dimension of the positive electrode tab 112 along the winding direction V is less than or equal to the dimension of the positive electrode body 111 along the winding direction V. Optionally, the ratio of the dimension of the positive electrode tab 112 along the winding direction V to the dimension of the positive electrode body 111 along the winding direction V can be 0.6-1, for example, it can be 0.6, 0.7, 0.8, 0.9 or 1.

[0217] As an example, the negative electrode active material layer 12b can be entirely disposed on the negative electrode main body portion 121, or it can be partially disposed on the negative electrode main body portion 121 and another part disposed on the negative electrode tab portion 122. Optionally, the negative electrode main body portion 121 includes the negative electrode active material layer 12b and the portion of the negative electrode current collector 12a covered by the negative electrode active material layer 12b. The negative electrode tab portion 122 includes the portion of the negative electrode current collector 12a not covered by the negative electrode active material layer 12b.

[0218] As an example, the dimension of the negative electrode tab 122 along the winding direction V is less than or equal to the dimension of the negative electrode body 121 along the winding direction V. Optionally, the ratio of the dimension of the negative electrode tab 122 along the winding direction V to the dimension of the negative electrode body 121 along the winding direction V is 0.6-1, for example, it can be 0.6, 0.7, 0.8, 0.9 or 1.

[0219] As an example, the positive electrode tab 112 and the negative electrode tab 122 can be located at the same end of the electrode assembly 10 in the Z-axis direction, or they can be located at opposite ends of the electrode assembly 10 in the Z-axis direction.

[0220] As an example, the positive electrode body 111, the negative electrode body 121, and the separator 13 constitute the electrode body 10a of the electrode assembly 10. The positive electrode tab 112 and the negative electrode tab 122 can be led out from one end of the electrode body 10a, or from both ends of the electrode body 10a respectively.

[0221] In some embodiments, the electrode assembly 10 has a cross section perpendicular to the axial direction Z, within which a virtual straight line X2 extends radially along the cylindrical battery cell 7. The virtual straight line X2 intersects the positive electrode body portion 111 N1 times, the negative electrode body portion 121 N2 times, and the separator 13 N3 times. The thickness of the positive electrode body portion 111 is T1, the thickness of the negative electrode body portion 121 is T2, and the thickness of the separator 13 is T3. The radial dimension of the receiving cavity is D. 0.65≤(N1×T1+N2×T2+N3×T3) / D≤0.95.

[0222] For example, the virtual straight line X2 may be perpendicular to and intersect with the central axis X1 of the cylindrical battery cell, and the central axis X1 is parallel to the axis Z.

[0223] For example, (N1×T1+N2×T2+N3×T3) / D can be 0.65, 0.95, or any value between 0.65 and 0.95. For instance, (N1×T1+N2×T2+N3×T3) / D can be 0.65, 0.67, 0.7, 0.72, 0.75, 0.77, 0.8, 0.82, 0.85, 0.87, 0.9, 0.92, 0.93, 0.94, or 0.95.

[0224] For example, the receiving cavity is a cylindrical cavity, and the radial dimension D of the receiving cavity can be the diameter of the receiving cavity.

[0225] The units for T1, T2, T3, and D are the same; for example, the unit for T1, T2, T3, and D is micrometer.

[0226] As an example, T1, T2, T3, N1, N2, N3, and D can be measured in the following manner:

[0227] Discharge the cylindrical battery cells to the lower cutoff voltage (e.g., 2.5V);

[0228] Using CT (Computed Tomography) technology, X-rays are used to obtain cross-sectional images of a cylindrical battery cell. This cross-section is perpendicular to the central axis of the cylindrical battery cell and shows the positive electrode body, the negative electrode body, and the separator.

[0229] Based on the image, a virtual straight line is defined, which can pass through the center of the cross section (the virtual straight line intersects the central axis); the number of times the virtual straight line intersects with the positive electrode body is counted, and this number can be taken as N1; the number of times the virtual straight line intersects with the negative electrode body is counted, and this number can be taken as N2; the number of times the virtual straight line intersects with the separator is counted, and this number can be taken as N3.

[0230] Based on this image, the radial dimension D of the receiving cavity is measured; for example, the dimension of the receiving cavity in a direction parallel to the virtual straight line is measured, which can be used as the radial dimension D.

[0231] Disassemble the cylindrical battery cell and unfold the positive electrode, negative electrode, and separator;

[0232] Fifty positions are randomly selected on the positive electrode body of the positive electrode sheet, and 50 thickness values ​​are measured. Then the average value of the 50 thickness values ​​is calculated, which can be the thickness T1 of the positive electrode body.

[0233] Arbitrarily select 50 positions on the negative electrode body of the negative electrode sheet, measure 50 thickness values, and then calculate the average value of the 50 thickness values. This average value can be the thickness T2 of the negative electrode body.

[0234] Select 50 arbitrary locations on the separator and measure 50 thickness values. Then calculate the average value of the 50 thickness values, which can be the thickness T3 of the separator.

[0235] In this embodiment, (N1×T1+N2×T2+N3×T3) / D is limited to less than or equal to 0.95, which allows a gap G to be formed between the positive electrode body 111 and the negative electrode body 121. During the cycling process of the cylindrical battery cell 7, the gap G provides space for the expansion of the negative electrode active material layer 12b, reducing the pressure between the positive electrode body 111 and the negative electrode body 121. This reduces the compression of the electrolyte in the internal pores of the positive electrode active material layer 11b and the negative electrode active material layer 12b, thereby reducing the concentration difference of electrolyte in different regions inside the electrode and improving the cycling performance of the cylindrical battery cell 7 with a larger diameter. The gap G can reduce the expansion of the electrode assembly 10, thereby reducing the compression effect on the casing 20, reducing the risk of deformation and cracking of the casing 20, and improving the reliability of the cylindrical battery cell 7. By limiting (N1×T1+N2×T2+N3×T3) / D to greater than or equal to 0.65, the ion migration path between the positive electrode body 111 and the negative electrode body 121 is shortened, the internal resistance of the cylindrical battery cell 7 is reduced, heat generation is decreased, and the impact of the gap G on the energy density is reduced. In this embodiment, (N1×T1+N2×T2+N3×T3) / D is set to 0.65-0.95, which can, to a certain extent, balance the reliability and energy density of the cylindrical battery cell 7.

[0236] In some embodiments, 0.70≤(N1×T1+N2×T2+N3×T3) / D≤0.90 can further balance the reliability and energy density of the cylindrical battery cell 7 and improve the cycle performance of the cylindrical battery cell 7.

[0237] In some embodiments, N3 > N2 > N1.

[0238] In the direction parallel to the virtual line X2, the negative electrode body 121 has more layers than the positive electrode body 111. The negative electrode body 121 can receive ions extracted from the positive electrode body 111, thereby reducing the risk of ion extraction and improving the reliability of the cylindrical battery cell 7. In the direction parallel to the virtual line X2, the separator 13 has more layers to insulate the negative electrode body 121 from the positive electrode body 111, reducing the risk of short circuits.

[0239] In some embodiments, N3 ≥ 2 × N2. In a direction parallel to the virtual straight line X2, each negative electrode main body 121 has an adjacent isolation member 13 on both sides.

[0240] In some embodiments, 0.65 ≤ T1 / T2 ≤ 0.95.

[0241] For example, T1 / T2 can be 0.65, 0.95, or any value between 0.65 and 0.95. For instance, T1 / T2 can be 0.65, 0.67, 0.7, 0.72, 0.75, 0.77, 0.8, 0.82, 0.85, 0.87, 0.9, 0.92, or 0.95.

[0242] With a fixed T1, limiting T1 / T2 to greater than or equal to 0.65 restricts the upper limit of the thickness of the negative electrode body 121, reducing the migration path of ions in the negative electrode body 121 during charging and improving fast charging and cycle performance. With a fixed T1, limiting T1 / T2 to less than or equal to 0.95 restricts the lower limit of the thickness of the negative electrode body 121, reducing the compaction density of the negative electrode active material layer 12b, reducing the expansion of the negative electrode active material layer 12b during charging, improving the cycle performance of the cylindrical battery cell 7, and reducing the risk of deformation and cracking of the casing 20.

[0243] In some embodiments, 0.7 ≤ T1 / T2 ≤ 0.9.

[0244] In some embodiments, T1 is 80μm-150μm.

[0245] For example, T1 can be 80 μm, 150 μm, or any value between 80 μm and 150 μm. For instance, T1 can be 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, or 150 μm.

[0246] For example, limiting T1 to greater than or equal to 80 μm can reduce the number of turns of the positive electrode 11, reduce the total length of the positive electrode current collector 11a along the winding direction V, reduce the space and volume occupied by the positive electrode current collector 11a, and improve energy density. Limiting T1 to less than or equal to 150 μm can reduce the thickness requirement of the negative electrode body 121, reduce the migration path of ions in the negative electrode body 121, and improve fast charging performance and cycle performance.

[0247] In some embodiments, T2 is 100μm-180μm.

[0248] For example, T2 can be 100 μm, 180 μm, or any value between 100 μm and 180 μm. For instance, T2 can be 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, or 180 μm.

[0249] For example, limiting T2 to greater than or equal to 100 μm can reduce the number of turns of the negative electrode sheet 12, reduce the total length of the negative electrode current collector 12a along the winding direction V, reduce the space and volume occupied by the negative electrode current collector 12a, and improve the energy density. The negative electrode body portion 121 can have a larger thickness to reduce the compaction density of the negative electrode active material layer 12b, reduce the expansion of the negative electrode active material layer 12b during charging, improve the cycle performance of the cylindrical battery cell 7, and reduce the risk of deformation and cracking of the casing 20.

[0250] By limiting T2 to less than or equal to 180 μm, the migration path of ions in the negative electrode body 121 is reduced during charging, thereby improving fast charging performance and cycle performance.

[0251] In some embodiments, T3 is 7μm-20μm.

[0252] For example, T3 can be 7 μm, 20 μm, or any value between 7 μm and 20 μm. For instance, T3 can be 7 μm, 8 μm, 10 μm, 12 μm, 13 μm, 15 μm, 17 μm, or 20 μm.

[0253] For example, limiting T3 to greater than or equal to 7 μm can improve the insulation effect of the separator 13, reduce the risk of the separator 13 being punctured by burrs or dendrites formed by ion precipitation, and improve the reliability of the cylindrical battery cell 7.

[0254] In some embodiments, D is 35mm-80mm.

[0255] As an example, D can be 35mm, 80mm, or any value between 35mm and 80mm. For example, D can be 35mm, 38mm, 40mm, 45mm, 50mm, 55mm, 60mm, 65mm, 70mm, 75mm, or 80mm.

[0256] In this embodiment, the housing 20 has a larger diameter cavity 20a, which can provide more space for the electrode assembly 10 and the electrolyte, thereby increasing the capacity of the cylindrical battery cell 7.

[0257] In some embodiments, the electrode assembly 10 has a central hole 10b at its center. Exemplarily, the central axis X1 passes through the central hole 10b.

[0258] The central hole 10b can provide space for the expansion of the negative electrode active material layer 12b, thereby reducing the squeezing effect on the outer shell 20, reducing the risk of deformation and cracking of the outer shell 20, and improving the reliability of the cylindrical battery cell 7.

[0259] The central hole 10b can serve as a flow channel for the electrolyte, improving the wetting effect of the electrolyte on the electrode assembly 10. In the event of thermal runaway in the cylindrical battery cell 7, the central hole 10b can serve as a gas venting channel, increasing the gas venting rate and reducing the risk of explosion.

[0260] In some embodiments, a gap G is provided between the positive electrode body portion 111 and the negative electrode body portion 121.

[0261] As an example, the gap G can be a space located between the positive electrode body portion 111 and the negative electrode body portion 121 that is not filled by the separator 13.

[0262] In some examples, a gap G is provided on the outer side of the positive electrode main body 111, that is, a gap G is provided between the outer surface of the positive electrode main body 111 and the negative electrode main body 121; in other examples, a gap G is provided on the inner side of the positive electrode main body 111, that is, a gap G is provided between the inner surface of the positive electrode main body 111 and the negative electrode main body 121; in still other examples, gaps G are provided on both the inner and outer sides of the positive electrode main body 111.

[0263] As an example, the gap G can be formed in a variety of ways.

[0264] For example, when winding the positive electrode 11, the separator 13 and the negative electrode 12, the tightness of the electrode assembly 10 after winding is adjusted by controlling the tension or other parameters of the three, thereby forming a gap G of a predetermined size.

[0265] For example, a gap G is formed between the positive electrode body 111 and the negative electrode body 121 by forming a recess on the surface of the positive electrode body 111 and / or by forming a recess on the surface of the negative electrode body 121. Optionally, the recess extends along the axial direction Z.

[0266] For example, a protruding structure is provided on the surface of one of the positive electrode main body 111, the negative electrode main body 121 and the separator 13 to form a gap G between the positive electrode main body 111 and the negative electrode main body 121.

[0267] During the cycling process of the cylindrical battery cell 7, the gap G provides space for the expansion of the negative electrode active material layer 12b, reducing the pressure between the positive electrode body 111 and the negative electrode body 121. This reduces the compression of the electrolyte in the internal pores of the positive electrode active material layer 11b and the negative electrode active material layer 12b, thereby reducing the concentration difference of electrolyte in different regions inside the electrode and improving the cycling performance of the cylindrical battery cell 7 with a larger diameter. The gap G can reduce the expansion of the electrode assembly 10, thereby reducing the compression of the casing 20, reducing the risk of deformation and cracking of the casing 20, and improving the reliability of the cylindrical battery cell 7. By setting the gap G, the increase in expansion force caused by increasing the diameter of the cylindrical battery cell 7 can be reduced, thereby increasing the capacity of the cylindrical battery cell 7.

[0268] The gap G can also accommodate electrolyte to improve the wetting effect of the electrolyte on the positive electrode 11 and the negative electrode 12, thereby improving the cycle performance of the cylindrical battery cell 7.

[0269] In addition, when the negative electrode 12 experiences ion deposition problems during cycling, such as lithium deposition, the gap G can provide space for the deformation of the separator 13, so that the separator 13 can release the pressure exerted on it by the lithium dendrites through deformation, thereby avoiding the separator 13 from being punctured to a certain extent, reducing the risk of short circuit and improving reliability.

[0270] In some embodiments, the negative electrode active material layer 12b includes a negative electrode active material, which includes at least one of silicon-based materials and carbon-based materials.

[0271] As an example, carbon-based materials include at least one of artificial graphite and natural graphite.

[0272] As an example, silicon-based materials include at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys.

[0273] In some embodiments, the negative electrode active material includes a carbon-based material. Carbon-based materials have higher cycle stability and can improve the cycle performance of the cylindrical battery cell 7.

[0274] In some embodiments, the negative electrode active material layer 12b includes a negative electrode active material, which includes a silicon-based material. The introduction of the silicon-based material can increase the capacity of the negative electrode active material and improve the energy density of the cylindrical battery cell 7. The gap G formed between the positive electrode body portion 111 and the negative electrode body portion 121 can provide space for the expansion of the silicon-based material, thereby reducing the influence of the silicon-based material on the expansion force.

[0275] For example, silicon can exist in the form of silicon-based materials, such as elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys.

[0276] In some embodiments, the silicon content of the silicon element in the negative electrode active material layer 12b is 2% to 19% by mass.

[0277] For example, the mass content of silicon in the negative electrode active material layer 12b can be 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or any combination of two of the above values.

[0278] The mass content of silicon in the negative electrode active material layer is a well-known concept in the art and can be detected using well-known equipment and methods. For example, the negative electrode sheet can be immersed in a solvent (e.g., water) to separate the negative electrode active material from the negative electrode current collector. The substances in the negative electrode active material layer can be obtained by filtration and used as a test sample. The silicon content can be obtained by using an ICAP7400 inductively coupled plasma atomic emission spectrometer from Thermo Fisher Scientific, USA, in accordance with the GB / T30902-2014 standard.

[0279] In this embodiment, the mass content of silicon in the negative electrode active material layer 12b is limited to greater than or equal to 2% to increase the capacity of the negative electrode sheet 12 and improve the energy density of the cylindrical battery cell 7. The gap G provides space for the expansion of the negative electrode active material layer 12b, thereby reducing the influence of silicon-based materials on expansion force. In this embodiment, the mass content of silicon in the negative electrode active material layer 12b is limited to less than or equal to 19% to limit the deformation of the cylindrical battery cell 7 and improve the cycle performance of the cylindrical battery cell 7.

[0280] In this embodiment, the mass content of silicon in the negative electrode active material layer 12b is limited to 2% to 19% to balance the expansion and capacity of the negative electrode sheet 12 to a certain extent, while taking into account the cycle performance and energy density of the cylindrical battery cell 7.

[0281] In some embodiments, the mass content of silicon in the negative electrode active material layer 12b is 6% to 13%.

[0282] In some embodiments, the areal density of the negative electrode 12 is greater than or equal to 3.2 mAh / cm³. 2 .

[0283] The capacity areal density of the negative electrode is a well-known concept in the art and can be detected using well-known equipment and methods. For example, the aforementioned negative electrode and lithium metal sheet can be used as the counter electrode, along with an electrolyte and a separator, and assembled into a CR2430 coin cell in an argon-protected glove box. After the resulting coin cell is left to stand for 12 hours, it is discharged at 25°C with a constant current of 0.05C to 0.005V, left to stand for 10 minutes, and then discharged again with a constant current of 50μA to 0.005V. After standing for 10 minutes, it is discharged again with a constant current of 10μA to 0.005V. Then, it is charged at a constant current of 0.1C to 2V, and the charging capacity is recorded. The ratio of the charging capacity to the area of ​​the negative electrode is the capacity areal density. As an example, the electrolyte and separator described in Example 1 below can be used.

[0284] The areal density of the negative electrode 12 is related to its expansion. In this embodiment, by limiting (N1×T1+N2×T2+N3×T3) / D to 0.65-0.95, the influence of increasing the areal density of the negative electrode 12 on the expansion force can be reduced, thereby increasing the capacity of the negative electrode 12 and improving the energy density of the cylindrical battery cell 7.

[0285] For example, the areal density of the negative electrode 12 can be 3.2 mAh / cm³. 2 3.3mAh / cm 2 3.33mAh / cm 2 3.5mAh / cm 2 3.8mAh / cm 2 3.9mAh / cm 2 4mAh / cm 2 4.2mAh / cm 2 4.5mAh / cm 2 4.8mAh / cm 2 4.9mAh / cm 2 5mAh / cm 2 5.2mAh / cm 2 5.5mAh / cm 2 5.8mAh / cm 2 6mAh / cm 2 6.2mAh / cm 2 6.5mAh / cm 2 6.8mAh / cm2 7mAh / cm 2 7.5mAh / cm 2 8mAh / cm 2 8.5mAh / cm 2 9mAh / cm 2 9.5mAh / cm 2 10mAh / cm 2 10.5mAh / cm 2 11mAh / cm 2 11.5mAh / cm 2 Or a range consisting of any two of the above values.

[0286] In some embodiments, the areal density of the negative electrode 12 is 3.3 mAh / cm³. 2 Up to 11.5mAh / cm 2 The embodiments of this application can, to a certain extent, balance the capacity and expansion of the negative electrode 12, while taking into account the energy density and cycle performance of the cylindrical battery cell 7.

[0287] In some embodiments, the areal density of the negative electrode 12 is 3.96 mAh / cm³. 2 Up to 7.56mAh / cm 2 This can further balance the energy density and cycle performance of the cylindrical battery cell 7.

[0288] In some embodiments, at least a portion of the gap G has a radial dimension W of 5 μm to 60 μm.

[0289] As an example, the radial dimension of the gap G can be the radial dimension of the gap G along the cylindrical battery cell 7. The radial dimension W of the gap G at different locations can be the same or different.

[0290] Optionally, the radial dimension W of each part of the gap G is 5μm-60μm.

[0291] Optionally, the radial dimension W of the gap G can be 5μm, 6μm, 8μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm or a range of any two of the above values.

[0292] As an example, the radial dimension of the gap G can be measured as follows:

[0293] Discharge the cylindrical battery cells to the lower cutoff voltage (e.g., 2.5V);

[0294] Using CT (Computed Tomography) technology, X-rays are used to obtain cross-sectional images of a cylindrical battery cell. This cross-section is perpendicular to the central axis of the cylindrical battery cell and shows the positive electrode body, the negative electrode body, and the separator.

[0295] Based on this image, a virtual straight line is defined, which can pass through the center of the cross section (the virtual straight line intersects the central axis);

[0296] Based on the image and the virtual line, along a direction away from the center of the cross-section and parallel to the virtual line, the first intersection point of the outer surface of the 6th layer positive electrode body and the virtual line is obtained, and the second intersection point of the inner surface of the 10th layer positive electrode body and the virtual line is obtained. The distance D1 between the first intersection point and the second intersection point is measured.

[0297] Disassemble the cylindrical battery cell and unfold the positive electrode, negative electrode, and separator;

[0298] Fifty positions are randomly selected on the positive electrode body of the positive electrode sheet, and 50 thickness values ​​are measured. Then the average value of the 50 thickness values ​​is calculated, which can be the thickness T1 of the positive electrode body.

[0299] Arbitrarily select 50 positions on the negative electrode body of the negative electrode sheet, measure 50 thickness values, and then calculate the average value of the 50 thickness values. This average value can be the thickness T2 of the negative electrode body.

[0300] Select 50 arbitrary locations on the separator and measure 50 thickness values. Then calculate the average value of the 50 thickness values, which can be the thickness T3 of the separator.

[0301] Between the outer surface of the 6th positive electrode main body and the inner surface of the 10th positive electrode main body, there are 3 positive electrode main bodies, 4 negative electrode main bodies, and 8 insulating components; 8 gaps are formed between the outer surface of the 6th positive electrode main body and the inner surface of the 10th positive electrode main body. W=(D1-3×T1-4×T2-8×T3) / 8.

[0302] In this embodiment, the radial dimension W of the gap G is limited to greater than or equal to 5 μm, which provides space for the expansion of the negative electrode active material layer 12b, reduces the expansion force, improves the cycle performance of the cylindrical battery cell 7, and reduces the risk of deformation and cracking of the casing 20. In another embodiment, the radial dimension W of the gap G is limited to less than or equal to 60 μm to shorten the ion migration path between the positive electrode active material layer 11b and the negative electrode active material layer 12b, reduce the internal resistance of the cylindrical battery cell 7, reduce heat generation, and reduce the impact of the gap G on energy density.

[0303] In some embodiments, the gap G includes a first gap G1 and a second gap G2, the first gap G1 being formed between the positive electrode body portion 111 and the separator 13, and the second gap G2 being formed between the negative electrode body portion 121 and the separator 13.

[0304] As an example, the radial dimension of the first gap G1 is W1, and the radial dimension of the second gap G2 is W2. The radial dimension W of the gap G is W = W1 + W2.

[0305] Both the first gap G1 and the second gap G2 can provide space for the expansion of the negative electrode active material layer 12b, thereby reducing the squeezing effect on the outer shell 20, reducing the risk of deformation and cracking of the outer shell 20, and improving the reliability of the cylindrical battery cell 7.

[0306] In some embodiments, a gap G is provided on the inner side of the positive electrode body portion 111, and no gap G is provided on the outer side of the positive electrode body portion 111. Optionally, the gap located on the inner side of the positive electrode body portion 111 includes a first gap G1 and a second gap G2.

[0307] In some other embodiments, a gap G is provided on the outer side of the positive electrode body portion 111, and no gap G is provided on the inner side of the positive electrode body portion 111. Optionally, the gap G located on the outer side of the positive electrode body portion 111 includes a first gap G1 and a second gap G2.

[0308] In some embodiments, gaps G are provided on both the inner and outer sides of the positive electrode main body 111. Optionally, the gaps located on the inner side of the positive electrode main body 111 include a first gap G1 and a second gap G2, and the gaps located on the outer side of the positive electrode main body 111 include a first gap G1 and a second gap G2. Specifically, a first gap G1 is formed between the inner surface of the positive electrode main body 111 and the separator 13 located on the inner side of the inner surface of the positive electrode main body 111, and another first gap G1 is formed between the outer surface of the positive electrode main body 111 and the separator 13 located on the outer side of the outer surface of the positive electrode main body 111; a second gap G2 is formed between the outer surface of the negative electrode main body 121 and the separator 13 located on the outer side of the outer surface of the negative electrode main body 121, and another second gap G2 is formed between the inner surface of the negative electrode main body 121 and the separator 13 located on the inner side of the inner surface of the negative electrode main body 121.

[0309] In some embodiments, the gap G extends along the winding direction V of the electrode assembly 10, and the gap G has a winding start end E1 and a winding end end E2.

[0310] The gap G is wound multiple times along the winding direction V.

[0311] As an example, the positive electrode body 111 has a positive electrode winding start end E3 and a positive electrode winding end E4, and the negative electrode body 121 has a negative electrode winding start end E5 and a negative electrode winding end E6. Along the winding direction V, the negative electrode winding end E6 extends beyond the positive electrode winding end E4; in the opposite direction of the winding direction V, the negative electrode winding start end E5 extends beyond the positive electrode winding start end E3. Both ends of the negative electrode body 121 extend beyond the positive electrode body 111 along the winding direction V, providing an intercalation space for active ions extracted from the positive electrode body 111, thereby reducing the risk of ion extraction. In the radial direction of the cylindrical battery cell 7, the winding start end E1 of the gap G corresponds to the positive electrode winding start end E3, and the winding end end E2 of the gap G corresponds to the positive electrode winding end E4.

[0312] In some embodiments, there are two gaps G, which are respectively disposed on both sides of the positive electrode body 111.

[0313] As an example, in the radial direction of the cylindrical battery cell 7, the winding start end E1 of the gap G located inside the positive electrode main body 111 is located inside the positive electrode winding start end E3, and the winding start end E1 of the gap G located outside the positive electrode main body 111 is located outside the positive electrode winding start end E3.

[0314] In this embodiment of the application, by setting two gaps G, the expansion of the electrode assembly 10 can be further reduced, thereby reducing the squeezing effect on the outer casing 20, reducing the risk of deformation and cracking of the outer casing 20, and improving the reliability of the cylindrical battery cell.

[0315] Figure 13 A partial cross-sectional view of the electrode assembly of a cylindrical battery cell provided for other embodiments of this application. Figure 13 It shows a ring of positive electrode, a ring of negative electrode, and a ring of separator.

[0316] Reference Figure 13 In some embodiments, the radial dimension of the portion of gap G near the winding end E2 is greater than the radial dimension of the portion of gap G near the winding start end E1.

[0317] In the embodiments of this application, the radial dimensions of different portions of the gap G along the winding direction V are compared within the same cross section perpendicular to the axial direction Z.

[0318] As an example, the portion of gap G near the winding end E2 can be: the portion of gap G located inside the winding end E2 and 10mm away from the winding end in the winding direction V; the portion of gap G near the winding start end E1 can be: the portion of gap G located inside the winding start end E1 and 10mm away from the winding start end in the winding direction V.

[0319] There can be one or more gaps G. In the embodiments of this application, the portion of gap G near the winding end E2 and the portion of gap G near the winding start end E1 refer to the same gap G.

[0320] As an example, the radial dimension of the portion of gap G near the winding start end E1 can be equal to the sum of the radial dimension of the portion of the first gap G1 near the winding start end E1 and the radial dimension of the portion of the second gap G2 near the winding start end E1.

[0321] As an example, the radial dimension of the portion of gap G near the winding end E2 can be equal to the sum of the radial dimension of the portion of the first gap G1 near the winding end E2 and the radial dimension of the portion of the second gap G2 near the winding end E2.

[0322] During the cycling process of the cylindrical battery cell 7, the expansion of the negative electrode body 121 gradually accumulates radially from the inside to the outside. In the embodiments of this application, the portion of the gap G near the winding end E2 has a larger radial dimension to provide more expansion space for the negative electrode body 121, absorb the accumulated expansion of the negative electrode body 121, thereby reducing the force between the electrode assembly 10 and the outer casing 20, reducing the deformation of the outer casing 20, reducing the risk of cracking of the outer casing 20, and improving reliability.

[0323] In some embodiments, the gap G is wound along the winding direction V to form m winding loops, where m ≥ 20 and m is a natural number; the innermost winding loop is the first winding loop.

[0324] For example, the first winding loop includes a winding start end E1; the first winding loop extends one revolution from the winding start end E1 along the winding direction V.

[0325] For example, the m-th winding loop includes a winding termination end E2; the m-th winding loop extends from the end of the (m-1)-th winding loop along the winding direction V to the winding termination end E2.

[0326] For example, the first to m-1 windings are all full turns; the m-th winding can be a full turn or not a full turn, for example, the m-th winding is 1 / 4 turn, 1 / 2 turn or 3 / 4 turn. For example, m is 20, 30, 40, 50, 60, 70, 80, 90, 100, 150 or 200.

[0327] In some embodiments, there are two gaps G, which are respectively disposed on both sides of the positive electrode body portion 111. For example, the gap G located inside the positive electrode body portion 111 can be defined as the inner gap, and the gap G located outside the positive electrode body portion 111 can be defined as the outer gap.

[0328] The inner gap is wound along the winding direction V to form m winding loops, and the outer gap is wound along the winding direction V to form m winding loops.

[0329] The q-th winding of the outer gap is located outside the q-th winding of the inner gap, and inside the (q+1)-th winding of the inner gap, where 1 ≤ q ≤ m-1. The m-th winding of the outer gap is located outside the m-th winding of the inner gap.

[0330] In some embodiments, the radial dimension of the kth winding is less than the radial dimension of the (k+10)th winding, where k is a natural number and 5≤k≤m-15.

[0331] In the 5th to m-15th windings, any one of the windings satisfies the aforementioned relationship. For example, the radial dimension of the 5th winding is smaller than the radial dimension of the 15th winding, the radial dimension of the 6th winding is smaller than the radial dimension of the 16th winding, ..., the radial dimension of the m-16th winding is smaller than the radial dimension of the m-6th winding, and the radial dimension of the m-15th winding is smaller than the radial dimension of the m-5th winding.

[0332] In this embodiment of the application, the kth winding and the (k+10th)th winding are two windings with the same gap G.

[0333] In this embodiment, the radial dimension of the kth winding and the (k+10th)th winding are compared within the same cross section perpendicular to the axial direction Z.

[0334] The (k+10)th winding is positioned further outward than the kth winding, and the radial dimension of the (k+10)th winding is larger than that of the kth winding. The (k+10)th winding can provide more expansion space for the inner negative electrode body 121, absorb the accumulated expansion of the negative electrode body 121, thereby reducing the force between the electrode assembly 10 and the housing 20, reducing the deformation of the housing 20, reducing the risk of cracking of the housing 20, and improving reliability.

[0335] In some embodiments, the gap G is wound along the winding direction V to form m winding loops, where m ≥ 20 and m is a natural number. The innermost winding loop is the first winding loop. The average radial dimension of the (m-9)th to (m-5)th winding loops is greater than the average radial dimension of the 5th to 9th winding loops.

[0336] In the embodiments of this application, the gap G can be one or two. The (m-9)th to (m-5)th winding turns and the 5th to 9th winding turns all belong to the same gap G.

[0337] In the embodiments of this application, the radial dimensions of the m-9 to m-5 windings and the radial dimensions of the 5th to 9th windings are measured and calculated in the same cross section perpendicular to the axial direction Z.

[0338] The portion of gap G near the winding end E2 has a larger radial dimension to provide more expansion space for the negative electrode body 121, absorb the accumulated expansion of the negative electrode body 121, thereby reducing the force between the electrode assembly 10 and the housing 20, reducing the deformation of the housing 20, reducing the risk of cracking of the housing 20, and improving reliability.

[0339] In some embodiments, the radial dimension W of at least a portion of the gap G gradually decreases along the winding direction V.

[0340] The radial dimension of the gap G changes gradually, reducing abrupt changes in the radial dimension of the gap G, reducing stress concentration in the negative electrode 12, and improving the cycle performance of the cylindrical battery cell 7.

[0341] Figure 14 A partial cross-sectional view of the electrode assembly of a cylindrical battery cell provided for other embodiments of this application.

[0342] In some embodiments, refer to Figure 14 The electrode assembly 10 includes a central region C1 and two end regions C2 arranged along the axial direction Z of the cylindrical battery cell 7, with the central region C1 located between the two end regions C2. The radial dimension of the portion of the gap G located in the central region C1 is smaller than the radial dimension of the portion of the gap G located in the end regions C2.

[0343] As an example, the separator 13 has a first end E7 and a second end E8 disposed opposite each other along the axial direction Z; the distance between the first end E7 and the second end E8 in the axial direction Z is L.

[0344] The end region C2 is a region with a certain size along the axial direction Z. One end region C2 extends from the first end E7 toward the second end E8 to a length L1, and the other end region C2 extends from the second end E8 toward the first end E7 to a length L1. The middle region C1 includes a region extending from the mid-section S toward the first end E7 to a length L2 and a region extending from the mid-section S toward the second end E8 to a length L2. The mid-section S is a section perpendicular to the axial direction Z; along the axial direction Z, the distance between the mid-section S and the first end E7 is equal to the distance between the mid-section S and the second end E8.

[0345] A portion of the positive electrode body 111 is located in the middle region C1, and another portion is located in the end region C2.

[0346] For example, L1 / L is 0.1-0.3, and can be 0.2. For example, L2 / L is 0.03-0.2, and can be 0.1.

[0347] For example, L1 can be 20mm and L2 can be 5mm.

[0348] As an example, the radial dimensions of the portion of gap G located in the middle region C1 and the radial dimensions of the portion of gap G located in the end region C2 can be measured in the following manner:

[0349] Using CT (Computed Tomography) technology, images of two cross-sections of a cylindrical battery cell are obtained using X-rays. Both cross-sections are perpendicular to the central axis of the cylindrical battery cell, and each cross-section shows the positive electrode body, the negative electrode body, and the separator. One cross-section passes through the middle region C1 of the electrode assembly, and the other cross-section passes through the end region C2 of the electrode assembly. The cross-section passing through the middle region C1 is defined as the first cross-section, and the cross-section passing through the end region C2 is defined as the second cross-section.

[0350] Based on the image of the first cross section, a first virtual straight line is defined, which can pass through the center of the first cross section (the first virtual straight line intersects the central axis);

[0351] Based on the image of the first cross section and the first virtual line, along a direction away from the center of the first cross section and parallel to the first virtual line, the third intersection point of the outer surface of the sixth positive electrode body and the first virtual line is obtained, the fourth intersection point of the inner surface of the tenth positive electrode body and the first virtual line is obtained, and the distance D2 between the third intersection point and the fourth intersection point is measured.

[0352] Based on the image of the second cross section, a second virtual straight line is defined, which can pass through the center of the second cross section (the second virtual straight line intersects the central axis);

[0353] Based on the image of the second cross section and the second virtual line, along a direction away from the center of the second cross section and parallel to the second virtual line, obtain the fifth intersection point between the outer surface of the sixth positive electrode body and the second virtual line, obtain the sixth intersection point between the inner surface of the tenth positive electrode body and the second virtual line, and measure the distance D3 between the fifth intersection point and the sixth intersection point.

[0354] Disassemble the cylindrical battery cell and unfold the positive electrode, negative electrode, and separator;

[0355] Fifty positions are randomly selected on the positive electrode body of the positive electrode sheet, and 50 thickness values ​​are measured. Then the average value of the 50 thickness values ​​is calculated, which can be the thickness T1 of the positive electrode body.

[0356] Arbitrarily select 50 positions on the negative electrode body of the negative electrode sheet, measure 50 thickness values, and then calculate the average value of the 50 thickness values. This average value can be the thickness T2 of the negative electrode body.

[0357] Select 50 arbitrary locations on the separator and measure 50 thickness values. Then calculate the average value of the 50 thickness values, which can be the thickness T3 of the separator.

[0358] Between the outer surface of the 6th positive electrode main body and the inner surface of the 10th positive electrode main body, there are 3 positive electrode main bodies, 4 negative electrode main bodies, and 8 insulating components; 8 gaps are formed between the outer surface of the 6th positive electrode main body and the inner surface of the 10th positive electrode main body.

[0359] The radial dimension of the portion of gap G located in the middle region C1 can be (D2-3×T1-4×T2-8×T3) / 8. The radial dimension of the portion of gap G located in the end region C2 can be (D3-3×T1-4×T2-8×T3) / 8.

[0360] In this embodiment, the gap G has a larger radial dimension in the end region C2 to facilitate the entry of electrolyte into the gap G, improve the wetting effect of electrolyte on the electrode, and enhance the cycle performance of the cylindrical battery cell 7.

[0361] In some embodiments, the radial dimension of the portion of the gap G located in the central region C1 is 5 μm-60 μm, and optionally 10 μm-30 μm.

[0362] In some embodiments, the electrode assembly 10 further includes a transition region C3 connecting the central region C1 and the end region C2.

[0363] In some embodiments, the radial dimension of the gap G decreases in the direction from the two end regions C2 to the middle region C1, so as to reduce the abrupt change in the radial dimension of the gap G, reduce the stress concentration of the negative electrode 12, and improve the cycle performance of the cylindrical battery cell 7.

[0364] For example, in the axial direction Z, the radial dimension of the clearance G shows a trend of first decreasing and then increasing.

[0365] Figure 15 A cross-sectional schematic diagram of the electrode assembly of a cylindrical battery cell provided in some embodiments of this application; Figure 16 for Figure 15 Enlarged illustration within the dashed box; Figure 17 This is a schematic diagram of the separator of the electrode assembly of a cylindrical battery cell provided in some embodiments of this application.

[0366] Reference Figures 15 to 17At least one of the positive electrode main body 111, the negative electrode main body 121 and the isolation member 13 includes a base part and a plurality of support parts 14, with the support parts 14 protruding from the base part.

[0367] The support part 14 can be rigid or flexible.

[0368] In the electrode assembly 10, one of the positive electrode main body 111, the negative electrode main body 121 and the separator 13 may be provided with a support part 14, or both may be provided with a support part 14, or all three may be provided with a support part 14.

[0369] In some examples, the positive electrode body portion 111 includes a base portion and a plurality of support portions 14. As an example, the base portion of the positive electrode body portion 111 may be a first base portion 1111, and the plurality of support portions 14 of the positive electrode body portion 111 protrude from the first base portion 1111.

[0370] The support portion 14 of the positive electrode main body portion 111 can be protruding entirely from the first base portion 1111, or it can be partially embedded in the first base portion 1111 and partially protruding from the first base portion 1111.

[0371] Optionally, the negative electrode main body 121 and the isolation member 13 may be provided with a support part 14, or they may not be provided with a support part 14.

[0372] Optionally, among the multiple support portions 14 of the positive electrode main body portion 111, some of the support portions 14 may contact the isolation member 13, or all of the support portions 14 may contact the isolation member 13.

[0373] Optionally, the multiple support portions 14 of the positive electrode body portion 111 are distributed separately.

[0374] The first base portion 1111 has two first surfaces 1111a disposed opposite to each other along its thickness direction. Optionally, one of the first surfaces 1111a of the first base portion 1111 is provided with a plurality of support portions 14. Of course, the first base portion 1111 may be provided with a plurality of support portions 14 along the radially inward first surface 1111a of the cylindrical battery cell 7, or the first base portion 1111 may be provided with a plurality of support portions 14 along the radially outward first surface 1111a of the cylindrical battery cell 7. Alternatively, both first surfaces 1111a of the first base portion 1111 may be provided with a plurality of support portions 14.

[0375] In some examples, the negative electrode main body 121 includes a base portion and a plurality of support portions 14. The base portion of the negative electrode main body 121 may be a second base portion 1211; the plurality of support portions 14 of the negative electrode main body 121 protrude from the second base portion 1211.

[0376] The support portion 14 of the negative electrode main body portion 121 may be protruding entirely from the second base portion 1211, or it may be partially embedded in the second base portion 1211 and partially protruding from the second base portion 1211.

[0377] Optionally, the positive electrode body 111 and the isolation member 13 may be provided with a support 14, or they may not be provided with a support 14.

[0378] Optionally, among the multiple support portions 14 of the negative electrode main body portion 121, some of the support portions 14 may contact the isolation member 13, or all of the support portions 14 may contact the isolation member 13.

[0379] Optionally, the multiple support portions 14 of the negative electrode main body 121 are distributed separately.

[0380] The second base portion 1211 has two second surfaces 1211a disposed opposite to each other along its thickness direction. Optionally, one second surface 1211a of the second base portion 1211 may be provided with a plurality of support portions 14. Specifically, the second base portion 1211 may be provided with a plurality of support portions 14 on the second surface 1211a of the second base portion 1211 that faces radially inward from the cylindrical battery cell 7, or it may be provided with a plurality of support portions 14 on the second surface 1211a of the second base portion 1211 that faces radially outward from the cylindrical battery cell 7. Alternatively, both second surfaces 1211a of the second base portion 1211 may be provided with a plurality of support portions 14.

[0381] In some examples, the spacer 13 includes a base portion and a plurality of support portions 14. The base portion of the spacer 13 may be a third base portion 131; the plurality of support portions 14 of the spacer 13 protrude from the third base portion 131.

[0382] The support portion 14 of the isolation member 13 may be integrally protruding from the third base portion 131, or it may be partially embedded in the third base portion 131 while the other part protrudes from the third base portion 131.

[0383] Optionally, the positive electrode main body 111 and the negative electrode main body 121 may be provided with a support part 14, or they may not be provided with a support part 14.

[0384] Optionally, the positive electrode body portion 111 may contact a portion of the support portion 14 of the insulating member 13, and / or, the negative electrode body portion 121 may contact a portion of the support portion 14 of the insulating member 13.

[0385] Optionally, the multiple supports 14 of the isolation member 13 are distributed separately.

[0386] The third base portion 131 has two third surfaces 131a disposed opposite to each other along its thickness direction. Optionally, one third surface 131a of the third base portion 131 is provided with a plurality of support portions 14. Of course, the third base portion 131 may be provided with a plurality of support portions 14 on the third surface 131a of the cylindrical battery cell 7 that faces radially inward, or the third base portion 131 may be provided with a plurality of support portions 14 on the third surface 131a of the cylindrical battery cell 7 that faces radially outward. Alternatively, both third surfaces 131a of the third base portion 131 may be provided with a plurality of support portions 14.

[0387] In some examples, one of the positive electrode body portion 111, the negative electrode body portion 121, and the separator 13 is provided with a support portion 14, while the other two are not provided with support portions 14. For example, the separator 13 includes a third base portion 131 and a plurality of support portions 14.

[0388] In some examples, at least two of the positive electrode body 111, the negative electrode body 121, and the separator 13 are provided with a support portion 14, which may be formed in the same or different ways.

[0389] Multiple support portions 14 protrude and support at least one of the positive electrode body portion 111 and the negative electrode body portion 121, thereby forming a gap G between the positive electrode body portion 111 and the negative electrode body portion 121. During the cycling process of the cylindrical battery cell 7, the gap G provides space for the expansion of the negative electrode active material layer 12b, reduces the pressure between the positive electrode body portion 111 and the negative electrode body portion 121, thereby reducing the compression of the electrolyte in the internal pores of the positive electrode active material layer 11b and the internal pores of the negative electrode active material layer 12b. This can reduce the concentration difference of electrolyte in different regions inside the electrode sheet and improve the cycling performance of the cylindrical battery cell 7 with a larger diameter. The gap G can reduce the expansion of the electrode assembly 10, thereby reducing the compression of the casing 20, reducing the risk of deformation and cracking of the casing 20, and improving the reliability of the cylindrical battery cell 7.

[0390] In some embodiments, the support portion 14 is configured to be compressible. During the cycling of the cylindrical battery cell 7, the support portion 14 can be compressed under pressure, thereby providing more expansion space for the negative electrode body portion 121. The compressible support portion 14 can release stress through compression deformation, thereby reducing the risk of the positive electrode body portion 111 or the negative electrode body portion 121 being damaged by the support portion 14 and improving reliability.

[0391] In some embodiments, the isolation member 13 includes a third base portion 131 and a plurality of support portions 14 protruding from the third base portion 131. The plurality of support portions 14 of the isolation member 13 include a fifth support portion 145 and a sixth support portion 146. On the same side of the isolation member 13, the height H5 of the fifth support portion 145 protruding from the third base portion 131 is greater than the height H6 of the sixth support portion 146 protruding from the third base portion 131.

[0392] There may be one or more fifth support portions 145. There may be one or more sixth support portions 146. Optionally, there may be multiple fifth support portions 145 and multiple sixth support portions 146.

[0393] The fifth support portion 145 has a relatively large height, which can support the positive electrode main body portion 111 or the negative electrode main body portion 121 to form a larger gap G, thereby providing more space for the expansion of the negative electrode main body portion 121. The sixth support portion 146 has a smaller height and occupies less space. As the negative electrode main body portion 121 expands, the gap G gradually decreases; the sixth support portion 146 can be compressed only after the negative electrode main body portion 121 has expanded to a certain extent, thus reducing the pressure on the negative electrode main body portion 121 in the initial stage of expansion. When the sixth support portion 146 is compressed, it can slow down the expansion of the negative electrode main body portion 121 to a certain extent, reduce the extruded electrolyte, and improve the cycle performance of the cylindrical battery cell 7.

[0394] In some embodiments, there are multiple fifth support portions 145 and multiple sixth support portions 146.

[0395] In some embodiments, the height H5 of the fifth support portion 145 is 1.1 to 15 times the height H6 of the sixth support portion 146, and optionally 2 to 7 times.

[0396] In some embodiments, at least one of the positive electrode body 111, the negative electrode body 121, and the separator 13 includes a plurality of organic particles P. The support portion 14 includes organic particles P.

[0397] For example, a plurality of organic particles P protrude and are disposed in at least one of the first substrate portion 1111, the second substrate portion 1211 and the third substrate portion 131.

[0398] For example, in the electrode assembly 10, one of the positive electrode main body 111, the negative electrode main body 121 and the separator 13 may be provided with organic particles P, or both may be provided with organic particles P, or all three may be provided with organic particles P.

[0399] Organic particles P can act as a support to form gaps G. When thermal runaway occurs in the cylindrical battery cell 7, organic particles P can form a gel film structure at high temperatures, thereby reducing the diffusion channels of active ions, delaying the time of thermal propagation, and thus improving the reliability of the cylindrical battery cell 7.

[0400] For example, organic particles P can be formed on the positive electrode body 111, the negative electrode body 121, or the separator 13 by coating. Forming the support portion 14 by coating organic particles P simplifies the molding process.

[0401] In some embodiments, the plurality of organic particles P includes a first organic particle P1 and a second organic particle P2, wherein the number-average particle size of the first organic particle P1 is greater than the number-average particle size of the second organic particle P2.

[0402] It should be noted that the number-average particle size of organic particles P is the arithmetic mean of the particle sizes of organic particles P, calculated based on the number of organic particles P. The particle size of organic particles P can also refer to the distance between the two farthest points on the organic particle P.

[0403] The first organic particles P1, with a larger number-average particle size, can support the positive electrode body 111 or the negative electrode body 121 to form a larger gap G, thereby providing more space for the expansion of the negative electrode body 121. The second organic particles P2, with a smaller number-average particle size, can be compressed after the negative electrode body 121 has expanded to a certain extent, thus reducing the pressure on the negative electrode body 121 during the initial expansion. When the second organic particles P2 are compressed, they can slow down the expansion of the negative electrode body 121 to a certain extent, reduce the extruded electrolyte, and improve the cycle performance of the cylindrical battery cell 7.

[0404] In some embodiments, the spacer 13 includes a third base portion 131 and a plurality of support portions 14 protruding from the third base portion 131. The plurality of support portions 14 of the spacer 13 includes a fifth support portion 145 and a sixth support portion 146. On the same side of the spacer 13, the height H5 of the fifth support portion 145 protruding from the third base portion 131 is greater than the height H6 of the sixth support portion 146 protruding from the third base portion 131. The plurality of organic particles P includes a first organic particle P1 and a second organic particle P2. The fifth support portion 145 includes the first organic particle P1, and the sixth support portion 146 includes the second organic particle P2.

[0405] By setting first organic particles P1 and second organic particles P2 with different number-average particle sizes, a fifth support portion 145 and a sixth support portion 146 with different heights can be formed. The fifth support portion 145 has a larger height, which can support the positive electrode main body portion 111 or the negative electrode main body portion 121 to form a larger gap G, thereby providing more space for the expansion of the negative electrode main body portion 121. The sixth support portion 146 can be compressed after the negative electrode main body portion 121 has expanded to a certain extent, which can reduce the pressure on the negative electrode main body portion 121 in the initial stage of expansion. When the sixth support portion 146 is compressed, it can slow down the expansion of the negative electrode main body portion 121 to a certain extent, reduce the extruded electrolyte, and improve the cycle performance of the cylindrical battery cell 7.

[0406] In some embodiments, the number-average particle size of the first organic particle P1 is >10 μm, and the number-average particle size of the second organic particle P2 is 2 μm-10 μm.

[0407] In some embodiments, the number-average particle size of the first organic particle P1 is 12 μm-25 μm. For example, the number-average particle size of the first organic particle P1 can be 12 μm, 13 μm, 15 μm, 16 μm, 18 μm, 20 μm, 21 μm, 22 μm, 24 μm or 25 μm.

[0408] In some embodiments, the number-average particle size of the second organic particle P2 is 2 μm-9 μm. For example, the number-average particle size of the first organic particle P1 can be 2 μm, 2.5 μm, 3 μm, 4 μm, 5 μm, 5.5 μm, 6 μm, 7 μm, 8 μm or 9 μm.

[0409] In some embodiments, the ratio of the number-average particle size of the first organic particle P1 to the number-average particle size of the second organic particle P2 is greater than or equal to 1.5.

[0410] In some embodiments, the first organic particle P1 is a secondary particle.

[0411] In some embodiments, the second organic particle P2 is a primary particle.

[0412] 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 aggregates. Secondary particles refer to aggregated particles formed by the aggregation of two or more primary particles.

[0413] In some embodiments, the plurality of organic particles P includes a first organic particle P1, the first organic particle P1 including a homopolymer or copolymer of fluorinated alkenyl monomer units, a homopolymer or copolymer of olefinic monomer units, a homopolymer or copolymer of unsaturated nitrile monomer units, a homopolymer or copolymer of epoxide monomer units, and one or more of the modified compounds of the above homopolymers or copolymers.

[0414] In some embodiments, the fluorinated alkenyl monomer unit may be selected from one or more of difluoroethylene, vinylidene fluoride, trifluoroethylene, trifluorochloroethylene, tetrafluoroethylene, and hexafluoropropylene.

[0415] In some embodiments, the olefin-based monomer unit may be selected from one or more of ethylene, propylene, butadiene, isoprene, etc.

[0416] In some embodiments, the unsaturated nitrile monomer unit may be selected from one or more of acrylonitrile, methacrylonitrile, etc.

[0417] In some embodiments, the alkyl oxide monomer unit may be selected from one or more of ethylene oxide, propylene oxide, etc.

[0418] In some embodiments, the first organic particle P1 includes one or more of the following: polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride, polyethylene, polypropylene, polyacrylonitrile, polyethylene oxide, copolymers of different fluorinated alkenyl monomer units, copolymers of fluorinated alkenyl monomer units and olefin monomer units, copolymers of fluorinated alkenyl monomer units and acrylic monomer units, copolymers of fluorinated alkenyl monomer units and acrylate monomer units, and modified compounds of the above homopolymers or copolymers.

[0419] In some embodiments, the first organic particle P1 may include one or more of the following: vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-trifluoroethylene-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene-acrylic acid copolymer, vinylidene fluoride-hexafluoropropylene-acrylate copolymer, and a modified compound of the above copolymers.

[0420] In some embodiments, the plurality of organic particles P includes a second organic particle P2, which includes one or more of the following: homopolymers or copolymers of acrylate monomer units, homopolymers or copolymers of acrylic monomer units, homopolymers or copolymers of styrene monomer units, polyurethane compounds, rubber compounds, and modified compounds of the above-mentioned homopolymers or copolymers.

[0421] In some embodiments, the second organic particle P2 comprises one or more of the following: a copolymer of acrylate monomer units and styrene monomer units, a copolymer of acrylate monomer units and styrene monomer units, a copolymer of acrylate 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 monomer units-unsaturated nitrile monomer units, and a modified compound of the above copolymers.

[0422] In some embodiments, the acrylate monomer unit may be selected from one or more of methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, methyl methacrylate, butyl methacrylate, isooctyl methacrylate, etc.

[0423] In some embodiments, the acrylic monomer unit may be selected from one or more of acrylic acid, methacrylic acid, etc.

[0424] In some embodiments, the styrene monomer unit may be selected from one or more of styrene, methylstyrene, etc.

[0425] In some embodiments, the unsaturated nitrile monomer unit may be selected from one or more of acrylonitrile, methacrylonitrile, etc.

[0426] In some embodiments, the second organic particle P2 may include one or more of the following: butyl acrylate-styrene copolymer, butyl methacrylate-isooctyl methacrylate copolymer, isooctyl methacrylate-styrene copolymer, methacrylate-methacrylate-styrene copolymer, methyl acrylate-isooctyl methacrylate-styrene copolymer, butyl acrylate-isooctyl methacrylate-styrene copolymer, butyl acrylate-isooctyl methacrylate-styrene copolymer, butyl methacrylate-isooctyl methacrylate-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 the above materials.

[0427] In some embodiments, the separator 13 includes a third base portion 131 and a plurality of support portions 14 protruding from the third base portion 131, wherein the support portions 14 of the separator 13 include organic particles P.

[0428] The organic particle P may protrude entirely from the third matrix portion 131. Alternatively, a portion of the organic particle P may be embedded in the third matrix portion 131, while another portion protrudes from the third matrix portion 131.

[0429] Organic particles P can support the positive electrode body 111 or the negative electrode body 121 to increase the gap G and provide space for the expansion of the negative electrode body 121.

[0430] In some embodiments, the third substrate portion 131 includes a base film 1311 and an inorganic particle layer 1312 disposed on the base film 1311. The organic particles P of the separator 13 are disposed on the inorganic particle layer 1312, and at least a portion of the organic particles P of the separator 13 protrudes from the inorganic particle layer 1312.

[0431] The inorganic particle layer 1312 includes multiple inorganic particles, and 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 enable the cylindrical battery cell 7 to have better cycle performance and reliability.

[0432] In some embodiments, inorganic particles can be coated onto the base film 1311 to form an inorganic particle layer 1312, and then a plurality of organic particles P can be coated onto the inorganic particle layer 1312. In other embodiments, the inorganic particles and organic particles P can be mixed first and then coated onto the base film 1311 together.

[0433] In some embodiments, one surface of the base film 1311 is coated with a coating comprising an inorganic particle layer 1312 and a plurality of organic particles P, and the other surface of the base film 1311 may be uncoated or coated with an inorganic particle layer 1312. In other embodiments, both surfaces of the base film 1311 are coated with a coating comprising an inorganic particle layer 1312 and organic particles P.

[0434] The formation of sufficient and unevenly distributed voids between the inorganic and organic particles P improves the permeability of the separator 13, giving the cylindrical battery cell 7 better cycle performance and reliability. The organic particles P can support the positive electrode body 111 or the negative electrode body 121 to increase the gap G and provide space for the expansion of the negative electrode body 121.

[0435] In some embodiments, the inorganic particles may 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), and magnesium fluoride (MgF2).

[0436] In some embodiments, the volume average particle size Dv50 of the inorganic particles is ≤2.5μm; for example, the particle size of the inorganic particles can be 0.5μm-2.5μm, 1.5μm-2.5μm, 0.3μm-0.7μm, etc.

[0437] In some embodiments, the surface of the base film 1311 facing the positive electrode 11 is coated with a coating comprising an inorganic particle layer 1312 and a plurality of organic particles P, and / or the surface of the base film 1311 facing the negative electrode 12 is coated with a coating comprising an inorganic particle layer 1312 and a plurality of organic particles P.

[0438] Figure 18 A partial cross-sectional schematic diagram of the electrode assembly of a cylindrical battery cell provided in other embodiments of this application; Figure 19 This is a schematic diagram of the separator of the electrode assembly of a cylindrical battery cell provided in other embodiments of this application.

[0439] Reference Figure 18 and Figure 19 In some embodiments, multiple support portions 14 are provided on both sides of the isolation member 13.

[0440] The gap G includes a first gap G1 and a second gap G2. The first gap G1 is formed between the positive electrode main body 111 and the separator 13, and the second gap G2 is formed between the negative electrode main body 121 and the separator 13.

[0441] In the thickness direction of the spacer 13, the support portions 14 located on both sides of the spacer 13 may or may not overlap.

[0442] By providing multiple support portions 14 on both sides of the separator 13, the gap G can be increased, providing more space for the expansion of the negative electrode 12.

[0443] In some embodiments, the base film 1311 has a coating comprising an inorganic particle layer 1312 and a plurality of organic particles P on both sides.

[0444] Figure 20 A partial cross-sectional schematic diagram of the electrode assembly of a cylindrical battery cell provided in some embodiments of this application; Figure 21 A schematic diagram of the positive electrode sheet of an electrode assembly provided in some embodiments of this application after being flattened; Figure 22 A cross-sectional schematic diagram of the positive electrode sheet of an electrode assembly provided in some embodiments of this application; Figure 23 This is a cross-sectional schematic diagram of the negative electrode sheet of an electrode assembly provided in some embodiments of this application.

[0445] Reference Figures 20 to 23 The positive electrode main body 111 includes a first base part 1111 and a plurality of support parts 14 protruding from the first base part 1111.

[0446] In this embodiment of the application, the support portion 14 may be provided on one side of the positive electrode main body portion 111, or the support portion 14 may be provided on both sides of the positive electrode main body portion 111.

[0447] In some embodiments, the positive electrode body portion 111 includes a plurality of positive electrode protrusions 1112 protruding from the surface of the first base portion 1111, and the positive electrode body portion 111 has a positive electrode recess 1113 on the side away from the positive electrode protrusions 1112, corresponding to the position of the positive electrode protrusions 1112. The support portion 14 of the positive electrode sheet 11 includes the positive electrode protrusions 1112.

[0448] As an example, the number of positive electrode recesses 1113 and positive electrode protrusions 1112 are the same, and they are set in a one-to-one correspondence.

[0449] The height of the multiple positive electrode protrusions 1112 protruding from the first base portion 1111 can be the same or different.

[0450] The positive electrode protrusion 1112 can support the separator 13 and the negative electrode body 121, thereby forming a gap G. The positive electrode recess 1113 can accommodate the electrolyte and also provide space for the expansion of the negative electrode body 121.

[0451] As an example, the positive electrode protrusion 1112 and the positive electrode recess 1113 can be formed by stamping the positive electrode sheet 11.

[0452] In some embodiments, organic particles may be disposed on the surface of the positive electrode protrusion 1112.

[0453] In some embodiments, all the positive electrode protrusions 1112 protrude toward the same side of the first base portion 1111. Correspondingly, a plurality of support portions 14 of the positive electrode body portion 111 are disposed on the same side of the first base portion 1111.

[0454] The embodiments of this application can simplify the forming process of the positive electrode 11.

[0455] In some embodiments, a plurality of positive electrode protrusions 1112 protrude from the same side of the first base portion 1111. Among the plurality of positive electrode protrusions 1112, a portion of the positive electrode protrusions 1112 protrude from the first base portion 1111 at a higher height, while another portion of the positive electrode protrusions 1112 protrude from the first base portion 1111 at a lower height. Exemplarily, the plurality of support portions 14 of the positive electrode body portion 111 include a first support portion and a second support portion. The first support portion includes positive electrode protrusions 1112 at a higher height, and the second support portion includes positive electrode protrusions 1112 at a lower height.

[0456] In some embodiments, the side of the separator 13 facing the positive electrode recess 1113 is provided with a plurality of support portions 14, and at least a portion of the plurality of support portions 14 of the separator 13 does not overlap with the positive electrode recess 1113 in the radial direction.

[0457] In some embodiments, the negative electrode main body 121 includes a second base portion 1211 and a plurality of support portions 14 protruding from the second base portion 1211.

[0458] In this embodiment of the application, the support portion 14 may be provided on one side of the negative electrode main body portion 121, or the support portion 14 may be provided on both sides of the negative electrode main body portion 121.

[0459] In some embodiments, the negative electrode main body 121 includes a plurality of negative electrode protrusions 1212 protruding from the surface of the second base portion 1211, and the negative electrode main body 121 has a negative electrode recess 1213 on the side away from the negative electrode protrusions 1212, corresponding to the position of the negative electrode protrusions 1212. The support portion 14 of the negative electrode main body 121 includes the negative electrode protrusions 1212.

[0460] As an example, the number of negative electrode recesses 1213 and negative electrode protrusions 1212 are the same, and they are set in a one-to-one correspondence.

[0461] The height of the multiple negative electrode protrusions 1212 protruding from the second base portion 1211 can be the same or different.

[0462] The negative electrode protrusion 1212 can support the separator 13 and the positive electrode body 111, thereby forming a gap G. The negative electrode recess 1213 can accommodate the electrolyte and also provide space for the expansion of the negative electrode body 121.

[0463] As an example, the negative electrode protrusion 1212 and the negative electrode recess 1213 can be formed by stamping the negative electrode sheet 12.

[0464] In some embodiments, organic particles may be disposed on the surface of the negative electrode protrusion 1212.

[0465] In some embodiments, all the negative electrode protrusions 1212 protrude toward the same side of the second base portion 1211. Correspondingly, a plurality of support portions 14 of the negative electrode body portion 121 are disposed on the same side of the second base portion 1211.

[0466] The embodiments of this application can simplify the forming process of the negative electrode 12.

[0467] In some embodiments, a plurality of negative electrode protrusions 1212 protrude from the same side of the second base portion 1211. Among the plurality of negative electrode protrusions 1212, a portion of the negative electrode protrusions 1212 protrude from the second base portion 1211 at a higher height, while another portion of the negative electrode protrusions 1212 protrude from the second base portion 1211 at a lower height. Exemplarily, the plurality of support portions 14 of the negative electrode body portion 121 include a third support portion and a fourth support portion. The third support portion includes a negative electrode protrusion 1212 at a higher height, and the fourth support portion includes a negative electrode protrusion 1212 at a lower height.

[0468] In some embodiments, the side of the isolator 13 facing the negative electrode recess 1213 is provided with a plurality of support portions 14, and at least a portion of the plurality of support portions 14 of the isolator 13 does not overlap with the negative electrode recess 1213 in the radial direction.

[0469] In some embodiments, the positive electrode body 111 is provided with a plurality of support portions 14 on the side facing the separator 13, and the separator 13 is provided with a plurality of support portions 14 on the side facing the positive electrode body 111. The plurality of support portions 14 of the positive electrode body 111 facing the separator 13 are at least partially opposite to the plurality of support portions 14 of the separator 13 facing the positive electrode sheet 11.

[0470] Optionally, the negative electrode main body 121 may be provided with a support part 14, or the support part 14 may not be provided.

[0471] As an example, both sides of the positive electrode main body 111 are provided with isolation members 13. The isolation member 13 located inside the positive electrode main body 111 is called the inner isolation member, and the isolation member 13 located outside the positive electrode main body 111 is called the outer isolation member.

[0472] In some examples, the positive electrode body 111 has a plurality of support portions 14 on the side facing the inner separator, and the inner separator has a plurality of support portions 14 on the side facing the positive electrode body 111. The plurality of support portions 14 of the positive electrode body 111 and the plurality of support portions 14 of the inner separator are at least partially opposite to each other. For example, the plurality of positive electrode protrusions 1112 of the positive electrode body 111 are at least partially opposite to the plurality of organic particles P of the inner separator.

[0473] In other examples, the positive electrode body 111 has a plurality of support portions 14 on the side facing the outer separator, and the outer separator has a plurality of support portions 14 on the side facing the positive electrode body 111. The plurality of support portions 14 of the positive electrode body 111 and the plurality of support portions 14 of the outer separator are at least partially opposite to each other. For example, the plurality of positive electrode protrusions 1112 of the positive electrode body 111 are at least partially opposite to the plurality of organic particles P of the outer separator.

[0474] In some other examples, multiple support portions 14 are provided on both sides of the positive electrode main body 111. Multiple support portions 14 are provided on the side of the inner separator facing the positive electrode main body 111, and multiple support portions 14 are provided on the side of the outer separator facing the positive electrode main body 111. The multiple support portions 14 of the positive electrode main body 111 facing the inner separator are at least partially opposite to the multiple support portions 14 of the inner separator facing the positive electrode sheet 11, and the multiple support portions 14 of the positive electrode main body 111 facing the outer separator are at least partially opposite to the multiple support portions 14 of the outer separator facing the positive electrode sheet 11.

[0475] By arranging the plurality of support portions 14 of the positive electrode body 111 and the plurality of support portions 14 of the separator 13 facing each other, the plurality of support portions 14 of the positive electrode body 111 and the plurality of support portions 14 of the separator 13 can at least partially abut against each other, thereby increasing the gap G and providing more space for the expansion of the negative electrode active material layer 12b.

[0476] As an example, embodiments of this application can reduce the depth of the positive electrode recess 1113 and the particle size of the organic particles P, reduce the damage to the positive electrode body 111 during the stamping process, and improve the cycle life of the cylindrical battery cell 7.

[0477] In some embodiments, the negative electrode main body 121 is provided with a plurality of support portions 14 on the side facing the insulating member 13, and the insulating member 13 is provided with a plurality of support portions 14 on the side facing the negative electrode main body 121. The plurality of support portions 14 of the negative electrode main body 121 facing the insulating member 13 are at least partially opposite to the plurality of support portions 14 of the insulating member 13 facing the negative electrode main body 121.

[0478] Optionally, the positive electrode body 111 may be provided with a support part 14, or the support part 14 may not be provided.

[0479] As an example, both sides of the negative electrode main body 121 are provided with isolation members 13. The isolation member 13 located inside the negative electrode main body 121 is called the inner isolation member, and the isolation member 13 located outside the negative electrode main body 121 is called the outer isolation member.

[0480] In some examples, the negative electrode main body 121 has a plurality of support portions 14 on the side facing the inner separator, and the inner separator has a plurality of support portions 14 on the side facing the negative electrode main body 121. The plurality of support portions 14 of the negative electrode main body 121 and the plurality of support portions 14 of the inner separator are at least partially opposite to each other. For example, the plurality of negative electrode protrusions 1212 of the negative electrode main body 121 are at least partially opposite to the plurality of organic particles P of the inner separator.

[0481] In other examples, the negative electrode main body 121 has a plurality of support portions 14 on the side facing the outer separator, and the outer separator has a plurality of support portions 14 on the side facing the negative electrode main body 121. The plurality of support portions 14 of the negative electrode main body 121 and the plurality of support portions 14 of the outer separator are at least partially opposite to each other. For example, the plurality of negative electrode protrusions 1212 of the negative electrode main body 121 are at least partially opposite to the plurality of organic particles P of the outer separator.

[0482] In some other examples, multiple support portions 14 are provided on both sides of the negative electrode main body 121. Multiple support portions 14 are provided on the side of the inner insulating member facing the negative electrode main body 121, and multiple support portions 14 are provided on the side of the outer insulating member facing the negative electrode main body 121. The multiple support portions 14 of the negative electrode main body 121 facing the inner insulating member are at least partially opposite to the multiple support portions 14 of the inner insulating member facing the negative electrode main body 121, and the multiple support portions 14 of the negative electrode main body 121 facing the outer insulating member are at least partially opposite to the multiple support portions 14 of the outer insulating member facing the negative electrode main body 121.

[0483] By arranging the plurality of support portions 14 of the negative electrode main body 121 and the plurality of support portions 14 of the insulating member 13 facing each other, the plurality of support portions 14 of the negative electrode main body 121 and the plurality of support portions 14 of the insulating member 13 can at least partially abut against each other, thereby increasing the gap G and providing more space for the expansion of the negative electrode main body 121.

[0484] As an example, embodiments of this application can reduce the depth of the negative electrode recess 1213 and the particle size of the organic particles P, reduce the damage to the negative electrode body 121 during the stamping process, and improve the cycle life of the cylindrical battery cell 7.

[0485] In some embodiments, the negative electrode main body 121 is provided with a plurality of support portions 14 on the side facing the positive electrode main body 111, and the positive electrode main body 111 is provided with a plurality of support portions 14 on the side facing the negative electrode main body 121. At least a portion of the plurality of support portions 14 of the negative electrode main body 121 facing the positive electrode main body 111 are disposed opposite to the plurality of support portions 14 of the positive electrode main body 111 facing the negative electrode main body 121.

[0486] Optionally, the isolation member 13 may or may not have a support part 14.

[0487] In some examples, a plurality of support portions 14 are provided on the outer side of the positive electrode main body 111, and a plurality of support portions 14 are provided on the inner side of the negative electrode main body 121. The plurality of support portions 14 on the outer side of the positive electrode main body 111 and the plurality of support portions 14 on the inner side of the negative electrode main body 121 are arranged facing each other and overlap radially.

[0488] In some examples, the inner side of the positive electrode main body 111 is provided with a plurality of support portions 14, and the outer side of the negative electrode main body 121 is provided with a plurality of support portions 14. The plurality of support portions 14 on the inner side of the positive electrode main body 111 and the plurality of support portions 14 on the outer side of the negative electrode main body 121 are arranged facing each other and overlap radially.

[0489] In some examples, multiple support portions 14 are provided on both the inner and outer sides of the positive electrode main body 111, and multiple support portions 14 are provided on both the inner and outer sides of the negative electrode main body 121; the multiple support portions 14 on the outer side of the positive electrode main body 111 and the multiple support portions 14 on the inner side of the negative electrode main body 121 are arranged facing each other and overlap in the radial direction, and the multiple support portions 14 on the inner side of the positive electrode main body 111 and the multiple support portions 14 on the outer side of the negative electrode main body 121 are arranged facing each other and overlap in the radial direction.

[0490] By arranging the plurality of support portions 14 of the negative electrode main body 121 and the plurality of support portions 14 of the positive electrode main body 111 facing each other, the plurality of support portions 14 of the negative electrode main body 121 and the plurality of support portions 14 of the positive electrode main body 111 can support each other, thereby increasing the gap G and providing more space for the expansion of the negative electrode main body 121.

[0491] As an example, embodiments of this application can reduce the depth of the negative electrode recess 1213 and the depth of the positive electrode recess 1113, reduce the damage to the positive electrode main body 111 and the negative electrode main body 121 during the stamping process, and improve the cycle life of the cylindrical battery cell 7.

[0492] In some embodiments, the positive electrode 11, the negative electrode 12, and the separator 13 are each provided with a plurality of support portions 14.

[0493] Optionally, multiple support portions 14 are provided on both sides of the isolation member 13.

[0494] Optionally, the outer side of the positive electrode 11 is provided with a plurality of support portions 14, and the inner side of the negative electrode 12 is provided with a plurality of support portions 14; alternatively, the inner side of the positive electrode 11 is provided with a plurality of support portions 14, and the outer side of the negative electrode 12 is provided with a plurality of support portions 14.

[0495] Figure 24 This is a cross-sectional schematic diagram of the positive electrode sheet provided in some other embodiments of this application.

[0496] Reference Figure 24 In some embodiments, the positive electrode body 111 includes a first base portion 1111 and a plurality of support portions 14 protruding from the first base portion 1111.

[0497] In some embodiments, the plurality of support portions 14 of the positive electrode body portion 111 include a first support portion 141 and a second support portion 142. On the same side of the positive electrode body portion 111, the height H1 of the first support portion 141 protruding from the first base portion 1111 is greater than the height H2 of the second support portion 142 protruding from the first base portion 1111.

[0498] There may be one or more first support portions 141. There may be one or more second support portions 142. Optionally, there may be multiple first support portions 141 and multiple second support portions 142.

[0499] The first support portion 141 has a relatively large height, which can support the negative electrode body portion 121 to form a larger gap G, thereby providing more space for the expansion of the negative electrode body portion 121. The second support portion 142 has a smaller height and occupies less space. As the negative electrode body portion 121 expands, the gap G gradually decreases; the second support portion 142 can be compressed only after the negative electrode body portion 121 has expanded to a certain extent, thus reducing the pressure on the negative electrode body portion 121 in the initial stage of expansion. When the second support portion 142 is compressed, it can slow down the expansion of the negative electrode body portion 121 to a certain extent, reduce the extruded electrolyte, and improve the cycle performance of the cylindrical battery cell 7.

[0500] In some embodiments, the height H1 of the first support portion 141 is 1.1 to 15 times the height H2 of the second support portion 142, and can be selected as 2 to 7 times.

[0501] In some embodiments, the support portion 14 of the positive electrode body portion 111 includes organic particles P disposed on the first substrate portion 1111.

[0502] The organic particle P may protrude entirely from the first matrix portion 1111. Alternatively, a portion of the organic particle P may be embedded in the first matrix portion 1111, while another portion protrudes from the first matrix portion 1111.

[0503] The organic particles P of the positive electrode body 111 can support the negative electrode body 121 to increase the gap G and provide space for the expansion of the negative electrode active material layer 12b.

[0504] In some embodiments, the first substrate portion 1111 includes a portion of the positive electrode current collector 11a covered with a positive electrode active material layer 11b, the positive electrode active material layer 11b, and a positive electrode particle coating 11c, wherein the positive electrode particle coating 11c is coated on the surface of the positive electrode active material layer 11b facing away from the positive electrode current collector. Organic particles P at least partially protrude from the positive electrode particle coating 11c.

[0505] The positive electrode particle coating 11c comprises multiple inorganic particles.

[0506] In some embodiments, a portion of the organic particle P is embedded in the positive electrode particle coating 11c, and a portion protrudes from the positive electrode particle coating 11c.

[0507] In some examples, inorganic particles can be coated onto the positive electrode active material layer 11b to form a positive electrode particle coating 11c, and then multiple organic particles P can be coated onto the positive electrode particle coating 11c. In other examples, inorganic particles and organic particles P can be mixed first and then coated together onto the positive electrode active material layer 11b.

[0508] In some embodiments, the plurality of organic particles P in the positive electrode body portion 111 includes a first organic particle P1 and a second organic particle P2, wherein the number-average particle size of the first organic particle P1 is greater than the number-average particle size of the second organic particle P2.

[0509] In some embodiments, the positive electrode body 111 includes a first base portion 1111 and a plurality of support portions 14 protruding from the first base portion 1111. The plurality of support portions 14 of the positive electrode body 111 includes a first support portion 141 and a second support portion 142. On the same side of the positive electrode body 111, the height H1 of the first support portion 141 protruding from the first base portion 1111 is greater than the height H2 of the second support portion 142 protruding from the first base portion 1111. The plurality of organic particles P include a first organic particle P1 and a second organic particle P2. The first support portion 141 includes the first organic particle P1, and the second support portion 142 includes the second organic particle P2.

[0510] By setting the first organic particles P1 and the second organic particles P2, a first support portion 141 and a second support portion 142 with different heights can be formed. The first support portion 141 has a larger height, which can support the negative electrode body portion 121 to form a larger gap G, thereby providing more space for the expansion of the negative electrode body portion 121. The second support portion 142 can be compressed after the negative electrode body portion 121 has expanded to a certain extent, which can reduce the pressure on the negative electrode body portion 121 in the initial stage of expansion. When the second support portion 142 is compressed, it can slow down the expansion of the negative electrode body portion 121 to a certain extent, reduce the extruded electrolyte, and improve the cycle performance of the cylindrical battery cell 7.

[0511] Figure 25 This is a cross-sectional schematic diagram of the negative electrode sheet provided in some other embodiments of this application.

[0512] Reference Figure 25 In some embodiments, the negative electrode main body 121 includes a second base portion 1211 and a plurality of support portions 14 protruding from the second base portion 1211.

[0513] In some embodiments, the plurality of support portions 14 of the negative electrode main body portion 121 include a third support portion 143 and a fourth support portion 144. On the same side of the negative electrode main body portion 121, the height H3 of the third support portion 143 protruding from the second base portion 1211 is greater than the height H4 of the fourth support portion 144 protruding from the second base portion 1211.

[0514] There may be one or more third support portions 143. There may be one or more fourth support portions 144. Optionally, there may be multiple third support portions 143 and multiple fourth support portions 144.

[0515] The third support portion 143 has a relatively large height, which can support the positive electrode body portion 111 to form a larger gap G, thereby providing more space for the expansion of the negative electrode body portion 121. The fourth support portion 144 has a smaller height and occupies less space. As the negative electrode body portion 121 expands, the gap G gradually decreases; the fourth support portion 144 can be compressed only after the negative electrode body portion 121 has expanded to a certain extent, thus reducing the pressure on the negative electrode body portion 121 in the initial stage of expansion. When the fourth support portion 144 is compressed, it can slow down the expansion of the negative electrode body portion 121 to a certain extent, reduce the extruded electrolyte, and improve the cycle performance of the cylindrical battery cell 7.

[0516] In some embodiments, the height H3 of the third support portion 143 is 1.1 to 15 times the height H4 of the fourth support portion 144, and optionally 2 to 7 times.

[0517] In some embodiments, the support portion 14 of the negative electrode body portion 121 includes organic particles P disposed on the second substrate portion 1211.

[0518] The organic particles P of the negative electrode main body 121 may protrude entirely from the second substrate 1211. Alternatively, a portion of the organic particles P of the negative electrode main body 121 may be embedded in the second substrate 1211, and another portion may protrude from the second substrate 1211.

[0519] The organic particles P of the negative electrode body 121 can support the positive electrode body 111 to increase the gap G and provide space for the expansion of the negative electrode active material layer 12b.

[0520] In some embodiments, the second substrate portion 1211 includes a portion of the negative electrode current collector 12a covered with a negative electrode active material layer 12b, the negative electrode active material layer 12b, and a negative electrode particle coating 12c, wherein the negative electrode particle coating 12c is coated on the surface of the negative electrode active material layer 12b facing away from the negative electrode current collector. Organic particles P at least partially protrude from the negative electrode particle coating 12c.

[0521] The negative electrode particle coating 12c of the negative electrode body 121 includes a plurality of inorganic particles.

[0522] In some embodiments, a portion of the organic particles P of the negative electrode body 121 is embedded in the negative electrode particle coating 12c, and a portion protrudes from the negative electrode particle coating 12c.

[0523] In some examples, inorganic particles can be coated onto the negative electrode active material layer 12b to form a negative electrode particle coating 12c, and then multiple organic particles P can be coated onto the negative electrode particle coating 12c. In other examples, inorganic particles and organic particles P can be mixed first and then coated together onto the negative electrode active material layer 12b.

[0524] In some embodiments, the plurality of organic particles P in the negative electrode body portion 121 include a first organic particle P1 and a second organic particle P2, wherein the number-average particle size of the first organic particle P1 is greater than the number-average particle size of the second organic particle P2.

[0525] In some embodiments, the negative electrode main body 121 includes a second base portion 1211 and a plurality of support portions 14 protruding from the second base portion 1211. The plurality of support portions 14 of the negative electrode main body 121 includes a third support portion 143 and a fourth support portion 144. On the same side of the negative electrode main body 121, the height of the third support portion 143 protruding from the second base portion 1211 is greater than the height of the fourth support portion 144 protruding from the second base portion 1211. The plurality of organic particles P include a first organic particle P1 and a second organic particle P2. The third support portion 143 includes the first organic particle P1, and the fourth support portion 144 includes the second organic particle P2.

[0526] By setting the first organic particles P1 and the second organic particles P2, a third support portion 143 and a fourth support portion 144 with different heights can be formed. The third support portion 143 has a larger height, which can support the positive electrode body portion 111 to form a larger gap G, thereby providing more space for the expansion of the negative electrode body portion 121. The fourth support portion 144 can be compressed after the negative electrode body portion 121 has expanded to a certain extent, which can reduce the pressure on the negative electrode body portion 121 in the initial stage of expansion. When the fourth support portion 144 is compressed, it can slow down the expansion of the negative electrode body portion 121 to a certain extent, reduce the extruded electrolyte, and improve the cycle performance of the cylindrical battery cell 7.

[0527] Figure 26 A partial cross-sectional view of the electrode assembly of a cylindrical battery cell provided for other embodiments of this application. Figure 26 It shows a ring of positive electrode, a ring of negative electrode, and a ring of separator.

[0528] Reference Figure 26 In some embodiments, the radial dimension of the portion of gap G near the winding start end E1 is less than or equal to the radial dimension of the portion of gap G near the winding end end E2.

[0529] During the cycling process of the cylindrical battery cell 7, the expansion of the negative electrode body 121 gradually accumulates radially from the inside to the outside. In the embodiments of this application, the portion of the gap G near the winding end E2 has a larger radial dimension to provide more expansion space for the negative electrode body 121, absorb the accumulated expansion of the negative electrode body 121, thereby reducing the force between the electrode assembly 10 and the outer casing 20, reducing the deformation of the outer casing 20, reducing the risk of cracking of the outer casing 20, and improving reliability.

[0530] In some embodiments, the radial dimensions of the gap G at various locations can be adjusted by changing the height of the support 14.

[0531] Figure 27 A partial cross-sectional view of the electrode assembly of a cylindrical battery cell provided for other embodiments of this application.

[0532] In some embodiments, the electrode assembly 10 includes a central region C1 and two end regions C2 arranged along the axial direction Z of the cylindrical battery cell 7, with the central region C1 located between the two end regions C2. The radial dimension of the portion of the gap G located in the central region C1 is smaller than the radial dimension of the portion of the gap G located in the end regions C2.

[0533] The gap G has a large radial dimension in the end region C2 to facilitate the entry of electrolyte into the gap G, improve the wetting effect of electrolyte on the electrode, and enhance the cycle performance of the cylindrical battery cell 7.

[0534] In some embodiments, the radial dimension of the gap G in each region can be adjusted by changing the height of the support 14.

[0535] Figure 28 A partial cross-sectional schematic diagram of the electrode assembly of a cylindrical battery cell provided in other embodiments of this application; Figure 29 A schematic diagram of the positive electrode sheet of a cylindrical battery cell in an unfolded state, provided in some other embodiments of this application; Figure 30 This is a schematic diagram of the negative electrode sheet of a cylindrical battery cell in an unfolded state, as provided in some other embodiments of this application.

[0536] Reference Figures 28 to 30 In some embodiments, the surface of the positive electrode body 111 opposite to the separator 13 is provided with a first recess 1114.

[0537] The first recess 1114 can be one or more.

[0538] For example, the positive electrode body 111 has isolation members 13 on both sides along its thickness direction. Optionally, the positive electrode body 111 has a first recess 1114 on one side along its thickness direction; alternatively, the positive electrode body 111 has a first recess 1114 on all sides along its thickness direction.

[0539] For example, in the thickness direction of the positive electrode body portion 111, the depth of the first recess 1114 is less than or equal to the thickness of the positive electrode active material layer 11b. The thickness of the positive electrode active material layer 11b is the thickness of the positive electrode active material layer 11b located on one side of the positive electrode current collector 11a.

[0540] By providing the first recess 1114, the gap between the positive electrode body 111 and the negative electrode body 121 can be increased. During the cycling process of the cylindrical battery cell 7, the first recess 1114 can provide space for the expansion of the negative electrode active material layer 12b, reducing the pressure between the positive electrode body 111 and the negative electrode body 121. This reduces the compression of the electrolyte in the internal pores of the positive electrode active material layer 11b and the negative electrode active material layer 12b, reduces the concentration difference of electrolyte in different regions inside the electrode, and improves the cycling performance of the cylindrical battery cell 7 with a larger diameter. The first recess 1114 can reduce the expansion of the electrode assembly 10, thereby reducing the compression effect on the casing 20, reducing the risk of deformation and cracking of the casing 20, and improving the reliability of the cylindrical battery cell 7.

[0541] The first recess 1114 can also accommodate electrolyte, which helps the electrolyte to wet the positive electrode body 111 and the negative electrode body 121.

[0542] In some embodiments, the first gap includes a first recess 1114.

[0543] In some embodiments, the first recess 1114 is formed on the positive electrode active material layer 11b, which can reduce the influence of the first recess 1114 on the positive electrode current collector 11a.

[0544] In some embodiments, the positive electrode body 111 does not have a protruding support portion.

[0545] In some embodiments, after the positive electrode body 111 is flattened, the two opposing surfaces of the positive electrode body along its own thickness direction can be planes.

[0546] In some embodiments, the depth of the first recess 1114 is less than the thickness of the positive electrode active material layer 11b in the thickness direction of the positive electrode body portion 111. Optionally, the ratio of the depth of the first recess 1114 to the thickness of the positive electrode active material layer 11b in the thickness direction of the positive electrode body portion 111 is 0.01-0.5.

[0547] In some embodiments, the first recess 1114 extends through the positive electrode body portion 111 along the axial direction Z to increase the gap between the positive electrode body portion 111 and the negative electrode body portion 121 and improve the wettability of the electrolyte.

[0548] In some embodiments, the first recess 1114 extends along the axial direction Z.

[0549] In some embodiments, the shape of the cross section of the first recess 1114 perpendicular to the axial direction Z is triangular, trapezoidal, semi-circular or other shapes.

[0550] In some embodiments, there are multiple first recesses 1114.

[0551] In some embodiments, at least a portion of the plurality of first recesses 1114 are disposed on the inner side of the positive electrode body portion 111. The inner side of the positive electrode body portion 111 has a large curvature. By disposing the first recesses 1114 on the inner side of the positive electrode body portion 111, stress can be released and the risk of positive electrode active material in the positive electrode active material layer 11b falling off can be reduced.

[0552] In addition, by placing the first recess 1114 inside the positive electrode body 111, the capacity of the positive electrode active material layer 11b inside the positive electrode body 111 can be reduced, thereby reducing the risk of ion deposition in the negative electrode active material layer 12b located inside the positive electrode active material layer 11b.

[0553] In some embodiments, at least a portion of the plurality of first recesses 1114 are disposed on the outer side of the positive electrode body portion 111.

[0554] In some embodiments, the positive electrode body 111 includes a plurality of first recesses 1114 spaced apart along the winding direction V. The plurality of first recesses 1114 can provide space for expansion of different regions of the negative electrode active material layer 12b, reducing the pressure between the positive electrode body 111 and the negative electrode body 121.

[0555] In some embodiments, a second recess 1214 is provided on the surface of the negative electrode main body 121 opposite to the separator 13.

[0556] The second recess 1214 can be one or more.

[0557] For example, the negative electrode main body 121 has isolation members 13 on both sides along its thickness direction. Optionally, the negative electrode main body 121 has a second recess 1214 on one side along its thickness direction; alternatively, the negative electrode main body 121 has a second recess 1214 on all sides along its thickness direction.

[0558] For example, in the thickness direction of the negative electrode body portion 121, the depth of the second recess 1214 is less than or equal to the thickness of the negative electrode active material layer 12b. The thickness of the negative electrode active material layer 12b is the thickness of the negative electrode active material layer 12b located on one side of the negative electrode current collector 12a.

[0559] By providing the second recess 1214, the gap between the positive electrode body 111 and the negative electrode body 121 can be increased. During the cycling process of the cylindrical battery cell 7, the second recess 1214 can provide space for the expansion of the negative electrode active material layer 12b, reducing the pressure between the positive electrode body 111 and the negative electrode body 121. This reduces the compression of the electrolyte in the internal pores of the positive electrode active material layer 11b and the internal pores of the negative electrode active material layer 12b, reduces the concentration difference of electrolyte in different regions inside the electrode, and improves the cycling performance of the cylindrical battery cell 7 with a larger diameter. The second recess 1214 can reduce the expansion of the electrode assembly 10, thereby reducing the compression effect on the casing 20, reducing the risk of deformation and cracking of the casing 20, and improving the reliability of the cylindrical battery cell 7.

[0560] The second recess 1214 can also accommodate electrolyte, which helps the electrolyte to wet the positive electrode body 111 and the negative electrode body 121.

[0561] In some embodiments, the second gap includes a second recess 1214.

[0562] In some embodiments, the second recess 1214 is formed in the negative electrode active material layer 12b, which can reduce the impact of the second recess 1214 on the negative electrode current collector 12a. The second recess 1214 can provide space for the expansion of the negative electrode active material layer 12b.

[0563] In some embodiments, the negative electrode body portion 121 does not have a protruding support portion.

[0564] In some embodiments, after the negative electrode body portion 121 is flattened, the two opposing surfaces of the negative electrode body portion 121 along its own thickness direction can be planes.

[0565] In some embodiments, the depth of the second recess 1214 is less than the thickness of the negative electrode body 121 in the thickness direction. Optionally, the ratio of the depth of the second recess 1214 to the thickness of the negative electrode body 121 in the thickness direction is 0.01-0.5.

[0566] In some embodiments, the second recess 1214 extends through the negative electrode body portion 121 along the axial direction Z to increase the gap between the positive electrode body portion 111 and the negative electrode body portion 121 and improve the wettability of the electrolyte.

[0567] In some embodiments, the second recess 1214 extends along the axial direction Z.

[0568] In some embodiments, the shape of the cross section of the second recess 1214 perpendicular to the axial direction Z is triangular, trapezoidal, semi-circular, or other shapes.

[0569] In some embodiments, there are multiple second recesses 1214.

[0570] In some embodiments, at least a portion of the plurality of second recesses 1214 are disposed on the inner side of the negative electrode main body 121. The inner side of the negative electrode main body 121 has a large curvature. By disposing the second recesses 1214 on the inner side of the negative electrode main body 121, stress can be relieved and the risk of negative electrode active material in the negative electrode active material layer 12b falling off can be reduced.

[0571] In some embodiments, at least a portion of the plurality of second recesses 1214 are disposed on the outer side of the negative electrode body portion 121.

[0572] In some embodiments, the negative electrode body portion 121 includes a plurality of second recesses 1214 spaced apart along the winding direction V. The plurality of second recesses 1214 can provide space for expansion of different regions of the negative electrode active material layer 12b, reducing the pressure between the positive electrode body portion 111 and the negative electrode body portion 121.

[0573] Figure 31 for Figure 4 A cross-sectional schematic diagram of the battery cell shown. Figure 32 for Figure 31 Enlarged view of the area within the circle.

[0574] Reference Figure 4 , Figure 5 , Figure 31 and Figure 32 In some embodiments, the positive electrode tab 112 is wound multiple turns along the winding direction V. Optionally, the end of the positive electrode tab 112 is bent by a flattening or smoothing process to form a multi-layered structure stacked in the axial direction Z.

[0575] In some embodiments, the negative electrode tab 122 is wound multiple turns along the winding direction V. Optionally, the end of the negative electrode tab 122 is bent by a flattening or smoothing process to form a multi-layered structure stacked in the axial direction Z.

[0576] In some embodiments, one of the positive electrode tab 112 and the negative electrode tab 122 is a first electrode tab 10c, and the other is a second electrode tab 10d. The cylindrical battery cell 7 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 10c, and the second electrode lead-out portion 7b being electrically connected to the second electrode tab 10d.

[0577] The first electrode lead-out portion 7a and the second electrode lead-out portion 7b are insulated from each other.

[0578] The first electrode lead-out portion 7a and the second electrode lead-out portion 7b are used to connect to an external circuit to enable charging or discharging of the cylindrical battery cell 7. Exemplarily, when multiple 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 to a busbar component.

[0579] The first electrode lead-out portion 7a can be an electrode terminal 30 disposed on the housing 20. The electrode terminal 30 is formed independently of the housing 20 and is assembled together during the production process of the cylindrical battery cell 7. As an example, the electrode terminal 30 is insulatedly disposed on the end cap 22 or the housing 21.

[0580] Alternatively, the first electrode lead-out portion 7a may also be part of the housing 20. For example, the first electrode lead-out portion 7a may be the end cap 22 of the housing 20, or the first electrode lead-out portion 7a may be the end wall 211 of the housing 21 opposite to the end cap 22.

[0581] The second electrode lead-out portion 7b can be an electrode terminal 30 disposed on the housing 20. Alternatively, the second electrode lead-out portion 7b can be part of the housing 20. For example, the second electrode lead-out portion 7b can be an end cap 22 of the housing 20, or the second electrode lead-out portion 7b can be an end wall 211 of the housing 21 opposite to the end cap 22.

[0582] In some embodiments, the first electrode lead-out portion 7a and the second electrode lead-out portion 7b are located on the same side of the electrode assembly 10 along the axial direction Z of the cylindrical battery cell 7.

[0583] When multiple cylindrical battery cells 7 are assembled into a group, the first electrode lead-out portion 7a and the second electrode lead-out portion 7b of the multiple cylindrical battery cells 7 can be arranged on the same side, which facilitates the connection between the current collector and the first electrode lead-out portion 7a and the second electrode lead-out portion 7b, and simplifies the battery structure.

[0584] In some embodiments, the housing 20 includes a housing 21 and an end cap 22. The housing 21 includes a side wall 212 and an end wall 211. The side wall 212 surrounds the electrode assembly 10. The end wall 211 and the end cap 22 are opposite each other along the axial direction Z of the cylindrical battery cell 7. The end cap 22 is sealed to the side wall 212.

[0585] The sidewall 212 and the endwall 211 can be formed integrally or independently. For example, the sidewall 212 and the endwall 211 can be formed integrally. Alternatively, the sidewall 212 and the endwall 211 can be formed independently and connected by welding or other means.

[0586] The end cap 22 can be insulated from the side wall 212 or electrically connected.

[0587] The end of the housing 21 away from the end wall 211 has an opening, and the end cap 22 covers the opening of the housing 21.

[0588] In some embodiments, the sidewall 212 and the endwall 211 may be integrally formed.

[0589] In some embodiments, one of the positive electrode tab 112 and the negative electrode tab 122 is a first electrode tab 10c, and the other is a second electrode tab 10d. The cylindrical battery cell 7 also includes an electrode terminal 30 insulated from the end wall 211, the first electrode tab 10c being electrically connected to the electrode terminal 30, and the second electrode tab 10d being electrically connected to the end wall 211.

[0590] The second pole ear 10d can be directly connected to the end wall 211, or indirectly connected to the end wall 211 through the end cap 22, side wall 212 or other components.

[0591] One of the electrode terminal 30 and the end wall 211 serves as the first electrode lead-out portion 7a, and the other serves as the second electrode lead-out portion 7b.

[0592] The electrode terminal 30 and the end wall 211 can serve as two exposed electrodes of the cylindrical battery cell 7. The electrode terminal 30 and the end wall 211 are located on the same side, which is beneficial for assembling multiple cylindrical battery cells 7 into a group and simplifies the battery structure.

[0593] In some embodiments, the cylindrical battery cell 7 further includes a first current collector 40, which is located on the side of the first tab 10c facing the end wall 211 and connected to the first tab 10c. The electrode terminal 30 abuts against and is connected to the surface of the first current collector 40 facing the end wall 211.

[0594] The first current collector 40 can act as a converter to realize the electrical connection between the first electrode ear 10c and the electrode terminal 30.

[0595] In some embodiments, the first current collector 40 is annular.

[0596] In some embodiments, the electrode terminal 30 has a terminal recess 31 on the side facing the first current collector 40. The bottom wall of the terminal recess 31 is welded to the first current collector 40.

[0597] By providing the terminal recess 31, the thickness of the bottom wall of the terminal recess 31 can be reduced, the power required to weld the electrode terminal 30 to the first current collector 40 from the outside can be reduced, the risk of welding particles falling into the casing 20 can be reduced, and the reliability of the cylindrical battery cell 7 can be improved.

[0598] By placing the terminal recess 31 inside the electrode terminal 30, the internal space of the cylindrical battery cell 7 can be increased.

[0599] In some embodiments, the electrode terminal 30 has a terminal recess 31 on the side opposite to the first current collector 40.

[0600] In some embodiments, the electrode terminal 30 has a terminal recess 31 on the side facing the first current collector 40, and another terminal recess 31 on the side of the electrode terminal 30 away from the first current collector 40; the corresponding portions of the bottom surfaces of the two terminal recesses 31 are welded to the first current collector 40.

[0601] In some embodiments, the bottom wall of the terminal recess 31 is provided with a through hole 32, which can be used to inject electrolyte.

[0602] In some embodiments, the cylindrical battery cell 7 further includes a cover plate 50, which is connected to the electrode terminal 30 and serves to separate the through hole 32 from the external space of the cylindrical battery cell 7.

[0603] In some embodiments, at least a portion of the cover plate 50 is received in the terminal recess 31.

[0604] In some embodiments, the first electrode lead-out portion 7a includes a cover plate 50 and an electrode terminal 30.

[0605] In some embodiments, the electrode terminal 30 is riveted to the end wall 211.

[0606] In some embodiments, the first tab 10c is located at one end of the electrode assembly 10 facing the end wall 211, and the second tab 10d is located at one end of the electrode assembly 10 facing the end cap 22. The cylindrical battery cell 7 also includes a second current collector 60 connected to the second tab 10d; the second current collector 60 is connected to at least one of the end cap 22 and the side wall 212.

[0607] In some examples, the second current collector 60 is connected to the end cap 22, which is electrically connected to the side wall 212. The second electrode ear 10d is electrically connected to the end wall 211 via the second current collector 60, the end cap 22, and the side wall 212.

[0608] In other examples, the second current collector 60 is connected to the sidewall 212. The second electrode ear 10d is electrically connected to the end wall 211 via the second current collector 60 and the sidewall 212. Optionally, the end cap 22 is insulated from the sidewall 212.

[0609] In some embodiments, the housing 20 includes a sidewall 212 surrounding the electrode assembly 10, the sidewall 212 being made of steel. The thickness of the sidewall 212 is 0.3 mm to 1.5 mm.

[0610] As an example, the thickness of the sidewall 212 is 0.3mm, 0.31mm, 0.32mm, 0.33mm, 0.35mm, 0.38mm, 0.40mm, 0.42mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, 0.95mm, 1mm, 1.05mm, 1.1mm, 1.15mm, 1.2mm, 1.3mm, 1.35mm, 1.4mm, 1.45mm, or 1.5mm.

[0611] In the embodiments of this application, the thickness of the sidewall has a meaning known in the art and can be detected using equipment and methods known in the art, such as a micrometer or vernier caliper.

[0612] As an example, the material of sidewall 212 includes stainless steel.

[0613] By limiting (N1×T1+N2×T2+N3×T3) / D to less than or equal to 0.95, the expansion force exerted by the electrode assembly 10 on the sidewall 212 can be reduced. Therefore, the steel sidewall 212 can have a thickness of less than or equal to 1.5 mm, thereby increasing the energy density of the cylindrical battery cell 7. The thickness of the steel sidewall 212 is greater than or equal to 0.3 mm to reduce the risk of deformation and breakage of the sidewall 212 under the expansion force of the electrode assembly 10, thus improving the reliability of the cylindrical battery cell 7.

[0614] The sidewall 212 has relatively high mechanical strength and is not easily deformed. When used in conjunction with the silicon-containing negative electrode 12, it is more conducive to improving the energy density of the battery cell and making the battery cell have excellent reliability.

[0615] In some embodiments, the thickness of the sidewall 212 is 0.3 mm to 1.2 mm.

[0616] In some embodiments, the thickness of the sidewall 212 is 0.3 mm to 0.9 mm, optionally 0.3 mm to 0.6 mm.

[0617] In some embodiments, the areal density of the negative electrode 12 is greater than or equal to 3.2 mAh / cm³. 2 The base material of the sidewall 212 includes steel, and the thickness of the sidewall 212 is 0.3 mm to 0.9 mm. The negative electrode sheet 12 with the above-mentioned areal density and the sidewall 212 with the above-mentioned thickness are used together to improve the energy density of the battery cell, while giving the battery cell excellent reliability and improving cycle performance.

[0618] In some embodiments, the end wall 211 is made of the same material as the side wall 212.

[0619] In some embodiments, the end cap 22 is made of steel.

[0620] In some embodiments, the height of the housing 20 is 1.3 to 4 times the diameter of the housing 20. Exemplarily, the height of the housing 20 may be the dimension of the housing 20 along the axial direction Z.

[0621] Optionally, the height of the outer casing 20 is 1.3 times, 1.4 times, 1.5 times, 1.6 times, 1.7 times, 1.8 times, 1.9 times, 2.0 times, 2.1 times, 2.2 times, 2.3 times, 2.4 times, 2.5 times, 2.6 times, 2.7 times, 2.8 times, 2.9 times, 3.0 times, 3.1 times, 3.2 times, 3.3 times, 3.4 times, 3.5 times, 3.6 times, 3.7 times, 3.8 times, 3.9 times, or 4.0 times the diameter of the outer casing 20.

[0622] When the housing 20 meets the above-mentioned size requirements, the structural stability of the housing 20 is high, which can improve the reliability of the cylindrical battery cell 7.

[0623] In some embodiments, the height of the housing 20 is 1.5 to 2.5 times the diameter of the housing 20.

[0624] In some embodiments, the height of the housing 20 is 50 mm to 150 mm. For example, the height of the housing 20 is 50 mm, 55 mm, 60 mm, 65 mm, 70 mm, 75 mm, 80 mm, 85 mm, 90 mm, 95 mm, 100 mm, 105 mm, 110 mm, 115 mm, 120 mm, 125 mm, 130 mm, 135 mm, 140 mm, 145 mm, or 150 mm.

[0625] Optionally, the height of the housing 20 is 60mm-100mm.

[0626] In some embodiments, the diameter of the housing 20 is 45 mm to 80 mm. For example, the diameter of the housing 20 is 45 mm, 50 mm, 55 mm, 60 mm, 65 mm, 70 mm, 75 mm or 80 mm.

[0627] Optionally, the diameter of the housing 20 is 45 mm to 60 mm.

[0628] Figure 33 This is a partial cross-sectional schematic diagram of a cylindrical battery cell provided for other embodiments of this application.

[0629] Reference Figure 33 In some embodiments, the first electrode ear 10c and the second electrode ear 10d are both located at the end of the electrode assembly 10 facing the end wall 211.

[0630] The first electrode ear 10c and the second electrode ear 10d can share space in the Z-axis, thereby improving space utilization and increasing energy density.

[0631] In some embodiments, the cylindrical battery cell 7 includes two electrode terminals 30 disposed on the end wall 211, and a first electrode tab 10c and a second electrode tab 10d are electrically connected to the two electrode terminals 30, respectively. The two electrode terminals 30 are a first electrode lead-out 7a and a second electrode lead-out 7b, respectively.

[0632] Optionally, the cylindrical battery cell 7 includes a first current collector 40 and a second current collector 60. The first current collector 40 is connected to a first tab 10c and an electrode terminal 30, and the second current collector 60 is connected to a second tab 10d and another electrode terminal 30.

[0633] In other embodiments, the cylindrical battery cell 7 includes an electrode terminal 30 disposed on the end wall 211, a first tab 10c electrically connected to the electrode terminal 30, and a second tab 10d electrically connected to the end wall 211.

[0634] In some embodiments, the projection of the first electrode portion 10c along the axial direction Z is fan-shaped.

[0635] In some embodiments, the projection of the second electrode ear 10d along the axial direction Z is fan-shaped.

[0636] Figure 34 This is a partial cross-sectional schematic diagram of a cylindrical battery cell provided for other embodiments of this application.

[0637] Reference Figure 34 In some embodiments, the sidewall 212 is provided with an inwardly protruding protrusion 2121.

[0638] For example, the protrusion 2121 can be a solid structure or a hollow structure.

[0639] In some embodiments, at least a portion of the protrusion 2121 is located between the end cap 22 and the second pole ear 10d in the axial direction Z.

[0640] The protrusion 2121 overlaps with the second electrode ear 10d in the axial direction Z. When the cylindrical battery cell 7 is subjected to external impact, it can restrict the movement of the second electrode ear 10d in the axial direction Z and reduce the risk of failure of the connection between the second electrode ear 10d and the second current collector 60.

[0641] In some embodiments, the second current collector 60 is connected to the protrusion 2121. As an example, the second current collector 60 may be welded to the protrusion 2121; alternatively, the second current collector 60 may also be press-fitted to the protrusion 2121.

[0642] For example, the second current collector 60 is connected to the side of the protrusion 2121 facing the second pole ear 10d, or it can be connected to the side of the protrusion 2121 facing the end cap 22.

[0643] Connecting the second current collector 60 to the protrusion 2121 can shorten the conductive path between the second electrode ear 10d and the end wall 211, reduce resistance, reduce heat generation, and improve the cycle performance of the cylindrical battery cell 7.

[0644] In some embodiments, a portion of the second current collector 60 is located on the side of the protrusion 2121 facing the end cap 22 and is connected to the protrusion 2121. The second current collector 60 is connected to the protrusion 2121 from the outside of the protrusion 2121, which can reduce assembly difficulty.

[0645] In some embodiments, the second current collector 60 is welded to the protrusion 2121.

[0646] In some embodiments, the outer side of the sidewall 212 is provided with a recess 2122, which corresponds to the position of the protrusion 2121. As an example, after the electrode assembly 10 is installed into the housing 21, the sidewall 212 is pressed from the outside to form an inwardly protruding protrusion 2121.

[0647] In some embodiments, the sidewall 212 further includes a crimping portion 2123, which extends from the end of the protrusion 2121 away from the endwall 211 and surrounds the end cap 22.

[0648] A portion of the crimping part 2123 is bent to form a flange structure, and a portion of the end cap 22 is located between the flange structure and the protrusion 2121 in the axial direction Z. The protrusion 2121 and the flange structure can limit the end cap 22 to fix the end cap 22 in the axial direction Z.

[0649] In some embodiments, the cylindrical battery cell 7 further includes an insulating member 70, which is disposed between the sidewall 212 and the end cap 22 and insulates the end cap 22 from the sidewall 212.

[0650] In some embodiments, a portion of the insulating member 70 is located between the second current collector 60 and the end cap 22 to insulate the second current collector 60 from the end cap 22.

[0651] According to some embodiments of this application, this application also provides a battery device including a plurality of cylindrical battery cells 7 of any of the above embodiments.

[0652] According to some embodiments of this application, this application also provides an electrical device, including a cylindrical battery cell 7 of any of the above embodiments, wherein the cylindrical battery cell 7 is used to provide electrical energy to the electrical device. The electrical device can be any of the aforementioned devices or systems that utilize the cylindrical battery cell 7.

[0653] Reference Figures 3 to 12 This application provides a cylindrical battery cell 7, which includes a housing 20, an electrode assembly 10, electrode terminals 30, a first current collector 40, and a second current collector 60.

[0654] The outer casing 20 includes a housing 21 and an end cap 22. The housing 21 includes an integrally formed side wall 212 and an end wall 211. The end wall 211 and the end cap 22 are opposite each other along the axial direction Z of the cylindrical battery cell 7. The end cap 22 is welded to the side wall 212.

[0655] Electrode terminals 30 are insulatedly disposed on end wall 211.

[0656] At least a portion of the electrode assembly 10 is housed within the housing 20. The electrode assembly 10 includes a positive electrode 11, a negative electrode 12, and a separator 13, which are wound together. The separator 13 is used to isolate the positive electrode 11 and the negative electrode 12.

[0657] The positive electrode 11 includes a positive electrode body 111 with a positive electrode active material layer 11b and a positive electrode tab 112 without a positive electrode active material layer 11b. The negative electrode 12 includes a negative electrode body 121 with a negative electrode active material layer 12b and a negative electrode tab 122 without a negative electrode active material layer 12b. The separator 13 is used to isolate the positive electrode body 111 and the negative electrode body 121.

[0658] The first current collector 40 connects the electrode terminal 30 and the positive electrode tab 112, and the second current collector 60 connects the negative electrode tab 122 and the end cap 22.

[0659] The thickness of the positive electrode body 111 is T1.

[0660] The thickness of the negative electrode body 121 is T2.

[0661] The thickness of the separator 13 is T3.

[0662] The electrode assembly 10 has a cross-section perpendicular to the axial direction Z. Within this cross-section, there is a virtual straight line extending radially along the cylindrical battery cell 7. The virtual straight line intersects the positive electrode body 111 N1 times, the negative electrode body 121 N2 times, and the separator 13 N3 times. The thickness of the positive electrode body 111 is T1, the thickness of the negative electrode body 121 is T2, and the thickness of the separator 13 is T3. The radial dimension of the receiving cavity is D.

[0663] 0.65≤(N1×T1+N2×T2+N3×T3) / D≤0.95.

[0664] Example

[0665] The following embodiments describe the contents disclosed in this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosures in this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0666] Example 1

[0667] 1. Preparation of positive electrode sheet

[0668] The positive electrode sheet includes a positive current collector and a positive active material layer. The positive active material layer is located on both sides of the positive current collector. The positive current collector is an aluminum foil. The positive active material layer is a film formed by uniformly coating a positive electrode slurry (solvent being N-methylpyrrolidone, NMP) onto the surface of the aluminum foil, followed by drying and cold pressing. The positive active material layer includes positive active material, conductive agent carbon black (Super P), and binder polyvinylidene fluoride (PVDF) in a weight ratio of 97:1:2. The portion of the positive current collector covered by the positive active material layer forms the positive electrode body of the positive electrode sheet, while the portion of the positive current collector not covered by the positive active material layer forms the positive electrode tab of the positive electrode sheet.

[0669] Positive electrode active materials include those with the molecular formula LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM 811 Layered transition metal oxides.

[0670] 2. Preparation of negative electrode sheet

[0671] The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer. The negative electrode active material layer is located on both sides of the negative electrode current collector. The negative electrode current collector is a copper foil. The negative electrode active material layer is a film layer formed by uniformly coating the surface of the copper foil with negative electrode slurry (solvent is deionized water), and then drying and cold pressing. The negative electrode active material layer includes silicon-based material (specifically silicon oxide compound), graphite, conductive carbon black, conductive carbon nanotubes, and binder polyacrylic acid in a weight ratio of 12.6:82.4:1.9:0.1:3. The portion of the negative electrode active material layer and the portion of the negative electrode current collector covered by the negative electrode active material layer form the negative electrode body of the negative electrode sheet, and the portion of the negative electrode current collector not covered by the negative electrode active material layer forms the negative electrode tab of the negative electrode sheet.

[0672] The areal density of the negative electrode active material layer is 9.0 mg / cm³. 2The porosity is 22.1%, and the compacted density is 1.7 g / cm³. 3 .

[0673] 3. Isolation components

[0674] We provide PE (polyethylene) based films.

[0675] 4. Preparation of electrolyte

[0676] The electrolyte consists of an organic solvent and a lithium salt. Ethyl carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1 to obtain an organic solvent. Then, fully dried lithium salt LiPF6 is dissolved in the mixed organic solvent to prepare an electrolyte with a lithium salt concentration of 1 mol / L.

[0677] 5. Preparation of cylindrical battery cells

[0678] The positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the positive and negative electrodes to provide isolation. The positive electrode, separator, and negative electrode are then wound to form an electrode assembly. This assembly is placed in a cylindrical shell, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping, a cylindrical battery cell is obtained. The electrode assembly and the shell are both cylindrical, comprising a housing and end caps. The housing includes integrally formed sidewalls and end walls, with the sidewalls surrounding the electrode assembly. The end caps and end walls are axially aligned with the housing. The cylindrical battery cell has a diameter of 46 mm and a height of 95 mm.

[0679] Performance testing

[0680] 1. Parameter measurement of cylindrical battery cells

[0681] At 25°C, the cylindrical battery cell prepared above was charged to 4.25V at 0.33C, then discharged to 2.5V at 0.33C, and then discharged to 2.5V at 0.1C.

[0682] Using CT (Computed Tomography) technology, X-rays are used to obtain cross-sectional images of a cylindrical battery cell. This cross-section is perpendicular to the central axis of the cylindrical battery cell and shows the positive electrode body, the negative electrode body, and the separator.

[0683] Based on the image, a virtual straight line is defined, which can pass through the center of the cross section (the virtual straight line intersects the central axis); the number of times the virtual straight line intersects with the positive electrode body is counted, and this number can be taken as N1; the number of times the virtual straight line intersects with the negative electrode body is counted, and this number can be taken as N2; the number of times the virtual straight line intersects with the separator is counted, and this number can be taken as N3.

[0684] Based on this image, the radial dimension D of the receiving cavity is measured;

[0685] Disassemble the cylindrical battery cell and unfold the positive electrode, negative electrode, and separator;

[0686] Fifty positions are randomly selected on the positive electrode body of the positive electrode sheet, and 50 thickness values ​​are measured. Then the average value of the 50 thickness values ​​is calculated, which can be the thickness T1 of the positive electrode body.

[0687] Arbitrarily select 50 positions on the negative electrode body of the negative electrode sheet, measure 50 thickness values, and then calculate the average value of the 50 thickness values. This average value can be the thickness T2 of the negative electrode body.

[0688] Select 50 arbitrary locations on the separator and measure 50 thickness values. Then calculate the average value of the 50 thickness values. This average value can be the thickness T3 of the separator.

[0689] Calculate (N1×T1+N2×T2+N3×T3) / D.

[0690] 2. Battery cycle performance test

[0691] At 45°C, the prepared cylindrical battery cells are fully charged at 1C and then fully discharged at 1C. This constitutes one charge-discharge cycle. The discharge capacity at this point is recorded as the first cycle discharge capacity. The cylindrical battery cells are then subjected to cyclic charge-discharge tests using the same method, and the discharge capacity after each cycle is recorded until the discharge capacity of the cylindrical battery cell decreases to 80% of its initial discharge capacity. The number of cycles at this point characterizes the cycle performance of the cylindrical battery cell. A higher number of cycles indicates better cycle performance.

[0692] It should be noted that in Example 1, two cylindrical battery cells were prepared according to the above method, and the four tests described above were performed on them respectively.

[0693] Example 2

[0694] Battery cells were prepared using a method similar to that of Example 1. However, unlike Example 1, Example 2 reduced the total length of the positive electrode sheet along the winding direction and the total length of the negative electrode sheet along the winding direction to reduce the number of turns of the positive electrode sheet and the negative electrode sheet.

[0695] Example 3

[0696] Battery cells were prepared using a method similar to that of Example 1. However, unlike Example 1, Example 3 reduced the total length of the positive electrode sheet along the winding direction and the total length of the negative electrode sheet along the winding direction to reduce the number of turns of the positive electrode sheet and the negative electrode sheet.

[0697] Example 4

[0698] Battery cells were prepared using a method similar to that of Example 1. However, unlike Example 1, Example 4 reduced the total length of the positive electrode sheet along the winding direction and the total length of the negative electrode sheet along the winding direction to reduce the number of turns of the positive electrode sheet and the negative electrode sheet.

[0699] Example 5

[0700] Battery cells were prepared using a method similar to that of Example 1. However, unlike Example 1, Example 5 increased the total length of the positive electrode sheet along the winding direction and the total length of the negative electrode sheet along the winding direction to increase the number of turns of the positive electrode sheet and the number of turns of the negative electrode sheet.

[0701] Comparative Example 1

[0702] Battery cells were prepared using a method similar to that of Example 1. However, unlike Example 1, Comparative Example 1 increased the total length of the positive electrode sheet along the winding direction and the total length of the negative electrode sheet along the winding direction to increase the number of turns of the positive electrode sheet and the number of turns of the negative electrode sheet.

[0703] Comparative Example 2

[0704] Battery cells were prepared using a method similar to that of Example 1. However, unlike Example 1, Comparative Example 2 reduced the total length of the positive electrode sheet along the winding direction and the total length of the negative electrode sheet along the winding direction to reduce the number of turns of the positive electrode sheet and the negative electrode sheet.

[0705] The test results for each embodiment and comparative example are shown in Table 1.

[0706] Table 1

[0707] <![CDATA[(N1×T1+N2×T2+N3×T3) / D]]> Number of cycles at 45℃ Example 1 0.9 1720 Example 2 0.8 1566 Example 3 0.7 1299 Example 4 0.65 1213 Example 5 0.95 1413 Comparative Example 1 0.98 1155 Comparative Example 2 0.6 1023

[0708] Referring to Table 1, limiting (N1×T1+N2×T2+N3×T3) / D to less than or equal to 0.95 allows for the formation of a gap between the positive and negative electrode main bodies. During the cycling process of the cylindrical battery cell, this gap provides space for the expansion of the negative electrode active material layer, reducing the pressure between the positive and negative electrode main bodies. This alleviates the compression of the electrolyte within the internal pores of both the positive and negative electrode active material layers, reducing the concentration difference of the electrolyte in different regions of the electrode and improving the cycle performance of cylindrical battery cells with larger diameters. Limiting (N1×T1+N2×T2+N3×T3) / D to greater than or equal to 0.65 shortens the ion migration path between the positive and negative electrode main bodies, reduces the internal resistance of the cylindrical battery cell, decreases heat generation, and improves the cycle performance of cylindrical battery cells with larger diameters. Setting (N1×T1+N2×T2+N3×T3) / D to 0.65-0.95 can improve the cycle performance of cylindrical battery cells and increase their cycle life.

[0709] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0710] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features. However, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A cylindrical battery cell, characterized in that, include: An outer casing having a receiving cavity, the outer diameter of the outer casing being ≥40mm; An electrode assembly is housed within the receiving cavity. The electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator. The positive electrode sheet, the negative electrode sheet, and the separator are wound together. The separator is used to isolate the positive electrode sheet and the negative electrode sheet. The positive electrode sheet includes a positive electrode body portion and a positive electrode tab portion disposed along the axial direction of the cylindrical battery cell. At least a portion of the positive electrode body portion is provided with a positive electrode active material layer, and at least a portion of the positive electrode tab portion is not provided with the positive electrode active material layer. The negative electrode sheet includes a negative electrode body portion and a negative electrode tab portion disposed along the axial direction. At least a portion of the negative electrode body portion is provided with a negative electrode active material layer, and at least a portion of the negative electrode tab portion is not provided with the negative electrode active material layer. The electrode assembly has a cross-section perpendicular to the axial direction, within which a virtual straight line extends radially along the cylindrical battery cell. The virtual straight line intersects the positive electrode body N1 times, the negative electrode body N2 times, and the separator N3 times. The thickness of the positive electrode body is T1, the thickness of the negative electrode body T2, and the thickness of the separator T3. The radial dimension of the receiving cavity is D. 0.65≤(N1×T1+N2×T2+N3×T3) / D≤0.

95.

2. The cylindrical battery cell according to claim 1, characterized in that, 0.70≤(N1×T1+N2×T2+N3×T3) / D≤0.

90.

3. The cylindrical battery cell according to claim 1, characterized in that, N3 > N2 > N1.

4. The cylindrical battery cell according to claim 1, characterized in that, 0.65≤T1 / T2≤0.

95.

5. The cylindrical battery cell according to claim 1, characterized in that, T1 is 80μm-150μm, T2 is 100μm-180μm, and T3 is 7μm-20μm.

6. The cylindrical battery cell according to claim 1, characterized in that, D is 35mm-80mm.

7. The cylindrical battery cell according to claim 1, characterized in that, The electrode assembly has a central hole in the middle.

8. The cylindrical battery cell according to claim 1, characterized in that, A gap is provided between the positive electrode body portion and the negative electrode body portion.

9. The cylindrical battery cell according to claim 8, characterized in that, The gap includes a first gap and a second gap, the first gap being formed between the positive electrode body and the insulating member, and the second gap being formed between the negative electrode body and the insulating member.

10. The cylindrical battery cell according to claim 8, characterized in that, At least a portion of the gap has a radial dimension of 5 μm to 60 μm.

11. The cylindrical battery cell according to claim 8, characterized in that, The gap extends along the winding direction of the electrode assembly, and the gap has a winding start end and a winding end.

12. The cylindrical battery cell according to claim 11, characterized in that, The gap is configured as two, and the two gaps are respectively disposed on both sides of the positive electrode body.

13. The cylindrical battery cell according to claim 11, characterized in that, The radial dimension of the portion of the gap near the winding end is greater than the radial dimension of the portion of the gap near the winding start end.

14. The cylindrical battery cell according to claim 11, characterized in that, The gap is wound along the winding direction to form m winding loops, where m ≥ 20 and m is a natural number; The innermost winding loop is the first winding loop; The radial dimension of the kth winding is less than the radial dimension of the (k+10)th winding, where k is a natural number and 5 ≤ k ≤ m-15.

15. The cylindrical battery cell according to claim 11, characterized in that, The gap is wound along the winding direction to form m winding loops, where m ≥ 20 and m is a natural number; The innermost winding loop is the first winding loop; The average radial dimension of the m-9 to m-5th windings is greater than the average radial dimension of the 5th to 9th windings.

16. The cylindrical battery cell according to claim 8, characterized in that, The electrode assembly includes a central region and two end regions arranged along the axial direction of the cylindrical battery cell, with the central region located between the two end regions; The radial dimension of the portion of the gap located in the middle region is smaller than the radial dimension of the portion of the gap located in the end region.

17. The cylindrical battery cell according to claim 16, characterized in that, The radial dimension of the gap decreases in both directions from the two end regions toward the middle region.

18. The cylindrical battery cell according to claim 1, characterized in that, The housing includes a sidewall surrounding the electrode assembly, the sidewall being made of steel and having a thickness of 0.3 mm to 1.5 mm, optionally 0.3 mm to 1.2 mm.

19. The cylindrical battery cell according to claim 1, characterized in that, The negative electrode active material layer includes a negative electrode active material, and the negative electrode active material includes a silicon-based material.

20. The cylindrical battery cell according to claim 1, characterized in that, The negative electrode has a capacity areal density greater than or equal to 3.2 mAh / cm³. 2 .

21. The cylindrical battery cell according to claim 20, characterized in that, The areal density of the negative electrode is 3.3 mAh / cm³. 2 Up to 11.5mAh / cm 2 .

22. The cylindrical battery cell according to claim 21, characterized in that, The areal density of the negative electrode is 3.96 mAh / cm³. 2 Up to 7.56mAh / cm 2 .

23. The cylindrical battery cell according to any one of claims 1-22, characterized in that, At least one of the positive electrode main body, the negative electrode main body, and the separator includes a base part and a plurality of support parts, wherein the support parts protrude from the base part.

24. The cylindrical battery cell according to claim 23, characterized in that, The support portion is configured to be compressible.

25. The cylindrical battery cell according to claim 23, characterized in that, The positive electrode main body includes the base part and a plurality of the support parts. The base part of the positive electrode main body is a first base part. The plurality of the support parts of the positive electrode main body protrude from the first base part. The plurality of the support parts of the positive electrode main body includes a first support part and a second support part. On the same side of the positive electrode main body, the height of the first support part protruding from the first base part is greater than the height of the second support part protruding from the first base part. and / or The negative electrode main body includes the base part and a plurality of the support parts. The base part of the negative electrode main body is a second base part. The plurality of the support parts of the negative electrode main body protrude from the second base part. The plurality of the support parts of the negative electrode main body includes a third support part and a fourth support part. On the same side of the negative electrode main body, the height of the third support part protruding from the second base part is greater than the height of the fourth support part protruding from the second base part. and / or The isolation member includes a base portion and a plurality of support portions. The base portion of the isolation member is a third base portion. The plurality of support portions of the isolation member protrude from the third base portion. The plurality of support portions of the isolation member includes a fifth support portion and a sixth support portion. On the same side of the isolation member, the height of the fifth support portion protruding from the third base portion is greater than the height of the sixth support portion protruding from the third base portion.

26. The cylindrical battery cell according to claim 23, characterized in that, At least one of the positive electrode body portion, the negative electrode body portion, and the separator includes a plurality of organic particles; The support portion includes the organic particles.

27. The cylindrical battery cell according to claim 26, characterized in that, The plurality of organic particles include a first organic particle and a second organic particle, wherein the number-average particle size of the first organic particle is greater than the number-average particle size of the second organic particle.

28. The cylindrical battery cell according to claim 26 or 27, characterized in that, The positive electrode main body includes the base portion and a plurality of supporting portions. The base portion of the positive electrode main body is a first base portion. The plurality of supporting portions of the positive electrode main body protrude from the first base portion. The plurality of supporting portions of the positive electrode main body includes a first supporting portion and a second supporting portion. On the same side of the positive electrode main body, the height of the first supporting portion protruding from the first base portion is greater than the height of the second supporting portion protruding from the first base portion. The plurality of organic particles include first organic particles and second organic particles. The first supporting portion includes the first organic particle, and the second supporting portion includes the second organic particle; and / or The negative electrode main body includes a base portion and a plurality of supporting portions. The base portion of the negative electrode main body is a second base portion. The plurality of supporting portions of the negative electrode main body protrude from the second base portion. The plurality of supporting portions of the negative electrode main body includes a third supporting portion and a fourth supporting portion. On the same side of the negative electrode main body, the height of the third supporting portion protruding from the second base portion is greater than the height of the fourth supporting portion protruding from the second base portion. The plurality of organic particles include first organic particles and second organic particles. The third supporting portion includes the first organic particles, and the fourth supporting portion includes the second organic particles; and / or The isolation member includes a base portion and a plurality of support portions. The base portion of the isolation member is a third base portion. The plurality of support portions of the isolation member protrude from the third base portion. The plurality of support portions of the isolation member includes a fifth support portion and a sixth support portion. On the same side of the isolation member, the height of the fifth support portion protruding from the third base portion is greater than the height of the sixth support portion protruding from the third base portion. The plurality of organic particles includes a first organic particle and a second organic particle. The fifth support portion includes the first organic particle, and the sixth support portion includes the second organic particle.

29. The cylindrical battery cell according to claim 26 or 27, characterized in that, The plurality of organic particles include a first organic particle, which comprises a homopolymer or copolymer of fluorinated alkenyl monomer units, a homopolymer or copolymer of olefinic monomer units, a homopolymer or copolymer of unsaturated nitrile monomer units, a homopolymer or copolymer of epoxide monomer units, and one of the modified compounds of the above homopolymers or copolymers.

30. The cylindrical battery cell according to claim 29, characterized in that, The first organic particle includes polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride, polyethylene, polypropylene, polyacrylonitrile, polyethylene oxide, copolymers of different fluorinated alkenyl monomer units, copolymers of fluorinated alkenyl monomer units and olefin monomer units, copolymers of fluorinated alkenyl monomer units and acrylic monomer units, copolymers of fluorinated alkenyl monomer units and acrylate monomer units, and one of the modified compounds of the above homopolymers or copolymers.

31. The cylindrical battery cell according to claim 26 or 27, characterized in that, The plurality of organic particles includes a second organic particle, which comprises one of the following: 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 compound, a rubber compound, and a modified compound of the above homopolymers or copolymers.

32. The cylindrical battery cell according to claim 31, characterized in that, The second organic particle comprises one of the following: a copolymer of acrylate monomer units and styrene monomer units; a copolymer of acrylate monomer units and styrene monomer units; a copolymer of acrylate 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 monomer units-unsaturated nitrile monomer units; and a modified compound of the above copolymers.

33. The cylindrical battery cell according to claim 23, characterized in that, The isolation member includes a base portion and a plurality of support portions. The base portion of the isolation member is a third base portion, and the plurality of support portions of the isolation member protrude from the third base portion. The support portions of the isolation member include organic particles.

34. The cylindrical battery cell according to claim 33, characterized in that, The third substrate includes a base film and an inorganic particle layer disposed on the base film; The organic particles of the separator are disposed on the inorganic particle layer and at least partially protrude from the inorganic particle layer.

35. The cylindrical battery cell according to claim 23, characterized in that, The positive electrode main body has a plurality of support portions on the side facing the insulating member, and the insulating member has a plurality of support portions on the side facing the positive electrode main body. The plurality of support portions of the positive electrode main body facing the insulating member are at least partially opposite to the plurality of support portions of the insulating member facing the positive electrode sheet; and / or, The negative electrode main body has a plurality of support portions on the side facing the insulating member, and the insulating member has a plurality of support portions on the side facing the negative electrode main body. The plurality of support portions of the negative electrode main body facing the insulating member are at least partially opposite to the plurality of support portions of the insulating member facing the negative electrode main body; and / or, The negative electrode main body is provided with a plurality of support portions on the side facing the positive electrode main body, and the positive electrode main body is provided with a plurality of support portions on the side facing the negative electrode main body. At least a portion of the plurality of support portions of the negative electrode main body facing the positive electrode main body are arranged opposite to the plurality of support portions of the positive electrode main body facing the negative electrode main body.

36. The cylindrical battery cell according to any one of claims 1-22, characterized in that, The surface of the positive electrode body opposite to the separator is provided with a first recess.

37. The cylindrical battery cell according to claim 36, characterized in that, The first recess is formed in the positive electrode active material layer.

38. The cylindrical battery cell according to claim 36, characterized in that, The first recess extends through the positive electrode body along the axial direction.

39. The cylindrical battery cell according to claim 36, characterized in that, There are multiple first recesses; at least a portion of the multiple first recesses are disposed on the inner side of the positive electrode body portion.

40. The cylindrical battery cell according to claim 36, characterized in that, The positive electrode body includes a plurality of first recesses spaced apart along the winding direction.

41. The cylindrical battery cell according to any one of claims 1-22, characterized in that, The surface of the negative electrode body opposite to the insulating member is provided with a second recess.

42. The cylindrical battery cell according to claim 41, characterized in that, The second recess is formed in the negative electrode active material layer.

43. The cylindrical battery cell according to claim 41, characterized in that, The second recess extends through the negative electrode body along the axial direction.

44. The cylindrical battery cell according to claim 41, characterized in that, There are multiple second recesses; at least a portion of the multiple second recesses are disposed on the inner side of the negative electrode body portion.

45. The cylindrical battery cell according to claim 41, characterized in that, The negative electrode body includes a plurality of second recesses spaced apart along the winding direction.

46. ​​The cylindrical battery cell according to claim 1, characterized in that, One of the positive electrode tabs and the negative electrode tabs is the first electrode tab, and the other is the second electrode tab; The cylindrical battery cell includes a first electrode lead-out portion and a second electrode lead-out portion, wherein the first electrode lead-out portion is electrically connected to the first electrode tab portion, and the second electrode lead-out portion is electrically connected to the second electrode tab portion. Along the axial direction of the cylindrical battery cell, the first electrode lead and the second electrode lead are located on the same side of the electrode assembly.

47. The cylindrical battery cell according to claim 1, characterized in that, The housing includes a shell and an end cap. The shell includes a side wall and an end wall. The side wall surrounds the electrode assembly. The end wall and the end cap are opposite each other along the axial direction of the cylindrical battery cell. The end cap is sealed to the side wall.

48. The cylindrical battery cell according to claim 47, characterized in that, One of the positive electrode tabs and the negative electrode tabs is the first electrode tab, and the other is the second electrode tab; The cylindrical battery cell also includes electrode terminals insulated from the end wall, with the first tab electrically connected to the electrode terminals and the second tab electrically connected to the end wall.

49. The cylindrical battery cell according to claim 48, characterized in that, It also includes a first current collector, which is located on the side of the first electrode portion facing the end wall and connected to the first electrode portion; The electrode terminal abuts against and connects to the surface of the first current collector facing the end wall.

50. The cylindrical battery cell according to claim 49, characterized in that, The electrode terminal has a terminal recess on the side facing the first current collector, and / or the electrode terminal has a terminal recess on the side away from the first current collector; The bottom wall of the terminal recess is welded to the first current collector.

51. The cylindrical battery cell according to claim 48, characterized in that, Both the first electrode tab and the second electrode tab are located at the end of the electrode assembly facing the end wall.

52. The cylindrical battery cell according to claim 48, characterized in that, The first electrode tab is located at the end of the electrode assembly facing the end wall, and the second electrode tab is located at the end of the electrode assembly facing the end cap; The cylindrical battery cell further includes a second current collector connected to the second electrode tab; the second current collector is connected to at least one of the end cap and the side wall.

53. The cylindrical battery cell according to claim 52, characterized in that, The sidewall is provided with an inwardly protruding part, and the second current collecting member is connected to the protruding part.

54. The cylindrical battery cell according to claim 53, characterized in that, A portion of the second current collector is located on the side of the protrusion facing the end cap and is connected to the protrusion.

55. The cylindrical battery cell according to claim 1, characterized in that, The height of the outer casing is 1.3 to 4 times the diameter of the outer casing.

56. The cylindrical battery cell according to claim 1, characterized in that, The height of the outer casing is 50mm to 150mm; and / or The diameter of the outer casing is 45mm to 80mm.

57. A battery device, characterized in that, It includes multiple cylindrical battery cells according to any one of claims 1-56.

58. An electrical appliance, characterized in that, Includes the battery device according to claim 57, the battery device being used to provide electrical energy.

Images