Battery monomer, battery device and electric device

Abstract

The utility model belongs to the technical field of batteries, and particularly relates to a single battery, a battery device and a power utilization device.The single battery comprises a shell and an electrode assembly, and the shell contains electrolyte; at least part of the electrode assembly is located in the shell, the electrode assembly comprises a separator, a first pole piece and a second pole piece, the polarities of the first pole piece and the second pole piece are opposite, and at least part of the separator is located between the first pole piece and the second pole piece; the first pole piece comprises a first current collector and a first active material layer, and the surface of the first current collector is connected with the first active material layer; wherein the first active material layer comprises a first active material part and a second active material part, at least one end, along the first direction, of the first active material part is connected with the second active material part, the thickness of the second active material part is smaller than that of the first active material part, and a groove is formed in the surface, opposite to the first current collector, of the first active material part; in the first direction, the grooves and the second active material parts are arranged at intervals, and the first direction is perpendicular to the thickness direction of the first current collector.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of batteries, and particularly relates to a battery monomer, a battery device and a power utilization device. BACKGROUND

[0002] Battery devices are widely used in electronic equipment, such as mobile phones, notebook computers, electric vehicles, electric cars, electric planes, electric ships, electric toy cars, electric toy ships, electric toy planes and electric tools.

[0003] A battery device usually comprises one or more battery monomers, and the cycle performance of a battery monomer directly affects the capacity retention rate, internal resistance and final service life of the battery monomer. Meanwhile, the use reliability of the battery monomer is directly related to the use stability of the battery monomer. Therefore, how to improve the cycle performance of the battery monomer and improve the use reliability of the battery monomer is an important research direction in the technical field of batteries.

[0004] The above statements are only used to provide background technical information related to the application, and do not necessarily constitute the prior art. CONTENT OF THE INVENTION

[0005] The purpose of the embodiments of the application is to provide a battery monomer, a battery device and a power utilization device, which can better balance the cycle performance and use reliability of the battery monomer.

[0006] The technical solution adopted by the embodiments of the application is:

[0007] In a first aspect, a battery monomer is provided, comprising a shell and an electrode assembly, the shell containing an electrolyte; at least part of the electrode assembly is located in the shell, the electrode assembly comprising a separator and first and second polar plates with opposite polarities, at least part of the separator being located between the first and second polar plates; the first polar plate comprises a first current collector and a first active material layer, the first current collector being connected with the first active material layer at least in part of an area of at least one surface thereof along a thickness direction of the first current collector, at least part of the first active material layer being located between the first current collector and the separator; wherein the first active material layer comprises a first active material part and a second active material part arranged along a first direction, the first active material part being connected with the second active material part at least at one end thereof along the first direction, the thickness of the second active material part being smaller than that of the first active material part, and the surface of the first active material part away from the first current collector being provided with a groove; along the first direction, the groove is arranged at intervals with the second active material part, and the first direction is perpendicular to the thickness direction of the first current collector.

[0008] By adopting the technical scheme of the embodiment, the surface of the first active material part away from the first current collector is provided with a groove. On one hand, the electrolyte can flow into the groove for storage, the stored electrolyte can infiltrate the first active material layer and provide a transmission path for ions, reduce the transmission resistance of the ions, and improve the cycle performance of the battery monomer. On the other hand, the groove can also provide a channel for the backflow of the electrolyte, reduce the difficulty of the backflow of the electrolyte, reduce the transmission resistance of the ions, improve the infiltration effect of the first pole piece, and also help to improve the cycle performance of the battery monomer. The thickness of the second active material part is small, and the groove is arranged away from the second active material part, so that the groove does not extend to the second active material part, reducing the risk of powder falling and even collapse of the second active material part caused by the extension of the groove to the second active material part, reducing the risk of short circuit of the battery monomer, and improving the use reliability of the battery monomer. It is beneficial to improve the capacity of the battery monomer. Therefore, the capacity, use reliability and cycle performance of the battery monomer can be well balanced.

[0009] In some embodiments, the distance between the second active material part and the groove is S1, wherein 0mm

[0010] By adopting the technical scheme of the embodiment, the groove does not extend to the second active material part, which is beneficial to improve the structural strength of the second active material part, can reduce the risk of powder falling and even collapse of the second active material part, and is beneficial to improve the capacity and use reliability of the battery monomer. It can also make the electrolyte on the side of the second active material part away from the first current collector close to the groove, so that the electrolyte can flow into the groove better, improve the infiltration effect of the first pole piece, and improve the cycle performance of the battery monomer. Therefore, the cycle performance, capacity and use reliability of the battery monomer can be balanced.

[0011] In some embodiments, in the direction of the first active material part pointing to the second active material part, the thickness of the second active material part decreases.

[0012] By adopting the technical scheme of the embodiment, the side of the second active material part away from the first current collector can form a flared mouth structure, and the large end of the flared mouth structure is arranged away from the first active material part. The flared mouth structure can make the electrolyte more easily absorbed between the first active material part and the second pole piece, and is more beneficial to improve the infiltration effect of the electrode assembly and improve the cycle performance of the battery monomer.

[0013] In some embodiments, the first active material part has a first surface away from the first current collector, and the second active material part has a second surface away from the first current collector, and the second surface is closer to the first current collector than the first surface.

[0014] By adopting the technical scheme of the embodiment, the side of the second surface away from the first current collector has more space for accommodating electrolyte, and the distance difference between the second surface and the first surface and the first current collector can be used to form a siphon effect, improve the electrolyte return speed, improve the wettability of the electrode assembly, and improve the cycle performance of the battery cell.

[0015] In some embodiments, along the first direction, one end of the first active material part is connected with the second active material part, and the other end of the first active material part is not connected with the second active material part, the surface of the first active material part away from the first current collector is provided with a groove, and along the first direction, the groove penetrates the end surface of the first active material part away from the second active material part; or, along the first direction, the end surface of the first active material part away from the second active material part is arranged in a spaced manner with the groove.

[0016] By adopting the technical scheme of the embodiment, the groove can be flexibly arranged on the first active material part to meet different use requirements.

[0017] In some embodiments, the distance between the end surface of the first active material part away from the second active material part and the groove is s, where 0mm≤s≤20mm, optionally, 0.1mm≤s≤8mm, and optionally, 0.5mm≤s≤3mm.

[0018] By adopting the technical scheme of the embodiment, the distance between the end surface of the first active material part away from the second active material part and the groove is close, and the electrolyte between the end surface of the first active material part away from the second active material part and the shell can flow into the groove quickly, thereby improving the wettability of the first electrode tab and being beneficial to improving the cycle performance of the battery cell.

[0019] In some embodiments, along the first direction, both ends of the first active material part are connected with the second active material part.

[0020] By adopting the technical scheme of the embodiment, both ends of the first electrode tab along the first direction can accommodate more electrolyte and form a siphon effect, thereby facilitating the return of electrolyte, improving the wettability of the electrode assembly, and improving the cycle performance of the battery cell.

[0021] In some embodiments, the first current collector comprises a first current collector main body and a first tab arranged in a connected manner along the first direction, at least part of the first current collector main body is covered with the first active material part and the second active material part, and the first tab is not covered with the first active material part and the second active material part.

[0022] By adopting the technical scheme of the embodiment, the first tab is led out from the end of the first electrode tab along the first direction, and the electrical connection of the first tab with other components can be facilitated.

[0023] In some embodiments, the first electrode tab is a negative electrode tab.

[0024] By adopting the technical scheme of this embodiment, the first pole piece is a negative pole piece, the first active material part and the second active material part include negative active materials, the groove is arranged in a spaced manner from the second active material part, the groove does not extend to the second active material part, the negative active material of the second active material part is not subjected to a slotting operation, and the negative active material of the second active material part is more, thereby reducing the risk of lithium precipitation of the battery monomer and being beneficial to improving the use performance of the battery monomer.

[0025] In some embodiments, the number of the first active material layers is two, and the two first active material layers respectively cover two surfaces of the first current collector along the thickness direction of the first current collector. At least one of the first active material layers is provided with a groove.

[0026] By adopting the technical scheme of this embodiment, the number of the active material of the first pole piece can be increased by arranging two first active material layers, which is beneficial to improving the capacity of the battery monomer. In addition, the groove is arranged more flexibly to meet different use requirements.

[0027] In some embodiments, the number of the grooves is multiple, and the multiple grooves include first grooves and second grooves formed along a first direction. In the two first active material layers, one of the two first active material layers is provided with the multiple first grooves, and the other of the two first active material layers is provided with the multiple second grooves. The first grooves and the second grooves are arranged in a staggered manner along the thickness direction of the first current collector.

[0028] By adopting the technical scheme of this embodiment, the two first active material layers are respectively provided with the multiple first grooves and the multiple second grooves to improve the wettability of the two first active material layers and improve the cycle performance of the battery monomer. In addition, the first grooves and the second grooves are arranged in a staggered manner along the thickness direction of the first current collector, which is beneficial to improving the structural strength of the first pole piece and improving the use reliability of the battery monomer.

[0029] In some embodiments, the multiple first grooves and the multiple second grooves are arranged alternately along a second direction, and the second direction is perpendicular to the first direction and the thickness direction of the first current collector.

[0030] By adopting the technical scheme of this embodiment, the multiple first grooves and the multiple second grooves can be uniformly distributed on the two first active material layers, which can improve the uniformity of the distribution of the electrolyte in the battery monomer and is beneficial to improving the cycle performance of the battery monomer.

[0031] In some embodiments, the spacing between adjacent first grooves and second grooves along the second direction is C, and C≥1.5mm, optionally, 1.8mm≤C≤5mm, and optionally, 2mm≤C≤3mm.

[0032] By adopting the technical scheme of the embodiment, the density of the first groove and the second groove is reasonable, the loss amount of the active material of the first active material layer can be reduced, and the structural strength of the first pole piece can be improved, so that the use reliability and the energy density of the battery monomer can be considered.

[0033] In some embodiments, the electrode assembly is in a wound structure, the first pole piece is wound to form a plurality of first pole piece winding turns, the first current collector includes a first current collector winding turn located at the first pole piece winding turn, the first active material layer includes a first active material winding turn located at the first pole piece winding turn, and the first active material layer has a first winding surface facing away from the corresponding first current collector winding turn; wherein the first winding surface of at least one first pole piece winding turn is provided with a groove.

[0034] By adopting the technical scheme of the embodiment, the electrode assembly is wound, the gap between the first pole piece and the second pole piece is small, the backflow of the electrolyte is not easy to enter between the first pole piece and the second pole piece, and the cycle performance of the battery monomer is not conducive to improvement; and the first winding surface of at least one first pole piece winding turn is provided with at least one groove, on the one hand, the electrolyte can flow into the groove for storage, the stored electrolyte can soak the first pole piece and provide a transmission path for ions, reduce the transmission resistance of the ions, and improve the cycle performance of the battery monomer; on the other hand, the groove can also provide a channel for the backflow of the electrolyte, reduce the difficulty of the backflow of the electrolyte, reduce the transmission resistance of the ions, improve the soaking effect of the first pole piece, and also be conducive to improving the cycle performance of the battery monomer.

[0035] In some embodiments, the number of grooves is a plurality, and the plurality of grooves includes at least one first groove formed in a first direction, and the first direction is parallel to the winding axis of the electrode assembly.

[0036] By adopting the technical scheme of the embodiment, the electrode assembly expands, the electrolyte is squeezed out from both ends of the electrode assembly along the first direction, the first groove is formed along the first direction, the backflow of the electrolyte squeezed out of the electrode assembly can be better guided, the backflow rate of the electrolyte is effectively improved, the soaking effect of the first pole piece is improved, and the cycle performance of the battery monomer is improved.

[0037] In some embodiments, the number of first grooves is a plurality, and the plurality of first grooves are arranged at intervals along a second direction, the distance between adjacent two first grooves is arranged in an increasing manner, and the second direction is the winding direction of the electrode assembly.

[0038] By adopting the technical scheme of the embodiment, after the first pole piece is wound in the winding direction of the electrode assembly, the number of first grooves close to the inner side of the electrode assembly is large, and the number of first grooves close to the outer side of the electrode assembly is small, which is conducive to improving the electrolyte backflow effect of the inner side of the electrode assembly, improving the soaking effect of the inner side of the electrode assembly, and thus improving the cycle performance of the battery monomer.

[0039] In some embodiments, the number of the first tab winding turns is n, n is a natural number, n is greater than or equal to 30, the innermost first tab winding turn is the first first tab winding turn, and at least one of the first 10 first tab winding turns is provided with a groove.

[0040] By adopting the technical scheme of this embodiment, at least one of the first 10 first tab winding turns is provided with a groove, which can improve the wettability of the inner side of the electrode assembly and improve the cycle performance of the battery cell.

[0041] In some embodiments, the number of the first tab winding turns is n, n is a natural number, n is greater than or equal to 30, the innermost first tab winding turn is the first first tab winding turn, and at least the first first tab winding turn is not provided with a groove.

[0042] By adopting the technical scheme of this embodiment, at least the first first tab winding turn is not provided with a groove, which is conducive to improving the structural strength of the first first tab winding turn, reducing the risk of powder falling, damage, or even fracture of the first first tab winding turn caused by grooving, and improving the use reliability of the battery cell. In addition, the first first tab winding turn is not provided with a groove, which can also reduce the number of grooves and improve the production efficiency of the first tab.

[0043] In some embodiments, at least the first three first tab winding turns are not provided with a groove.

[0044] By adopting the technical scheme of this embodiment, at least the first to third first tab winding turns are not provided with a groove, which is conducive to improving the structural strength of the first to third first tab winding turns, reducing the risk of powder falling, damage, or even fracture of the first to third first tab winding turns caused by grooving, and improving the use reliability of the battery cell. In addition, the first to third first tab winding turns are not provided with a groove, which can also reduce the number of grooves and improve the production efficiency of the first tab.

[0045] In some embodiments, the electrode assembly is provided with a center hole, and the first first tab winding turn is closest to the center hole compared with other first tab winding turns.

[0046] By adopting the technical scheme of this embodiment, the center hole can be used to accommodate electrolyte and also allow electrolyte to flow, thereby wetting the first tab winding turns located on the inner side, improving the wettability of the inner side of the electrode assembly, and improving the cycle performance of the battery cell. In addition, the first tab winding turns located on the inner side can be wetted by the electrolyte in the center hole, which can reduce the need for the first tab winding turns located on the inner side to be provided with grooves, thereby improving the structural strength of the first tab winding turns located on the inner side and reducing the problem of powder falling of the first tab winding turns located on the inner side, so that the cycle performance and use reliability of the battery cell can be effectively balanced.

[0047] In some embodiments, the number of the first pole piece winding turns is n, n≥30, n is a natural number; the innermost first pole piece winding turn is the first first pole piece winding turn; at least the last two first pole piece winding turns are not provided with the groove.

[0048] By adopting the technical scheme of this embodiment, at least the last two first pole piece winding turns are not provided with the groove, which is beneficial to improve the structural strength of the last two first pole piece winding turns, reduce the risk of fracture of the last two first pole piece winding turns, and thus effectively improve the use reliability of the battery monomer. In addition, the last two first pole piece winding turns are not provided with the groove, which can reduce the number of grooves and improve the production and processing efficiency of the first pole piece.

[0049] In some embodiments, at least the last ten first pole piece winding turns are not provided with the groove.

[0050] By adopting the technical scheme of this embodiment, at least the last ten first pole piece winding turns are not provided with the groove, which is beneficial to improve the structural strength of the last ten first pole piece winding turns, reduce the risk of fracture of the last ten first pole piece winding turns, and thus better improve the use reliability of the battery monomer. In addition, the last ten first pole piece winding turns are not provided with the groove, which can reduce the number of grooves and improve the production and processing efficiency of the first pole piece.

[0051] In some embodiments, the number of the first pole piece winding turns is n, n≥30, n is a natural number; the innermost first pole piece winding turn is the first first pole piece winding turn; the first f first pole piece winding turns and the last q first pole piece winding turns are not provided with the groove; all the first pole piece winding turns between the fth first pole piece winding turn and the last q first pole piece winding turn are provided with the groove, f+q

[0052] By adopting the technical scheme of this embodiment, the first pole piece winding turns located on the inner side and the outer side are not provided with the groove, which is beneficial to improve the structural strength of the first pole piece winding turns located on the inner side and the outer side, improve the use reliability of the battery monomer, and in addition, can also reduce the number of grooves and improve the production and processing efficiency of the first pole piece; and the electrode assembly is grooved in the middle region between the inner side and the outer side, which is beneficial to improve the wettability of the electrode assembly in the middle region between the inner side and the outer side and improve the cycle performance of the battery monomer.

[0053] In some embodiments, 30≤n≤80, and optionally, 60≤n≤75.

[0054] By adopting the technical scheme of the embodiment, the number of the first tab winding turns is large, the capacity of the battery monomer is large, and the impregnation difficulty of the electrode assembly is large, and in the embodiment, the recesses can be selectively arranged on the inner side or the outer side of the electrode assembly, so that the impregnation effect of the electrode assembly is improved, and the structural strength of the inner side or the outer side of the electrode assembly can be improved, and the use reliability, the capacity and the cycle performance of the electrode assembly can be considered.

[0055] In some embodiments, the number of the first tab winding turns provided with the recesses is v, 0.23≤v / n≤1, v and n are positive integers, and optionally, 0.3≤v / n≤0.7.

[0056] By adopting the technical scheme of the embodiment, the first tab winding turns can be selectively grooved, which is beneficial to simultaneously considering the manufacturing of the first tab, the use reliability of the battery monomer and the cycle performance of the battery monomer.

[0057] In some embodiments, the first tab has a first winding end, the second tab has a second winding end, the innermost first tab winding turn is the first first tab winding turn, and the second winding end is located between the second last first tab winding turn and the third last first tab winding turn; the positions corresponding to the end surface of the first winding end and the end surface of the second winding end of the second last first tab winding turn are not provided with the recesses; and / or, the positions corresponding to the end surface of the first winding end and the end surface of the second winding end of the third last first tab winding turn are not provided with the recesses.

[0058] By adopting the technical scheme of the embodiment, the risk that the second last first tab winding turn is cut by the end surface of the first winding end and / or the end surface of the second winding end can be reduced, and the use reliability of the battery monomer is improved.

[0059] In some embodiments, the second last first tab winding turn is provided with the recesses, and the recesses are arranged away from at least one of the end surface of the first winding end and the end surface of the second winding end; or, the second last first tab winding turn is not provided with the recesses.

[0060] By adopting the technical scheme of the embodiment, the risk that the second last first tab winding turn is cut by the end surface of the first winding end and / or the end surface of the second winding end can be reduced, and the use reliability of the battery monomer is improved.

[0061] In some embodiments, the first tab has a first winding start end, the second tab has a second winding start end, the innermost first tab winding turn is the first first tab winding turn, and the second winding start end is located between the first two first tab winding turns; the positions corresponding to the end surface of the first winding start end and the end surface of the second winding start end of the first two first tab winding turns are not provided with the recesses; and / or, the positions corresponding to the end surface of the first winding start end and the end surface of the second winding start end of the first two first tab winding turns are not provided with the recesses.

[0062] By adopting the technical scheme of the embodiment, the risk that the first two first tab winding turns are sheared by the end face of the first winding starting end and / or the end face of the second winding starting end can be reduced, and the use reliability of the battery cell is improved.

[0063] In some embodiments, the first two first tab winding turns are provided with grooves, and the grooves are arranged away from at least one of the end face of the first winding starting end and the end face of the second winding starting end; or, the first two first tab winding turns are not provided with grooves.

[0064] By adopting the technical scheme of the embodiment, the risk that the first two first tab winding turns are sheared by the end face of the first winding starting end and / or the end face of the second winding starting end can be reduced, and the use reliability of the battery cell is improved.

[0065] In some embodiments, the first tab is a negative tab, and the second tab is a positive tab; or, the second tab is a negative tab, and the first tab is a positive tab.

[0066] By adopting the technical scheme of the embodiment, the polarity of the first tab and the second tab can be flexibly set to meet different use requirements.

[0067] In some embodiments, the electrode assembly comprises a flat area and two bending areas, and the two bending areas are located at two ends of the flat area; the first active winding turn comprises a first active bending part located at the bending area and a first active flat part located at the flat area; the first active flat part of at least one first active winding turn is provided with a groove; and / or, the first active bending part of at least one first active winding turn is provided with a groove.

[0068] By adopting the technical scheme of the embodiment, the impregnation effect of the flat area and / or the bending area can be improved, and the cycle performance of the battery cell is improved.

[0069] In some embodiments, the first active flat part of all the first active winding turns is provided with a groove, and the first active bending part of all the first active winding turns is not provided with a groove.

[0070] By adopting the technical scheme of the embodiment, the first active bending part in the bending area is bent, which increases the risk of powder falling of the first active bending part. However, the first active bending part of all the first active winding turns is not provided with a groove, which is beneficial to improve the structural strength of the first active bending part, reduce the risk of powder falling in the bending area, and improve the capacity and use reliability of the battery cell. At the same time, all the first active flat parts are provided with grooves 144, which can effectively improve the impregnation effect of the flat area and improve the cycle performance of the battery cell. Therefore, the cycle performance, capacity and use reliability of the battery cell can be considered at the same time.

[0071] In some embodiments, the battery cell is a cylindrical battery cell.

[0072] By adopting the technical scheme of the embodiment, the electrode assembly in the cylindrical battery monomer is tightly wound, which is not conducive to the backflow of the electrolyte, and the first pole piece is provided with a groove, which is conducive to the backflow of the electrolyte, improves the impregnation effect of the electrode assembly, and can effectively improve the impregnation effect of the cylindrical battery monomer.

[0073] In some embodiments, the thickness of the first active material layer is t, and the groove depth of the groove is h, wherein 0.05≤h / t≤0.84, and optionally, 0.08≤h / t≤0.8; and optionally, 0.1≤h / t≤0.5.

[0074] By adopting the technical scheme of the embodiment, the groove can store electrolyte and guide the backflow of the electrolyte, improve the impregnation effect of the first pole piece, and improve the cycle performance of the battery monomer; the groove does not penetrate the first active material layer, and the first current collector is not exposed, reducing the risk of direct reaction of the first current collector with ions. In addition, compared with the groove penetrating the first active material layer, the first active material layer removes less active material by grooving, which is conducive to improving the active material capacity of the first pole piece and reducing the risk of degradation of the use performance of the battery monomer due to insufficient active material capacity of the first pole piece. Therefore, the cycle performance and use performance of the battery monomer can be considered.

[0075] In some embodiments, the groove depth of the groove is h, and 0μm<h≤50μm, and optionally, 6μm≤h≤30μm.

[0076] By adopting the technical scheme of the embodiment, the groove depth is reasonable, so that the groove can store electrolyte and guide the backflow of the electrolyte, improve the impregnation effect of the first pole piece, and improve the cycle performance of the battery monomer; in addition, the first active material layer removes less active material by grooving, which is conducive to improving the active material capacity of the first pole piece and reducing the risk of degradation of the use performance of the battery monomer due to insufficient active material capacity of the first pole piece. Therefore, the cycle performance and use performance of the battery monomer can be considered.

[0077] In some embodiments, the groove width of the groove is w, wherein 30μm≤w≤1000μm; and optionally, 50μm≤w≤500μm; and optionally, 80μm≤w≤120μm.

[0078] By adopting the technical scheme of the embodiment, the groove can store electrolyte and guide the electrolyte backflow, the impregnation effect of the first tab is improved, the cycle performance of the battery monomer is improved, and the processing and manufacturing of the groove are facilitated; the active material removed from the first active material layer can be reduced, which is conducive to improving the active material capacity of the first tab, and the risk of the use performance of the battery monomer being reduced due to insufficient active material capacity of the first tab can be reduced; in addition, the groove is not easily flattened during the hot pressing process of the first tab, and the shape of the groove can be stably maintained. Therefore, the cycle performance and use performance of the battery monomer can be considered.

[0079] In some embodiments, the groove has a groove width w and a groove depth h, and 0.05≤h / w≤1; optionally, 0.1≤h / w≤0.5.

[0080] By adopting the technical scheme of the embodiment, under the condition that h is constant, the groove width is not too large, so that the groove is not easily flattened during the hot pressing process of the first tab, and the shape of the groove can be stably maintained; also, the electrolyte has a relatively wide channel during backflow, which is conducive to the backflow of the electrolyte and improves the cycle performance of the battery monomer; therefore, the processing and manufacturing of the groove and the cycle performance of the battery monomer can be considered.

[0081] In some embodiments, along the first direction, the size of the first active material layer is L, and the groove depth is h, and 5×10 -5 ≤h / L≤5×10 -4 .

[0082] By adopting the technical scheme of the embodiment, under the condition that L is constant, the design of h / L≥5×10 -5 can make the electrolyte backflow faster and improve the impregnation effect of the first tab; in addition, the design of h / L≤5×10 -4 can reduce the risk of the first current collector being exposed and the excessive loss of active material of the first tab caused by the groove depth being too large, and therefore, the capacity, cycle performance, and use reliability of the battery monomer can be considered.

[0083] In some embodiments, along the first direction, the size of the first active material layer is L, and the groove depth is h, wherein L≥60mm and h≥6μm.

[0084] By adopting the technical scheme of the embodiment, for the battery monomer with L≥60mm, h≥6μm makes the groove store more electrolyte and better guide the electrolyte backflow, which can effectively improve the impregnation effect of the first tab and improve the cycle performance of the battery monomer.

[0085] In some embodiments, along the first direction, the size of the groove is l, the size of the first active material layer is L, and 0.8≤l / L≤1; optionally, 0.9≤l / L≤0.98.

[0086] By adopting the technical solutions of this embodiment, along the first direction, the size of the groove and the size of the first active material layer are not much different or the same, and the two ends of the groove are relatively close to the two ends of the first active material layer, so that the electrolyte squeezed out from the two ends of the electrode assembly can quickly flow back through the groove, which can effectively improve the impregnation effect of the first pole piece and improve the cycle performance of the battery monomer.

[0087] In some embodiments, 60mm≤L≤330mm, and optionally, 70mm≤L≤200mm.

[0088] By adopting the technical solutions of this embodiment, the design of 60mm≤L≤330mm, along the first direction, the size of the first active material layer is large, and the first active material layer contains more active material, which improves the capacity of the battery monomer; however, in the first direction, the distance of the squeezed electrolyte flowing back to the middle part of the first active material layer is far, which increases the difficulty of the squeezed electrolyte flowing back to the middle part of the first active material layer, and in combination with the design of 0.8≤l / L≤1, the squeezed electrolyte can quickly flow back to the middle part of the first active material layer through the groove, which is conducive to improving the impregnation effect of the first pole piece and improving the cycle performance of the battery monomer, so the capacity and cycle performance of the battery monomer can be considered.

[0089] In some embodiments, the groove comprises a first groove segment and a second groove segment arranged along the first direction, the first groove segment is connected with the second groove segment at at least one end along the first direction, the groove depth of the first groove segment is greater than the groove depth of the second groove segment, and / or the groove width of the first groove segment is greater than the groove width of the second groove segment.

[0090] By adopting the technical solutions of this embodiment, the size of the second groove segment is smaller than that of the first groove segment, so that the electrolyte is easy to produce a siphon effect at the second groove segment, which is conducive to the rapid flow of the electrolyte, improves the impregnation effect of the first pole piece, and improves the cycle performance of the battery monomer.

[0091] In some embodiments, along the direction of the first groove segment pointing to the second groove segment, the groove depth of the second groove segment is arranged to decrease from the first groove segment; and / or, along the direction of the first groove segment pointing to the second groove segment, the groove width of the second groove segment is arranged to decrease from the first groove segment.

[0092] By adopting the technical scheme of the embodiment, the size of the second groove section gradually decreases in the direction away from the first groove section compared to the size of the first groove section, a pressure difference of electrolyte flow can be formed, the second groove section can generate a better siphon effect, electrolyte can be more quickly sucked into the second groove section and quickly returned to the first groove section through the second groove section, and the first wetting effect can be better improved, and the cycle performance of the battery monomer can be improved.

[0093] In some embodiments, the groove comprises a plurality of sub-sections, and the plurality of sub-sections are spaced apart along the first direction.

[0094] By adopting the technical scheme of the embodiment, the groove comprises a plurality of sub-sections, which can reduce the removal of active material by slotting the first active material layer and reduce the loss amount of active material of the first pole piece, thereby facilitating to improve the capacity and use performance of the battery monomer. In addition, the plurality of sub-sections are spaced apart, which is beneficial to improve the structural strength and rigidity of the first pole piece compared to using an integral groove, and is beneficial to the use reliability of the battery monomer.

[0095] In some embodiments, the spacing between the two adjacent sub-sections is d, and 0.1mm≤d≤1mm; optionally, 0.3mm≤d≤0.6mm.

[0096] By adopting the technical scheme of the embodiment, the two adjacent sub-sections are spaced apart, which reduces the loss amount of active material of the first pole piece and improves the use performance of the battery monomer. In addition, the electrolyte between the two adjacent sub-sections can flow to each other, which makes the distribution of the electrolyte more uniform and is beneficial to improve the cycle performance of the battery monomer.

[0097] In some embodiments, the number of grooves is a plurality, and the plurality of grooves are spaced apart along the second direction; along the second direction, the sub-sections of one of the two adjacent grooves are staggered with at least part of the sub-sections of the other groove, and the second direction is perpendicular to the thickness direction of the first current collector and the first direction.

[0098] By adopting the technical scheme of the embodiment, the plurality of sub-sections of the two adjacent grooves are staggered, which is beneficial to improve the uniformity of the distribution of the electrolyte, is beneficial to improve the wetting effect of the first pole piece, and is beneficial to improve the cycle performance of the battery monomer.

[0099] In some embodiments, the number of grooves is a plurality, and the plurality of grooves form a plurality of groups of grooves, each group of grooves comprises a plurality of intersecting grooves, and the plurality of groups of grooves are spaced apart along the second direction, and the second direction is perpendicular to the thickness direction of the first current collector.

[0100] By adopting the technical scheme of the embodiment, the plurality of grooves are divided into a plurality of groups, each group of grooves includes a plurality of intersecting grooves, and the electrolyte can flow in the plurality of grooves, which is conducive to improving the uniformity of electrolyte distribution, improving the wettability of the first pole piece, and improving the cycle performance of the battery monomer. In addition, the plurality of groups of grooves are arranged at intervals along the second direction, which can reduce the loss of active material of the first pole piece, is conducive to improving the use performance and capacity of the battery monomer, and can also improve the structural strength and rigidity of the first pole piece, which is conducive to improving the use reliability of the battery monomer.

[0101] In some embodiments, the second pole piece includes a second current collector and a second active material layer, the second current collector is connected with the second active material layer at least in part of an area of at least one surface along a thickness direction of the second current collector, and at least part of the second active material layer is located between the second current collector and the separator.

[0102] In some embodiments, the electrode assembly has a wound structure, and m gaps are formed between the first active material layer and the second active material layer, m is greater than or equal to 30, and m is a natural number; the innermost one of the m gaps is the first gap; and an average value of radial dimensions of the m-13th to m-5th gaps is greater than an average value of radial dimensions of the 5th to 13th gaps.

[0103] By adopting the technical scheme of the embodiment, in the cycle process of the battery monomer, the expansion of the electrode assembly gradually accumulates from the inside to the outside along the radial direction, and the expansion accumulation force of the outside of the electrode assembly is large; the average value of the radial dimensions of the m-13th to m-5th gaps is large, which can provide more expansion space for the expansion of the outside of the electrode assembly, absorb the expansion amount accumulated by the expansion of the electrode assembly, and thus reduce the acting force between the electrode assembly and the shell, reduce the deformation amount of the shell, reduce the risk of cracking of the shell, and improve the reliability. In addition, the average value of the radial dimensions of the 5th to 13th gaps is small, which can increase the compactness of the inside of the electrode assembly, and is conducive to improving the energy density of the battery monomer.

[0104] In some embodiments, the gap winding turns include a first gap sub-turn and a second gap sub-turn, the first gap sub-turn is located between the first active material layer and the separator, and the second gap sub-turn is located between the second active material layer and the separator.

[0105] By adopting the technical scheme of the embodiment, the first gap sub-turn and the second gap sub-turn can both provide space for the expansion of the electrode assembly, thereby reducing the extrusion effect on the shell, reducing the risk of deformation and cracking of the shell, and improving the reliability of the battery monomer.

[0106] In some embodiments, the radial dimension of the first gap winding turn is smaller than the radial dimension of the mth gap winding turn.

[0107] By adopting the technical scheme of the embodiment, the radial dimension of the mth gap winding coil is large, which can provide more expansion space for the electrode assembly, absorb the accumulated expansion amount of the electrode assembly, and thus reduce the acting force between the electrode assembly and the shell, reduce the deformation amount of the shell, reduce the risk of cracking of the shell, and improve the reliability.

[0108] In some embodiments, the m gap winding coils are divided into j groups of gap winding coils in the order from the inner side to the outer side of the electrode assembly; the innermost group of gap winding coils is the first group of gap winding coils, and each group of gap winding coils from the first group to the j-1th group includes 9 gap winding coils, 1≤m-9×(j-1)≤9, and j is a natural number; the average value of the radial dimensions of the first group to the j-1th group of gap winding coils is set to increase.

[0109] By adopting the technical scheme of the embodiment, the average value of the radial dimensions of the first group to the j-1th group of gap winding coils is set to increase, the radial dimensions of the gap winding coils increase from the inner side to the outer side of the electrode assembly, the radial dimension of the gap winding coil on the outer side of the electrode assembly is large, which can also provide more expansion space for the electrode assembly, absorb the accumulated expansion amount of the electrode assembly, and thus reduce the acting force between the electrode assembly and the shell, reduce the deformation amount of the shell, reduce the risk of cracking of the shell, and improve the reliability. In addition, the radial dimension of the gap winding coil on the outer side of the electrode assembly is small, which can effectively increase the compactness of the structure on the inner side of the electrode assembly, and is conducive to improving the energy density of the battery cell.

[0110] In some embodiments, the first current collector includes a first current collector body and a first tab connected to each other, at least a part of the first current collector body is covered with a first active material layer, and the first tab is not covered with the first active material layer.

[0111] The second current collector includes a second current collector body and a second tab connected to each other, at least a part of the second current collector body is covered with a second active material layer, and the second tab is not covered with the second active material layer.

[0112] In some embodiments, the shell includes a shell body and an end cover, the shell body includes a side wall and an end wall connected to each other, the side wall surrounds the electrode assembly, the end wall and the end cover are oppositely distributed along the axial direction of the battery cell, and the end cover is sealingly connected to the side wall.

[0113] The end cover is insulated and provided with an electrode terminal, the second tab is electrically connected to the electrode terminal, and at least one of the side wall and the end wall is electrically connected to the first tab.

[0114] Alternatively, the end wall is insulated and provided with an electrode terminal, the second tab is electrically connected to the electrode terminal, and at least one of the end cover and the side wall is electrically connected to the first tab.

[0115] By adopting the technical scheme of the embodiment, the output electrode of the battery cell can be flexibly arranged to meet different needs.

[0116] In some embodiments, the battery cell further comprises a first current collecting member and a second current collecting member; the first tab and the second tab are respectively located at two ends of the electrode assembly along the axial direction of the battery cell, and the second tab is located at a side of the electrode assembly close to the electrode terminal; the second current collecting member is electrically connected between the second tab and the electrode terminal;

[0117] The electrode terminal is insulated from the end cover, the first current collecting member is located between the first tab and the end wall, the first current collecting member is electrically connected with the first tab, and at least one of the side wall and the end wall is electrically connected with the first current collecting member;

[0118] Alternatively, the electrode terminal is insulated from the end wall, the first current collecting member is located between the first tab and the end cover, the first current collecting member is electrically connected with the first tab, and at least one of the side wall and the end cover is electrically connected with the first current collecting member.

[0119] By adopting the technical scheme of the embodiment, the switching effect of the first current collecting member and the second current collecting member makes the assembly operation of the battery cell simpler.

[0120] In some embodiments, the electrode terminal is insulated from the end wall; the side wall is provided with a protruding portion protruding inwardly, and along the axial direction of the battery cell, the protruding portion is located at a side of the first tab facing the end cover; the second current collecting member comprises a first connecting portion, a second connecting portion and a third connecting portion, the second connecting portion is connected between the first connecting portion and the third connecting portion; the first connecting portion is connected to the first tab, at least part of the third connecting portion is located between the protruding portion and the end cover, and the third connecting portion is connected to a side of the protruding portion facing away from the first tab.

[0121] By adopting the technical scheme of the embodiment, at least part of the third connecting portion is arranged between the protruding portion and the end cover, and the third connecting portion is connected to a side of the protruding portion facing the end cover, so that the first current collecting member can be assembled through the opening of the shell, and the installation of the first current collecting member is facilitated; in addition, the protruding portion also limits the third connecting portion, improves the installation stability of the first current collecting member, improves the connection reliability between the first current collecting member and the first tab and between the first current collecting member and the protruding portion, and improves the use reliability of the battery cell.

[0122] In a second aspect, a battery device is provided, comprising a plurality of the above-mentioned battery cells.

[0123] By adopting the technical scheme of the embodiment, the battery cell has good cycle performance and good use reliability, which is conducive to improving the use performance and service life of the battery device.

[0124] In a third aspect, a power consuming device is provided, comprising the above-mentioned battery cell or the above-mentioned battery device, and the battery cell or the battery device is used for storing or providing electric energy.

[0125] By adopting the technical solution of this embodiment, the battery cells have good cycle performance and good reliability, and the battery device has good performance and long service life, which is conducive to improving the performance and service life of the electrical device.

[0126] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0127] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0128] Figure 1 This application provides structural schematic diagrams of vehicles for some embodiments;

[0129] Figure 2 Schematic diagram of a battery device provided for some embodiments of this application;

[0130] Figure 3 This is a schematic diagram of the structure of a battery cell provided in some embodiments of this application;

[0131] Figure 4 for Figure 3 The diagram shows an exploded battery cell;

[0132] Figure 5 A cross-sectional schematic diagram of a battery cell provided in some embodiments of this application;

[0133] Figure 6 A partial cross-sectional schematic diagram of the electrode assembly of a battery cell provided in some embodiments of this application;

[0134] Figure 7 for Figure 6 Schematic diagram of the cross section at point AA;

[0135] Figure 8 A schematic diagram of the first electrode sheet in its unfolded state, provided in some embodiments of this application;

[0136] Figure 9 for Figure 8 Schematic diagram of the cross section at point CC;

[0137] Figure 10 for Figure 8 Schematic diagram of the cross section at point DD;

[0138] Figure 11 For Figure 6 A local enlarged view at B in the middle;

[0139] Figure 12 A structural schematic view of the first pole piece in an unfolded state according to some embodiments of the application;

[0140] Figure 13 A structural schematic view of the first pole piece in an unfolded state according to some embodiments of the application;

[0141] Figure 14 A structural schematic view of the first pole piece in an unfolded state according to some embodiments of the application;

[0142] Figure 15 A structural schematic view of the first pole piece in an unfolded state according to some embodiments of the application;

[0143] Figure 16 A structural schematic view of the first pole piece in an unfolded state according to some embodiments of the application;

[0144] Figure 17 A structural schematic view of the first pole piece in an unfolded state according to some embodiments of the application;

[0145] Figure 18 A structural schematic view of the first pole piece in an unfolded state according to some embodiments of the application;

[0146] Figure 19 A structural schematic view of the first pole piece in an unfolded state according to some embodiments of the application;

[0147] Figure 20 A sectional view of an electrode assembly according to some embodiments of the application;

[0148] Figure 21 For Figure 20 A local enlarged view at E in the middle;

[0149] Figure 22 For Figure 20 A sectional view of the bending region in

[0150] Figure 23 A structural schematic view of the first pole piece in an unfolded state according to some embodiments of the application;

[0151] Figure 24 For Figure 23 A sectional view at F-F in the middle;

[0152] Figure 25A structural schematic view of the first pole piece in an unfolded state is provided for some embodiments of the present application.

[0153] Figure 26 A structural schematic view of the first pole piece in an unfolded state is provided for some embodiments of the present application. Figure 25 A sectional view of the middle H-H.

[0154] Figure 27 A structural schematic view of the first pole piece in an unfolded state is provided for some embodiments of the present application.

[0155] Figure 28 A structural schematic view of the first pole piece in an unfolded state is provided for some embodiments of the present application.

[0156] Figure 29 A structural schematic view of the first pole piece in an unfolded state is provided for some embodiments of the present application.

[0157] Figure 30 A structural schematic view of the first pole piece in an unfolded state is provided for some embodiments of the present application.

[0158] Figure 31 A sectional schematic view of a battery cell is provided for some embodiments of the present application.

[0159] Figure 32 A sectional schematic view of a battery cell is provided for some embodiments of the present application. Figure 31 An enlarged view of the middle I.

[0160] Figure 33 A sectional schematic view of a battery cell is provided for some embodiments of the present application.

[0161] In the drawings, various elements are labeled the same as in the description.

[0162] 1 vehicle; 2 battery device; 3 controller; 4 motor; 5 case; 51 first case; 52 second case; 6 battery cell; 10 electrode assembly; 101 center hole; 11 positive electrode sheet; 111 positive electrode current collector; 112 positive electrode active material layer; 12 negative electrode sheet; 121 negative electrode current collector; 122 negative electrode active material layer; 13 separator; 14 first electrode sheet; 141 first current collector; 1411 first current collector body; 1412 first tab; 142 first active material layer; 1421 first surface; 1421c measurement region; 1421d outer edge line; 1422 first active material portion; 1423 second active material portion; 1424 first face; 1425 second face; 143 first electrode sheet winding; 1431 first current collector winding; 1432 first active material winding; 1433 first winding face; 1434 first active material bending portion; 1435 first active material flat portion; 144 recess; 144b notch; 1441 first recess; 1442 first groove segment; 1443 second groove segment; 1444 second recess; 1445 subsegment; 1446 first groove; 1447 second groove; 15 second electrode sheet; 151 second current collector; 1511 second current collector body; 1512 second tab; 152 second active material layer; 1521 second surface; 153 second electrode sheet winding; 1531 second current collector winding; 1532 second active material winding; 1533 second winding face; 1534 second active material bending portion; 1535 second active material flat portion; 20 housing; 21 case; 211 end wall; 212 side wall; 2121 protrusion; 2122 recess; 2123 crimping portion; 22 end cap; 30 electrode terminal; 31 through hole; 40 cover plate; 60 first current collecting member; 61 first connecting portion; 62 second connecting portion; 63 third connecting portion; 70 second current collecting member; 80 insulating member. DETAILED DESCRIPTION

[0163] In order to make the technical problems to be solved, technical solutions and beneficial effects of the present application more clearly, the present application will be further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application.

[0164] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application; the terms "include" and "have" and any variations thereof used in the specification and claims of the present application and the above description of drawings are intended to cover the inclusion not the exclusion of one or more elements.

[0165] In the description of the embodiments of the present application, the technical terms "first", "second" and the like are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features.

[0166] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearance of the phrase in various places in the specification does not necessarily all refer to the same embodiment, nor is it necessarily independent or alternative embodiments to each other. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined in any suitable manner with other embodiments.

[0167] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " in this paper generally represents that the front and rear associated objects are a "or" relationship.

[0168] In the description of the embodiments of the present application, the term "a plurality of" refers to two or more (including two), and similarly, "a plurality of groups" refers to two or more groups (including two groups), and "a plurality of pieces" refers to two or more pieces (including two pieces). The meaning of "several" is one or more, unless otherwise explicitly and specifically limited.

[0169] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the embodiments of the present application.

[0170] In the description of the embodiments of the present application, unless explicitly defined and limited otherwise, the technical terms "mounting", "connection", "connecting", "fixing" and the like should be understood in a broad sense, for example, can be fixed connection, can also be detachable connection, or integral; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction relationship of two elements. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0171] In the description of the embodiments of the present application, unless explicitly defined and limited otherwise, when an element is referred to as "fixed to" or "disposed on" another element, it can be directly on another element or indirectly on the other element. When an element is referred to as "connected to" another element, it can be directly connected to another element or indirectly connected to the other element.

[0172] The battery cell can be a secondary battery, which refers to a battery cell that can be activated by charging after discharging to continue to use.

[0173] The battery device can refer to a single physical module that includes one or more battery cells to provide higher voltage and capacity.

[0174] The battery cell generally includes an electrode assembly and a case for accommodating the electrode assembly. The electrode assembly generally includes a separator and two polar plates of opposite polarity, and the separator separates the two polar plates.

[0175] During the cyclic charging and discharging of the battery cell, the active material on the polar plate will swell due to the insertion of ions, causing the pressure between the active material layers of the two polar plates to increase, and the electrolyte between the active material layers of the two polar plates is squeezed out, reducing the effect of the active material layer of the polar plate being soaked by the electrolyte, increasing the resistance of ion transmission, and not conducive to improving the cycle performance of the battery cell. At the same time, the edge of the active material layer of the polar plate is prone to powder falling or collapse, and the falling powder is prone to form a conductive channel between the two polar plates, causing the battery cell to short circuit and affecting the use reliability of the battery cell.

[0176] Based on this, the embodiments of the present application provide a technical scheme, which reasonably designs the structure of the polar plate, so that the polar plate has a good soaking effect, and the risk of powder falling and collapse at the edge of the active material layer of the polar plate is small, which is conducive to improving the use reliability of the battery cell. Therefore, the cycle performance and use reliability of the battery cell can be well balanced.

[0177] The battery cell described in the embodiments of the present application is applicable to a battery device and a power consumption device using the battery device. The power consumption device can be a device using the battery device as a power source or various energy storage systems using the battery device as an energy storage element. The power consumption device can be, but is not limited to, a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, an electric vehicle, an electric automobile, a ship, a spacecraft, and the like. Among them, the electric toy can include a fixed or mobile electric toy, such as a game console, an electric automobile toy, an electric ship toy, and an electric aircraft toy, and the spacecraft can include an airplane, a rocket, a space shuttle, and a spacecraft, and the like.

[0178] The following embodiments are described by taking a vehicle 1 as an example for convenience of description.

[0179] As shown in Figure 1 , the vehicle 1 is provided with a battery device 2 inside, which can be arranged at the bottom, head or tail of the vehicle 1. The battery device 2 can be used for power supply of the vehicle 1, for example, the battery device 2 can be used as an operating power source of the vehicle 1.

[0180] The vehicle 1 can also include a controller 3 and a motor 4, the controller 3 being used to control the battery device 2 to supply power to the motor 4, for example, for the working power demand of the vehicle 1 during starting, navigation and driving.

[0181] In some embodiments of the present application, the battery device 2 can not only be used as an operating power source of the vehicle 1, but also be used as a driving power source of the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0182] Referring to Figure 2 , in some embodiments, the battery device 2 can include one or more battery cell assemblies for providing voltage and capacity.

[0183] The battery cell assembly can include a plurality of battery cells 6 connected in series, in parallel or in a mixed manner through a busbar component. The mixed connection means that there are both series and parallel connections among the plurality of battery cells 6.

[0184] The battery cell 6 can be a secondary battery cell, which means that the battery cell can be activated by charging after discharging to continue to be used.

[0185] As an example, the battery cell 6 can be a lithium ion battery cell, a sodium ion battery cell, a sodium lithium ion battery cell, a lithium metal battery cell, a sodium metal battery cell, a lithium sulfur battery cell, a magnesium ion battery cell, a nickel hydrogen battery cell, a nickel cadmium battery cell, a lead-acid battery cell, and the like.

[0186] In some embodiments, the battery cell assembly is typically formed by arranging a plurality of battery cells 6; as an example, the battery cell assembly can be a battery module, which is formed by arranging and fixing a plurality of battery cells 6 into one independent module. As an example, the battery module can be formed by bundling a plurality of battery cells 6 by a cable tie.

[0187] In some embodiments, the battery device 2 can be a battery pack, which includes a box 5 and one or more battery cell assemblies accommodated in the box 5. As an example, the battery cell assembly can be a battery module, which can be accommodated in the box 5 by fixing the battery module in the box 5. As an example, the battery cell assembly can also be accommodated in the box 5 by fixing a plurality of battery cells 6 directly in the box 5.

[0188] In some embodiments, the box 5 for accommodating the battery cells 6 can be of various structures.

[0189] In some embodiments, the box 5 can include a first box 51 and a second box 52. The first box 51 and the second box 52 are fastened so that an enclosed space is formed inside the box 5 to accommodate the battery cell assembly. Here, the enclosed means covered or closed, which can be sealed or unsealed. The first box 51 can be a top cover or a bottom plate.

[0190] In some embodiments, the box 5 can include a top cover, a frame and a bottom plate. The top cover and the bottom plate are connected with the frame so that an enclosed space is formed inside the box 5 to accommodate the battery cell assembly. As an example, the frame can include a plurality of side beams.

[0191] In some embodiments, the box 5 can be part of the chassis structure of the vehicle 1. For example, part of the box 5 can be at least part of the floor of the vehicle 1, or part of the box 5 can be at least part of the cross beam and the longitudinal beam of the vehicle 1.

[0192] In some embodiments, the battery device 2 can be an energy storage device.

[0193] The energy storage device can be used in energy storage power stations, wind power systems, solar power systems, mobile power systems or temporary power supply systems, etc. The energy storage device can store electrical energy as needed and output electrical energy at appropriate times. For example, the energy storage device can store electrical energy during the off-peak period of electricity consumption, and provide electrical energy for relevant users or electrical equipment during the peak period of electricity consumption.

[0194] In some embodiments, the energy storage device includes an energy storage container, an energy storage cabinet, etc.

[0195] Reference is made to Figures 3-7As shown, the battery cell 6 according to embodiments of the present application includes a housing 20 and an electrode assembly 10, at least a portion of the electrode assembly 10 being accommodated in the housing 20.

[0196] The housing 20 can be a hollow structure, and an accommodation space for accommodating the electrode assembly 10 and electrolyte is formed inside the housing 20. Exemplarily, the housing 20 of the battery cell 6 is a cylindrical housing 20.

[0197] In some embodiments, the housing 20 can be a metal housing 20, for example, the housing 20 can be a steel shell, an aluminum shell, a composite metal shell (such as a copper-aluminum composite shell), or other metal shells. Alternatively, the housing 20 can also be a non-metal housing, for example, a plastic shell (such as polypropylene) or the like.

[0198] In some embodiments, the housing 20 can be a sealed structure or a non-sealed structure. As an example, when the housing 20 is a non-sealed structure, the housing 20 serves to protect the electrode assembly, and a sealing bag is further included between the housing 20 and the electrode assembly 10, the sealing bag being used to package the electrode assembly 10 and electrolyte. Specifically, the sealing bag can be a bag-shaped insulating member or an aluminum-plastic film. When the housing is a sealed structure, the sealing bag is used to package the electrode assembly 10 and electrolyte and other components.

[0199] As an example, the battery cell 10 can be a cylindrical battery cell, a prismatic battery cell, a soft-pack battery cell, or a battery cell of other shapes, and the prismatic battery cell includes a square battery cell, a blade-shaped battery cell, a multi-prismatic battery cell, for example, a hexagonal battery cell, and the like.

[0200] In some embodiments, the housing 20 includes a shell 21 and an end cover 22, the shell 21 having an opening, and the end cover 22 being connected to the shell 21 and covering the opening.

[0201] The shell 21 is a component used to cooperate with the end cover 22 to form an internal cavity of the battery cell 6, and the internal cavity formed can be used to accommodate the electrode assembly 10, electrolyte, and other components.

[0202] The shell 21 and the end cover 22 can be independent components. Exemplarily, an opening can be provided on the shell 21, and the internal cavity of the battery cell is formed by covering the opening with the end cover 22 at the opening.

[0203] The shell 21 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, and the like.

[0204] The shape of the end cover 22 can be adapted to the shape of the housing 21 to fit the housing 21. The material of the end cover 22 can be the same as or different from the material of the housing 21. Optionally, the end cover 22 can be made of a material with certain hardness and strength (e.g., copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.), so that the end cover 22 is less likely to deform when subjected to extrusion and collision, and the battery cell can have higher structural strength and improved reliability.

[0205] The end cover 22 is connected to the housing 21 by welding, bonding, clamping, or other means.

[0206] The housing 21 can be open at one end or both ends. In some examples, the housing 21 can be a structure open at one side, and the end cover 22 is provided as one and covers the housing 21. In other examples, the housing 21 can also be a structure open at both sides, and the end cover 22 is provided as two, and the two end covers 22 cover the two openings of the housing 21, respectively.

[0207] In some embodiments, the housing 21 includes an integrally formed side wall 212 and an end wall 211, the end wall 211 and the end cover 22 are opposite along the axial direction of the battery cell 6, and the end cover 22 is sealingly connected to the side wall 212.

[0208] The electrode assembly 10 is a component in which electrochemical reactions occur in the battery cell 6. The electrode assembly 10 can be entirely accommodated in the case 20 or partially accommodated in the case 20. For example, a portion of the tab of the electrode assembly 10 can extend outside the case 20.

[0209] Optionally, the electrode assembly 10 is entirely accommodated in the case 20.

[0210] In some embodiments, the electrode assembly 10 includes a positive electrode sheet 11 and a negative electrode sheet 12. During charging and discharging of the battery cell 6, active ions (e.g., lithium ions) are intercalated and deintercalated between the positive electrode sheet 11 and the negative electrode sheet 12.

[0211] In some embodiments, the positive electrode sheet 11 can include a positive electrode current collector 111 and a positive electrode active material layer 112 provided on at least one surface of the positive electrode current collector 111.

[0212] As an example, the positive electrode current collector 111 has two surfaces opposite in the thickness direction thereof, and the positive electrode active material layer 112 is provided on either one or both of the two opposite surfaces of the positive electrode current collector 111.

[0213] As an example, the positive electrode current collector 111 can employ a metal foil, a conductive polymer material, a carbon material, or a composite current collector. For example, as a metal foil, a pure metal, an alloy, a surface-treated metal, including but not limited to stainless steel, copper, aluminum, nickel, a nickel alloy, titanium, or silver, and the like can be employed. The composite current collector can include a high molecular material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, an aluminum alloy, nickel, a nickel alloy, titanium, a titanium alloy, silver, and a silver alloy, and the like) on a high molecular material base material (such as a base material of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, and the like).

[0214] As an example, the positive electrode active material layer 112 includes a positive electrode active material, which can include at least one of a lithium-containing phosphate, a lithium transition metal oxide, and a modified compound of each thereof. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery positive electrode active material can also be used. These positive electrode active materials can be used alone only one or two or more can be used in combination. Examples of the lithium-containing phosphate can include, but are not limited to, at least one of lithium iron phosphate (such as LiFeP04 (which can also be referred to simply as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnP04), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon. Examples of the lithium transition metal oxide can include, but are not limited to, at least one of lithium cobalt oxide (such as LiCo02), lithium nickel oxide (such as LiNi02), lithium manganese oxide (such as LiMn02, LiMn204), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (which can also be referred to simply as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (which can also be referred to simply as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (which can also be referred to simply as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (which can also be referred to simply as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (which can also be referred to simply as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.8 Co 0.15 Al0.05 O2) and modified compounds thereof, and the like. The modified compounds refer to substances obtained by modification means such as doping or coating on the basis of the above-mentioned substances.

[0215] In some embodiments, the negative electrode sheet 12 can include a negative electrode current collector 121 and a negative electrode active material layer 122 provided on at least one surface of the negative electrode current collector 121.

[0216] As an example, the negative electrode current collector 121 has two surfaces opposite in the thickness direction thereof, and the negative electrode active material layer 122 is provided on either one or both of the two surfaces of the negative electrode current collector 121.

[0217] As an example, the negative electrode current collector 121 can employ a metal foil, a conductive polymer material, a carbon material, or a composite current collector. For example, as the metal foil, a pure metal, an alloy, a surface-treated metal, including but not limited to stainless steel, copper, aluminum, nickel, a nickel alloy, titanium, or silver, and the like can be employed. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (copper, a copper alloy, nickel, a nickel alloy, titanium, a titanium alloy, silver, and a silver alloy, and the like) on a polymer material base material (such as a base material of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, and the like).

[0218] As an example, the negative electrode active material can employ a negative electrode active material for the battery cell 6 known in the art. As an example, the negative electrode active material can include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, a silicon-based material, a tin-based material, and lithium titanate, and the like. The silicon-based material can be selected from at least one of elemental silicon, a silicon oxide compound, a silicon-carbon composite, a silicon-nitrogen composite, and a silicon alloy. The tin-based material can be selected from at least one of elemental tin, a tin oxide compound, and a tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a negative electrode active material for the battery cell 6 can also be used. These negative electrode active materials can be used alone only or in combination of two or more.

[0219] In some embodiments, the material of the positive electrode current collector 111 can be aluminum, and the material of the negative electrode current collector 121 can be copper.

[0220] In some embodiments, the electrode assembly 10 further includes a separator 13 provided between the positive electrode sheet 11 and the negative electrode sheet 12. The separator 13 can function to prevent short circuiting of the positive and negative electrodes while allowing the active ions to pass therethrough.

[0221] The separator 13 can be partially positioned between the positive electrode sheet 11 and the negative electrode sheet 12. For example, the separator 13 can protrude from the positive electrode sheet 11 and the negative electrode sheet 12 at both ends in the axial direction of the battery cell 6. Alternatively, the entire separator 13 can be positioned between the positive electrode sheet 11 and the negative electrode sheet 12.

[0222] In some embodiments, the separator 13 is a separator film. The separator film of the present application can be any porous structure separator film known to have good chemical stability and mechanical stability.

[0223] For example, the main material of the separator film can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator film can be a single layer film or a multi-layer composite film, and is not particularly limited. When the separator film is a multi-layer composite film, the materials of the respective layers can be the same or different. The separator 13 can be a separate member positioned between the positive electrode sheet 11 and the negative electrode sheet 12, or can be attached to the surface of the positive electrode sheet 11 or the surface of the negative electrode sheet 12. An inorganic particle coating, an organic particle coating, or an organic / inorganic composite coating can be applied to the surface of the separator film.

[0224] In some embodiments, the battery cell 6 further includes an electrolyte that functions to conduct ions between the positive electrode sheet 11 and the negative electrode sheet 12. The electrolyte of the present application can be selected as needed.

[0225] In some embodiments, the electrolyte includes an electrolyte salt and a solvent.

[0226] In some embodiments, the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonylimide, lithium bis-trifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro oxalate borate, lithium di-oxalate borate, lithium difluoro di-oxalate phosphate, and lithium tetrafluoro oxalate phosphate.

[0227] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, butanedisulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent can also be an ether-based solvent. The ether-based solvent can include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ether.

[0228] In some embodiments, the electrolyte can also optionally include an additive. For example, the additive can include a negative electrode film-forming additive, a positive electrode film-forming additive, and an additive capable of improving certain performance of the battery cell 6, such as an additive capable of improving overcharge / fast charge performance of the battery cell 6, an additive capable of improving high-temperature performance of the battery cell 6, an additive capable of improving low-temperature performance of the battery cell 6, and the like.

[0229] The electrode assembly 10 can be a wound structure, a stacked structure, or a hybrid structure of a wound and a stacked structure.

[0230] In some embodiments, the positive electrode sheet 11, the negative electrode sheet 12, and the separator 13 are wound.

[0231] The electrode assembly 10 is a wound structure. For example, the positive electrode sheet 11, the separator 13, and the negative electrode sheet 12 are wound in a cylindrical wound structure.

[0232] In some embodiments, the electrode assembly 10 is a stacked structure.

[0233] For example, a plurality of positive electrode sheets 11 and a plurality of negative electrode sheets 12 can be alternately stacked.

[0234] For example, a plurality of positive electrode sheets 11 can be provided, and the negative electrode sheet 12 can be folded to form a plurality of folded sections that are stacked. One positive electrode sheet 11 can be interposed between adjacent folded sections.

[0235] For example, both the positive electrode sheet 11 and the negative electrode sheet 12 can be folded to form a plurality of folded sections that are stacked.

[0236] For example, a plurality of separators 13 can be provided, and each of the separators 13 can be interposed between any adjacent positive electrode sheet 11 or negative electrode sheet 12.

[0237] For example, the separators 13 can be continuously provided and interposed between any adjacent positive electrode sheet 11 or negative electrode sheet 12 by being folded or wound.

[0238] In some embodiments, the electrode assembly 10 can have a cylindrical shape, a flat shape, or a polygonal shape.

[0239] In some embodiments, the electrode assembly 10 can be provided with tabs that can guide current out of the electrode assembly 10. The tabs can include positive tabs and negative tabs.

[0240] Referring to Figures 3-9As shown, in some embodiments, the battery cell 6 comprises a housing 20 containing an electrolyte, and an electrode assembly 10 at least partially located in the housing 20, the electrode assembly 10 comprising a separator 13 and first and second polar plates 14 and 15 of opposite polarity, at least part of the separator 13 being located between the first and second polar plates 14 and 15; the first polar plate 14 comprising a first current collector 141 and a first active material layer 142, the first active material layer 142 being connected to at least part of at least one surface of the first current collector 141 along a thickness direction Y of the first current collector 141, at least part of the first active material layer 142 being located between the first current collector 141 and the separator 13; wherein the first active material layer 142 comprises a first active material portion 1422 and a second active material portion 1423 arranged along a first direction Z, the second active material portion 1423 being connected to at least one end of the first active material portion 1422 along the first direction Z, the second active material portion 1423 having a thickness smaller than that of the first active material portion 1422, and the surface of the first active material portion 1422 opposite to the first current collector 141 being provided with a groove 144; along the first direction Z, the groove 144 is arranged spaced apart from the second active material portion 1423, and the first direction Z is perpendicular to the thickness direction Y of the first current collector 141.

[0241] One of the first and second polar plates 14 and 15 is the positive polar plate 11 as described above, and the other is the negative polar plate 12 as described above.

[0242] Part of the separator 13 is located between the first and second polar plates 14 and 15. Alternatively, the entire separator 13 is located between the first and second polar plates 14 and 15.

[0243] For example, the first polar plate 14 is the negative polar plate 12, the first polar plate 14 comprises the first current collector 141 which is the negative current collector 121 as described above, and the first active material layer 142 which is the negative active material layer 122 as described above, or the first polar plate 14 is the positive polar plate 11, the first current collector 141 is the positive current collector 111 as described above, and the first active material layer 142 is the positive active material layer 112 as described above.

[0244] The first current collector 141 is covered with the first active material layer 142 on one surface thereof along the thickness direction Y thereof, or the first current collector 141 is covered with the first active material layer 142 on both surfaces thereof along the thickness direction Y thereof.

[0245] The first active material layer 142 can cover part of the surface of the first current collector 141, or can cover the entire surface of the first current collector 141.

[0246] The first active material layer 142 can be directly covered on the first current collector 141, or other layer structures, such as a conductive protective layer, can be further arranged between the first active material layer 142 and the first current collector 141. The conductive protective layer can be formed by mixing a conductive agent and a binder. The binder bonds the first active material layer 142 and the first current collector 141, and the conductive agent is responsible for conducting electrons. The conductive agent can be carbon black, graphite, etc., and the binder can be polyvinylidene fluoride, etc.

[0247] In some examples, the first direction Z can be the axial direction of the battery cell 6.

[0248] Referring to Figure 8 In some examples, the first direction Z can be the width direction of the first tab 14 when the first tab 14 is in the unfolded state, as shown in FIG. 1A. Figure 6 In some examples, the first direction Z can be parallel to the winding axis X2 of the electrode assembly 10 when the first tab 14 is in the wound state, as shown in FIG. 1B.

[0249] In some examples, the first direction Z can be the length direction of the first tab 14 or a direction intersecting the length direction of the first tab 14 and the width direction of the first tab 14 when the first tab 14 is in the unfolded state.

[0250] The first active material layer 142 includes a first active material portion 1422 and a second active material portion 1423 arranged along the first direction Z. The first active material portion 1422 is the main part of the first active material layer 142, and the second active material portion 1423 is located at the edge of the first active material layer 142.

[0251] In some examples, the first active material portion 1422 is connected with the second active material portion 1423 at one end along the first direction Z, or the first active material portion 1422 is connected with the second active material portion 1423 at both ends along the first direction Z.

[0252] The thickness of the second active material portion 1423 is less than the thickness of the first active material portion 1422. The boundary between the first active material portion 1422 and the second active material portion 1423 can refer to the thickness transition position of the first active material layer 142. The second active material portion 1423 can be referred to as a thinned region of the first active material layer 142.

[0253] In some examples, the second active material portion 1423 and the first active material portion 1422 can have a substantially equal thickness structure. The thickness of the second active material portion 1423 is less than the thickness of the first active material portion 1422, so that the second active material portion 1423 and the first active material portion 1422 form a stepped structure.

[0254] In some examples, the first active material portion 1422 can be substantially an equal-thickness structure, and the thickness of the second active material portion 1423 decreases from the first active material portion 1422 in a direction in which the first active material portion 1422 points to the second active material portion 1423, so that the thickness of the second active material portion 1423 is less than the thickness of the first active material portion 1422. The direction in which the first active material portion 1422 points to the second active material portion 1423 can be referred to as a direction indicated by an arrow Z in FIG. 14. Figure 9

[0255] The surface of the first active material portion 1422 away from the first current collector 141 is provided with a groove 144, that is, the surface of the first active material portion 1422 facing the adjacent separator 13 is provided with the groove 144. The groove 144 can be machined on the surface of the first active material portion 1422 by using a laser or mechanical cutting, etc.

[0256] In the first direction Z, there is a distance between the second active material portion 1423 and the groove 144, so that the groove 144 of the first active material portion 1422 does not extend to the second active material portion 1423.

[0257] ​During the charging and discharging of the battery monomer 6, ions can move back and forth between the second pole piece 15 and the first active material layer 142 of the first pole piece 14 through the separator 13 and the electrolyte, thereby realizing the transmission of electric energy of the battery monomer 6. Meanwhile, during the charging and discharging of the battery monomer 6, the electrode assembly 10 expands, the distance between the separator 13 and the first active material layer 142 decreases, and the electrolyte between the first active material layer 142 and the separator 13 is squeezed out. The first active material layer 142 includes the first active material part 1422 and the second active material part 1423 arranged along the first direction Z, and the second active material part 1423 is connected to at least one end of the first active material part 1422 along the first direction Z. The surface of the first active material part 1422 away from the first current collector 141 is provided with a groove 144. On the one hand, the electrolyte can flow into the groove 144 for storage, the stored electrolyte can infiltrate the first active material layer 142 and provide a transmission path for ions, reduce the transmission resistance of ions, and improve the cycle performance of the battery monomer 6. On the other hand, the groove 144 can also provide a channel for the backflow of the electrolyte, reduce the backflow difficulty of the electrolyte, reduce the transmission resistance of the ions, improve the infiltration effect of the first pole piece 14, and also help to improve the cycle performance of the battery monomer 6. Moreover, the thickness of the second active material part 1423 is smaller than the thickness of the first active material part 1422, and the groove 144 is arranged apart from the second active material part 1423 along the first direction Z. The small thickness of the second active material part 1423 and the arrangement of the groove 144 apart from the second active material part 1423 make the groove 144 not extend to the second active material part 1423, reduce the risk of powdering or even collapsing of the second active material part 1423 caused by the extension of the groove 144 to the second active material part 1423, reduce the risk of short circuit of the battery monomer 6, improve the use reliability of the battery monomer 6, and also help to improve the capacity of the battery monomer 6. Therefore, the capacity, use reliability and cycle performance of the battery monomer 6 can be well balanced.

[0258] Meanwhile, the thickness of the second active material part 1423 is smaller than the thickness of the first active material part 1422, so that the surface of the second active material part 1423 away from the first current collector 141 is closer to the first current collector 141 than the surface of the first active material part 1422 away from the first current collector 141. On the one hand, the rolling force on the edge of the first active material layer 142 during the rolling of the first pole piece 14 can be reduced, and the risk of cracking of the edge of the first active material layer 142 can be reduced. On the other hand, the side of the second active material part 1423 away from the first current collector 141 can accommodate more electrolyte, thereby facilitating the backflow of the electrolyte. Moreover, the difference in thickness between the second active material part 1423 and the first active material part 1422 can form a siphon effect, improve the speed of backflow of the electrolyte, improve the infiltration effect of the electrode assembly 10, and improve the cycle performance of the battery monomer 6.

[0259] In some embodiments, the distance between the second active material portion and the groove is S1, where 0mm < S1≤ 18mm, and optionally, 2mm≤ S1≤ 8mm.

[0260] In some examples, S1 can be 18mm or any value between 0mm and 18mm, for example, S1 can be 0.1mm, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 12mm, 14mm, 16mm, 18mm.

[0261] S1>0mm, so that the groove 144 does not extend to the second active material portion 1423, which is conducive to improving the structural strength of the second active material portion 1423, and can reduce the risk of powdering or even collapse of the second active material portion 1423, which is conducive to improving the capacity and use reliability of the battery monomer 6; the design of S1≤ 18mm makes the electrolyte located on the side of the second active material portion 1423 away from the first current collector 141 closer to the groove 144, so that the electrolyte can flow better into the groove 144, improving the wettability of the first tab 14 and improving the cycle performance of the battery monomer 6. Therefore, the cycle performance, capacity and use reliability of the battery monomer 6 can be taken into account.

[0262] In some embodiments, 2mm≤ S1≤ 8mm, which can better take into account the use reliability and cycle performance of the battery monomer 6.

[0263] In some embodiments, the second tab 15 includes a second current collector 151 and a second active material layer 152, the second current collector 151 is connected with the second active material layer 152 at least in part of at least one surface along the thickness direction of the second current collector 151, and at least part of the second active material layer 152 is located between the second current collector 151 and the separator 13.

[0264] In some examples, the second tab 15 is a negative tab 12, the second tab 15 includes a second current collector 151 and a second active material layer 152, the second current collector 151 is the negative current collector 121 described above, and the second active material layer 152 is the negative active material layer 122 described above, or the second tab 15 is a positive tab 11, the second current collector 151 is the positive current collector 111 described above, and the second active material layer 152 is the positive active material layer 112 described above.

[0265] The second current collector 151 is covered with the second active material layer 152 on one surface along the thickness direction of the second current collector 151, or the second current collector 151 is covered with the second active material layer 152 on both surfaces along the thickness direction of the second current collector 151.

[0266] The second active material layer 152 can cover a partial area of the surface of the second current collector 151, or can cover the entire area of the surface of the second current collector 151.

[0267] The second active material layer 152 can be directly covered on the second current collector 151, or other layer structures such as a conductive protective layer can be further arranged between the second active material layer 152 and the second current collector 151.

[0268] In some embodiments, along a direction from the first active material part 1422 to the second active material part 1423, the thickness of the second active material part 1423 decreases.

[0269] For example, along a direction from the first active material part 1422 to the second active material part 1423, the thickness of the second active material part 1423 decreases in a step manner, so that the second active material part 1423 has a stepped structure; or, along a direction from the first active material part 1422 to the second active material part 1423, the thickness of the second active material part 1423 decreases slowly, and the shape of the second active material part 1423 is more smooth, which is beneficial to reduce stress concentration and improve the structural strength of the positive electrode sheet 11.

[0270] In some examples, along a direction from the first active material part 1422 to the second active material part 1423, the end surface of the second active material layer 152 exceeds the end surface of the second active material part 1423 close to the first active material part 1422, and the thickness of the second active material part 1423 decreases, so that a horn structure can be formed between the second active material part 1423 and the second active material layer 152. The large end of the horn structure is arranged away from the first active material part 1422. The arrangement of the horn structure makes the electrolyte more easily absorbed between the first active material part 1422 and the second electrode sheet 15, which is more beneficial to improve the soaking effect of the electrode assembly 10 and improve the cycle performance of the battery monomer 6.

[0271] In some examples, along a direction from the first active material part 1422 to the second active material part 1423, the end surface of the second active material layer 152 does not exceed the end surface of the second active material part 1423 close to the first active material part 1422, and the second active material parts 1423 of adjacent two first electrode sheet winding turns 143 also form a horn structure. The large end of the horn structure is arranged away from the first active material part 1422. The arrangement of the horn structure makes the electrolyte more easily absorbed between the first active material part 1422 and the second electrode sheet 15, which is more beneficial to improve the soaking effect of the electrode assembly 10 and improve the cycle performance of the battery monomer 6.

[0272] In some embodiments, the first active material portion 1422 has a first face 1424 facing away from the first current collector 141, and the second active material portion 1423 has a second face 1425 facing away from the first current collector 141, the second face 1425 being closer to the first current collector 141 than the first face 1424.

[0273] The distance between the second face 1425 and the first current collector 141 is less than the distance between the first face 1424 and the first current collector 141.

[0274] In some examples, the first face 1424 and the second face 1425 jointly form the first surface 1421, and the first face 1424 is provided with the groove 144 that does not extend to the second face 1425.

[0275] By adopting the technical solution of this embodiment, the side of the second face 1425 facing away from the first current collector 141 has more space for accommodating electrolyte, and the difference in distance between the second face 1425 and the first face 1424 and the first current collector 141 can be utilized to form a siphon effect, improve the speed of electrolyte backflow, improve the wettability of the electrode assembly 10, and improve the cycle performance of the battery cell 6.

[0276] In some embodiments, along the first direction Z, one end of the first active material portion 1422 is connected with the second active material portion 1423, and the other end of the first active material portion 1422 is not connected with the second active material portion 1423, and the surface of the first active material portion 1422 facing away from the current collector is provided with the groove 144, and along the first direction Z, the groove 144 penetrates the end face of the first active material portion 1422 facing away from the second active material portion 1423.

[0277] The groove 144 penetrates the end face of the first active material portion 1422 facing away from the second active material portion 1423 and forms an opening, which can directly suck the electrolyte between the end face of the first active material portion 1422 facing away from the second active material portion 1423 and the shell 20 into the groove 144, improve the wettability of the first electrode tab 14, and be conducive to improving the cycle performance of the battery cell 6.

[0278] In some embodiments, along the first direction Z, one end of the first active material portion 1422 is connected with the second active material portion 1423, and the other end of the first active material portion 1422 is not connected with the second active material portion 1423, and along the first direction Z, the end face of the first active material portion 1422 facing away from the second active material portion 1423 is spaced apart from the groove 144.

[0279] Along the first direction Z, the end face of the first active material portion 1422 facing away from the second active material portion 1423 is spaced apart from the groove 144, so that the groove 144 does not penetrate the end face of the first active material portion 1422 facing away from the second active material portion 1423.

[0280] By adopting the technical solutions of this embodiment, the end face of the first active material part 1422 facing away from the second active material part 1423 is spaced apart from the groove 144, which is beneficial to improve the structural strength of the end of the first active material part 1422 facing away from the second active material part 1423, and can reduce the risk of powder falling or even collapse of the end of the first active material part 1422 facing away from the second active material part 1423.

[0281] In some embodiments, the distance between the end face of the first active material part 1422 facing away from the second active material part 1423 and the groove 144 is s, and 0mm≤s≤20mm.

[0282] In some examples, s can be 0mm, 20mm, or any value between 0mm and 20mm, for example, s can be 0mm, 0.1mm, 0.2mm, 0.5mm, 1mm, 2mm, 2.5mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 15mm, 20mm.

[0283] The design of 0mm≤s≤20mm makes the distance between the end face of the first active material part 1422 facing away from the second active material part 1423 and the groove 144 closer, and the electrolyte between the end face of the first active material part 1422 facing away from the second active material part 1423 and the shell 20 can flow into the groove 144 faster, improving the immersion effect of the first tab 14 and being beneficial to improve the cycle performance of the battery monomer 6.

[0284] In some embodiments, 0.1mm≤s≤8mm.

[0285] s≥0.1mm makes the end face of the first active material part 1422 facing away from the second active material part 1423 spaced apart from the groove 144, which is beneficial to improve the structural strength of the end of the first active material part 1422 facing away from the second active material part 1423, and can reduce the risk of powder falling or even collapse of the end of the first active material part 1422 facing away from the second active material part 1423; the design of s≤8mm makes the distance between the end face of the first active material part 1422 facing away from the second active material part 1423 and the groove 144 closer, and the electrolyte between the end face of the first active material part 1422 facing away from the second active material part 1423 and the shell 20 can flow into the groove 144 faster, improving the immersion effect of the first tab 14 and being beneficial to improve the cycle performance of the battery monomer 6. Therefore, the structural strength of the edge of the first tab 14 and the cycle performance of the battery monomer 6 can be considered.

[0286] In some embodiments, 0.5mm≤s≤3mm, which can better consider the structural strength of the edge of the first tab 14 and the cycle performance of the battery monomer 6.

[0287] In some embodiments, along the first direction Z, both ends of the first active material portion 1422 are connected with the second active material portion 1423, which is conducive to the first tab 14 to accommodate more electrolyte at both ends along the first direction Z, thereby facilitating the backflow of electrolyte, improving the wetting effect of the electrode assembly 10, and improving the cycle performance of the battery cell 6.

[0288] In some embodiments, the first current collector 141 includes a first current collector body 1411 and a first tab 1412 arranged and connected along the first direction Z, at least part of the first current collector body 1411 is covered with the first active material layer 142, and the first tab 1412 is not covered with the first active material layer 142.

[0289] Along the first direction Z, the first current collector 141 is divided into two parts, wherein the part covered with the first active material layer 142 is referred to as the first current collector body 1411, and the other part not covered with the first active material layer 142 is referred to as the first tab 1412. The interface between the first tab 1412 and the first current collector body 1411 can be based on the end surface of the first active material layer 142. The first tab 1412 is used for electrical connection with the output electrode to facilitate the input and output of electric energy.

[0290] In some examples, the first current collector body 1411 can be completely covered with the first active material layer 142, or can be partially covered with the first active material layer 142. For example, the side of the first current collector body 1411 away from the first tab 1412 is not covered with the first active material layer 142.

[0291] By adopting the technical solution of this embodiment, the first tab 1412 is led out from the end of the first tab 14 along the first direction Z, which facilitates the electrical connection of the first tab 1412 with other components.

[0292] In some embodiments, the first tab 14 is a negative tab 12.

[0293] The first tab 14 is a negative tab 12, the first active material portion 1422 and the second active material portion 1423 include negative active materials, the groove 144 is arranged spaced apart from the second active material portion 1423, the groove 144 does not extend to the second active material portion 1423, the negative active material of the second active material portion 1423 is not subjected to a slotting operation, and the negative active material of the second active material portion 1423 is more, which reduces the risk of lithium precipitation of the battery cell 6 and is conducive to improving the use performance of the battery cell 6.

[0294] Referring to Figure 8 and Figure 10As shown, in some embodiments, the number of the first active material layers 142 is two, and the two first active material layers 142 respectively cover two surfaces of the first current collector 141 along the thickness direction Y of the first current collector 141. At least one of the first active material layers 142 is provided with the groove 144.

[0295] The two surfaces of the first current collector 141 along the thickness direction Y of the first current collector 141 are respectively covered with the first active material layers 142. Among the two first active material layers 142, one of the first active material layers 142 is provided with the groove 144, and the other first active material layer 142 is not provided with the groove 144, or both of the first active material layers 142 are provided with the groove 144.

[0296] By adopting the technical scheme of this embodiment, the number of the first active material layers 142 is two, which can increase the number of the active material of the first pole piece 14 and is beneficial to increasing the capacity of the battery monomer 6. In addition, the groove 144 is more flexible in setting, so as to meet different use requirements.

[0297] In some embodiments, the number of the grooves 144 is multiple, and the multiple grooves 144 include a first groove 1446 and a second groove 1447 formed along the first direction Z. Among the two first active material layers 142, one of the first active material layers 142 is provided with the multiple first grooves 1446, and the other first active material layer 142 is provided with the multiple second grooves 1447. Along the thickness direction Y of the first current collector 141, the first groove 1446 and the second groove 1447 are arranged in a staggered manner.

[0298] Both of the two first active material layers 142 are provided with the groove 144. The groove 144 of one of the first active material layers 142 is the first groove 1446, and the groove 144 of the other first active material layer 142 is the second groove 1447. The first groove 1446 and the second groove 1447 are formed along the first direction Z.

[0299] The first groove 1446 formed along the first direction Z can be understood as that, along the first direction Z, the first groove 1446 extends from one side of the first surface 1421 to the other side, but it is not required that the first groove 1446 completely extends along the first direction Z.

[0300] In some examples, the first groove 1446 can extend linearly along the first direction Z, or can extend obliquely relative to the first direction Z, or, along the first direction Z, the first groove 1446 extends in an arc shape or a bent shape from one side of the first surface 1421 to the other side. Of course, it can also be other extension modes.

[0301] The second groove 1447 formed along the first direction Z can be understood as that, along the first direction Z, the second groove 1447 extends from one side of the first surface 1421 to the other side, but it is not required that the second groove 1447 completely extends along the first direction Z.

[0302] In some examples, the second grooves 1447 can extend linearly along the first direction Z, can extend obliquely relative to the first direction Z, or can extend arcuately or bently from one side of the first surface 1421 to the other side along the first direction Z. Of course, other extension manners can also be adopted.

[0303] The number of the first grooves 1446 is multiple, and the number of the second grooves 1447 is multiple, so as to improve the impregnation effect of the first pole piece 14.

[0304] In some examples, along the thickness direction Y of the first current collector 141, in the adjacent first groove 1446 and the second groove 1447, the projection of the first groove 1446 does not coincide with or partially coincides with the projection of the second groove 1447.

[0305] For example, one second groove 1447 or multiple second grooves 1447 can be correspondingly arranged between two adjacent first grooves 1446.

[0306] By adopting the technical scheme of this embodiment, the two first active material layers 142 are respectively provided with multiple first grooves 1446 and multiple second grooves 1447, so as to improve the impregnation effect of the two first active material layers 142 and improve the cycle performance of the battery monomer 6. In addition, along the thickness direction Y of the first current collector 141, the first grooves 1446 and the second grooves 1447 are staggered, which is beneficial to improve the structural strength of the first pole piece 14 and improve the use reliability of the battery monomer 6.

[0307] In some embodiments, along the second direction X, the multiple first grooves 1446 and the multiple second grooves 1447 are alternately arranged, and the second direction X is perpendicular to the first direction Z and the thickness direction Y of the first current collector.

[0308] In some examples, the electrode assembly 10 is in a wound structure, and when the first pole piece 14 is in a wound state, the second direction X can be a winding direction V of the electrode assembly 10.

[0309] In some examples, when the first pole piece 14 is in an unfolded state, the second direction X can be a length direction of the first pole piece 14.

[0310] For example, one second groove 1447 can be correspondingly arranged between two adjacent first grooves 1446.

[0311] By adopting the technical scheme of this embodiment, the multiple first grooves 1446 and the multiple second grooves 1447 can be uniformly distributed on the two first active material layers 142, which can improve the uniformity of the distribution of the electrolyte in the battery monomer 6 and is beneficial to improve the cycle performance of the battery monomer 6.

[0312] In some embodiments, along the second direction X, the distance between adjacent first groove 1446 and second groove 1447 is C, where C ≥ 1.5 mm.

[0313] In some examples, the distance C between adjacent first slots 1446 and second slots 1447 along the second direction X can refer to the distance between the center plane of the first slot 1446 perpendicular to the second direction X and the center plane of the second slot 1447 perpendicular to the second direction X.

[0314] In some examples, C is 1.5mm or any value greater than 1.5mm. For example, C is 1.5mm, 1.8mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, or 10mm.

[0315] By adopting the technical solution of this embodiment, the design with C≥1.5mm and the reasonable density setting of the first groove 1446 and the second groove 1447 can reduce the loss of active material in the first active material layer 142 and also help improve the structural strength of the first electrode 14. Therefore, the reliability and energy density of the battery cell 6 can be taken into account.

[0316] In some embodiments, 1.8mm ≤ C ≤ 5mm, and optionally, 2mm ≤ C ≤ 3mm.

[0317] With a design of 1.8mm≤C≤5mm, the spacing between adjacent first grooves 1446 and second grooves 1447 is reasonably designed, and the grooves 144 of the two first active material layers 142 are reasonably distributed. This is beneficial to improving the wetting performance of the first electrode 14, reducing the loss of active material in the first active material layer 142, and improving the structural strength of the first electrode 14. Therefore, the cycle performance, reliability, and energy density of the battery cell 6 can be taken into account.

[0318] In some embodiments, 2mm≤C≤3mm can better balance the cycle performance, reliability and energy density of the battery cell 6.

[0319] See Figure 5 , Figure 6 and Figure 11 As shown, in some embodiments, the electrode assembly 10 is a wound structure, with the first electrode 14 wound to form a plurality of first electrode winding coils 143, the first current collector 141 including a first current collector winding coil 1431 located on the first electrode winding coil 143, and the first active material layer 142 including a first active winding coil 1432 located on the first electrode winding coil 143, the first active material layer 142 having a first winding surface 1433 facing away from the corresponding first current collector winding coil 1431; wherein, at least one first winding surface 1433 of the first electrode winding coil 143 is provided with a groove 144.

[0320] In some examples, the first tab 14, the second tab 15 and the separator 13 are stacked along the thickness direction Y of the first current collector 141, and then wound from one end of the first tab 14 to the other end along the second direction X, so as to form a wound structure. For example, the wound structure can be a cylindrical structure.

[0321] In some examples, the battery cell 6 is a cylindrical battery cell, the cylindrical battery cell has a center axis X1 which is a geometric center line of the cylindrical battery cell, the axial direction of the electrode assembly 10 is parallel to or close to parallel to the center axis X1, and the winding axis X2 of the electrode assembly 10 can coincide with the center axis X1. The first direction Z can be the axial direction of the cylindrical battery cell 6.

[0322] In some examples, the battery cell 6 can also be a square battery cell, and the winding axis X2 of the electrode assembly 10 can refer to the center line of the winding of the first tab 14 or the second tab 15 or the separator 13.

[0323] In some examples, the winding direction V of the electrode assembly 10 can refer to the direction of counterclockwise rotation or clockwise rotation around the winding axis X2 of the electrode assembly 10.

[0324] In the battery cell 6, the side of the electrode assembly 10 close to the winding axis X2 of the electrode assembly 10 is referred to as the inner side of the electrode assembly 10, and the side of the electrode assembly 10 away from the winding axis X2 of the electrode assembly 10 is referred to as the outer side of the electrode assembly 10.

[0325] The electrode assembly 10 is a wound structure, the first tab 14 is wound for multiple turns along the winding direction V of the electrode assembly 10, the first tab 14 has a first winding starting end A1 and a first winding ending end A2, the first winding starting end A1 can refer to the end of the first tab 14 closest to the winding axis X2 of the electrode assembly 10, and the first winding ending end A2 can refer to the end of the first tab 14 farthest from the winding axis X2 of the electrode assembly 10.

[0326] The first current collector 141 is also wound for multiple turns along the winding direction V of the electrode assembly 10, the winding starting end of the first current collector 141 can refer to the end of the first current collector 141 closest to the winding axis X2 of the electrode assembly 10, and the winding ending end of the first current collector 141 can refer to the end of the first current collector 141 farthest from the winding axis X2 of the electrode assembly 10.

[0327] The first active material layer 142 is also wound in multiple turns along the winding direction V of the electrode assembly 10, and a winding start end of the first active material layer 142 can refer to an end of the first active material layer 142 closest to the winding axis X2 of the electrode assembly 10, and a winding end end of the first active material layer 142 can refer to an end of the first active material layer 142 farthest from the winding axis X2 of the electrode assembly 10.

[0328] The surface of the first active material layer 142 facing away from the first current collector 141 is a first surface 1421, and the first surface 1421 is wound in multiple turns along the winding direction V of the electrode assembly 10.

[0329] From the winding start end of the first active material layer 142 to the winding end end of the first active material layer 142, the first tab 14 is wound into multiple first tab winding turns 143, and the first tab winding turn 143 closest to the winding axis X2 of the electrode assembly 10 is the first first tab winding turn 143, and the first tab winding turns 143 from the first to the second last are all full turns, and the second last first tab winding turn 143 can be a full turn or less than a full turn, for example, 1 / 4 turn, 1 / 2 turn, or 3 / 4 turn.

[0330] For example, a plane M is made from the winding axis X2 of the electrode assembly 10 and the winding start end of the first active material layer 142, the plane M extends from the winding axis X2 of the electrode assembly 10 towards the winding start end of the first active material layer 142 until it extends to the outside of the first tab 14, the plane M intersects the first tab 14 and divides the first tab 14 into multiple first tab winding turns 143 according to the intersection points of the plane M and the first tab 14, and the part of the first tab 14 between the adjacent two intersection points forms the first tab winding turn 143 of a full turn; if the winding end end of the first active material layer 142 intersects the plane M exactly, the second last first tab winding turn 143 is also a full turn; if the winding end end of the first active material layer 142 does not intersect the plane M, the part of the first tab 14 between the outermost intersection point and the winding end end of the first active material layer 142 forms the second last first tab winding turn 143, and the second last first tab winding turn 143 is less than a full turn.

[0331] Based on the winding start end of the first active material layer 142 and the winding end end of the first active material layer 142, the first tab winding turns 143 can be divided, so that each first tab winding turn 143 includes a first current collector winding turn 1431 and a first active material winding turn 1432.

[0332] For example, along the reverse direction of the winding direction V of the electrode assembly 10, the winding start end of the first current collector 141 exceeds the winding start end of the first active material layer 142, the portion of the first current collector 141 exceeding the first active material layer 142 does not belong to the first first tab winding turn 143, at this time, the winding start end of the first active material layer 142 can be the first winding start end A1.

[0333] For example, along the winding direction V of the electrode assembly 10, the winding end of the first current collector 141 exceeds the winding end of the first active material layer 142, the portion of the first current collector 141 exceeding the first active material layer 142 does not belong to the last first tab winding turn 143, at this time, the winding end of the first active material layer 142 can be the first winding end A2.

[0334] For example, the winding start end of the first current collector 141 is aligned with the winding start end of the first active material layer 142, the winding end of the first current collector 141 is aligned with the winding end of the first active material layer 142, the winding start end of the first current collector 141 and the winding start end of the first active material layer 142 jointly form the first winding start end A1, and the winding end of the first current collector 141 and the winding end of the first active material layer 142 jointly form the first winding end A2.

[0335] The portion of the first current collector 141 located in the first tab winding turn 143 is the first current collector winding turn 1431, the portion of the first active material layer 142 located in the first tab winding turn 143 is the first active material winding turn 1432, and the portion of the first surface 1421 located in the first tab winding turn 143 is the first winding surface 1433.

[0336] If the first current collector 141 is covered with the first active material layer 142 along both surfaces in the thickness direction Y thereof, each first tab winding turn 143 includes the first current collector winding turn 1431 and two first active material winding turns 1432, and the two first active material winding turns 1432 are respectively located on the inner side and the outer side of the first current collector 141.

[0337] If the first current collector 141 is covered with the first active material layer 142 along one surface in the thickness direction Y thereof, each first tab winding turn 143 includes the first current collector winding turn 1431 and one first active material winding turn 1432, and the first active material winding turn 1432 is located on one side of the first current collector winding turn 1431.

[0338] The first active material winding turn 1432 is located between the first current collector winding turn 1431 and the separator 13, so that ions can be inserted into or extracted from the first active material winding turn 1432 through the separator 13, thereby realizing the charging and discharging of the battery cell.

[0339] The first active winding turn 1432 has a first winding surface 1433 facing away from the corresponding first current collecting winding turn 1431, where the "corresponding first current collecting winding turn 1431" refers to the first current collecting winding turn 1431 in the same first pole piece winding turn 143 as the first active winding turn 1432. The surface of the first active winding turn 1432 facing away from the first current collecting winding turn 1431 connected thereto is the first winding surface 1433, and the spacer 13 is located between the second pole piece 15 and the first winding surface 1433. During the expansion of the electrode assembly 10, the distance between the second pole piece 15 and the first winding surface 1433 decreases, thereby extruding the electrolyte between the second pole piece 15 and the first winding surface 1433.

[0340] The first winding surface 1433 of at least one first pole piece winding turn 143 is provided with at least one groove 144. For example, the number of first pole piece winding turns 143 provided with the groove 144 is one or more. The first winding surface 1433 can be provided with one or more grooves 144. The cross-sectional shape of the groove 144 can be rectangular, trapezoidal, circular arc-shaped, or inverted triangular, etc.

[0341] For example, one or more first pole piece winding turns 143 close to the inner side of the electrode assembly 10 are not provided with the groove 144; or one or more first pole piece winding turns 143 close to the outer side of the electrode assembly 10 are not provided with the groove 144; or one or more first pole piece winding turns 143 located at the middle position of the electrode assembly 10 are not provided with the groove 144.

[0342] For example, all the first pole piece winding turns 143 are provided with the groove 144.

[0343] By adopting the technical scheme of this embodiment, the electrode assembly 10 is wound, the gap between the first pole piece 14 and the second pole piece 15 is small, and the backflowing electrolyte is not easy to enter between the first pole piece 14 and the second pole piece 15, which is not conducive to improving the cycle performance of the battery monomer 6. At least one first winding surface 1433 of the first pole piece winding turn 143 is provided with at least one groove 144. On the one hand, the electrolyte can flow into the groove 144 for storage, the stored electrolyte can soak the first pole piece 14 and provide a transmission path for ions, reduce the transmission resistance of ions, and improve the cycle performance of the battery monomer 6. On the other hand, the groove 144 can also provide a channel for the backflow of the electrolyte, reduce the difficulty of the backflow of the electrolyte, reduce the transmission resistance of the ions, improve the soaking effect of the first pole piece 14, and also help to improve the cycle performance of the battery monomer 6.

[0344] The electrode assembly 10 is in a wound structure, the second tab 15 is wound in multiple turns along a winding direction V of the electrode assembly 10, the second tab 15 is wound to form multiple second tab winding turns 153, the second current collector 151 includes a second current collector winding turn 1531 located at the second tab winding turn 153, the second active material layer 152 includes a second active material winding turn 1532 located at the second tab winding turn 153, and the second active material layer 152 has a second surface 1521 facing away from the second current collector winding turn 1531. The second tab 15 has a second winding starting end B1 and a second winding ending end B2, the second winding starting end B1 can refer to an end of the second tab 15 closest to a winding axis X2 of the electrode assembly 10, and the second winding ending end B2 can refer to an end of the second tab 15 farthest from the winding axis X2 of the electrode assembly 10.

[0345] The second current collector 151 is also wound in multiple turns along the winding direction V of the electrode assembly 10, the winding starting end of the second current collector 151 can refer to an end of the second current collector 151 closest to the winding axis X2 of the electrode assembly 10, and the winding ending end of the second current collector 151 can refer to an end of the second current collector 151 farthest from the winding axis X2 of the electrode assembly 10.

[0346] The second active material layer 152 is also wound in multiple turns along the winding direction V of the electrode assembly 10, the winding starting end of the second active material layer 152 can refer to an end of the second active material layer 152 closest to the winding axis X2 of the electrode assembly 10, and the winding ending end of the second active material layer 152 can refer to an end of the second active material layer 152 farthest from the winding axis X2 of the electrode assembly 10.

[0347] The surface of the second active material layer 152 facing away from the second current collector 151 is the second surface 1521, and the second surface 1521 is wound in multiple turns along the winding direction V of the electrode assembly 10.

[0348] From the winding starting end of the second active material layer 152 to the winding ending end of the second active material layer 152, the second tab 15 is wound into multiple second tab winding turns 153, the second tab winding turn 153 closest to the winding axis X2 of the electrode assembly 10 is the first second tab winding turn 153, the second tab winding turns 153 from the first to the second last are all in a complete turn structure, and the second last second tab winding turn 153 can be in a complete turn structure or a structure less than one turn, for example, 1 / 4 turn, 1 / 2 turn, or 3 / 4 turn.

[0349] For example, the winding axis X2 of the electrode assembly 10 and the winding start end of the second active material layer 152 form a plane N, the plane N extends from the winding axis X2 of the electrode assembly 10 toward the winding start end of the second active material layer 152 until extending to the outside of the second tab 15, the plane N intersects the second tab 15 and divides the second tab 15 into a plurality of second tab winding turns 153 according to the intersection points of the plane N and the second tab 15, the portion of the second tab 15 between two adjacent intersection points forms a second tab winding turn 153 of a full turn structure; if the winding end of the second active material layer 152 intersects the plane N, the last second tab winding turn 153 is also of a full turn structure; if the winding end of the second active material layer 152 does not intersect the plane N, the portion of the second tab 15 between the outermost intersection point and the winding end of the second active material layer 152 forms the last second tab winding turn 153, the last second tab winding turn 153 is of a less than one turn structure.

[0350] The second tab winding turn 153 is divided based on the winding start end of the second active material layer 152 and the winding end of the second active material layer 152, so that each second tab winding turn 153 includes a second current collector winding turn 1531 and a second active material winding turn 1532.

[0351] For example, in the direction opposite to the winding direction V of the electrode assembly 10, the winding start end of the second current collector 151 exceeds the winding start end of the second active material layer 152, the portion of the second current collector 151 exceeding the second active material layer 152 does not belong to the first second tab winding turn 153, at this time, the winding start end of the second active material layer 152 can be a second winding start end B1.

[0352] For example, in the winding direction V of the electrode assembly 10, the winding end of the second current collector 151 exceeds the winding end of the second active material layer 152, the portion of the second current collector 151 exceeding the second active material layer 152 does not belong to the last second tab winding turn 153, at this time, the winding end of the second active material layer 152 can be a second winding end B2.

[0353] For example, the winding start end of the second current collector 151 is aligned with the winding start end of the second active material layer 152, the winding end of the second current collector 151 is aligned with the winding end of the second active material layer 152, the winding start end of the second current collector 151 and the winding start end of the second active material layer 152 jointly form a second winding start end B1, and the winding end of the second current collector 151 and the winding end of the second active material layer 152 jointly form a second winding end B2.

[0354] The portion of the second current collector 151 located at the second tab winding circle 153 is a second current collector winding circle 1531, and the portion of the second active material layer 152 located at the second tab winding circle 153 is a second active material winding circle 1532. The portion of the second surface 1521 located at the second tab winding circle 153 is a second winding surface 1533.

[0355] From the inner side to the outer side of the electrode assembly 10, the first active material winding circle 1432 and the second active material winding circle 1532 are arranged alternately in sequence, and the separator 13 is wound and arranged to separate the first active material winding circle 1432 and the second active material winding circle 1532.

[0356] The second active material winding circle 1532 is located between the second current collector winding circle 1531 and the separator 13, so that ions can be inserted or extracted from the second active material winding circle 1532 through the separator 13, thereby realizing the charging and discharging of the battery cell.

[0357] The second active material winding circle 1532 has a second winding surface 1533 facing away from the corresponding second current collector winding circle 1531. Here, the "corresponding second current collector winding circle 1531" refers to the second current collector winding circle 1531 located in the same second tab winding circle 153 as the second active material winding circle 1532. The surface of the second current collector winding circle 1531 facing away from the second active material winding circle 1532 is the second winding surface 1533, and the separator 13 is located between the first winding surface 1433 and the second winding surface 1533. During the expansion of the electrode assembly 10, the distance between the first winding surface 1433 and the second winding surface 1533 decreases, thereby expelling the electrolyte between the first winding surface 1433 and the second winding surface 1533.

[0358] The second winding surface 1533 of at least one second tab winding circle 153 is provided with at least one groove 144. For example, the number of second tab winding circles 153 provided with grooves 144 is one or more. The second winding surface 1533 can be provided with one or more grooves 144.

[0359] For example, one or more second tab winding circles 153 near the inner side of the electrode assembly 10 are not provided with grooves 144; or, one or more second tab winding circles 153 near the outer side of the electrode assembly 10 are not provided with grooves 144, or one or more second tab winding circles 153 located at the middle position of the electrode assembly 10 are not provided with grooves 144.

[0360] For example, all second tab winding circles 153 are provided with grooves 144.

[0361] The first winding surface 1433 and the second winding surface 1533 are oppositely arranged, and the first winding surface 1433 and the second winding surface 1533 are each provided with a groove 144. The groove 144 of the first active winding loop 1432 and the groove 144 of the second active winding loop 1532 can store electrolyte and guide the return flow of the electrolyte. The first active winding loop 1432 and the second active winding loop 1532 have good wetting effect, which is beneficial to improve the cycle performance of the battery monomer 6.

[0362] The groove 144 structure of the second winding surface 1533 can be the same as or different from that of the first winding surface 1433. For the convenience of description, the first winding surface 1433 is provided with a groove 144 as an example.

[0363] Referring to Figure 12 In some embodiments, the number of grooves 144 is multiple, and the multiple grooves 144 include at least one first groove 1441. The first groove 1441 is formed along the first direction Z, and the first direction Z is parallel to the winding axis X2 of the electrode assembly.

[0364] The first pole piece winding loop 143 is provided with multiple grooves 144. Among the multiple grooves 144, at least one groove 144 is referred to as a first groove 1441. The first groove 1441 is formed along the first direction Z. It can be understood that the first groove 1441 extends from one side of the first surface 1421 to the other side along the first direction Z, but it is not required that the first groove 1441 extends completely along the first direction Z.

[0365] In some examples, the first groove 1441 can extend linearly along the first direction Z, or can extend obliquely relative to the first direction Z, or the first groove 1441 can extend arcuately or bently from one side of the first surface 1421 to the other side along the first direction Z. Of course, it can also be other extension modes.

[0366] Referring to Figure 12 and Figure 13 As shown in the figures, the first groove 1441 can be arranged to deviate from one end of the first active winding loop 1432 along the first direction Z, or can be located at the middle of the first active material layer 142.

[0367] In the battery monomer 6, the electrode assembly 10 expands, and the electrolyte is squeezed out from the electrode assembly 10 along the two ends of the first direction Z. The first groove 1441 is formed along the first direction Z, which can better guide the return flow of the electrolyte squeezed out by the electrode assembly 10, effectively improve the return flow rate of the electrolyte, improve the wetting effect of the first pole piece 14, and improve the cycle performance of the battery monomer 6.

[0368] Referring to Figure 14As shown, in some embodiments, the plurality of grooves 144 can further include a second groove 1444, the second groove 1444 being arranged intersecting the first groove 1441, the plurality of first grooves 1441 and the plurality of second grooves 1444 forming a grid structure.

[0369] Referring to Figure 15 As shown, in some embodiments, the groove 144 can be a straight structure, the groove 144 can also be arranged obliquely relative to the first direction Z.

[0370] Referring to Figure 16 As shown, in some embodiments, the groove 144 can also be a wave structure, for example, the groove 144 extends in a wave shape along the second direction X, the second direction X being the winding direction V of the electrode assembly.

[0371] In some embodiments, the groove 144 can also extend along the winding direction V of the electrode assembly 10, on the one hand, the groove 144 can store electrolyte, on the other hand, it can also guide the electrolyte to flow back along the winding direction V of the electrode assembly 10, improve the uniformity of the distribution of the electrolyte along the winding direction V of the electrode assembly 10, and improve the wetting effect of the first tab 14. Of course, in other embodiments, the groove 144 can also have other structures.

[0372] Referring to Figure 17 As shown, in some embodiments, the number of the first grooves 1441 is a plurality, the plurality of first grooves 1441 are arranged at intervals along the second direction X, and the distance between the adjacent two first grooves 1441 is arranged to be increased, the second direction X being the winding direction V of the electrode assembly.

[0373] The plurality of first grooves 1441 are arranged at unequal intervals, for example, along the winding direction V of the electrode assembly 10, the distance between the adjacent two first grooves 1441 is arranged to be increased in steps, so that the distance between the adjacent two first grooves 1441 in some sections of the first tab 14 is the same.

[0374] For example, along the winding direction V of the electrode assembly 10, the distance between the adjacent two first grooves 1441 is sequentially increased, so that in the entire first tab 14, the distance between the adjacent two first grooves 1441 is different.

[0375] Along the winding direction V of the electrode assembly 10, the plurality of first grooves 1441 are arranged at intervals, the distance between the adjacent two first grooves 1441 is arranged to be increased, so that the distance between the adjacent two first grooves 1441 close to the inner side of the electrode assembly 10 is smaller than the distance between the adjacent two first grooves 1441 close to the outer side of the electrode assembly 10.

[0376] By adopting the technical scheme of the embodiment, after the first tab 14 is wound along the winding direction V of the electrode assembly 10, the number of the first grooves 1441 close to the inner side of the electrode assembly 10 is large, and the number of the first grooves 1441 close to the outer side of the electrode assembly 10 is small, which is beneficial to improving the electrolyte backflow effect of the inner side of the electrode assembly 10 and improving the wetting effect of the inner side of the electrode assembly 10, thereby improving the cycle performance of the battery monomer 6.

[0377] In particular, in the case that the gap between the first tab 14 and the second tab 15 close to the inner side of the electrode assembly 10 is small, the number of the first grooves 1441 close to the inner side of the electrode assembly 10 is large, which can effectively improve the wetting effect of the inner side of the electrode assembly 10, thereby effectively improving the cycle performance of the battery monomer 6.

[0378] Of course, in other examples, the plurality of first grooves 1441 can also be equidistantly arranged.

[0379] Referring to Figure 18 In some embodiments, as shown in the figure, the number of the first tab winding turns 143 is n, n≥30, n is a natural number, the innermost one of the first tab winding turns 143 is the first first tab winding turn 143, and at least one of the first 10 first tab winding turns 143 is provided with a groove 144.

[0380] For example, n is 30, 40, 50, 60, 70, 80, 90, 100, 150, or 200.

[0381] The plurality of first tab winding turns 143 are sequentially arranged from the inner side to the outer side of the electrode assembly 10, and the innermost one of the first tab winding turns 143 is the first first tab winding turn 143, which is closest to the winding axis X2 of the electrode assembly 10 compared with other first tab winding turns 143.

[0382] At least one of the first 10 first tab winding turns 143 is provided with a groove 144. From the first to the tenth first tab winding turn 143, one first tab winding turn 143 is provided with a groove 144; or from the first to the tenth first tab winding turn 143, a plurality of first tab winding turns 143 are provided with a groove 144. The eleventh to the nth first tab winding turn 143 can be partially provided with a groove 144, can be entirely provided with a groove 144, or can be entirely not provided with a groove 144.

[0383] For example, the first and second first tab winding turns 143 are not provided with a groove 144, and the third to the tenth first tab winding turns 143 are all provided with a groove 144.

[0384] For example, the first to fifth first pole piece winding turns 143 are not provided with the groove 144, and the sixth to tenth first pole piece winding turns 143 are each provided with the groove 144.

[0385] For example, the first to tenth first pole piece winding turns 143 are each provided with the groove 144. Of course, in other examples, the grooves 144 can also have other distribution manners in the first to tenth first pole piece winding turns 143.

[0386] By adopting the technical scheme of this embodiment, the number of the first pole piece winding turns 143 is n, n≥30, the number of winding turns of the first pole piece 14 is large, the impregnation requirement of the inside of the electrode assembly 10 is large, and at least one of the first ten first pole piece winding turns 143 is provided with the groove 144, so that the impregnation effect of the inside of the electrode assembly 10 is improved, and the cycle performance of the battery monomer 6 is improved.

[0387] Referring to Figure 19 In some embodiments, the number of the first pole piece winding turns 143 is n, n≥30, n is a natural number, the innermost one of the first pole piece winding turns 143 is the first first pole piece winding turn 143, and at least the first first pole piece winding turn 143 is not provided with the groove 144.

[0388] The first first pole piece winding turn 143 is not provided with the groove 144, and at least one of the second to n-th first pole piece winding turns 143 is provided with the groove 144.

[0389] After the first pole piece 14 is wound, the winding radius of the first pole piece winding turn 143 closer to the inside is smaller, and the winding stress of the first pole piece winding turn 143 closer to the inside is larger, wherein the winding radius of the first first pole piece winding turn 143 is smallest, the winding stress of the first first pole piece winding turn 143 is largest, and the first first pole piece winding turn 143 is not provided with the groove 144, which is beneficial to improve the structural strength of the first first pole piece winding turn 143, reduce the risk of powder falling, damage, or even fracture of the first first pole piece winding turn 143 caused by grooving, and improve the capacity and use reliability of the battery monomer 6; in addition, the first first pole piece winding turn 143 not being provided with the groove 144 can also reduce the number of grooves, which is beneficial to improve the production efficiency of the first pole piece 14.

[0390] In some embodiments, at least the first three first pole piece winding turns 143 are not provided with the groove 144.

[0391] The first to third first pole piece winding turns 143 are not provided with the groove 144. At least one of the fourth to n-th first pole piece winding turns 143 is provided with the groove 144.

[0392] By adopting the technical scheme of the embodiment, the winding radius of the first to third first pole piece winding turns 143 is small, the winding stress of the first to third first pole piece winding turns 143 is large, and the first to third first pole piece winding turns 143 are not provided with the grooves 144, which is beneficial to improve the structural strength of the first to third first pole piece winding turns 143, reduce the risk of powder falling, damage, and even fracture of the first to third first pole piece winding turns 143 caused by grooving, and improve the use reliability of the battery monomer 6. In addition, the first to third first pole piece winding turns 143 are not provided with the grooves 144, which can also reduce the number of grooves and improve the production efficiency of the first pole piece 14.

[0393] Referring to Figure 6 As shown in the drawings, in some embodiments, the electrode assembly 10 is provided with a center hole 101, and the first first pole piece winding turn 143 is closest to the center hole 101 compared with other first pole piece winding turns 143.

[0394] For example, the winding axis X2 of the electrode assembly 10 passes through the center hole 101.

[0395] The center hole 101 can be used to accommodate and flow electrolyte, so as to soak the first pole piece winding turns 143 located on the inner side, improve the soaking effect of the inner side of the electrode assembly 10, improve the cycle performance of the battery monomer 6, and in addition, the first pole piece winding turns 143 located on the inner side can be soaked by the electrolyte in the center hole 101, which can reduce the need for the first pole piece winding turns 143 located on the inner side to be provided with grooves 144, improve the structural strength of the first pole piece winding turns 143 on the inner side, and reduce the problem of powder falling of the first pole piece winding turns 143 on the inner side, so as to effectively balance the cycle performance and use reliability of the battery monomer 6.

[0396] The center hole 101 can also provide space for the expansion of the inner side of the electrode assembly 10, so as to reduce the extrusion effect on the shell 20, reduce the risk of deformation and cracking of the shell 20, and improve the reliability of the battery monomer 6.

[0397] When the battery monomer 6 appears thermal runaway, the center hole 101 can be used as a gas discharge channel to improve the discharge rate of the gas and reduce the risk of explosion.

[0398] Referring to Figure 19 As shown in the drawings, in some embodiments, the number of first pole piece winding turns 143 is n, n≥30, and n is a natural number; the innermost one of the first pole piece winding turns 143 is the first first pole piece winding turn 143; and at least the last two first pole piece winding turns 143 are not provided with the grooves 144.

[0399] The n-1th to nth first pole piece winding turns 143 are not provided with the grooves 144. At least one of the 1st to n-2th first pole piece winding turns 143 is provided with the groove 144.

[0400] The electrode assembly 10 expands, and the expansion force of the electrode assembly 10 is accumulated on the outer side, and the expansion accumulation force of the last two first pole piece winding turns 143 is the largest, and the last two first pole piece winding turns 143 are not provided with the grooves 144, which is beneficial to improve the structural strength of the last two first pole piece winding turns 143 and reduce the risk of fracture of the last two first pole piece winding turns 143, thereby effectively improving the use reliability of the battery monomer 6. In addition, the last two first pole piece winding turns 143 are not provided with the grooves 144, which can reduce the number of grooves and improve the production and processing efficiency of the first pole piece 14.

[0401] In some embodiments, at least the last 10 first pole piece winding turns 143 are not provided with the grooves 144.

[0402] The n-9th to nth first pole piece winding turns 143 are not provided with the grooves 144. At least one of the 1st to n-8th first pole piece winding turns 143 is provided with the groove 144.

[0403] The expansion accumulation force of the last 10 first pole piece winding turns 143 is larger, and the last 10 first pole piece winding turns 143 are not provided with the grooves 144, which is beneficial to improve the structural strength of the last 10 first pole piece winding turns 143 and reduce the risk of fracture of the last 10 first pole piece winding turns 143, thereby better improving the use reliability of the battery monomer 6. In addition, the last 10 first pole piece winding turns 143 are not provided with the grooves 144, which can reduce the number of grooves and improve the production and processing efficiency of the first pole piece 14.

[0404] In particular, in some battery monomers 6, the gap between the first pole piece 14 and the second pole piece 15 on the outer side is large, the wettability of the first pole piece winding turns 143 on the outer side is better, and the first pole piece winding turns 143 on the outer side are not provided with the grooves 144, which can improve the structural strength of the first pole piece winding turns 143 on the outer side. Therefore, the use reliability and cycle performance of the battery monomer 6 can be considered.

[0405] In some embodiments, the number of the first pole piece winding turns 143 is n, n>30, n is a natural number; the innermost one of the first pole piece winding turns 143 is the 1st first pole piece winding turn 143; the first f first pole piece winding turns 143 are not provided with the grooves 144, and the last q first pole piece winding turns 143 are not provided with the grooves 144; all the first pole piece winding turns 143 between the fth first pole piece winding turn 143 and the last q first pole piece winding turn 143 are provided with the grooves 144, f+q

[0406] f and q are natural numbers greater than 1, for example, f is 1, 3, 5, 7, 10, 20, etc., and q is 1, 5, 10, 15, 20, 30, 40, etc.

[0407] For example, when f is 1 and q is 1, the first first-plate winding turn 143 is not provided with the groove 144, the second to the n-1th first-plate winding turn 143 are each provided with the groove 144, and the nth first-plate winding turn 143 is not provided with the groove 144.

[0408] For example, when f>1 and q>1, the first to the fth first-plate winding turn 143 are not provided with the groove 144, the f+1th to the n-qth first-plate winding turn 143 are provided with the groove 144, and the n-q+1th to the nth first-plate winding turn 143 are not provided with the groove 144.

[0409] By adopting the technical solutions of this embodiment, the first-plate winding turns 143 located at the inner side and the outer side are not provided with the groove 144, which is beneficial to improving the structural strength of the first-plate winding turns 143 at the inner side and the outer side, improving the use reliability of the battery monomer 6, and in addition, the number of grooves can be reduced, and the production and processing efficiency of the first plate 14 can be improved; and the electrode assembly 10 is grooved at the middle region between the inner side and the outer side, which is beneficial to improving the wettability of the electrode assembly 10 at the middle region between the inner side and the outer side, and improving the cycle performance of the battery monomer 6.

[0410] In some embodiments, 30≤n≤80.

[0411] For example, n is 30, 40, 50, 60, 65, 70, 75, 80, 90, etc.

[0412] The design of 30≤n≤80 makes the number of first-plate winding turns 143 large, the capacity of the battery monomer 6 large, and the wettability of the electrode assembly 10 difficult, and in the embodiments of the present application, the groove 144 can be selectively arranged at the inner side or the outer side of the electrode assembly 10, so as to improve the wettability of the electrode assembly 10, and also improve the structural strength of the inner side or the outer side of the electrode assembly 10, and the use reliability, capacity and cycle performance of the electrode assembly 10 can be taken into account.

[0413] In some embodiments, 60≤n≤75, which better takes into account the use reliability, capacity and cycle performance of the electrode assembly 10.

[0414] In some embodiments, the number of first-plate winding turns 143 provided with the groove 144 is v, and 0.23≤v / n≤1, v and n are positive integers, and optionally, 0.3≤v / n≤0.7.

[0415] In some examples, the value of v / n can be 0.23, 1, or any value between 0.23 and 1; for example, the value of v / n can be, but is not limited to, 0.23, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1.

[0416] The design with 0.23≤v / n≤1 can meet the wetting requirements of the electrode assembly 10 and improve the cycle performance of the battery cell 6.

[0417] In some embodiments, 0.3 ≤ v / n ≤ 0.7.

[0418] With a v / n ≥ 0.3 design, the number of first electrode winding coils 143 with grooves 144 can better meet the wetting requirements of the electrode assembly 10 and improve the cycle performance of the battery cell 6; with a v / n ≤ 0.7 setting, some of the first electrode winding coils 143 are not provided with grooves 144, which helps to reduce the number of grooves and improve the production efficiency of the first electrode 14.

[0419] See Figure 5 , Figure 6 and Figure 19 As shown, in some embodiments, the first electrode 14 has a first winding end A2, the second electrode 15 has a second winding end B2, the innermost first electrode winding coil 143 is the first first electrode winding coil 143, and the second winding end B2 is located between the last two first electrode winding coils 143; the last two first electrode winding coils 143 are not provided with grooves 144 at the positions corresponding to the end faces of the first winding end A2; and / or, the last two first electrode winding coils 143 are not provided with grooves 144 at the positions corresponding to the end faces of the second winding end B2.

[0420] The first electrode 14 has a first winding end A2 and a first winding start end A1. Along the winding direction V of the electrode assembly 10, of the two relatively distributed ends of the first electrode 14, the end closer to the winding axis X2 of the electrode assembly 10 is the first winding start end A1, and the end farther from the winding axis X2 of the electrode assembly 10 is the first winding end A2. Along the winding direction V of the electrode assembly 10, of the two relatively distributed end faces of the first electrode 14, the end face closer to the winding axis X2 of the electrode assembly 10 is the end face of the first winding start end A1, and the end face farther from the winding axis X2 of the electrode assembly 10 is the end face of the first winding end A2.

[0421] For example, along the winding direction V of the electrode assembly 10, the first winding end A2 can refer to the end of the penultimate first electrode winding 143 that is away from the penultimate first electrode winding 143, and the first winding start end A1 can refer to the end of the first first electrode winding 143 that is away from the second first electrode winding 143.

[0422] The second tab 15 has a second winding end B2 and a second winding start B1, of which the two ends of the second tab 15 are oppositely distributed along the winding direction V of the electrode assembly 10, wherein the end close to the winding axis X2 of the electrode assembly 10 is the second winding start B1, and wherein the end away from the winding axis X2 of the electrode assembly 10 is the second winding end B2. The second tab 15 has two end faces oppositely distributed along the winding direction V of the electrode assembly 10, wherein the end face close to the winding axis X2 of the electrode assembly 10 is the end face of the second winding start B1, and wherein the end face away from the winding axis X2 of the electrode assembly 10 is the end face of the second winding end B2.

[0423] For example, the second winding end B2 can refer to the end of the last second tab winding loop 153 away from the second-to-last second tab winding loop 153, and the second winding start B1 can refer to the end of the first second tab winding loop 153 away from the second second tab winding loop 153, along the winding direction V of the electrode assembly 10.

[0424] In some examples, after the winding of the second tab 15 is completed, the first tab 14 continues to be wound forward for a distance and continues to be wound for less than one loop, so that the second winding end B2 can be completely covered by the second-to-last first tab winding loop 143, and the second winding end B2 is located between the second-to-last first tab winding loop 143 and the first winding end A2, and no second tab winding loop 153 is arranged between the first winding end A2 and the second-to-last first tab winding loop 143, along the winding direction V of the electrode assembly 10.

[0425] The position corresponding to the end face of the first winding end A2 of the second-to-last first tab winding loop 143 is not provided with a groove 144, and it can be understood that the position corresponding to the end face of the first winding end A2 opposite to the second-to-last first tab winding loop 143 is not provided with a groove 144.

[0426] The position corresponding to the end face of the second winding end B2 of the second-to-last first tab winding loop 143 is not provided with a groove 144, and it can be understood that the position corresponding to the end face of the second winding end B2 opposite to the second-to-last first tab winding loop 143 is not provided with a groove 144, and the position corresponding to the end face of the second winding end B2 opposite to the second-to-last first tab winding loop 143 is not provided with a groove 144.

[0427] In the expansion process of the electrode assembly 10, the second last first tab winding 143 is pressed by the first last first tab winding 143, in this process, the edge of the end face of the first winding end A2 presses the second last first tab winding 143, the end face of the second winding end B2 is clamped between the second last two first tab windings 143, and the edge of the end face of the second winding end B2 presses the second last first tab winding 143 and the second last first tab winding 143; if the second last two first tab windings 143 are provided with a groove 144 corresponding to the position of the end face of the first winding end A2, the end face of the first winding end A2 is opposite to the groove 144 and presses the groove 144, the structural strength of the groove 144 is poor, and the end face of the first winding end A2 has the risk of cutting the second last two first tab windings 143, and for the same reason, if the second last two first tab windings 143 are provided with a groove 144 corresponding to the position of the end face of the second winding end B2, the end face of the second winding end B2 is opposite to the groove 144 and presses the groove 144, the structural strength of the groove 144 is poor, and the end face of the second winding end B2 has the risk of cutting the second last two first tab windings 143.

[0428] In some examples, the first tab 14 has a first winding end A2, the second tab 15 has a second winding end B2, the innermost first tab winding 143 is the first first tab winding 143, and the second winding end B2 is located between the second last two first tab windings 143; the position corresponding to the end face of the first winding end A2 of the second last two first tab windings 143 is not provided with a groove 144.

[0429] For example, the position corresponding to the end face of the first winding end A2 of the second last second tab winding 143 is not provided with a groove 144.

[0430] In the expansion process of the electrode assembly 10, the position corresponding to the end face of the first winding end A2 of the second last two first tab windings 143 is not provided with a groove 144, the structural strength of the position corresponding to the end face of the first winding end A2 of the second last two first tab windings 143 is good, the risk of cutting the second last two first tab windings 143 by the end face of the first winding end A2 is reduced, and the use reliability of the battery monomer 6 is improved.

[0431] In some examples, the first tab 14 has a first winding end A2, the second tab 15 has a second winding end B2, the innermost first tab winding 143 is the first first tab winding 143, and the second winding end B2 is located between the second last two first tab windings 143; the position corresponding to the end face of the second winding end B2 of the second last two first tab windings 143 is not provided with a groove 144.

[0432] For example, the position corresponding to the end surface of the second winding end B2 of the last first pole piece winding turn 143 is not provided with the groove 144; the position corresponding to the end surface of the second winding end B2 of the second last first pole piece winding turn 143 is not provided with the groove 144.

[0433] In the process of expansion of the electrode assembly 10, the position corresponding to the end surface of the second winding end B2 of the second last first pole piece winding turn 143 is not provided with the groove 144, the structural strength of the position corresponding to the end surface of the second winding end B2 of the second last first pole piece winding turn 143 is good, the risk of the second last first pole piece winding turn 143 being cut off by the end surface of the second winding end B2 is reduced, and the use reliability of the battery monomer 6 is improved.

[0434] In some examples, the first pole piece 14 has a first winding end A2, the second pole piece 15 has a second winding end B2, the innermost first pole piece winding turn 143 is the first first pole piece winding turn 143, and the second winding end B2 is located between the second last first pole piece winding turn 143; the position corresponding to the end surface of the first winding end A2 of the second last first pole piece winding turn 143 is not provided with the groove 144; the position corresponding to the end surface of the second winding end B2 of the second last first pole piece winding turn 143 is not provided with the groove 144.

[0435] For example, the position corresponding to the end surface of the second winding end B2 of the last first pole piece winding turn 143 is not provided with the groove 144; the position corresponding to the end surface of the second winding end B2 of the second last first pole piece winding turn 143 is not provided with the groove 144, and the position corresponding to the end surface of the first winding end A2 of the second last first pole piece winding turn 143 is not provided with the groove 144.

[0436] In the process of expansion of the electrode assembly 10, the position corresponding to the end surface of the first winding end A2 and the end surface of the second winding end B2 of the second last first pole piece winding turn 143 is not provided with the groove 144, the structural strength of the position corresponding to the end surface of the first winding end A2 and the end surface of the second winding end B2 of the second last first pole piece winding turn 143 is good, the risk of the second last first pole piece winding turn 143 being cut off by the end surface of the first winding end A2 and the end surface of the second winding end B2 is reduced, and the use reliability of the battery monomer 6 is improved.

[0437] In some examples, the second last first pole piece winding turn 143 is provided with the groove 144, and the groove 144 is arranged to be staggered with at least one of the end surface of the first winding end A2 and the end surface of the second winding end B2.

[0438] The second-to-last first pole piece winding turn 143 is provided with a groove 144. It can be understood that at least one of the second-to-last first pole piece winding turn 143 or the third-to-last first pole piece winding turn 143 is provided with a groove 144. The second-to-last first pole piece winding turn 143 is provided with a groove 144, which can improve the wetting effect of the second-to-last first pole piece winding turn 143 and improve the cycle performance of the battery monomer 6.

[0439] In some examples, the second-to-last first pole piece winding turn 143 is provided with a groove 144, and the groove 144 is arranged away from the end face of the first winding end A2.

[0440] For example, the second-to-last first pole piece winding turn 143 is provided with a groove 144, and the groove 144 is arranged away from the end face of the first winding end A2. The second-to-last first pole piece winding turn 143 can be provided with a groove 144 or not.

[0441] The groove 144 of the second-to-last first pole piece winding turn 143 is not arranged opposite to the end face of the first winding end A2, which reduces the risk of the second-to-last first pole piece winding turn 143 being cut off by the end face of the first winding end A2, and improves the use reliability of the battery monomer 6.

[0442] In some examples, the second-to-last first pole piece winding turn 143 is provided with a groove 144, and the groove 144 is arranged away from the end face of the second winding end B2.

[0443] For example, the second-to-last first pole piece winding turn 143 is provided with a groove 144, and the second-to-last first pole piece winding turn 143 is not provided with a groove 144, and the groove 144 of the second-to-last first pole piece winding turn 143 is arranged away from the end face of the second winding end B2.

[0444] For example, the second-to-last first pole piece winding turn 143 is provided with a groove 144, and the second-to-last first pole piece winding turn 143 is not provided with a groove 144, and the groove 144 of the second-to-last first pole piece winding turn 143 is arranged away from the end face of the second winding end B2.

[0445] For example, the second-to-last first pole piece winding turn 143 and the third-to-last first pole piece winding turn 143 are provided with grooves 144, and the groove 144 of the second-to-last first pole piece winding turn 143 and the groove 144 of the third-to-last first pole piece winding turn 143 are arranged away from the end face of the second winding end B2.

[0446] The groove 144 of the second-to-last first pole piece winding turn 143 is not arranged opposite to the end face of the second winding end B2, which reduces the risk of the second-to-last first pole piece winding turn 143 being cut off by the end face of the second winding end B2, and improves the use reliability of the battery monomer 6.

[0447] In some examples, the last two first pole piece winding turns 143 are provided with grooves 144, and the grooves 144 are arranged away from the end faces of the first winding end A2 and the second winding end B2.

[0448] For example, the last first pole piece winding turn 143 is provided with a groove 144, the second last first pole piece winding turn 143 is not provided with a groove 144, and the groove 144 of the last first pole piece winding turn 143 is arranged away from the end face of the second winding end B2.

[0449] For example, the second last first pole piece winding turn 143 is provided with a groove 144, the last first pole piece winding turn 143 is not provided with a groove 144, and the groove 144 of the second last first pole piece winding turn 143 is arranged away from the end faces of the first winding end A2 and the second winding end B2.

[0450] For example, the last first pole piece winding turn 143 and the second last first pole piece winding turn 143 are provided with grooves 144, the groove 144 of the last first pole piece winding turn 143 and the groove 144 of the second last first pole piece winding turn 143 are arranged away from the end face of the second winding end B2, and the groove 144 of the second last first pole piece winding turn 143 is arranged away from the end face of the first winding end A2.

[0451] The grooves 144 of the last two first pole piece winding turns 143 are not arranged opposite to the end face of the second winding end B2, and the grooves 144 of the last two first pole piece winding turns 143 are not arranged opposite to the end face of the first winding end A2, which reduces the risk of the last two first pole piece winding turns 143 being cut off by the end faces of the first winding end A2 and the second winding end B2, and improves the use reliability of the battery monomer 6.

[0452] In some embodiments, the last two first pole piece winding turns 143 are not provided with grooves 144.

[0453] The last first pole piece winding turn 143 and the second last first pole piece winding turn 143 are not provided with grooves 144.

[0454] By adopting the technical scheme of this embodiment, the last two first pole piece winding turns 143 are not provided with grooves 144, on the one hand, the structural strength of the last two first pole piece winding turns 143 is improved, and on the other hand, the risk of the last two first pole piece winding turns 143 being cut off by the end faces of the first winding end A2 and the second winding end B2 is reduced, and the use reliability of the battery monomer 6 is improved.

[0455] Referring to Figure 5 ,Figure 6 and Figure 18 As shown in FIG. 12, in some embodiments, the first pole piece 14 has a first winding start end A1, the second pole piece 15 has a second winding start end B1, the innermost first pole piece winding turn 143 is the first first pole piece winding turn 143, and the second winding start end B1 is located between the first two first pole piece winding turns 143; the first two first pole piece winding turns 143 are not provided with the groove 144 at positions corresponding to the end surface of the first winding start end A1; and / or, the first two first pole piece winding turns 143 are not provided with the groove 144 at positions corresponding to the end surface of the second winding start end B1.

[0456] In some examples, along the winding direction V of the electrode assembly 10, the second pole piece 15 starts winding after the first pole piece 14 winds for a distance, and the first pole piece 14 winds less than one turn before the second pole piece 15 winds, so that the first two first pole piece winding turns 143 can completely cover the second winding start end B1, and the second winding start end B1 is located between the first two first pole piece winding turns 143, and no second pole piece winding turn 153 is provided between the first winding start end A1 and the second first pole piece winding turn 143.

[0457] The first two first pole piece winding turns 143 are not provided with the groove 144 at positions corresponding to the end surface of the first winding start end A1, and it can be understood that the first winding start end A1 is not provided with the groove 144 at positions opposite to the second first pole piece winding turn 143.

[0458] The first two first pole piece winding turns 143 are not provided with the groove 144 at positions corresponding to the end surface of the second winding start end B1, and it can be understood that the second winding start end B1 is not provided with the groove 144 at positions opposite to the second first pole piece winding turn 143, and the second winding start end B1 is not provided with the groove 144 at positions opposite to the first first pole piece winding turn 143.

[0459] In the expansion process of the electrode assembly 10 or under the self-restoring force of the first electrode tab 14, the first first electrode winding 143 is pressed by the second first electrode winding 143, the edge of the end face of the first winding starting end A1 is pressed by the second first electrode winding 143, the end face of the second winding starting end B1 is clamped between the first two first electrode windings 143, and the edge of the end face of the second winding starting end B1 is pressed by the first first electrode winding 143 and the second first electrode winding 143; if the first two first electrode windings 143 are provided with a groove 144 at a position corresponding to the end face of the first winding starting end A1, the end face of the first winding starting end A1 is opposite to the groove 144 and presses the groove 144, the structural strength of the groove 144 is poor, and the end face of the first winding starting end A1 has a risk of cutting the first two first electrode windings 143; similarly, if the first two first electrode windings 143 are provided with a groove 144 at a position corresponding to the end face of the second winding starting end B1, the end face of the second winding starting end B1 is opposite to the groove 144 and presses the groove 144, the structural strength of the groove 144 is poor, and the end face of the second winding starting end B1 has a risk of cutting the first two first electrode windings 143.

[0460] In some examples, the first electrode tab 14 has a first winding starting end A1, the second electrode tab 15 has a second winding starting end B1, the innermost first electrode winding 143 is the first first electrode winding 143, and the second winding starting end B1 is located between the first two first electrode windings 143; the position corresponding to the end face of the first winding starting end A1 of the first two first electrode windings 143 is not provided with a groove 144.

[0461] For example, the position corresponding to the end face of the first winding starting end A1 of the second first electrode winding 143 is not provided with a groove 144.

[0462] In the expansion process of the electrode assembly 10 or under the self-restoring force of the first electrode tab 14, the position corresponding to the end face of the first winding starting end A1 of the first two first electrode windings 143 is not provided with a groove 144, the structural strength of the position corresponding to the end face of the first winding starting end A1 of the first two first electrode windings 143 is good, the risk of cutting the first two first electrode windings 143 by the end face of the first winding starting end A1 is reduced, and the use reliability of the battery monomer 6 is improved.

[0463] In some examples, the first electrode tab 14 has a first winding starting end A1, the second electrode tab 15 has a second winding starting end B1, the innermost first electrode winding 143 is the first first electrode winding 143, and the second winding starting end B1 is located between the first two first electrode windings 143; the position corresponding to the end face of the second winding starting end B1 of the first two first electrode windings 143 is not provided with a groove 144.

[0464] For example, the first first-pole-piece winding turn 143 corresponding to the end face of the second winding start end B1 is not provided with the groove 144; the second first-pole-piece winding turn 143 corresponding to the end face of the second winding start end B1 is not provided with the groove 144.

[0465] In the expansion process of the electrode assembly 10 or under the self-recovery force of the first-pole-piece 14, the first two first-pole-piece winding turns 143 corresponding to the end faces of the first winding start end A1 and the second winding start end B1 are not provided with the groove 144, the structural strength of the first two first-pole-piece winding turns 143 corresponding to the end faces of the first winding start end A1 and the second winding start end B1 is good, the risk of the first two first-pole-piece winding turns 143 being cut by the end faces of the first winding start end A1 and the second winding start end B1 is reduced, and the use reliability of the battery monomer 6 is improved.

[0466] In some examples, the first-pole-piece 14 has a first winding start end A1, the second-pole-piece 15 has a second winding start end B1, the innermost first-pole-piece winding turn 143 is the first first-pole-piece winding turn 143, and the second winding start end B1 is located between the first two first-pole-piece winding turns 143; the first two first-pole-piece winding turns 143 corresponding to the end face of the first winding start end A1 are not provided with the groove 144; the first two first-pole-piece winding turns 143 corresponding to the end face of the second winding start end B1 are not provided with the groove 144.

[0467] For example, the first first-pole-piece winding turn 143 corresponding to the end face of the second winding start end B1 is not provided with the groove 144; the second first-pole-piece winding turn 143 corresponding to the end face of the second winding start end B1 is not provided with the groove 144, and the second first-pole-piece winding turn 143 corresponding to the end face of the first winding start end A1 is not provided with the groove 144.

[0468] In the expansion process of the electrode assembly 10 or under the self-recovery force of the first-pole-piece 14, the first two first-pole-piece winding turns 143 corresponding to the end faces of the first winding start end A1 and the second winding start end B1 are not provided with the groove 144, the structural strength of the first two first-pole-piece winding turns 143 corresponding to the end faces of the first winding start end A1 and the second winding start end B1 is good, the risk of the first two first-pole-piece winding turns 143 being cut by the end faces of the first winding start end A1 and the second winding start end B1 is reduced, and the use reliability of the battery monomer 6 is improved.

[0469] In some examples, the first two first-pole-piece winding turns 143 are provided with the groove 144, and the groove 144 is arranged to be staggered with at least one of the end face of the first winding start end A1 and the end face of the second winding start end B1.

[0470] The first two first pole piece winding turns 143 are provided with grooves 144. It can be understood that at least one of the first first pole piece winding turn 143 or the second first pole piece winding turn 143 is provided with the groove 144. The first two first pole piece winding turns 143 are provided with the grooves 144, which can improve the wetting effect of the first two first pole piece winding turns 143 and improve the cycle performance of the battery monomer 6.

[0471] In some examples, the first two first pole piece winding turns 143 are provided with grooves 144, and the grooves 144 are arranged away from the end face of the first winding starting end A1.

[0472] For example, the second first pole piece winding turn 143 is provided with a groove 144, and the groove 144 is arranged away from the end face of the first winding starting end A1. The first first pole piece winding turn 143 can be provided with a groove 144 or not.

[0473] The grooves 144 of the first two first pole piece winding turns 143 are not arranged opposite to the end face of the first winding starting end A1, which reduces the risk of the first two first pole piece winding turns 143 being cut off by the end face of the first winding starting end A1, and improves the use reliability of the battery monomer 6.

[0474] In some examples, the first two first pole piece winding turns 143 are provided with grooves 144, and the grooves 144 are arranged away from the end face of the second winding starting end B1.

[0475] For example, the first first pole piece winding turn 143 is provided with a groove 144, and the second first pole piece winding turn 143 is not provided with a groove 144, and the groove 144 of the first first pole piece winding turn 143 is arranged away from the end face of the second winding starting end B1.

[0476] For example, the second first pole piece winding turn 143 is provided with a groove 144, and the first first pole piece winding turn 143 is not provided with a groove 144, and the groove 144 of the second first pole piece winding turn 143 is arranged away from the end face of the second winding starting end B1.

[0477] For example, the first first pole piece winding turn 143 and the second first pole piece winding turn 143 are provided with grooves 144, and the groove 144 of the first first pole piece winding turn 143 and the groove 144 of the second first pole piece winding turn 143 are arranged away from the end face of the second winding starting end B1.

[0478] The grooves 144 of the first two first pole piece winding turns 143 are not arranged opposite to the end face of the second winding starting end B1, which reduces the risk of the first two first pole piece winding turns 143 being cut off by the end face of the second winding starting end B1, and improves the use reliability of the battery monomer 6.

[0479] In some examples, the first two first pole piece winding turns 143 are provided with grooves 144, and the grooves 144 are arranged away from the end faces of the first winding start end A1 and the second winding start end B1.

[0480] For example, the first first pole piece winding turn 143 is provided with a groove 144, the second first pole piece winding turn 143 is not provided with a groove 144, and the groove 144 of the first first pole piece winding turn 143 is arranged away from the end face of the second winding start end B1.

[0481] For example, the second first pole piece winding turn 143 is provided with a groove 144, the first first pole piece winding turn 143 is not provided with a groove 144, and the groove 144 of the second first pole piece winding turn 143 is arranged away from the end faces of the first winding start end A1 and the second winding start end B1.

[0482] For example, the first first pole piece winding turn 143 and the second first pole piece winding turn 143 are provided with grooves 144, the groove 144 of the first first pole piece winding turn 143 and the groove 144 of the second first pole piece winding turn 143 are both arranged away from the end face of the second winding start end B1, and the groove 144 of the second first pole piece winding turn 143 is arranged away from the end face of the first winding start end A1.

[0483] The grooves 144 of the first two first pole piece winding turns 143 are not arranged opposite to the end face of the second winding start end B1, and the grooves 144 of the first two first pole piece winding turns 143 are not arranged opposite to the end face of the first winding start end A1, which reduces the risk of the first two first pole piece winding turns 143 being cut by the end faces of the first winding start end A1 and the second winding start end B1, and improves the use reliability of the battery monomer 6.

[0484] In some embodiments, the first two first pole piece winding turns 143 are not provided with grooves 144.

[0485] The first first pole piece winding turn 143 and the second first pole piece winding turn 143 are not provided with grooves 144.

[0486] By adopting the technical scheme of this embodiment, the first two first pole piece winding turns 143 are not provided with grooves 144, on the one hand, the structural strength of the first two first pole piece winding turns 143 is improved, and on the other hand, the risk of the first two first pole piece winding turns 143 being cut by the end faces of the first winding start end A1 and the second winding start end B1 is reduced, and the use reliability of the battery monomer 6 is improved.

[0487] In some embodiments, the first pole piece 14 is a negative pole piece 12, and the second pole piece 15 is a positive pole piece 11.

[0488] On the basis that the second winding ending end B2 is located at the second first tab 14 winding end, along the winding direction V of the electrode assembly 10, the winding ending end of the negative tab 12 exceeds the winding ending end of the positive tab 11, and the part of the negative tab 12 exceeding the positive tab 11 can provide more embedding space for ions, reduce the risk of lithium precipitation, and improve the use reliability of the battery cell 6.

[0489] On the basis that the second winding starting end B1 is located at the second first tab 14 winding end, along the winding direction V of the electrode assembly 10, the negative tab 12 needs to be wound for a distance before the positive tab 11 starts to be wound, and the part of the negative tab 12 wound first can provide more embedding space for ions, reduce the risk of lithium precipitation, and improve the use reliability of the battery cell 6.

[0490] In other embodiments, the second tab 15 is a negative tab 12, and the first tab 14 is a positive tab 11.

[0491] Referring to Figures 20-22 In some embodiments, as shown in the drawings, the electrode assembly 10 includes a flat area E2 and two bending areas E1 located at both ends of the flat area E2; the first active winding loop 1432 includes a first active bending part 1434 located in the bending area E1 and a first active flat part 1435 located in the flat area E2; and the first active flat part 1435 of at least one first active winding loop 1432 is provided with a groove 144.

[0492] The flat area E2 is an area where the electrode assembly 10 has a flat structure, and the part of the first tab 14 located in the flat area E2 and the part of the second tab 15 located in the flat area E2 are both arranged substantially flat. The part of the first tab winding loop 143 located in the flat area E2 and the part of the second tab winding loop 153 located in the flat area E2 are both arranged substantially flat.

[0493] The bending area E1 is an area where the electrode assembly 10 has a bending structure, and the part of the first tab 14 located in the bending area E1 and the part of the second tab 15 located in the bending area E1 are both bent. The part of the first tab winding loop 143 located in the bending area E1 and the part of the second tab winding loop 153 located in the bending area E1 are both bent.

[0494] In some examples, the part of the first tab 14 located in the bending area E1 and the part of the second tab 15 located in the bending area E1 are both circular arcs, and the part of the first tab winding loop 143 located in the bending area E1 and the part of the second tab winding loop 153 located in the bending area E1 are both circular arcs.

[0495] The part of the first active winding loop 1432 located in the bending area E1 is a first active bending part 1434, and the part of the first active winding loop 1432 located in the flat area E2 is a first active flat part 1435.

[0496] In some examples, the first active flat portion 1435 of one first active winding circle 1432 is provided with the groove 144, or the active flat portions of the plurality of first active winding circles 1432 are provided with the groove 144.

[0497] For example, the first active flat portion 1435 of all the first active winding circles 1432 is provided with the groove 144.

[0498] Compared with the bending area E1, the gap between the first pole piece 14 and the second pole piece 15 in the flat area E2 is small, and the electrolyte is difficult to flow back. The first active flat portion 1435 of at least one first active winding circle 1432 is provided with the groove 144, which can store electrolyte or provide a flow-back channel for electrolyte, thereby improving the wettability of the flat area E2 and effectively improving the cycle performance of the battery monomer 6.

[0499] In some embodiments, the electrode assembly 10 includes the flat area E2 and two bending areas E1 located at both ends of the flat area E2; the first active winding circle 1432 includes the first active bending portion 1434 located in the bending area E1 and the first active flat portion 1435 located in the flat area E2, and the first active bending portion 1434 of at least one first active winding circle 1432 is provided with the groove 144.

[0500] In some examples, the first active bending portion 1434 of one first active winding circle 1432 is provided with the groove 144, or the active bending portions of the plurality of first active winding circles 1432 are provided with the groove 144.

[0501] For example, the first active bending portion 1434 of all the first active winding circles 1432 is provided with the groove 144.

[0502] By adopting the technical scheme of the embodiment, the first active bending portion 1434 of at least one first active winding circle 1432 is provided with the groove 144, which can store electrolyte or provide a flow-back channel for electrolyte, thereby improving the wettability of the bending area E1 and improving the cycle performance of the battery monomer 6.

[0503] In some embodiments, the electrode assembly 10 comprises a flat region E2 and two bending regions E1 located at two ends of the flat region E2; the first active winding coil 1432 comprises a first active bending part 1434 located at the bending region E1 and a first active flat part 1435 located at the flat region E2; the first active flat part 1435 of at least one first active winding coil 1432 is provided with a groove 144; and the first active bending part 1434 of at least one first active winding coil 1432 is provided with a groove 144, so as to improve the wetting effect of the flat region E2 and the bending region E1 at the same time, thereby improving the cycle performance of the battery monomer 6.

[0504] In some embodiments, the first active flat part 1435 of all the first active winding coils 1432 is provided with a groove 144, and the first active bending part 1434 of all the first active winding coils 1432 is not provided with a groove 144.

[0505] The first active bending part 1434 in the bending region E1 is bent, which increases the risk of powder falling from the first active bending part 1434. However, since the first active bending part 1434 of all the first active winding coils 1432 is not provided with a groove 144, the structural strength of the first active bending part 1434 is improved, the risk of powder falling from the bending region E1 is reduced, and the capacity and use reliability of the battery monomer 6 are improved. At the same time, since all the first active flat parts 1435 are provided with a groove 144, the wetting effect of the flat region E2 is effectively improved, and the cycle performance of the battery monomer 6 is improved. Therefore, the cycle performance, capacity and use reliability of the battery monomer 6 can be considered at the same time.

[0506] In some embodiments, the battery monomer 6 is a cylindrical battery monomer.

[0507] The electrode assembly 10 in the cylindrical battery monomer is tightly wound, which is not conducive to the backflow of electrolyte. However, since the first electrode sheet 14 is provided with a groove 144, the backflow of electrolyte is facilitated, the wetting effect of the electrode assembly 10 is improved, and the wetting effect of the cylindrical battery monomer is effectively improved.

[0508] In some embodiments, the second active winding coil 1532 located at the bending region E1 is a second active bending part 1534, and the second active winding coil 1532 located at the flat region E2 is a second active flat part 1535; the second active flat part 1535 of at least one second active winding coil 1532 is provided with a groove 144; and / or, the second active bending part 1534 of at least one second active winding coil 1532 is provided with a groove 144, so as to improve the wetting effect of the electrode assembly 10 and improve the cycle performance of the battery monomer 6.

[0509] Referring to Figure 23 and Figure 24As shown, in some embodiments, the thickness of the first active material layer 142 is t, and the groove depth of the groove 144 is h, where 0.05≤h / t≤0.84.

[0510] In some examples, the first groove 1441 forms a notch 144b on the first surface 1421, the area of the first surface 1421 within a preset distance from the notch 144b is the measurement area 1421c, and the thickness of the first active material layer 142 at the measurement area 1421c is equal to the thickness t of the first active material layer 142. The preset distance is 5 mm.

[0511] The measurement area 1421c can refer to an area formed by the notch 144b and an outer edge line 1421d of the measurement area 1421c. The outer edge line 1421d is arranged outside the notch 144b, has the same shape as the notch 144b, and is 5 mm away from the notch 144b.

[0512] In some examples, along the first direction Z, the groove depth of the groove 144 varies, and the maximum groove depth of the groove 144 is equal to the groove depth h of the groove 144. For example, along the first direction Z, the groove depth of the end of the groove 144 is less than the groove depth of the middle of the groove 144, and the groove depth of the middle of the groove 144 is equal to the groove depth h of the groove 144.

[0513] In some examples, the value of h / t can be 0.05, 0.84, or any value between 0.05 and 0.84. For example, but not limited to, the value of h / t can be 0.05, 0.08, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.81, 0.84.

[0514] The design of h / t≥0.05 enables the groove 144 to store electrolyte and guide the electrolyte backflow, improves the wettability of the first electrode tab 14, and improves the cycle performance of the battery monomer 6. The design of h / t≤0.84 enables the groove 144 not to penetrate the first active material layer 142, and the first current collector 141 is not exposed, reducing the risk of direct reaction between the first current collector 141 and ions. In addition, compared with the groove 144 penetrating the first active material layer 142, the first active material layer 142 removes less active material, which is beneficial to improve the active material capacity of the first electrode tab 14 and reduce the risk of degradation of the use performance of the battery monomer 6 caused by insufficient active material capacity of the first electrode tab 14. Therefore, the cycle performance and use performance of the battery monomer 6 can be considered.

[0515] In particular, the first pole piece 14 is the negative pole piece 12, the groove 144 does not penetrate the negative active material layer 122, so that the ions do not directly react with the first current collector 141, reducing the lithium precipitation problem of the battery monomer 6, in addition, the negative active material layer 122 removes the negative active material, which is beneficial to reduce the risk of lithium precipitation caused by insufficient negative active material, and improve the use performance of the battery monomer 6.

[0516] In some embodiments, 0.08≤h / t≤0.8, which can better balance the cycle performance and use performance of the battery monomer 6.

[0517] In some embodiments, 0.1≤h / t≤0.5, which can better balance the cycle performance and use performance of the battery monomer 6.

[0518] In some embodiments, the groove 144 has a groove depth h, and 0μm<h≤50μm.

[0519] In some examples, the value of h can be 50μm or any value between 0~50μm, for example, the value of h can be but not limited to 0μm, 2μm, 4μm, 6μm, 10μm, 20μm, 30μm, 40μm, 50μm.

[0520] The design of 0μm<h≤50μm makes the groove depth h of the groove 144 reasonable, so that the groove 144 can store electrolyte and guide the electrolyte backflow, improve the infiltration effect of the first pole piece 14, and improve the cycle performance of the battery monomer 6; in addition, the active material removed by the first active material layer 142 is less, which is beneficial to improve the active material capacity of the first pole piece 14, and also can reduce the risk of reducing the use performance of the battery monomer 6 caused by insufficient active material capacity of the first pole piece 14. Therefore, the cycle performance and use performance of the battery monomer 6 can be balanced.

[0521] In some embodiments, 6μm≤h≤30μm, which can better balance the cycle performance and use performance of the battery monomer 6.

[0522] In some embodiments, the groove 144 has a groove width w, and 30μm≤w≤1000μm.

[0523] In some examples, along the first direction Z, the groove width of the groove 144 does not change, and the groove width of the groove 144 at any position is equal to the groove width w of the groove 144.

[0524] In some examples, along the first direction Z, the groove width of the groove 144 changes, and the maximum groove width of the groove 144 is equal to the groove width w of the groove 144. For example, along the first direction Z, the groove width of the end of the groove 144 is less than the groove width of the middle of the groove 144, and the groove width of the middle of the groove 144 is equal to the groove width w of the groove 144.

[0525] In some examples, the value of w can be 30 pm, 1000 pm, or any value between 30 pm and 1000 pm, for example, but not limited to, 30 pm, 40 pm, 50 pm, 60 pm, 70 pm, 80 pm, 100 pm, 110 pm, 140 pm, 180 pm, 200 pm, 300 pm, 400 pm, 500 pm, 600 pm, 800 pm, 1000 pm.

[0526] The design of w≥30 pm enables the groove 144 to store electrolyte and guide the electrolyte backflow, improves the impregnation effect of the first tab 14, improves the cycle performance of the battery monomer 6, and also facilitates the processing and manufacturing of the groove 144; the design of w≤1000 pm can reduce the active material removed from the first active material layer 142, which is conducive to improving the active material capacity of the first tab 14, and can also reduce the risk of degradation of the use performance of the battery monomer 6 due to insufficient active material capacity of the first tab 14; in addition, during the hot pressing process of the first tab 14, the groove 144 is not easily flattened, and the shape of the groove 144 can be stably maintained. Therefore, the cycle performance and use performance of the battery monomer 6 can be considered.

[0527] In some embodiments, 50 pm≤w≤500 pm, which can better consider the cycle performance and use performance of the battery monomer 6.

[0528] In some embodiments, 80 pm≤w≤120 pm, which can better consider the cycle performance and use performance of the battery monomer 6.

[0529] In some embodiments, the groove 144 has a groove width w and a groove depth h, and 0.05≤h / w≤1.

[0530] In some examples, the value of h / w can be 0.05, 1, or any value between 0.05 and 1, for example, but not limited to, 0.05, 0.08, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.

[0531] With h being constant, the design of h / w≥0.05 enables the groove width w of the groove 144 not to be too large, so that during the hot pressing process of the first tab 14, the groove 144 is not easily flattened, and the shape of the groove 144 can be stably maintained; the design of h / w≤1 enables the electrolyte to have a relatively wide channel during backflow, which is conducive to the backflow of the electrolyte and improves the cycle performance of the battery monomer 6; therefore, the processing and manufacturing of the groove 144 and the cycle performance of the battery monomer 6 can be considered.

[0532] In some embodiments, 0.1≤h / w≤0.5, which can better balance the processing of the groove 144 and the cycle performance of the battery cell 6.

[0533] On the basis of 0μm

[0534] In some embodiments, along the first direction Z, the size of the first active material layer 142 is L, and the groove depth of the groove 144 is h, 5×10 -5 ≤h / L≤5×10 -4 .

[0535] In some examples, the value of h / L can be 5×10 -5 , 5×10 -4 , or any value between 5×10 -5 ~5×10 -4 , for example, but not limited to, 5×10 -5 , 7×10 -5 , 9×10 -5 , 1×10 -4 , 2×10 -4 , 3×10 -4 , 4×10 -4 , 5×10 -4 .

[0536] In some embodiments, along the first direction Z, the size of the first active material layer 142 is L, and the groove depth of the groove 144 is h, 5×10 -5 , which can make the electrolyte flow back quickly and improve the wettability of the first electrode tab 14; in addition, the design of h / L≤5×10 -4 , which can reduce the risk of the first current collector 141 being exposed and the active material of the first electrode tab 14 being excessively lost due to the excessive groove depth h of the groove 144, thus, the capacity, cycle performance, and use reliability of the battery cell 6 can be balanced.

[0537] In some embodiments, along the first direction Z, the size of the first active material layer 142 is L, and the groove depth of the groove 144 is h, wherein L≥60mm and h≥6μm.

[0538] In some examples, the value of L can be 60mm or any value greater than 60mm, for example, but not limited to, 60mm, 70mm, 80mm, 90mm, 100mm, 110mm, 120mm, 130mm, 150mm, 200mm, 300mm, 400mm.

[0539] In some examples, the value of h can be 6 μm or any value greater than 6 μm. For example, the value of h can be, but is not limited to, 6 μm, 10 μm, 20 μm, 30 μm, 40 μm, and 50 μm.

[0540] By adopting the technical solution of this embodiment, for battery cells 6 with L≥60mm and h≥6μm, the groove 144 can store more electrolyte and guide electrolyte reflux better, which can effectively improve the wetting effect of the first electrode 14 and improve the cycle performance of the battery cell 6.

[0541] In some embodiments, along the first direction Z, the size of the groove 144 is l, and the size of the first active material layer 142 is L, 0.8≤l / L≤1; optionally, 0.9≤l / L≤0.98.

[0542] In some examples, the value of l / L can be 0.8, 1, or any value between 0.8 and 1. For example, the value of l / L can be, but is not limited to, 0.8, 0.85, 0.9, 0.95, 0.98, 0.99, and 1.

[0543] The design of 0.8≤l / L≤1 ensures that the size l of the groove 144 and the size L of the first active material layer 142 are not much different or the same along the first direction Z. The two ends of the groove 144 are close to the two ends of the first active material layer 142, so that the electrolyte squeezed out from the two ends of the electrode assembly 10 can quickly flow back through the groove 144, which can effectively improve the wetting effect of the first electrode 14 and improve the cycle performance of the battery cell 6.

[0544] In some embodiments, 0.9 ≤ l / L ≤ 0.98 can better improve the cycle performance of the battery cell 6.

[0545] In some embodiments, 60mm ≤ L ≤ 330mm.

[0546] In some examples, the value of L can be 60mm, 330mm, or any value between 60mm and 330mm. For example, the value of L can be, but is not limited to, 60mm, 70mm, 80mm, 90mm, 100mm, 110mm, 100mm, 150mm, 200mm, 250mm, 300mm, and 330mm.

[0547] By adopting the technical solution of this embodiment, with the design of 60mm≤L≤330mm, the size of the first active material layer 142 is larger along the first direction Z, and the first active material layer 142 can accommodate more active material, thereby increasing the capacity of the battery cell 6. However, in the first direction Z, the distance for the extruded electrolyte to flow back to the middle of the first active material layer 142 is long, which increases the difficulty of the extruded electrolyte flowing back to the middle of the first active material layer 142. However, combined with the design of 0.8≤l / L≤1, the extruded electrolyte can quickly flow back to the middle of the first active material layer 142 through the groove 144, which is beneficial to improving the wetting effect of the first electrode 14 and improving the cycle performance of the battery cell 6. Therefore, the capacity and cycle performance of the battery cell 6 can be balanced.

[0548] In some embodiments, 70mm≤L≤200mm can better balance the capacity and cycle performance of the battery cell 6.

[0549] See Figure 25 and Figure 26 As shown, in some embodiments, the groove 144 includes a first groove segment 1442 and a second groove segment 1443 arranged along a first direction Z. At least one end of the first groove segment 1442 is connected to the second groove segment 1443 along the first direction Z. The groove depth of the first groove segment 1442 is greater than the groove depth of the second groove segment 1443, and / or the groove width of the first groove segment 1442 is greater than the groove width of the second groove segment 1443.

[0550] Along the first direction Z, one end of the first groove segment 1442 is connected to the second groove segment 1443, or both ends of the first groove segment 1442 are connected to the second groove segment 1443.

[0551] For example, the groove 144 is divided into three segments along the first direction Z. The middle segment is the first groove segment 1442, and the two ends are the second groove segments 1443. The first groove segment 1442 and the second groove 1444 are divided based on the groove depth change point of the groove 144 or the groove width change point of the first groove segment 1442.

[0552] The depth of the first groove segment 1442 is greater than the depth of the second groove segment 1443. For example, the first groove segment 1442 and the second groove segment 1443 are of equal depth, and the bottom surface of the first groove segment 1442 and the bottom surface of the second groove segment 1443 form a stepped structure.

[0553] The width of the first groove segment 1442 is greater than the width of the second groove segment 1443. For example, the first groove segment 1442 and the second groove segment 1443 are both of equal width, and the side of the first groove segment 1442 and the side of the second groove segment 1443 form a stepped structure.

[0554] In some examples, the groove 144 includes first groove segments 1442 and second groove segments 1443 arranged along the first direction Z, the first groove segments 1442 are connected with the second groove segments 1443 at at least one end along the first direction Z, the groove depth of the first groove segments 1442 is greater than that of the second groove segments 1443, so that the electrolyte is more prone to generate a siphon effect at the second groove segments 1443, which is more conducive to the rapid return flow of the electrolyte, improves the wetting effect of the first pole piece 14, and improves the cycle performance of the battery cell 6.

[0555] In some examples, the groove 144 includes first groove segments 1442 and second groove segments 1443 arranged along the first direction Z, the first groove segments 1442 are connected with the second groove segments 1443 at at least one end along the first direction Z, the groove width of the first groove segments 1442 is greater than that of the second groove segments 1443, so that the electrolyte is more prone to generate a siphon effect at the second groove segments 1443, which is more conducive to the rapid return flow of the electrolyte, improves the wetting effect of the first pole piece 14, and improves the cycle performance of the battery cell 6.

[0556] In some examples, the groove 144 includes first groove segments 1442 and second groove segments 1443 arranged along the first direction Z, the first groove segments 1442 are connected with the second groove segments 1443 at at least one end along the first direction Z, the groove depth of the first groove segments 1442 is greater than that of the second groove segments 1443, the groove width of the first groove segments 1442 is greater than that of the second groove segments 1443, so that the electrolyte is more prone to generate a siphon effect at the second groove segments 1443, which is more conducive to the rapid return flow of the electrolyte, improves the wetting effect of the first pole piece 14, and improves the cycle performance of the battery cell 6.

[0557] In some examples, along the direction in which the first groove segment 1442 points to the second groove segment 1443, the groove depth of the second groove segment 1443 is arranged to decrease from the first groove segment 1442; and / or, along the direction in which the first groove segment 1442 points to the second groove segment 1443, the groove width of the second groove segment 1443 is arranged to decrease from the first groove segment 1442.

[0558] For example, the first groove segment 1442 is an equal-depth structure, the second groove segment 1443 is a non-equal-depth structure, the groove depth of the second groove segment 1443 is arranged to decrease from the first groove segment 1442, and the groove depth of the second groove segment 1443 can decrease from the first groove segment 1442 in steps or slowly to form a smooth structure and reduce stress concentration at the second groove segment 1443.

[0559] For example, the first groove segment 1442 is an equal-width structure, the second groove segment 1443 is a non-equal-width structure, the groove width of the second groove segment 1443 is arranged to decrease from the first groove segment 1442, and the groove width of the second groove segment 1443 can decrease from the first groove segment 1442 in steps or slowly to form a smooth structure and reduce stress concentration at the second groove segment 1443.

[0560] In some examples, the groove depth of the second groove section 1443 decreases from the first groove section 1442 in the direction from the first groove section 1442 to the second groove section 1443, and the groove depth of the second groove section 1443 gradually decreases compared with the groove depth of the first groove section 1442, so as to form a pressure difference of electrolyte flow, the second groove section 1443 can generate a better siphon effect, and the electrolyte can be quickly sucked into the second groove section 1443 and quickly returned to the first groove section 1442 through the second groove section 1443, so as to better improve the first soaking effect and improve the cycle performance of the battery cell 6.

[0561] In some examples, the groove width of the second groove section 1443 decreases from the first groove section 1442 in the direction from the first groove section 1442 to the second groove section 1443, and the groove width of the second groove section 1443 gradually decreases compared with the groove width of the first groove section 1442, so as to form a pressure difference of electrolyte flow, the second groove section 1443 can generate a better siphon effect, and the electrolyte can be quickly sucked into the second groove section 1443 and quickly returned to the first groove section 1442 through the second groove section 1443, so as to better improve the first soaking effect and improve the cycle performance of the battery cell 6.

[0562] In some examples, the groove depth of the second groove section 1443 decreases from the first groove section 1442 in the direction from the first groove section 1442 to the second groove section 1443, and the groove width of the second groove section 1443 decreases from the first groove section 1442 in the direction from the first groove section 1442 to the second groove section 1443, so as to form a larger pressure difference of electrolyte flow, the second groove section 1443 can generate a better siphon effect, and the electrolyte can be quickly sucked into the second groove section 1443 and quickly returned to the first groove section 1442 through the second groove section 1443, so as to better improve the first soaking effect and improve the cycle performance of the battery cell 6.

[0563] Referring to Figures 27-29 In some embodiments, the groove 144 includes a plurality of sub-sections 1445, and the plurality of sub-sections 1445 are spaced apart in the first direction Z.

[0564] The groove 144 has a segmented structure, the groove 144 includes a plurality of sub-sections 1445, and adjacent two sub-sections 1445 are not connected and have a distance, and the plurality of sub-sections 1445 can be equidistantly arranged or non-equidistantly arranged.

[0565] By adopting the technical scheme of the embodiment, the groove 144 includes a plurality of subsegments 1445, which can reduce the loss of active material of the first active material layer 142 and the first pole piece 14, and help to improve the capacity and use performance of the battery monomer. In addition, the plurality of subsegments 1445 are arranged at intervals, which helps to improve the structural strength and rigidity of the first pole piece 14 compared with the use of a whole segment groove 144, and helps to improve the use reliability of the battery monomer 6.

[0566] In some embodiments, along the first direction Z, the distance between the two adjacent subsegments 1445 is d, and 0.1mm≤d≤1mm.

[0567] In some examples, the value of d can be 0.1mm, 1mm or any value between 0.1mm and 1mm. For example, the value of d can be, but is not limited to, 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm or 1mm.

[0568] The design of d≥0.1mm allows the two adjacent subsegments 1445 to be arranged at intervals, reduces the loss of active material of the first pole piece 14, and improves the use performance of the battery monomer 6. The design of d≤1mm allows the electrolyte between the two adjacent subsegments 1445 to flow, which makes the distribution of the electrolyte more uniform and helps to improve the cycle performance of the battery monomer 6.

[0569] In some embodiments, 0.3mm≤d≤0.6mm, which can better balance the cycle performance and use performance of the battery monomer 6.

[0570] In some embodiments, the distance between the two adjacent subsegments 1445 of one of the two grooves 144 can be the same as or different from the distance between the two adjacent subsegments 1445 of the other groove 144.

[0571] Referring to FIGS. 1, 2 and 3, Figure 20 and Figure 21 As shown in the figures, the number of grooves 144 is a plurality, and the plurality of grooves 144 are arranged at intervals along the second direction X. Along the second direction X, in the two adjacent grooves 144, the subsegments 1445 of one of the grooves 144 are arranged at least partially staggered with the subsegments 1445 of the other groove 144, and the second direction X is perpendicular to the first direction Z and the thickness direction Y of the first current collector.

[0572] For example, in the two adjacent grooves 144, along the second direction X, the projection of the subsegments 1445 of one of the grooves 144 does not overlap or partially overlaps with the projection of the subsegments 1445 of the other groove 144.

[0573] In some examples, in the two adjacent grooves 144, the electrolyte in the two adjacent sub-segments 1445 in the first groove 144 is not easy to infiltrate to the middle position of the two sub-segments 1445, and the sub-segment 1445 of the second groove 144 is oppositely arranged with the middle position between the two adjacent sub-segments 1445 of the first groove 144, so that the sub-segment 1445 of the second groove 144 can be used to infiltrate the middle position between the two adjacent sub-segments 1445 of the first groove 144, reduce the infiltration dead angle of the first pole piece 14, improve the uniformity of the electrolyte distribution, and help to improve the infiltration effect of the first pole piece 14 and the cycle performance of the battery monomer 6.

[0574] By adopting the technical scheme of this embodiment, the multiple sub-segments 1445 of the two adjacent grooves 144 are staggered, which is beneficial to improve the uniformity of the electrolyte distribution, improve the infiltration effect of the first pole piece 14, and improve the cycle performance of the battery monomer 6.

[0575] Referring to Figure 30 In some embodiments, the number of grooves 144 is multiple, and the multiple grooves 144 form multiple groups of grooves 144. Each group of grooves 144 includes multiple intersecting grooves 144, and the multiple groups of grooves 144 are arranged in the second direction X. The second direction X is perpendicular to the thickness direction Y of the first current collector.

[0576] The multiple grooves 144 are divided into multiple groups, and each group of grooves 144 includes multiple intersecting grooves 144. In some examples, each group of grooves 144 includes two intersecting grooves 144, and the two grooves 144 form an X-shaped structure. Of course, in other examples, each group of grooves 144 can also include three, four, or more than five grooves 144.

[0577] By adopting the technical scheme of this embodiment, the multiple grooves 144 are divided into multiple groups, and each group of grooves 144 includes multiple intersecting grooves 144. The electrolyte can flow in the multiple grooves 144, which is beneficial to improve the uniformity of the electrolyte distribution, improve the infiltration effect of the first pole piece 14, and improve the cycle performance of the battery monomer 6. In addition, the multiple groups of grooves 144 are arranged in the second direction X, which can reduce the loss of the active material of the first pole piece 14, is beneficial to improve the use performance and capacity of the battery monomer 6, and can also improve the structural strength and rigidity of the first pole piece 14, and is beneficial to improve the use reliability of the battery monomer 6.

[0578] Referring to Figure 5 and Figure 6As shown, in some embodiments, the electrode assembly 10 is in a winding structure, and m gaps are formed between the first active material layer 142 and the second active material layer 152, m≥30, m is a natural number; the innermost one of the m gaps is the first gap winding circle G; the average of the radial dimensions of the m-13th to m-5th gap winding circles G is greater than the average of the radial dimensions of the 5th to 13th gap winding circles G.

[0579] For example, m is 30, 40, 50, 60, 70, 80, 90, 100, 150, or 200.

[0580] For example, referring to Figure 6 As shown, after the first tab 14 and the second tab 15 are wound, two gaps are formed between the first active material layer 142 and the second active material layer 152, and the gaps can be spaces between the first tab 14 and the second tab 15 that are not filled by the separator 13.

[0581] The two gaps are divided into a first gap and a second gap, the first gap is wound to form a gap winding circle G, and the second gap is wound to form m-a gap winding circles G. The gap winding circles G of the first gap and the gap winding circles G of the second gap are arranged alternately from the inside to the outside of the electrode assembly 10, that is, the first gap winding circle G and the second gap winding circle G are arranged alternately from the center to the periphery of the electrode assembly 10.

[0582] For example, the first gap and the second gap can be formed in various ways.

[0583] For example, when winding the first tab 14, the separator 13, and the second tab 15, the tightness of the electrode assembly 10 after winding is adjusted by controlling the tension or other parameters of the three, thereby forming the first gap and the second gap with a predetermined size.

[0584] During the cycle of the battery monomer 6, the gap winding circle G can provide space for the expansion of the electrode assembly 10, reduce the pressure between the first active material layer 142 and the second active material layer 152, thereby reducing the amount of electrolyte squeezed out between the first tab 14 and the second tab 15. On this basis, in combination with the groove 144, the immersion effect of the first tab 14 and the second tab 15 can be effectively improved, the cycle performance of the battery monomer 6 is improved, in addition, the first gap and the second gap can reduce the expansion amount of the electrode assembly 10, thereby reducing the squeezing effect on the shell 20, reducing the risk of deformation and cracking of the shell 20, and improving the reliability of the battery monomer 6.

[0585] From the inside to the outside of the electrode assembly 10, the m gap winding circles G are sequentially arranged. The first gap winding circle G is closest to the center axis X1 of the battery monomer 6 compared with other gap winding circles G.

[0586] For example, a first gap winding circle G is formed between the first first-pole-piece winding circle 143 and the first second-pole-piece winding circle 153, a second gap winding circle G is formed between the first second-pole-piece winding circle 153 and the second first-pole-piece winding circle 143, a third gap winding circle G is formed between the second first-pole-piece winding circle 143 and the second second-pole-piece winding circle 153, and so on, and finally, m gap winding circles are formed.

[0587] In some examples, the average value of the radial dimension of the fifth to thirteenth gap winding circles G can be measured in the following manner:

[0588] Discharge the battery cell 6 to the lower limit cut-off voltage (for example, 2.5 V);

[0589] Using the CT (Computed Tomography) technique, an image of the cross section of the battery cell 6 is obtained by X-ray, the cross section being perpendicular to the central axis X1 of the battery cell 6 and intersecting the first active material layer 142 and the second active material layer 152, and the cross section showing the first pole piece 14, the second pole piece 15, and the separator 13.

[0590] Based on the image and the virtual straight line X3, a first intersection point of the outer surface of the third first-pole-piece winding circle 143 and the virtual straight line X3 is obtained, a second intersection point of the inner surface of the seventh second-pole-piece winding circle 153 and the virtual straight line X3 is obtained, and the distance D1 between the first intersection point and the second intersection point is measured, in a direction away from the center of the cross section and parallel to the virtual straight line X3.

[0591] Disassemble the battery cell 6 and unfold the first pole piece 14, the second pole piece 15, and the separator 13;

[0592] Fifty positions are randomly selected on the surface of the first active material layer 142, the thickness values of the 50 first pole pieces 14 are measured, and then the average value of the 50 thickness values is calculated, which can be the thickness T1 of the first pole piece 14;

[0593] Fifty positions are randomly selected on the surface of the second active material layer 152, the thickness values of the 50 second pole pieces 15 are measured, and then the average value of the 50 thickness values is calculated, which can be the thickness T2 of the second pole piece 15;

[0594] Fifty positions are randomly selected on the separator 13, the 50 thickness values are measured, and then the average value of the 50 thickness values is calculated, which can be the thickness T3 of the separator 13.

[0595] The outer surface of the 3rd first pole piece winding circle 143 and the inner surface of the 7th second pole piece winding circle 153 are provided with 4 first pole piece winding circles 143, 4 second pole piece winding circles 153 and 9 layers of isolation pieces 13; the outer surface of the 3rd first pole piece winding circle 143 and the inner surface of the 7th second pole piece winding circle 153 form 9 gap winding circles G, and the average value W1 of the radial dimensions of the 5th to 13th gap winding circles G is (D1-4×T1-4×T2-9×T3) / 9.

[0596] Similarly, based on the image and the virtual straight line X3, the third intersection point of the inner surface of the 3rd last second pole piece winding circle 153 and the virtual straight line X3 is obtained in the direction away from the center of the section and parallel to the virtual straight line X3, the fourth intersection point of the outer surface of the 8th last first pole piece winding circle 143 and the virtual straight line X3 is obtained, and the distance D2 between the third intersection point and the fourth intersection point is measured;

[0597] The inner surface of the 3rd last second pole piece winding circle 153 and the outer surface of the 8th last first pole piece winding circle 143 are provided with 4 first pole piece winding circles 143, 4 second pole piece winding circles 153 and 9 layers of isolation pieces 13; the inner surface of the 3rd last second pole piece winding circle 153 and the outer surface of the 8th last first pole piece winding circle 143 form 9 gap winding circles G, and the average value W2 of the radial dimensions of the m-13th to m-5th gap winding circles G is (D2-4×T1-4×T2-9×T3) / 9.

[0598] Wherein, W1W2.

[0599] During the cycle of the battery cell 6, the expansion of the electrode assembly 10 gradually accumulates from inside to outside in the radial direction, and the expansion accumulation force of the outer side of the electrode assembly 10 is large; the m-13th to m-5th gap winding turns G are arranged outward compared to the 5th to 13th gap winding turns G, and the average value of the radial dimension of the m-13th to m-5th gap winding turns G is greater than the average value of the radial dimension of the 5th to 9th gap winding turns G, so that the gap winding turns G on the outer side of the electrode assembly 10 have a larger radial dimension, which can provide more expansion space for the outer side of the electrode assembly 10, absorb the accumulated expansion amount of the electrode assembly 10, and effectively reduce the acting force between the electrode assembly 10 and the shell 20, reduce the deformation amount of the shell 20, reduce the risk of cracking of the shell 20, and improve the reliability of the battery cell 6; in addition, the gap winding turns G on the outer side of the electrode assembly 10 have a larger radial dimension, which is also beneficial to reducing the amount of electrolyte extruded from the outer side of the electrode assembly 10, and is beneficial to improving the cycle performance of the battery cell 6; the average value of the radial dimension of the 5th to 9th gap winding turns G is small, so that the gap winding turns G on the inner side of the electrode assembly 10 have a larger radial dimension, which can increase the compactness of the inner side of the electrode assembly 10, and is beneficial to improving the energy density of the battery cell 6.

[0600] In some embodiments, the gap winding turns G include a first gap sub-turn G1 and a second gap sub-turn G2, the first gap sub-turn G1 is located between the first active material layer 142 and the separator 13, and the second gap sub-turn G2 is located between the second active material layer 152 and the separator 13.

[0601] For example, the radial dimension of the first gap sub-turn G1 is W3, and the radial dimension of the second gap sub-turn G2 is W4. The radial dimension W of the gap winding turns G is W3+W4.

[0602] The first gap sub-turn G1 and the second gap sub-turn G2 can both provide space for the expansion of the electrode assembly 10, thereby reducing the extrusion effect on the shell 20, reducing the risk of deformation and cracking of the shell 20, and improving the reliability of the battery cell 6.

[0603] In some embodiments, the radial dimension of the first gap winding turn G is smaller than the radial dimension of the mth gap winding turn G.

[0604] By adopting the technical scheme of the embodiment, the radial dimension of the mth gap winding circle G is large, so that there is a large gap space between the first active material layer 142 and the second active material layer 152 on the outside of the electrode assembly 10, which can provide more expansion space for the outside of the electrode assembly 10, absorb the accumulated expansion amount of the electrode assembly 10, and thus effectively reduce the acting force between the electrode assembly 10 and the shell 20, reduce the deformation amount of the shell 20, reduce the risk of cracking of the shell 20, and improve the reliability. In addition, the large gap between the first active material layer 142 and the second active material layer 152 on the outside of the electrode assembly 10 is also beneficial to reducing the amount of electrolyte squeezed out of the outside of the electrode assembly 10, and is beneficial to improving the cycle performance of the battery monomer 6. The radial dimension of the first gap winding circle G is small, so that there is a small gap between the first active material layer 142 and the second active material layer 152 on the inside of the electrode assembly 10, which can increase the compactness of the inside of the electrode assembly 10, and is beneficial to improving the energy density of the battery monomer 6.

[0605] In some embodiments, the m gap winding circles G are divided into j groups of gap winding circles G in the order of the inside to the outside of the electrode assembly 10; that is, from the center to the periphery of the electrode assembly 10, the m gap winding circles G are divided into j groups of gap winding circles G.

[0606] The innermost group of gap winding circles G is the first group of gap winding circles G, and each group of gap winding circles G in the first group to the j-1 group includes 9 gap winding circles G, 1≤m-9×(j-1)≤9, and j is a natural number; the average value of the radial dimensions of the first group to the j-1 group of gap winding circles G is incrementally arranged.

[0607] From the inside to the outside of the electrode assembly 10, the m gap winding circles G are divided into j groups, and the group of gap winding circles G closest to the center axis X1 of the battery monomer 6 is the first group of gap winding circles G. The first group to the j-1 group of gap winding circles G each includes 9 gap winding circles G, and the number of the jth group of gap winding circles G is 1, 2, 3, 4, 5, 6, 7, 8, or 9.

[0608] For example, the first to ninth gap winding circles G form the first group of gap winding circles G, the tenth to eighteenth gap winding circles G form the second group of gap winding circles G, the nineteenth to twenty-seventh gap winding circles G form the third group of gap winding circles G, and so on.

[0609] For example, the average value of the radial dimensions of the first group of gap winding circles G can be measured in the following manner, and the average value of the radial dimensions of the other groups of gap winding circles G can also be obtained in the following measurement manner.

[0610] Discharge the battery monomer 6 to the lower limit cut-off voltage (for example, 2.5V);

[0611] An image of the cross section of the battery cell 6 is acquired using the X-ray described above;

[0612] Based on the image, a virtual straight line X3 is set, which can pass through the center of the cross section (the virtual straight line X3 intersects with the central axis X1);

[0613] Based on the image and the virtual straight line X3, the fifth intersection point of the outer surface of the first 1st first pole piece winding ring 143 and the virtual straight line X3, and the sixth intersection point of the inner surface of the fifth 5th second pole piece winding ring 153 and the virtual straight line X3 are acquired along the direction away from the center of the cross section and parallel to the virtual straight line X3, and the distance D3 between the fifth intersection point and the sixth intersection point is measured;

[0614] The outer surface of the first 1st first pole piece winding ring 143 and the inner surface of the fifth 5th second pole piece winding ring 153 are provided with four first pole piece winding rings 143, four second pole piece winding rings 153, and nine separators 13; the outer surface of the first 1st first pole piece winding ring 143 and the inner surface of the fifth 5th second pole piece winding ring 153 form nine gap winding rings G, and the average value W5 of the radial dimensions of the first group of gap winding rings G is (D3-4×T1-4×T2-9×T3) / 9.

[0615] By adopting the technical scheme of the embodiment, the average values of the radial dimensions of the first group to the (j-1)th group of gap winding rings G are set to increase, the radial dimensions of the gap winding rings G of the electrode assembly 10 increase from the inside to the outside, and the radial dimensions of the gap winding rings G of the electrode assembly 10 increase, so that the radial dimensions of the gap winding rings G on the outside of the electrode assembly 10 are large, which can provide more expansion space for the electrode assembly 10, absorb the accumulated expansion amount of the electrode assembly 10, and further reduce the acting force between the electrode assembly 10 and the shell 20, the deformation amount of the shell 20, and the risk of cracking of the shell 20, thereby improving the reliability. In addition, the radial dimensions of the gap winding rings G on the inside of the electrode assembly 10 are small, which can effectively increase the compactness of the structure on the inside of the electrode assembly 10, and is beneficial to improving the energy density of the battery cell 6.

[0616] Referring to Figure 7 As shown in the drawings, in some embodiments, the first current collector 141 includes a first current collector body 1411 and a first tab 1412 connected to each other, at least part of the first current collector body 1411 is covered with a first active material layer 142, and the first tab 1412 is not covered with the first active material layer 142; the second current collector 151 includes a second current collector body 1511 and a second tab 1512 connected to each other, at least part of the second current collector body 1511 is covered with a second active material layer 152, and the second tab 1512 is not covered with the second active material layer 152.

[0617] Along the axial direction of the battery cell 6, the second current collector 151 is divided into two parts, wherein the part covered with the second active material layer 152 is referred to as the second current collector main body 1511, and the other part not covered with the second active material layer 152 is referred to as the second tab 1512, and the interface between the second tab 1512 and the second current collector main body 1511 can be based on the end face of the second active material layer 152 close to the second tab 1512. The second tab 1512 is used for electrical connection with the output electrode to facilitate the input and output of electric energy.

[0618] In some examples, the second current collector main body 1511 can be completely covered with the second active material layer 152, or can be partially covered with the second active material layer 152, for example, the side of the second current collector main body 1511 away from the second tab 1512 is not covered with the second active material layer 152.

[0619] By adopting the technical solution of this embodiment, the first tab 1412 is led out from the end of the first electrode plate 14 along the axial direction of the battery cell 6, and the second tab 1512 is led out from the end of the second electrode plate 15 along the axial direction of the battery cell 6, which can facilitate the input or output of the battery cell 6.

[0620] Referring to Figures 31-33 As shown in the figure, in some embodiments, the shell 20 includes a housing 21 and an end cover 22, the housing 21 includes a side wall 212 and an end wall 211 connected together, the side wall 212 surrounds the electrode assembly 10, the end wall 211 and the end cover 22 are oppositely distributed along the axial direction of the battery cell 6, and the end cover 22 is sealingly connected to the side wall 212; the end cover 22 is insulatively provided with an electrode terminal 30, the second tab 1512 is electrically connected to the electrode terminal 30, and at least one of the side wall 212 and the end wall 211 is electrically connected to the first tab 1412.

[0621] The end cover 22 is provided with the electrode terminal 30, the electrode terminal 30 is insulatively separated from the end cover 22, and the electrode terminal 30 serves as an output electrode for outputting or inputting electric energy.

[0622] The second tab 1512 can be directly connected to the electrode terminal 30, for example, the second tab 1512 can be directly welded to the electrode terminal 30, and the second tab 1512 can also be welded to the electrode terminal 30 through a conductive member.

[0623] The first tab 1412 can be directly connected to the end wall 211, or can be indirectly connected to the end wall 211 through the side wall 212 or other components.

[0624] The first tab 1412 can also be directly connected to the side wall 212, or can be indirectly connected to the side wall 212 through the end wall 211 or other components.

[0625] The electrode terminal 30 serves as one exposed electrode of the battery cell 6, and the side wall 212 or the end wall 211 serves as another exposed electrode of the battery cell 6, so that the circuit connection between the battery cells 6 is simpler and more flexible, and the assembly of a plurality of battery cells 6 into a group is facilitated, and the battery structure is simplified.

[0626] In some embodiments, the electrode terminal 30 is provided with a through hole 31, which can be used for injecting electrolyte.

[0627] In some embodiments, the battery cell 6 further comprises a cover plate 40 connected to the electrode terminal 30 and used to separate the through hole 31 from the external space of the battery cell 6.

[0628] In some embodiments, the shell 20 comprises a shell body 21 and an end cover 22, the shell body 21 comprises a side wall 212 connected to an end wall 211, the side wall 212 surrounds the electrode assembly 10, the end wall 211 and the end cover 22 are distributed opposite to each other along the axial direction of the battery cell 6, and the end cover 22 is sealingly connected to the side wall 212; the end wall 211 is insulated and provided with the electrode terminal 30, the second tab 1512 is electrically connected to the electrode terminal 30, and at least one of the end cover 22 and the side wall 212 is electrically connected to the first tab 1412.

[0629] The end wall 211 is provided with the electrode terminal 30, the electrode terminal 30 is insulated and separated from the end wall 211, and the electrode terminal 30 serves as an output electrode for outputting or inputting electric energy.

[0630] The second tab 1512 can be directly connected to the electrode terminal 30, for example, the second tab 1512 can be directly welded to the electrode terminal 30, and the second tab 1512 can also be welded to the electrode terminal 30 through a conductive member.

[0631] The first tab 1412 can be directly connected to the end cover 22, or indirectly connected to the end wall 211 through the side wall 212 or other components.

[0632] The first tab 1412 can be directly connected to the side wall 212, or indirectly connected to the side wall 212 through the end cover 22 or other components.

[0633] The electrode terminal 30 serves as one exposed electrode of the battery cell 6, and the side wall 212 or the end cover 22 serves as another exposed electrode of the battery cell 6, so that the circuit connection between the battery cells 6 is simpler and more flexible, and the assembly of a plurality of battery cells 6 into a group is facilitated, and the battery structure is simplified.

[0634] In some embodiments, the battery cell 6 further comprises a first current collecting member 60 and a second current collecting member 70; the first tab 1412 and the second tab 1512 are respectively located at two ends of the electrode assembly 10 along the axial direction of the battery cell 6, and the second tab 1512 is located at the side of the electrode assembly 10 close to the electrode terminal 30; the second current collecting member 70 is electrically connected between the second tab 1512 and the electrode terminal 30; the electrode terminal 30 is insulated and arranged on the end cover 22, the first current collecting member 60 is located between the first tab 1412 and the end wall 211, the first current collecting member 60 is electrically connected with the first tab 1412, and at least one of the side wall 212 and the end wall 211 is electrically connected with the first current collecting member 60.

[0635] The second tab 1512 and the first tab 1412 are located at two ends of the electrode assembly 10, which can reduce the risk of short circuit of the battery cell 6.

[0636] The second current collecting member 70 can play a role of adapter, facilitating the electrical connection between the second tab 1512 and the electrode terminal 30.

[0637] For example, the second current collecting member 70 is welded with the second tab 1512, and the second current collecting member 70 is welded with the electrode terminal 30.

[0638] In some examples, the second current collecting member 70 is a circular ring.

[0639] The first current collecting member 60 can play a role of adapter, facilitating the electrical connection between the first tab 1412 and at least one of the side wall 212 and the end wall 211.

[0640] For example, the first current collecting member 60 is welded with the first tab 1412, the second current collecting member 70 is welded with the side wall 212, or the first current collecting member 60 is welded with the end wall 211.

[0641] In some embodiments, the battery cell 6 further comprises a first current collecting member 60 and a second current collecting member 70; the first tab 1412 and the second tab 1512 are respectively located at two ends of the electrode assembly 10 along the axial direction of the battery cell 6, and the second tab 1512 is located at the side of the electrode assembly 10 close to the electrode terminal 30; the second current collecting member 70 is electrically connected between the second tab 1512 and the electrode terminal 30; the electrode terminal 30 is insulated and arranged on the end wall 211, the first current collecting member 60 is located between the first tab 1412 and the end cover 22, the first current collecting member 60 is electrically connected with the first tab 1412, and at least one of the side wall 212 and the end cover 22 is electrically connected with the first current collecting member 60.

[0642] The first current collecting member 60 can play a role of adapter, facilitating the electrical connection between the first tab 1412 and at least one of the side wall 212 and the end cover 22.

[0643] For example, the first current collecting member 60 is welded to the first tab 1412, the second current collecting member 70 is welded to the side wall 212, or the first current collecting member 60 is welded to the end cover 22.

[0644] In some embodiments, the electrode terminal 30 is insulated and arranged on the end wall 211; the side wall 212 is provided with a protrusion 2121 protruding inwardly, and the protrusion 2121 is located on a side of the first tab 1412 facing the end cover 22 along the axial direction of the battery cell 6; the second current collecting member 70 comprises a first connecting portion 61, a second connecting portion 62, and a third connecting portion 63, the second connecting portion 62 is connected between the first connecting portion 61 and the third connecting portion 63; the first connecting portion 61 is connected to the first tab 1412, at least part of the third connecting portion 63 is located between the protrusion 2121 and the end cover 22, and the third connecting portion 63 is connected to a side of the protrusion 2121 facing away from the first tab 1412.

[0645] The side wall 212 is provided with a protrusion 2121 protruding inwardly. For example, the protrusion 2121 can be a solid structure or a hollow structure.

[0646] In the axial direction of the battery cell 6, at least part of the protrusion 2121 is located between the end cover 22 and the first tab 1412.

[0647] The protrusion 2121 overlaps the first tab 1412 in the axial direction of the battery cell 6, which can limit the movement of the first tab 1412 along the axial direction of the battery cell 6 when the battery cell 6 is subjected to external impact, and reduce the risk of disconnection between the first tab 1412 and the first current collecting member 60.

[0648] The first current collecting member 60 comprises a first connecting portion 61, a second connecting portion 62, and a third connecting portion 63; the first connecting portion 61 is welded to the first tab 1412; the third connecting portion 63 is connected to the protrusion 2121. For example, the third connecting portion 63 can be welded to the protrusion 2121; alternatively, the third connecting portion 63 can also be crimped to the protrusion 2121. The first connecting portion 61 can be welded to the first tab 1412.

[0649] At least part of the third connecting portion 63 is arranged between the protrusion 2121 and the end cover 22, and the third connecting portion 63 is connected to a side of the protrusion 2121 facing the end cover 22, so that the first current collecting member 60 can be assembled through the end cover 22, facilitating the installation of the first current collecting member 60; in addition, the protrusion 2121 also limits the third connecting portion 63, improving the installation stability of the first current collecting member 60, improving the connection reliability between the first current collecting member 60 and the first tab 1412 and between the first current collecting member 60 and the protrusion 2121, and improving the use reliability of the battery cell 6.

[0650] In some embodiments, the third connecting portion 63 is welded to the protrusion 2121.

[0651] In some embodiments, the outer side of the side wall 212 is provided with a recess 2122 corresponding to the position of the convex portion 2121. As an example, after the electrode assembly 10 is installed into the shell 21, the convex portion 2121 is formed by extruding the side wall 212 from the outer side.

[0652] In some embodiments, the side wall 212 further comprises a crimping portion 2123 extending from the convex portion 2121 away from one end of the end wall 211 and arranged around the end cover 22.

[0653] Part of the crimping portion 2123 is arranged in a bent manner and forms a flange structure, and part of the end cover 22 is located between the flange structure and the convex portion 2121 in the axial direction of the battery monomer 6. The convex portion 2121 and the flange structure can limit the end cover 22 to achieve the fixation of the end cover 22 in the axial direction of the battery monomer 6.

[0654] In some embodiments, the battery monomer 6 further comprises an insulating piece 80 arranged between the side wall 212 and the end cover 22 and insulating the end cover 22 from the side wall 212.

[0655] In some embodiments, part of the insulating piece 80 is located between the third connecting portion 63 and the end cover 22 to insulate the first current collecting member 60 from the end cover 22.

[0656] In some embodiments, a battery device 2 is provided, comprising a plurality of the above-mentioned battery monomers 6.

[0657] By adopting the technical scheme of this embodiment, the battery monomer 6 has good cycle performance, which is conducive to improving the use performance and service life of the battery device 2.

[0658] In some embodiments, an electric device is provided, comprising the above-mentioned battery monomer 6 or the above-mentioned battery device 2, and the battery monomer or the battery device 2 is used for storing or providing electric energy.

[0659] By adopting the technical scheme of this embodiment, the battery monomer 6 has good cycle performance, the battery device 2 has good use performance and long service life, which is conducive to improving the use performance and service life of the electric device.

[0660] Referring to Figures 3-9 As shown in the drawings, the embodiments of the present application provide a battery monomer 6, which comprises a shell 20, an electrode assembly 10, an electrode terminal 30, a first current collecting member 60 and a second current collecting member 70.

[0661] The shell 20 comprises a shell 21 and an end cover 22, the shell 21 comprises an integrally formed side wall 212 and an end wall 211, the end wall 211 and the end cover 22 are opposite along the axial direction of the battery monomer 6, and the end cover 22 is welded to the side wall 212.

[0662] The electrode terminal 30 is insulatively arranged on the end wall 211.

[0663] At least part of the electrode assembly 10 is accommodated in the case 20. The electrode assembly 10 includes the first tab 14, the second tab 15, and the separator 13, and the second tab 15, the first tab 14, and the separator 13 are woundly arranged, and the separator 13 is used to separate the second tab 15 and the first tab 14.

[0664] The first tab 14 includes the first current collector 141 and the first active material layer 142 covering the surface of the first current collector 141. The second tab 15 includes the second current collector 151 and the second active material layer 152 covering the surface of the second current collector 151. The part of the first current collector 141 not covered by the first active material layer 142 forms the first tab 1412, and the part of the second current collector 151 not covered by the second active material layer 152 forms the second tab 1512, and the first current collecting member 60 connects the first tab 1412 and the side wall 212, and the second current collecting member 70 connects the electrode terminal 30 and the second tab 1512.

[0665] The first active material layer 142 includes the first active material part 1422 and the second active material part 1423 arranged along the first direction Z, the second active material part 1423 is connected to at least one end of the first active material part 1422 along the first direction Z, the thickness of the second active material part 1423 is less than the thickness of the first active material part 1422, and the surface of the first active material part 1422 away from the first current collector 141 is provided with a groove 144; along the first direction Z, the groove 144 is arranged at intervals with the second active material part 1423, and the first direction Z is perpendicular to the thickness direction Y of the first current collector 141.

[0666] The above description of the various embodiments tends to emphasize the differences between the various embodiments, and the same or similar parts can be referred to each other, and for the sake of brevity, will not be repeated here.

[0667] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should be covered in the scope of the claims and the description of the present application. Especially, as long as there is no structural conflict, each technical feature mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized by, The application relates to a battery, comprising: a housing containing electrolyte; an electrode assembly at least partially located in the housing, the electrode assembly comprising a separator and first and second polar plates of opposite polarity, at least part of the separator being located between the first and second polar plates; the first polar plate comprising a first current collector and a first active material layer, the first active material layer being connected to at least part of at least one surface of the first current collector along the thickness direction of the first current collector, at least part of the first active material layer being located between the first current collector and the separator; wherein the first active material layer comprises a first active material portion and a second active material portion arranged along a first direction, the first active material portion being connected to the second active material portion at at least one end along the first direction, the second active material portion having a thickness smaller than that of the first active material portion, and the first active material portion being provided with a groove on the surface facing away from the first current collector; along the first direction, the groove is spaced apart from the second active material portion, and the first direction is perpendicular to the thickness direction of the first current collector.

2. The battery cell of claim 1, wherein: The distance between the second active material portion and the groove is S1, wherein 0mm 3. The battery cell of claim 2, wherein: 2mm 4. The battery cell of claim 1, wherein: along the direction in which the first active material portion points to the second active material portion, the thickness of the second active material portion decreases.

5. The battery cell of claim 4, wherein: The first active material portion has a first surface facing away from the first current collector, and the second active material portion has a second surface facing away from the first current collector, the second surface being closer to the first current collector than the first surface.

6. The battery cell of claim 4, wherein: along the first direction, one end of the first active material portion is connected to the second active material portion, and the other end of the first active material portion is not connected to the second active material portion, the first active material portion is provided with the groove on the surface facing away from the first current collector, and along the first direction, the groove penetrates through the end surface of the first active material portion facing away from the second active material portion; or, along the first direction, the end surface of the first active material portion facing away from the second active material portion is spaced apart from the groove.

7. The battery cell of claim 6, wherein: The distance between the end surface of the first active material portion facing away from the second active material portion and the groove is s, wherein 0mm 8. The battery cell of claim 7, wherein: 0.1mm 9. The battery cell of claim 8, wherein: 0.5mm 10. The battery cell of any one of claims 1-6, wherein: along the first direction, both ends of the first active material portion are connected to the second active material portion.

11. The battery cell of any one of claims 1-6, wherein: The first current collector comprises a first current collector body and a first tab arranged along the first direction and connected to each other, at least part of the first current collector body is covered with the first active material layer, and the first tab is not covered with the first active material layer.

12. The battery cell of any one of claims 1-6, wherein: The first polar plate is a negative polar plate.

13. The battery cell of any one of claims 1-6, wherein: The number of the first active material layers is two, the two first active material layers are respectively covered on both surfaces of the first current collector along the thickness direction of the first current collector, and at least one of the first active material layers is provided with the groove.

14. The battery cell of claim 13, wherein: The number of the grooves is multiple, the multiple grooves include first grooves and second grooves formed along the first direction, one of the two first active material layers is provided with multiple first grooves, and the other is provided with multiple second grooves; along the thickness direction of the first current collector, the first grooves and the second grooves are arranged staggeredly.

15. The battery cell of claim 14, wherein: Along the second direction, the multiple first grooves and the multiple second grooves are arranged alternately, the second direction being perpendicular to the first direction and the thickness direction of the first current collector.

16. The battery cell of claim 15, wherein: Along the second direction, the distance between adjacent first grooves and second grooves is C, wherein C≥1.5mm.

17. The battery cell of claim 16, wherein: 1.8mm≤C≤5mm.

18. The battery cell of claim 17, wherein: 2mm≤C≤3mm.

19. The battery cell of any one of claims 1-6, wherein: The electrode assembly is in a wound structure, the first tab is wound to form multiple first tab winding turns, the first current collector includes a first current collector winding turn located in the first tab winding turn, the first active material layer includes a first active material winding turn located in the first tab winding turn, the first active material winding turn has a first winding surface facing away from the corresponding first current collector winding turn; wherein the first winding surface of at least one first tab winding turn is provided with the groove.

20. The battery cell of claim 19, wherein: The number of the grooves is multiple, the multiple grooves include first grooves and second grooves formed along the first direction, one of the two first active material layers is provided with multiple first grooves, and the other is provided with multiple second grooves; along the thickness direction of the first current collector, the first grooves and the second grooves are arranged staggeredly.

21. The battery cell of claim 20, wherein: The number of the grooves is multiple, the multiple grooves include first grooves and second grooves formed along the first direction, one of the two first active material layers is provided with multiple first grooves, and the other is provided with multiple second grooves; along the thickness direction of the first current collector, the first grooves and the second grooves are arranged staggeredly.

22. The battery cell of claim 19, wherein: The number of the first tab winding turns is n, n≥30, n being a natural number, the innermost first tab winding turn being the first first tab winding turn, at least one of the first 10 first tab winding turns being provided with the groove.

23. The battery cell of claim 19, wherein: The number of the first tab winding turns is n, n≥30, n being a natural number, the innermost first tab winding turn being the first first tab winding turn, at least the first first tab winding turn being not provided with the groove.

24. The battery cell of claim 23, wherein: At least the first 3 first tab winding turns are not provided with the groove.

25. The battery cell of claim 23, wherein: The electrode assembly is provided with a center hole, the first first tab winding turn being closest to the center hole compared with other first tab winding turns.

26. The battery cell of claim 19, wherein: The number of the first tab winding turns is n, n≥30, n being a natural number, the innermost first tab winding turn being the first first tab winding turn, at least the last 2 first tab winding turns being not provided with the groove.

27. The battery cell of claim 26, wherein: At least the last 10 first tab winding turns are not provided with the groove.

28. The battery cell of claim 19, wherein: The number of the first pole piece winding turns is n, n≥30, n is a natural number; the innermost one of the first pole piece winding turns is the first first pole piece winding turn; the first f first pole piece winding turns are not provided with the groove; the last q first pole piece winding turns are not provided with the groove; all the first pole piece winding turns between the fth first pole piece winding turn and the last q first pole piece winding turn are provided with the groove, f+q<n, f and q are positive integers.

29. The battery cell of any one of claims 22-28, wherein: 30≤n≤80。 30. The battery cell of claim 29, wherein: 60≤n≤75。 31. The battery cell of any one of claims 22-28, wherein: The number of the first pole piece winding turns provided with the groove is v, 0.23≤v / n≤1, v and n are positive integers.

32. The battery cell of claim 31, wherein: 0.3≤v / n≤0.

7.

33. The battery cell of claim 19, wherein: The first pole piece has a first winding end, the second pole piece has a second winding end, the innermost first pole piece winding turn is the first first pole piece winding turn, the second winding end is located between the second last first pole piece winding turn and the third last first pole piece winding turn; the positions corresponding to the end surface of the first winding end of the second last first pole piece winding turn and the third last first pole piece winding turn are not provided with the groove; and / or, the positions corresponding to the end surface of the second winding end of the second last first pole piece winding turn and the third last first pole piece winding turn are not provided with the groove.

34. The battery cell of claim 33, wherein: The second last first pole piece winding turn and the third last first pole piece winding turn are provided with the groove, the groove is arranged staggered with at least one of the end surface of the first winding end and the end surface of the second winding end; or, the second last first pole piece winding turn and the third last first pole piece winding turn are not provided with the groove.

35. The battery cell of claim 19, wherein: The first pole piece has a first winding start, the second pole piece has a second winding start, the innermost first pole piece winding turn is the first first pole piece winding turn, the second winding start is located between the first two first pole piece winding turns; the positions corresponding to the end surface of the first winding start of the first two first pole piece winding turns are not provided with the groove; and / or, the positions corresponding to the end surface of the second winding start of the first two first pole piece winding turns are not provided with the groove.

36. The battery cell of claim 35, wherein: The first two first pole piece winding turns are provided with the groove, the groove is arranged staggered with at least one of the end surface of the first winding start and the end surface of the second winding start; or, the first two first pole piece winding turns are not provided with the groove.

37. The battery cell of claim 19, wherein: The first pole piece is a negative pole piece, and the second pole piece is a positive pole piece; or, the second pole piece is a negative pole piece, and the first pole piece is a positive pole piece.

38. The battery cell of claim 19, wherein: The electrode assembly comprises a flat area and two bending areas, the two bending areas are located at the two ends of the flat area; the first active winding turn comprises a first active bending part located at the bending area and a first active flat part located at the flat area; the first active flat part of at least one first active winding turn is provided with the groove; and / or, the first active bending part of at least one first active winding turn is provided with the groove.

39. The battery cell of claim 38, wherein: The first active flat part of all the first active winding turns is provided with the groove, and the first active bending part of all the first active winding turns is not provided with the groove.

40. The battery cell of claim 19, wherein: The battery cell is a cylindrical battery cell.

41. The battery cell of any one of claims 1-6, wherein: The first active material layer has a thickness of t, and the groove has a groove depth of h, wherein 0.05≤h / t≤0.

84.

42. The battery cell of claim 41, wherein: 0.08≤h / t≤0.

8.

43. The battery cell of claim 42, wherein: 0.1≤h / t≤0.

5.

44. The battery cell of any one of claims 1-6, wherein: The groove has a groove depth of h, and 0μm<h≤50μm.

45. The battery cell of claim 44, wherein: 6μm≤h≤30μm.

46. The battery cell of any one of claims 1-6, wherein: The groove has a groove width of w, wherein 30μm≤w≤1000μm.

47. The battery cell of claim 46, wherein: 50μm≤w≤500μm.

48. The battery cell of claim 47, wherein: 80μm≤w≤120μm.

49. The battery cell of any one of claims 1-6, wherein: The groove has a groove width of w, and a groove depth of h, and 0.05≤h / w≤1.

50. The battery cell of claim 49, wherein: 0.1≤h / w≤0.

5.

51. The battery cell of any one of claims 1-6, wherein: In the first direction, the size of the first active material layer is L, the groove depth of the groove is h, 5x10 -5 ≤h / L≤5x10 -4 .

52. The battery cell of any one of claims 1-6, wherein: In the first direction, the first active material layer has a size of L, and the groove has a groove depth of h, wherein L≥60mm, and h≥6μm.

53. The battery cell of any one of claims 1-6, wherein: In the first direction, the groove has a size of l, and the first active material layer has a size of L, and 0.8≤l / L≤1.

54. The battery cell of claim 53, wherein: 0.9≤l / L≤0.98。 55. The battery cell of claim 53, wherein: 60mm≤L≤330mm.

56. The battery cell of claim 55, wherein: 70mm≤L≤200mm.

57. The battery cell of any one of claims 1-6, wherein: The groove comprises a first groove segment and a second groove segment arranged along the first direction, at least one end of the first groove segment is connected with the second groove segment along the first direction, the groove depth of the first groove segment is greater than the groove depth of the second groove segment, and / or the groove width of the first groove segment is greater than the groove width of the second groove segment.

58. The battery cell of claim 57, wherein: In the direction of the first groove segment pointing to the second groove segment, the groove depth of the second groove segment is arranged to decrease from the first groove segment; and / or in the direction of the first groove segment pointing to the second groove segment, the groove width of the second groove segment is arranged to decrease from the first groove segment.

59. The battery cell of any one of claims 1-6, wherein: The groove comprises a plurality of sub-segments, and the plurality of sub-segments are arranged at intervals along the first direction.

60. The battery cell of claim 59, wherein: The interval between two adjacent sub-segments is d, and 0.1mm≤d≤1mm.

61. The battery cell of claim 60, wherein: 0.3mm≤d≤0.6mm.

62. The battery cell of claim 59, wherein: The groove has a plurality of groove numbers, and the plurality of grooves are arranged at intervals along a second direction; in two adjacent grooves along the second direction, at least part of the sub-segments of one groove is arranged to be staggered with the sub-segments of the other groove, and the second direction is perpendicular to the first direction and the thickness direction of the first current collector.

63. The battery cell of any one of claims 1-6, wherein: The groove has a plurality of groove numbers, and the plurality of grooves form a plurality of groups of grooves, each group of grooves comprises a plurality of intersecting grooves, and the plurality of groups of grooves are arranged at intervals along a second direction, and the second direction is perpendicular to the thickness direction of the first current collector.

64. The battery cell of any one of claims 1-6, wherein: The second pole piece comprises a second current collector and a second active material layer, at least part of the area of at least one surface of the second current collector along the thickness direction of the second current collector is connected with the second active material layer, and at least part of the second active material layer is located between the second current collector and the separator.

65. The battery cell of claim 64, wherein: The electrode assembly has a winding structure, and m gap winding turns are formed between the first active material layer and the second active material layer, m≥30, and m is a natural number; the innermost one of the gap winding turns is the first gap winding turn; the average value of the radial size of the m-13th to m-5th gap winding turns is greater than the average value of the radial size of the 5th to 13th gap winding turns.

66. The battery cell of claim 65, wherein: The gap winding turns comprise a first gap sub-turn and a second gap sub-turn, the first gap sub-turn is located between the first active material layer and the separator, and the second gap sub-turn is located between the second active material layer and the separator.

67. The battery cell of claim 65, wherein: The radial size of the first gap winding turn is smaller than the radial size of the mth gap winding turn.

68. The battery cell of claim 67, wherein: The m gap winding turns are divided into j groups of gap winding turns in the order from the inside to the outside of the electrode assembly; the innermost group of gap winding turns is the first group of gap winding turns, each group of gap winding turns from the first group to the j-1th group comprises 9 gap winding turns, 1≤m-9×(j-1)≤9, and j is a natural number; the average of the radial sizes of the first group to the j-1th group of gap winding turns is arranged in ascending order.

69. The battery cell of claim 64, wherein: The first current collector comprises a first current collector body and a first tab connected to each other, at least part of the first current collector body is covered with the first active material layer, and the first tab is not covered with the first active material layer; the second current collector comprises a second current collector body and a second tab connected to each other, at least part of the second current collector body is covered with the second active material layer, and the second tab is not covered with the second active material layer.

70. The battery cell of claim 69, wherein: The shell comprises a shell body and an end cover, the shell body comprises a side wall and an end wall connected to each other, the side wall surrounds the electrode assembly, the end wall and the end cover are oppositely distributed along the axial direction of the battery cell, and the end cover is sealingly connected to the side wall; the end cover is insulated and provided with an electrode terminal, the second tab is electrically connected to the electrode terminal, and at least one of the side wall and the end wall is electrically connected to the first tab; or, the end wall is insulated and provided with an electrode terminal, the second tab is electrically connected to the electrode terminal, and at least one of the end cover and the side wall is electrically connected to the first tab.

71. The battery cell of claim 70, wherein: The battery cell further comprises a first current collecting member and a second current collecting member; the first tab and the second tab are respectively located at two ends of the electrode assembly along the axial direction of the battery cell, and the second tab is located on the side of the electrode assembly close to the electrode terminal; The second current collecting member is electrically connected between the second tab and the electrode terminal; the electrode terminal is insulated and arranged on the end cover, the first current collecting member is located between the first tab and the end wall, the first current collecting member is electrically connected to the first tab, and at least one of the side wall and the end wall is electrically connected to the first current collecting member; or, the electrode terminal is insulated and arranged on the end wall, the first current collecting member is located between the first tab and the end cover, the first current collecting member is electrically connected to the first tab, and at least one of the side wall and the end cover is electrically connected to the first current collecting member.

72. The battery cell of claim 71, wherein: The electrode terminal is insulated from the end wall; the side wall is provided with a protrusion protruding inward, and along the axial direction of the battery monomer, the protrusion is located on the side of the first tab facing the end cover; the second current collecting member includes a first connecting portion, a second connecting portion, and a third connecting portion, the second connecting portion is connected between the first connecting portion and the third connecting portion; the first connecting portion is connected to the first tab, at least part of the third connecting portion is located between the protrusion and the end cover, and the third connecting portion is connected to the side of the protrusion away from the first tab.

73. A battery device, comprising: A plurality of battery monomers according to any one of claims 1-72 are included.

74. An electrical device, comprising: A battery monomer according to any one of claims 1-72 or a battery device according to claim 73 is used for storing or providing electric energy.

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