Battery cell, battery device, and electric device

Abstract

The present application discloses a battery cell, a battery device, and an electric device. The battery cell comprises a casing and an electrode assembly, wherein the casing accommodates an electrolyte; at least part of the electrode assembly is located in the casing, the electrode assembly comprises a first electrode sheet, a separator and a second electrode sheet, the first electrode sheet comprises a first current collector and a first active material layer, the first current collector is connected to the first active material layer, and at least part of the first active material layer is located between the first current collector and the separator; in a first direction, the size of the first active material layer is greater than or equal to 150 mm, and the first direction is parallel to the direction of gravity; and the first active material layer has a first surface facing away from the first current collector, the separator has a second surface in the thickness direction thereof, and at least one of the first surface and the second surface is provided with a recess.

Description

Battery cells, battery packs and electrical devices

[0001] Cross-references to related applications

[0002] This application claims the rights to the following international patent applications filed on December 2, 2024, entitled "Battery Cell, Battery Device and Electrical Device" (PCT / CN2024 / 136239), "Battery Cell, Battery Device and Electrical Device" (PCT / CN2024 / 136246), and "Cylindrical Battery Cell, Battery Device and Electrical Device" (PCT / CN2024 / 136244). The prior art of this application is incorporated herein by reference in the following three applications: International Patent Application PCT / CN2024 / 136238, filed on February 2, 2025, entitled “Battery Cell, Battery Device and Electrical Device”; International Patent Application PCT / CN2025 / 075132, filed on January 26, 2025, entitled “Battery Cell, Battery Device and Electrical Device”; and International Patent Application PCT / CN2024 / 136240, filed on December 2, 2024, entitled “Cylindrical Battery Cell, Battery Device and Electrical Device”. Technical Field

[0003] This application belongs to the field of battery technology, and in particular relates to a battery cell, a battery device, and an electrical device. Background Technology

[0004] Battery cells are widely used in electrical devices, such as mobile phones, laptops, electric vehicles, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and power tools, etc.

[0005] As the capacity requirements for individual battery cells gradually increase, the size of the active material layer on the electrodes of these cells is becoming larger, especially in the direction of gravity. However, with the gradual increase in the size of the active material layer, the requirements for the fast-charging capability of the battery cells are also becoming more stringent. Improving the fast-charging performance of individual battery cells is an important research direction in the field of battery technology.

[0006] The above statements are for the purpose of providing background information in relation to this application only and do not necessarily constitute prior art.

[0007] Application content

[0008] The purpose of this application is to provide a battery cell, a battery device, and an electrical device that can improve the fast charging capability of the battery cell.

[0009] The technical solution adopted in the embodiments of this application is:

[0010] In a first aspect, a battery cell is provided, the battery cell including a casing and an electrode assembly, the casing containing an electrolyte; at least a portion of the electrode assembly is located within the casing, the electrode assembly including a first electrode, a separator, and a second electrode, the first electrode and the second electrode having opposite polarities, the first electrode and the second electrode being located on opposite sides of the separator along its own thickness direction; the first electrode including a first current collector and a first active material layer, at least a portion of at least one surface of the first current collector along its own thickness direction being connected to the first active material layer, at least a portion of the first active material layer being located between the first current collector and the separator; along a first direction, the size of the first active material layer is greater than or equal to 150 mm, the first direction being parallel to the direction of gravity; the first active material layer having a first surface facing away from the first current collector, the separator having a second surface along its own thickness direction, at least one of the first surface and the second surface being provided with a groove.

[0011] By adopting the technical solution of this embodiment, for a battery cell with a first active material layer having a dimension greater than or equal to 150 mm along the first direction, during the charging and discharging process of the battery cell, ions pass through the separator and are inserted and extracted back and forth between the second electrode and the first electrode via the electrolyte, thereby realizing the electrical energy transfer of the battery cell; and the first surface of the first active material layer and / or the second surface of the separator are provided with grooves, which can be used to store electrolyte or provide flow channels for electrolyte, which is beneficial to improve the wetting effect of electrolyte on electrode components, improve ion transport rate, improve the cycle performance and fast charging performance of the battery cell, and better balance the capacity and fast charging performance of the battery cell.

[0012] In some embodiments, the first surface is provided with a groove, and the groove provided in the first active material layer is the first groove.

[0013] By adopting the technical solution of this embodiment, the first active material layer is provided with a first groove, which serves as a storage channel or flow channel for the electrolyte, thereby improving the wetting effect of the first electrode, increasing the ion transport rate, and improving the cycle performance of the battery cell.

[0014] In some embodiments, the first active material layer includes a first active material portion and a second active material portion disposed along a first direction. At least one end of the first active material portion along the first direction is connected to the second active material portion. The thickness of the second active material portion is less than the thickness of the first active material portion. The first active material portion is provided with a first groove. Along the first direction, the second active material portion is disposed at a distance from the first groove.

[0015] By adopting the technical solution of this embodiment, the first active material portion is provided with a first groove, which can improve the wetting effect of the first active material portion and improve the cycle performance of the battery cell. The second active material portion is spaced apart from the first groove, which is beneficial to improving the structural strength of the second active material portion and reducing the risk of powder shedding or even collapse of the second active material portion. This is beneficial to improving the capacity and reliability of the battery cell. Therefore, the cycle performance, capacity and reliability of the battery cell can be balanced. In addition, the thickness of the second active material portion is less than that of the first active material portion. Compared with the first active material portion, the second active material portion contains less active material, and the first groove does not extend to the second active material portion, which reduces the risk of lithium plating and other problems due to the reduction of active material in the second active material portion.

[0016] In some embodiments, along the first direction, the distance between the second active material portion and the first groove is S1, where 0 mm < S1 ≤ 12 mm.

[0017] By adopting the technical solution of this embodiment, S1 > 0 mm, the first groove will not extend to the second active material part, which is beneficial to improving the structural strength of the second active material part and reducing the risk of powder shedding or even collapse of the second active material part, which is beneficial to improving the capacity and reliability of the battery cell. The design of S1 ≤ 12 mm makes the electrolyte located on the side of the second active material part away from the first active material part closer to the first groove, so that the electrolyte can flow into the first groove better, improving the wetting effect of the first electrode and improving the cycle performance of the battery cell.

[0018] In some embodiments, 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 surface of the first active material portion facing away from the first current collector is provided with a first groove, and along the first direction, the end face of the first active material portion facing away from the second active material portion is spaced apart from the first groove.

[0019] By adopting the technical solution of this embodiment, the end face of the first active material part facing away from the second active material part is spaced apart from the first groove, which is beneficial to improve the structural strength of the end face of the first active material part facing away from the second active material part. It can improve the problem of edge defects caused by the first groove penetrating the end face of the first active material part facing away from the second active material part, which can lead to tape breakage during processing and edge cracking and cracking of the first electrode during long-term cycling, and even the risk of seriously reduced reliability.

[0020] In some embodiments, the distance between the end face of the first active material portion facing away from the second active material portion and the first groove is s, where 1mm≤s≤3mm.

[0021] By adopting the technical solution of this embodiment, the design of 1mm≤s≤3mm makes the distance between the end face of the first active material part facing away from the second active material part and the first groove closer. The electrolyte located between the end face of the first active material part facing away from the second active material part and the outer shell can flow into the first groove more quickly, improving the wetting effect of the first electrode sheet and helping to improve the cycle performance of the battery cell.

[0022] In some embodiments, there are multiple first grooves, the first grooves extend along a first direction, and the multiple first grooves are spaced apart along a second direction, the first direction is perpendicular to the second direction, and the second direction is perpendicular to the thickness direction of the first current collector.

[0023] By adopting the technical solution of this embodiment, the first groove extends along the first direction, which is beneficial to improving the climbing ability of the electrolyte along the first direction, improving the wetting effect of the upper part of the first active material layer, and improving the fast charging performance and cycle performance of the battery cell. In addition, the multiple first grooves are distributed at intervals, so that the electrolyte has multiple flow channels and storage channels in the second direction, which can better improve the climbing ability of the electrolyte and improve the fast charging performance and cycle performance of the battery cell.

[0024] In some embodiments, the distance between two adjacent first grooves ranges from 1 mm to 10 mm.

[0025] By adopting the technical solution of this embodiment, the distance between two adjacent first grooves is reasonably designed, which facilitates processing and can also effectively guide the flow of electrolyte in the battery cell, improve the wetting effect of the electrode assembly, and improve the fast charging performance and cycle performance of the battery cell; for example, the reasonable distribution density of the first grooves allows the electrolyte to have sufficient channels, so that it can quickly climb from the bottom to the top of the electrode assembly, effectively improving the electrolyte climbing ability.

[0026] In some embodiments, the first electrode includes two first active material layers, which respectively cover two surfaces of the first current collector along its own thickness direction. The number of first grooves is multiple, including first grooves and second grooves extending along a first direction. In the two first active material layers, one is provided with multiple first grooves, and the other is provided with multiple second grooves. The first grooves and second grooves are staggered along the thickness direction of the first current collector.

[0027] By adopting the technical solution of this embodiment, the two first active material layers are respectively provided with multiple first grooves and multiple second grooves to improve the wetting effect of the two first active material layers and improve the cycle performance of the battery cell; in addition, the first grooves and second grooves are staggered along the thickness direction of the first current collector, which is beneficial to improve the structural strength of the first electrode and improve the reliability of the battery cell.

[0028] In some embodiments, a plurality of first grooves and a plurality of second grooves are alternately arranged along a second direction, the second direction being perpendicular to the first direction and the thickness direction of the first current collector.

[0029] By adopting the technical solution of this embodiment, multiple first tanks and multiple second tanks can be evenly distributed on two first active material layers, which can improve the uniformity of electrolyte distribution in the battery cell and is beneficial to improving the cycle performance of the battery cell.

[0030] In some embodiments, along the second direction, the distance between adjacent first and second slots is C, where C ≥ 1.5 mm, optionally 1.8 mm ≤ C ≤ 5 mm, and optionally 2 mm ≤ C ≤ 3 mm.

[0031] By adopting the technical solution of this embodiment, the design with C≥1.5mm and the reasonable density setting of the first and second grooves can reduce the loss of active material in the first active material layer and also help improve the structural strength of the first electrode. Therefore, the reliability and capacity of the battery cell can be taken into account.

[0032] In some embodiments, the first groove includes a plurality of sub-segments, which are spaced apart along a first direction.

[0033] By adopting the technical solution of this embodiment, the first groove includes multiple sub-segments, which can reduce the removal of active material by grooving the first active material layer and reduce the loss of active material in the first electrode, which is beneficial to improving the capacity and performance of the battery cell. The first active material layer has a large size along the first direction, and the multiple sub-segments are arranged at intervals along the first direction, which can process the first active material layer in multiple segments at intervals, which is beneficial to reduce the processing difficulty and can also reduce processing errors caused by long-distance processing.

[0034] In some embodiments, the distance between two adjacent segments is d, where 0.5mm ≤ d ≤ 2.5mm.

[0035] By adopting the technical solution of this embodiment, the distance between two adjacent sub-segments is smaller, and the electrolyte in the lower sub-segment can easily enter the upper sub-segment, which is beneficial to improving the electrolyte's crawling ability and also facilitates processing and manufacturing.

[0036] In some embodiments, the first groove includes a plurality of sub-segments extending along a first direction, the plurality of sub-segments being spaced apart along a second direction, wherein in two adjacent sub-segments, the upper end of one sub-segment and the lower end of the other sub-segment are projected along the second direction, the second direction being perpendicular to the first direction and the thickness direction of the first current collector.

[0037] By adopting the technical solution of this embodiment, in two adjacent sub-segments, the upper end of one sub-segment and the lower end of the other sub-segment are projected along the second direction, so that liquid can be stored or electrolyte can flow at the close position of the two adjacent sub-segments, and the first electrode is more fully wetted; in addition, the close ends of the two adjacent sub-segments are spaced apart to reduce the risk of processing overlap and reduce the loss of active material.

[0038] In some embodiments, the first current collector includes a first current collector body and a first electrode tab, the first electrode tab being connected to the upper end of the first current collector body, at least a portion of the first current collector body being covered with a first active material layer, and the first electrode tab not being covered with the first active material layer; the number of first grooves is multiple, and the multiple first grooves are arranged at intervals along a second direction; the first active material layer includes a first half and a second half connected to each other, the first half being located above the second half, the segment located in the first half being a first segment, the segment located in the second half being a second segment, the depth of at least one first segment being less than the depth of at least one second segment, and / or, the distance between two adjacent first segments being less than the distance between two adjacent second segments.

[0039] By adopting the technical solution of this embodiment, the first tab is located on the upper side, making the current density of the first half greater than that of the second half. Compared with the second half, the first half requires more active material to improve the charging window. The design that the depth of at least one first segment is less than the depth of the second segment helps to reduce the amount of active material removed from the first half, thereby allowing the first half to retain more active material area to improve the charging window. Furthermore, the distance between two adjacent first segments is smaller than the distance between two adjacent second segments. The segment distribution in the first half is denser than that in the second half, providing more channels for electrolyte creep and improving the creep effect of the electrode assembly. The second half has a lower current density, a deeper second segment, and a sparser distribution, which can take into account the differences in charging needs in different areas caused by uneven current density, thus helping the battery cell achieve better performance.

[0040] In some embodiments, the depth range of at least one first segment is 10 μm to 15 μm; and / or, the depth range of at least one second segment is 15 μm to 20 μm.

[0041] By adopting the technical solution of this embodiment, the depth of at least one first segment is set within the above-mentioned range. The depth of the first segment is reasonable, which facilitates processing and manufacturing. The first segment can also guide the electrolyte to rise well while taking into account the charging requirements. The depth of at least one second segment is set within the above-mentioned range. The depth of the second segment is reasonable, which facilitates processing and manufacturing. The second segment can also guide the electrolyte to rise well while taking into account the performance of the battery cell.

[0042] In some embodiments, the distance between two adjacent first segments ranges from 0.5 mm to 2 mm; and / or, the distance between two adjacent second segments ranges from 2.5 mm to 6 mm.

[0043] By adopting the technical solution of this embodiment, the distance between two adjacent first segments is set within the above-mentioned range, the distance between two adjacent first segments is reasonable, the first half has more segments, and more channels to guide the electrolyte to climb, while the first half can also retain more active material to improve the charging window; the distance between two adjacent second segments is set within the above-mentioned range, the distance between two adjacent second segments is reasonable, the second half has more segments, and more channels to guide the electrolyte to climb.

[0044] In some embodiments, the second half includes a first half and a second half connected together, the ratio of the dimension of the second half along the first direction to the dimension of the first active material layer along the first direction is 0.2, and the depth of at least one second segment in the second half is less than the depth of at least one second segment in the first half.

[0045] By adopting the technical solution of this embodiment, during the charging process, the first active material layer has a large dimension along the first direction, and the first half is close to the first electrode, resulting in a short current path, low resistance, high current density, and fast charging speed. The second half is far from the electrode, resulting in a long current path, high resistance, and low current density, causing the SOC of the second half to be significantly lower than that of the first half during the initial charging phase. When the first half is nearly fully charged (e.g., SOC ≥ 90%), the charging current will preferentially flow to the not-yet-fully-charged second half, especially the second half, because it is closer to the bottom, has the longest current path, and the lowest SOC during the initial charging phase. At this time, most of the final charging current will be concentrated in the second half, causing this part to need to quickly absorb a large amount of charge. This results in the depth of at least one second segment in the second half being less than the depth of at least one second segment in the first half. The shallower second segment in the second half can retain more active material, which is beneficial to improving the charging capacity of the second half. This allows the voltage of the second half to be stabilized within a preset charging window, thereby suppressing lithium plating and improving cycle life.

[0046] In some embodiments, the depth range of at least one second segment located in the second half of the sub-part is 5 μm to 15 μm.

[0047] By adopting the technical solution of this embodiment, the depth of at least one second segment in the second half of the sub-sub ...

[0048] In some embodiments, the electrode assembly is a wound structure, the first electrode is wound to form a plurality of first electrode windings, the first current collector includes a first current collector winding located in the first electrode winding, the first active material layer includes a first active winding located in the first electrode winding, and the first surface includes a first winding surface located in the first electrode winding; wherein, at least one first winding surface of the first electrode winding is provided with a first groove.

[0049] By adopting the technical solution of this embodiment, the electrode assembly is wound in a way that the gap between the first electrode and the second electrode is small. This makes it difficult for the returned electrolyte to enter between the first electrode and the second electrode, which is not conducive to improving the cycle performance of the battery cell. However, at least one first groove is provided on the first winding surface of at least one first electrode winding ring. On the one hand, the electrolyte can flow into the first groove for storage. The stored electrolyte can wet the first electrode and provide a transport path for ions, reducing the ion transport resistance and improving the cycle performance of the battery cell. On the other hand, the first groove can also provide a channel for the return of electrolyte, reducing the difficulty of electrolyte return, reducing the ion transport resistance, improving the wetting effect of the first electrode, and also helping to improve the cycle performance of the battery cell.

[0050] In some embodiments, there are multiple first grooves, the first grooves extend along a first direction, and the multiple first grooves are spaced apart along a second direction, the second direction being the winding direction of the electrode assembly.

[0051] By adopting the technical solution of this embodiment, the first groove extends along the first direction, which is conducive to the electrolyte climbing upward along the first groove and improves the electrolyte climbing ability; in addition, multiple first grooves are spaced apart along the winding direction of the electrode assembly, so that the electrolyte can be distributed along the winding direction of the electrode assembly, which can effectively improve the electrolyte climbing ability of the electrode assembly.

[0052] In some embodiments, the electrode assembly includes a flat region and two bent regions located at both ends of the flat region; the first active winding includes a first active bent portion located in the bent region and a first active flat portion located in the flat region; at least one first active winding has a first active flat portion having a first groove; and / or, at least one first active winding has a first active bent portion having a first groove.

[0053] By adopting the technical solution of this embodiment, the first active straight portion of at least one first active winding ring is provided with a first groove, which is beneficial to improve the wetting effect of the straight area and improve the fast charging performance and cycle performance of the battery cell; the first active bending portion of at least one first active winding ring is provided with a first groove, which is beneficial to improve the wetting effect of the bending area and improve the fast charging performance and cycle performance of the battery cell.

[0054] In some embodiments, the first active straight portion of all first active windings is provided with a first groove, while the first active bent portion of all first active windings is not provided with a first groove.

[0055] By adopting the technical solution of this embodiment, the bending of the first active bending portion in the bending area increases the risk of powder shedding from the first active bending portion. However, since the first active bending portions of all the first active windings do not have first grooves, it is beneficial to improve the structural strength of the first active bending portion, reduce the risk of powder shedding in the bending area, and improve the capacity and reliability of the battery cell. Compared with the bending area, the gap between the first electrode and the second electrode in the straight area is small, making electrolyte reflux difficult. However, by providing first grooves for all the first active straight portions, the first grooves can be used to store electrolyte or provide a reflux channel for electrolyte, which is beneficial to improve the wetting effect in the straight area, thereby effectively improving the cycle performance of the battery cell.

[0056] In some embodiments, the first electrode has a first winding end, the second electrode has a second winding end, the innermost first electrode winding is the first first electrode winding, and the second winding end is located between the last two first electrode windings; the last two first electrode windings are not provided with a first groove at the position corresponding to the end face of the first winding end; and / or, the last two first electrode windings are not provided with a first groove at the position corresponding to the end face of the second winding end.

[0057] By adopting the technical solution of this embodiment, the position corresponding to the end face of the last two first electrode windings and the end face of the first winding termination is not provided with a first groove, and the structural strength at the position corresponding to the end face of the last two first electrode windings and the end face of the first winding termination is good, reducing the risk of the last two first electrode windings being sheared by the end face of the first winding termination, and improving the reliability of the battery cell; the position corresponding to the end face of the second winding termination is not provided with a first groove, and the structural strength at the position corresponding to the end face of the last two first electrode windings and the end face of the second winding termination is good, reducing the risk of the last two first electrode windings being sheared by the end face of the second winding termination, and improving the reliability of the battery cell.

[0058] In some embodiments, the last two first electrode windings are provided with a first groove, which is offset from at least one of the end face of the first winding end and the end face of the second winding end; or, the last two first electrode windings are not provided with a first groove.

[0059] By adopting the technical solution of this embodiment, the risk of the first electrode being cut off is reduced, and the reliability of the battery cell is improved.

[0060] In some embodiments, the first electrode has a first winding start end, the second electrode has a second winding start end, the innermost first electrode winding ring is the first first electrode winding ring, and the second winding start end is located between the first two first electrode winding rings; the first groove is not provided at the position corresponding to the end face of the first two first electrode winding rings and the first winding start end; and / or, the first groove is not provided at the position corresponding to the end face of the second winding start end of the first two first electrode winding rings.

[0061] By adopting the technical solution of this embodiment, the first groove is not provided at the position corresponding to the end face of the first two first electrode windings and the end face of the first winding start end. The structural strength at the position corresponding to the end face of the first two first electrode windings and the end face of the first winding start end is good, reducing the risk of the first two first electrode windings being sheared by the end face of the first winding start end, and improving the reliability of the battery cell. Similarly, the first groove is not provided at the position corresponding to the end face of the second winding start end of the first two first electrode windings. The structural strength at the position corresponding to the end face of the second winding start end of the first two first electrode windings and the end face of the second winding start end is good, reducing the risk of the first two first electrode windings being sheared by the end face of the second winding start end, and improving the reliability of the battery cell.

[0062] In some embodiments, the first two first electrode windings are provided with a first groove, which is offset from at least one of the end face of the first winding start end and the end face of the second winding start end; or, the first two first electrode windings are not provided with a first groove.

[0063] By adopting the technical solution of this embodiment, the risk of the first electrode being cut off is reduced, and the reliability of the battery cell is improved.

[0064] In some embodiments, the electrode assembly has a stacked structure.

[0065] By adopting the technical solution of this embodiment, the first electrode is provided with a first groove, which can serve as a storage channel and flow channel for electrolyte, which is beneficial to improving the wetting effect of the first electrode and improving the fast charging capability and cycle performance of large-size stacked battery cells.

[0066] In some embodiments, the first groove extends along a first direction.

[0067] By adopting the technical solution of this embodiment, the first groove extends along the first direction, which is beneficial to improve the climbing ability of the electrolyte, improve the wetting effect of the top of the electrode assembly, and effectively improve the fast charging capability and cycle performance of large-size stacked battery cells.

[0068] In some embodiments, the first current collector includes a first current collector body and a first electrode connected together along a first direction, wherein at least a portion of the first current collector body is covered with a first active material layer and the first electrode is not covered with the first active material layer; or, the first current collector includes a first current collector body and a first electrode connected together along a second direction, wherein at least a portion of the first current collector body is covered with the first active material layer and the first electrode is not covered with the first active material layer, and the second direction is perpendicular to the first direction and the thickness direction of the first current collector.

[0069] By adopting the technical solution of this embodiment, the first tab can be disposed on one side of the first electrode sheet along the first direction, or it can be disposed on one side of the first electrode sheet along the second direction, that is, the first electrode sheet is provided with a first groove, which can be flexibly applied to battery cells with different stacked structures.

[0070] In some embodiments, the ratio of the groove depth of the first groove to the thickness of the first active material layer ranges from 0.15 to 0.7.

[0071] By adopting the technical solution of this embodiment, the depth of the first groove is reasonable relative to the thickness of the first active material layer, and the distance between the bottom surface of the first groove and the first current collector is reasonable. This facilitates the rapid flow of electrolyte in the first groove to the first current collector, improves the wetting effect of the first electrode, and improves the fast charging performance and cycle performance of the battery cell.

[0072] In some embodiments, the groove depth of the first groove is h, where 10μm≤h≤40μm.

[0073] By adopting the technical solution of this embodiment, the depth of the first groove is reasonable, enabling the first groove to store electrolyte and guide electrolyte flow, thereby improving the wetting effect of the first electrode and enhancing the cycle performance of the battery cell. Furthermore, reducing the amount of active material removed by the groove in the first active material layer helps increase the active material capacity of the first electrode and reduces the risk of performance degradation in the battery cell due to insufficient active material capacity. Therefore, both the cycle performance and overall performance of the battery cell can be balanced.

[0074] In some embodiments, the width of the first groove is w, where 70μm≤w≤170μm.

[0075] By adopting the technical solution of this embodiment, the groove width of the first groove is reasonable, so that the first groove has a capillary effect, which effectively improves the flow of electrolyte, improves the wetting of electrode components, and improves the fast charging performance and cycle performance of battery cells. It also makes the active material removed by the groove of the first active material layer reasonable, reducing the risk of the battery cell's performance deteriorating due to insufficient active material capacity of the first electrode.

[0076] In some embodiments, along the first direction, the size of the first groove is l, and the size of the first active material layer is L, where 0.8 ≤ l / L ≤ 1; optionally, 0.9 ≤ l / L ≤ 0.98.

[0077] By adopting the technical solution of this embodiment, the dimensions of the first direction and the dimensions of the first active material layer are not much different or the same. The height of the first groove is high, which is beneficial to improve the electrolyte creeping ability. In addition, the two ends of the first groove along the first direction 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 first direction, which can effectively improve the wetting effect of the first electrode and improve the cycle performance of the battery cell.

[0078] In some embodiments, the first electrode is a negative electrode and the second electrode is a positive electrode.

[0079] By adopting the technical solution of this embodiment, the negative electrode sheet is provided with a first groove, which allows the negative electrode sheet to be better wetted and improves the performance of the battery cell.

[0080] In some embodiments, the size of the first active material layer along the first direction is L, 160mm≤L≤500mm, and optionally, 165mm≤L≤350mm.

[0081] By adopting the technical solution of this embodiment, the size of the first active material layer is larger along the first direction, and the first active material layer contains more active material, thereby improving the capacity of the battery cell; at the same time, combined with the first groove, it can better improve the wetting problem of the first electrode sheet, and can better balance the capacity of the battery cell and the fast charging performance.

[0082] In some embodiments, the second surface is provided with a groove, and the groove provided on the separator is a second groove.

[0083] By adopting the technical solution of this embodiment, the separator is provided with a second groove, which serves as a storage channel or flow channel for the electrolyte. This is beneficial to improving the wetting effect of the electrode assembly, increasing the ion transport rate, and improving the cycle performance and fast charging capability of the battery cell.

[0084] In some embodiments, the separator includes a base film and a coating, wherein at least one surface of the base film along the thickness direction of the separator is covered with the coating; a second surface is formed on the surface of the coating opposite to the base film, and at least a portion of the second groove is located in the coating.

[0085] By adopting the technical solution of this embodiment, it is convenient to manufacture the second groove.

[0086] In some embodiments, the second groove does not penetrate the coating along the thickness direction of the separator.

[0087] By adopting the technical solution of this embodiment, the second groove that does not penetrate the coating can provide a certain liquid storage space, and because the coating material is retained at the bottom, it can improve the overall structural integrity and mechanical strength of the coating, which is beneficial to improving the performance of the separator.

[0088] In some embodiments, the coating includes a first coating and a second coating of different materials. The first coating includes a plurality of coating portions. The second coating continuously covers the surface of the base film. The plurality of coating portions are spaced apart on the surface of the second coating facing away from the base film. Adjacent coating portions and the second coating surround to form a second groove.

[0089] By adopting the technical solution of this embodiment, the coating adopts a two-layer structure, and the performance of the coating can be flexibly set to meet different usage requirements.

[0090] In some embodiments, the coating includes a first coating and a second coating of different materials. The first coating includes a plurality of coating portions covering the surface of the base film. The second coating includes a plurality of filling portions covering the surface of the base film. The plurality of coating portions and the plurality of filling portions are alternately distributed along a second direction, which is perpendicular to the first direction and the thickness direction of the separator. Two adjacent coating portions and the filling portion located between the two adjacent coating portions together form a second groove.

[0091] By adopting the technical solution of this embodiment, the first coating and the second coating form a single-layer composite structure, which is beneficial to reduce the thickness of the separator and improve the volumetric energy density of the battery cell; multiple coating parts and multiple filling parts are arranged alternately in the second direction, the overall structure is regular and convenient for coating production.

[0092] In some embodiments, the first coating is a polymer coating or a polymer-ceramic coating, and the second coating is a ceramic coating.

[0093] By adopting the technical solution of this embodiment, the first coating is a polymer coating, which is beneficial to improving the adhesion between the separator and the first electrode and / or the second electrode, and reducing the risk of interlayer delamination during battery cell cycling; the first coating is a polymer ceramic coating, which can significantly improve the overall performance of the battery cell; the second coating is a ceramic coating, which has heat resistance and insulation properties, which is beneficial to improving the high temperature resistance and insulation performance of the separator, and improving the reliability of the battery cell.

[0094] In some embodiments, the ratio of the groove depth of the second groove to the coating thickness ranges from 0.3 to 0.9.

[0095] By adopting the technical solution of this embodiment, the ratio of the groove depth to the coating thickness of the second groove is within this range, the second groove can better serve as an electrolyte wetting channel, and the bottom of the second groove has a portion of coating material so that the separator has good performance.

[0096] In some embodiments, the coating thickness ranges from 1 μm to 3.5 μm, and the groove depth of the second groove ranges from 0.2 μm to 3 μm.

[0097] By adopting the technical solution of this embodiment, the depth of the second groove is reasonable relative to the thickness of the coating, the second groove can serve as a good wetting channel for the electrolyte, and the bottom of the second groove has part of the coating material so that the separator has good performance.

[0098] In some embodiments, the second groove penetrates the coating along the thickness direction of the separator.

[0099] By adopting the technical solution of this embodiment, the second groove penetrates the coating and has a relatively deep depth, which can accommodate more electrolyte, which is conducive to electrolyte reflux, improves the wetting effect of the electrode assembly, and improves the fast charging performance and cycle performance of the battery cell. In addition, the second groove can penetrate the coating along the thickness direction of the separator, exposing the base film. The base film can be directly dissipated by the second groove, reducing the thermal load of the separator and improving the performance of the battery cell.

[0100] In some embodiments, the coating is a ceramic coating, a polymer coating, or a polymer-ceramic coating.

[0101] By adopting the technical solution of this embodiment, the coating can be a ceramic coating, which can improve the heat resistance and puncture resistance of the separator, reduce the self-discharge of the battery cell during use, and thus improve the yield of the battery cell; the coating can be a polymer coating, which can enhance the adhesion between the separator and the first and / or second electrode, reduce the deformation of the battery cell during cycling, and improve the hardness of the battery cell, while also improving the wettability of the separator, enhancing liquid absorption, and improving cycle life; the coating can be a polymer-ceramic coating, which combines the advantages of ceramic coating and polymer coating, possessing both the good heat resistance and puncture resistance of ceramic coating and the excellent adhesion and flexibility of polymer coating, and can more significantly improve the overall performance of the battery cell, such as cycle performance and reliability.

[0102] In some embodiments, there are multiple second grooves, the second grooves extend along a first direction, and the multiple second grooves are spaced apart along a second direction, the second direction being perpendicular to the first direction and the thickness direction of the separator.

[0103] By adopting the technical solution of this embodiment, the second groove extends along the first direction, which can guide the electrolyte to climb up in the first direction, which is beneficial to improving the electrolyte climbing performance of high-performance battery cells.

[0104] In some embodiments, the second groove penetrates the coating along the first direction.

[0105] By adopting the technical solution of this embodiment, the electrolyte located at the opposite two end faces of the separator along the first direction can flow directly into the second groove for reflux, which is beneficial to improving the wetting effect of the electrode assembly and improving the cycle performance of the battery cell.

[0106] In some embodiments, the width of the second groove ranges from 0.5 mm to 12 mm.

[0107] By adopting the technical solution of this embodiment, the groove width of the second groove is set within the above-mentioned range, so that the second groove has a capillary effect, which effectively improves the flow of electrolyte, improves the wetting of electrode components, and improves the fast charging performance and cycle performance of battery cells.

[0108] In some embodiments, the second groove is a straight groove, and the length direction of the second groove is not perpendicular to the first direction.

[0109] By adopting the technical solution of this embodiment, the second groove is a straight groove, and the length direction of the second groove is not perpendicular to the first direction, so that the second groove can guide the electrolyte to diffuse upward, improve the electrolyte's climbing ability, improve the wetting effect of the electrode assembly, reduce the ion transport resistance, improve the electrolyte distribution uniformity, and improve the cycle performance of the battery cell.

[0110] In some embodiments, the angle between the length direction of the second groove and the first direction ranges from 0° to 45°; optionally, the angle between the length direction of the second groove and the first direction ranges from 0° to 30°.

[0111] By adopting the technical solution of this embodiment, the angle between the length direction of the second groove and the first direction is set within the above range, and the length direction of the second groove is parallel to or nearly parallel to the vertical direction. The electrolyte at the bottom can quickly climb along the second groove, thereby improving the wetting effect of the upper part of the electrode assembly and thus effectively improving the cycle performance of the battery cell.

[0112] In some embodiments, the spacer has a second groove on each of its opposite sides along its thickness direction.

[0113] By adopting the technical solution of this embodiment, a second groove is provided on both sides of the separator, which can better wet the first electrode and the second electrode, reduce the ion transport resistance, and help improve the cycle performance of the battery cell.

[0114] In some embodiments, the projections of the second grooves located on both sides of the spacer along its thickness direction intersect.

[0115] By adopting the technical solution of this embodiment, the projections of the second grooves located on both sides of the separator along its thickness direction intersect, which is beneficial to improving the structural stability of the separator and the reliability of the battery cell. Furthermore, since the electrolyte can pass through the separator, the electrolyte in the second groove opposite the first electrode can penetrate the separator and wet the second electrode, and the electrolyte in the second groove opposite the second electrode can penetrate the separator and wet the first electrode. Since the projections of the second grooves on both sides of the separator intersect, both the first and second electrodes on both sides of the separator receive more sufficient electrolyte wetting in the projection areas of the second grooves, improving the uniformity of electrolyte distribution and enhancing the cycle performance of the battery cell.

[0116] In some embodiments, the battery cell is a prismatic battery cell.

[0117] By adopting the technical solution of this embodiment, the first electrode and / or the separator are provided with grooves, which is beneficial to improving the cycle performance and fast charging performance of the high-square-shell battery cell.

[0118] In some embodiments, the housing includes a housing and an end cap, the electrode assembly is located inside the housing, the end cap is disposed at the opening of the housing, the surface with the largest area of ​​the electrode assembly is the third surface, the housing has a first sidewall, the first sidewall is disposed opposite to the third surface, and the thickness of the first sidewall ranges from 0.1 mm to 0.8 mm.

[0119] By adopting the technical solution of this embodiment, the thickness of the first sidewall is set within the aforementioned range. The smaller the thickness of the first sidewall, the easier it is to deform, thereby providing expansion space for the electrode assembly, reducing the amount of electrolyte squeezed out between the first and second electrodes, which is beneficial to improving the wetting effect of the electrode assembly and improving the cycle performance and fast charging performance of the battery cell. At the same time, the expansion space provided by the first sidewall helps to reduce the degree of compression between the first and second electrodes during expansion, facilitating the return of electrolyte between the first and second electrodes, and also facilitating the return of electrolyte into the groove, which is also beneficial to improving the wetting effect of the electrode assembly and improving the cycle performance and fast charging performance of the battery cell.

[0120] In some embodiments, the housing includes a housing and an end cap, the electrode assembly is located inside the housing, the end cap is disposed at the opening of the housing, the surface with the largest area of ​​the electrode assembly is the third surface, the housing has a first sidewall, a second sidewall and a third sidewall, the first sidewall is disposed opposite to the second sidewall, the first sidewall is disposed opposite to the third surface, the third surface is located between the first sidewall and the second sidewall, the third sidewall is connected between the first sidewall and the second sidewall, and the thickness of the first sidewall is less than the thickness of the third sidewall.

[0121] By adopting the technical solution of this embodiment, the thickness of the first sidewall is less than the thickness of the third sidewall, and the first sidewall is more easily deformable relative to the third sidewall. This provides expansion space for the electrode assembly, reduces the amount of electrolyte squeezed out between the first and second electrodes, and helps to improve the wetting effect of the electrode assembly, thereby improving the cycle performance and fast charging performance of the battery cell. At the same time, the expansion space provided by the first sidewall helps to reduce the degree of compression between the first and second electrodes during expansion, facilitating the return of electrolyte to the space between the first and second electrodes, and also facilitating the return of electrolyte into the groove. This also helps to improve the wetting effect of the electrode assembly, and improve the cycle performance and fast charging performance of the battery cell.

[0122] Secondly, a battery device is provided, comprising the aforementioned battery cell.

[0123] By adopting the technical solution of this embodiment, the battery cells have high capacity and good fast charging performance, which is beneficial to improving the performance of the battery device.

[0124] Thirdly, an electrical device is provided, including the aforementioned battery cell or battery device, wherein the battery cell or battery device is used to store or provide electrical energy.

[0125] By adopting the technical solution of this embodiment, the battery cells have high capacity and good fast charging performance, and the battery device has good performance, which is conducive to improving the performance of the power 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 is a structural schematic diagram of a vehicle provided in some embodiments of this application;

[0129] Figure 2 is a schematic diagram of a battery device provided in some embodiments of this application;

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

[0131] Figure 4 is an exploded view of the battery cell shown in Figure 3;

[0132] Figure 5 is a cross-sectional schematic diagram of an electrode assembly provided in some embodiments of this application;

[0133] Figure 6 is a schematic diagram of the second pole piece in an unfolded state according to some embodiments of this application;

[0134] Figure 7 is a cross-sectional view along line BB in Figure 6;

[0135] Figure 8 is a schematic diagram of the first electrode sheet in an unfolded state according to some embodiments of this application;

[0136] Figure 9 is a cross-sectional view along line B1-B1 in Figure 8;

[0137] Figure 10 is a schematic diagram of the structure of various first pole pieces in the unfolded state provided in some embodiments of this application;

[0138] Figure 11 is a schematic diagram of the structure of various first pole pieces in an unfolded state according to some embodiments of this application;

[0139] Figure 12 is a cross-sectional view along line CC in Figure 8;

[0140] Figure 13 is a schematic diagram of the first electrode sheet in an unfolded state according to some embodiments of this application;

[0141] Figure 14 is a schematic diagram of the first electrode sheet in an unfolded state according to some embodiments of this application;

[0142] Figure 15 is a cross-sectional view along line DD in Figure 13;

[0143] Figure 16 is a schematic diagram of the first electrode sheet in an unfolded state according to some embodiments of this application;

[0144] Figure 17 is a magnified view of a portion of point A in Figure 5;

[0145] Figure 18 is a cross-sectional view of the bending area in Figure 5;

[0146] Figure 19 is a structural schematic diagram of the isolation member in the unfolded state provided in some embodiments of this application;

[0147] Figure 20 is a structural schematic diagram of various isolation components in an unfolded state provided in some embodiments of this application;

[0148] Figure 21 is a cross-sectional view along EE in Figure 19;

[0149] Figure 22 is a cross-sectional view of the isolation member provided in some other embodiments of this application along the EE section in Figure 19;

[0150] Figure 23 is a cross-sectional view of the isolation member provided in some embodiments of this application along the EE section in Figure 19;

[0151] Figure 24 is a cross-sectional view of the isolation member provided in some embodiments of this application along the EE section in Figure 19;

[0152] Figure 25 is a schematic diagram of the structure of the isolation member in the unfolded state according to some embodiments of this application;

[0153] Figure 26 is a schematic diagram of the structure of the isolation component shown in Figure 25 in the deployed state;

[0154] Figure 27 is a schematic diagram of the structure of a battery cell provided in some embodiments of this application;

[0155] Figure 28 is a cross-sectional view along line FF in Figure 27;

[0156] Figure 29 is a magnified view of point G in Figure 28.

[0157] In the figures, the following labels are used: 1. Vehicle; 2. Battery unit; 3. Controller; 4. Motor; 5. Housing; 51. First housing; 52. Second housing; 6. Battery cell; 10. Electrode assembly; 101. Third surface; 11. Positive electrode; 111. Positive current collector; 112. Positive active material layer; 12. Negative electrode; 121. Negative current collector; 122. Negative active material layer; 13. Separator; 1301. Second surface; 131. Base film; 13 2. Coating; 13201, Ceramic coating; 13202, Polymer coating; 1321, Second groove; 1322, Coating part; 1323, First coating; 1324, Second coating; 13241, Filling part; 14, First electrode; 141, First current collector; 1411, First current collector body; 1412, First tab; 142, First active material layer; 1421, First surface; 1422, First active material part; 1423. Second active material section; 1424. First half; 1425. Second half; 14251. First sub-segment; 14252. Second sub-segment; 143. First electrode winding coil; 1431. First current collector winding coil; 1432. First active winding coil; 1433. First winding surface; 1434. First active bending section; 1435. First active straight section; 144. First groove; 1441. First slot; 14 42. Second groove; 1443. Sub-segment; 14431. First sub-segment; 14432. Second sub-segment; 15. Second electrode; 151. Second current collector; 152. Second active material layer; 16. Groove; 20. Outer shell; 21. Housing; 211. End wall; 2111. Third side wall; 212. Side wall; 2121. First side wall; 2122. Second side wall; 22. End cap; 221. Pressure relief mechanism; 30. Electrode terminal. Detailed Implementation

[0158] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0159] In the description of the embodiments of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" and "second" may explicitly or implicitly include at least one of that feature.

[0160] In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise expressly and specifically limited.

[0161] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0162] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0163] In the description of this application, it should be understood that the terms "inner", "outer", "side", "upper", "bottom", "front", "rear", etc., indicating the orientation or positional relationship are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0164] In the description of this application, it should be noted that the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0165] It should also be noted that in the embodiments of this application, the same reference numerals are used to represent the same component or part. For the same part in the embodiments of this application, the reference numerals may only be used to mark one part or component as an example. It should be understood that the reference numerals are also applicable to other identical parts or components.

[0166] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0167] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0168] Battery cells are widely used in electrical devices, such as mobile phones, laptops, electric vehicles, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and power tools, etc.

[0169] As the capacity requirements for individual battery cells gradually increase, the size of the active material layer on the electrodes of these cells is becoming larger, especially in the direction of gravity. However, with the increasing size of the active material layer, the demands on the fast-charging capability of the battery cells are also rising. During the charging and discharging process of a battery cell, the electrolyte plays a role in transporting ions, which mainly move back and forth between the electrodes through the electrolyte. However, improved fast-charging performance requires ions to move rapidly between the electrodes through the electrolyte, placing higher demands on the electrolyte's wetting of the electrodes to achieve better fast-charging and cycle performance. Therefore, improving the fast-charging and cycle performance of individual battery cells is an important research topic in battery engineering.

[0170] Based on this, this application provides a battery cell, which includes a casing and an electrode assembly. The casing contains an electrolyte. At least a portion of the electrode assembly is located inside the casing. The electrode assembly includes a first electrode, a separator, and a second electrode. The first and second electrodes have opposite polarities and are located on opposite sides of the separator along its thickness direction. The first electrode includes a first current collector and a first active material layer. At least a portion of at least one surface of the first current collector along its thickness direction is connected to the first active material layer. At least a portion of the first active material layer is located between the first current collector and the separator. Along a first direction, the size of the first active material layer is greater than or equal to 150 mm, and the first direction is parallel to the direction of gravity. The first active material layer has a first surface facing away from the first current collector, and the separator has a second surface along its thickness direction. At least one of the first and second surfaces is provided with a groove.

[0171] By adopting the technical solution of this embodiment, for a battery cell with a first active material layer having a dimension greater than or equal to 150 mm along the first direction, during the charging and discharging process of the battery cell, ions pass through the separator and are inserted and extracted back and forth between the second electrode and the first electrode via the electrolyte, thereby realizing the electrical energy transfer of the battery cell; and the first surface of the first active material layer and / or the second surface of the separator are provided with grooves, which can be used to store electrolyte or provide flow channels for electrolyte, which is beneficial to improve the wetting effect of electrolyte on electrode components, improve ion transport rate, improve the cycle performance and fast charging performance of the battery cell, and better balance the capacity and fast charging performance of the battery cell.

[0172] The battery cells described in this application are applicable to battery devices and electrical devices that use battery devices. Electrical devices can be equipment that uses battery devices as a power source or various energy storage systems that use battery devices as energy storage elements. Electrical devices can be, but are not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0173] For ease of explanation, the following embodiments will be described using vehicle 1 as an example of an electrical device.

[0174] As shown in Figure 1, a battery device 2 is installed inside the vehicle 1. The battery device 2 can be located at the bottom, front, or rear of the vehicle 1. The battery device 2 can be used to power the vehicle 1; for example, the battery device 2 can serve as the operating power source for the vehicle 1.

[0175] The vehicle 1 may also include a controller 3 and a motor 4. The controller 3 is used to control the battery device 2 to supply power to the motor 4, for example, for the power needs of the vehicle 1 during starting, navigation and driving.

[0176] In some embodiments of this application, the battery device 2 can not only serve as the operating power source for the vehicle 1, but also as the driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0177] Referring to Figure 2, in some embodiments, the battery device 2 may include one or more battery cell assemblies for providing voltage and capacity.

[0178] A battery cell assembly may include multiple battery cells 6, which are connected in series, parallel, or mixed connection via a busbar. Mixed connection means that multiple battery cells 6 are connected in both series and parallel.

[0179] Battery cell 6 can be a secondary battery cell. A secondary battery cell refers to a battery cell that can be recharged after being discharged, allowing the active materials to be activated and continue to be used.

[0180] 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-metal hydride battery cell, a nickel-cadmium battery cell, a lead-acid battery cell, etc.

[0181] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells 6; as an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells 6 into a single module. As an example, a battery module can be formed by bundling multiple battery cells 6 together with cable ties.

[0182] In some embodiments, the battery device 2 may be a battery pack, which includes a housing 5 and one or more battery cell assemblies housed within the housing 5. As an example, the battery cell assembly may be a battery module, which can be housed within the housing 5 by securing the battery module to the housing 5. Alternatively, as an example, the battery cell assembly may be housed within the housing 5 by directly securing multiple battery cells 6 to the housing 5.

[0183] In some embodiments, the housing 5 is used to house the battery cell 6, and the housing 5 can have various structures.

[0184] In some embodiments, the housing 5 may include a first housing 51 and a second housing 52. The first housing 51 and the second housing 52 are fastened together to form a closed space inside the housing 5 to house the battery cell assembly. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first housing 51 may be a top cover or a bottom plate.

[0185] In some embodiments, the housing 5 may include a top cover, a frame, and a bottom plate. The top cover and the bottom plate are respectively connected to the frame, so that the interior of the housing 5 forms an enclosed space to accommodate the battery cell assembly. As an example, the frame may include multiple side beams.

[0186] In some embodiments, the housing 5 may be part of the chassis structure of the vehicle 1. For example, a portion of the housing 5 may be at least a portion of the floor of the vehicle 1, or a portion of the housing 5 may be at least a portion of the crossbeams and longitudinal beams of the vehicle 1.

[0187] In some embodiments, the battery device 2 may be an energy storage device.

[0188] Energy storage devices can be used in energy storage power stations, wind power generation systems, solar power generation systems, mobile power systems, or temporary power supply systems. Energy storage devices can store electrical energy as needed and output it when appropriate. For example, energy storage devices can store electrical energy during off-peak hours and provide power to relevant users or electrical equipment during peak hours.

[0189] In some embodiments, the energy storage device includes an energy storage container, an energy storage cabinet, etc.

[0190] The battery cell 6 of this application will be described in detail below with reference to Figures 3 to 29 and specific embodiments. In the embodiments of this application, referring to Figure 5, the winding direction of the electrode assembly can be referred to the direction indicated by arrow V; referring to Figures 6 and 7, the second electrode 15 is in an unfolded state, the thickness direction of the second electrode 15 can be referred to the Y direction, the length direction of the second electrode 15 can be referred to the X direction, and the width direction of the second electrode 15 can be referred to the Z direction. Referring to Figures 8 to 16, the first electrode 14 is in an unfolded state, the thickness direction of the first electrode 14 can be referred to the Y direction, the length direction of the first electrode 14 can be referred to the X direction, and the width direction of the first electrode 14 can be referred to the Z direction. Referring to Figures 19 to 26, the separator 13 is in an unfolded state, the thickness direction of the separator 13 can be referred to the Y1 direction, the length direction of the separator 13 can be referred to the X1 direction, and the width direction of the separator can be referred to the Z1 direction. Referring to Figures 3, 4, 27-29, the height direction of the battery cell 6 and the height direction of the casing 21 can be referred to the Z' direction, the length direction of the battery cell 6 and the length direction of the casing 21 can be referred to the Y' direction, the thickness direction of the battery cell 6 and the thickness direction of the casing 21 can be referred to the X' direction, and the thickness direction of the electrode assembly can be referred to the X' direction.

[0191] Please refer to Figures 3 to 9. This application provides a battery cell 6, which includes a housing 20 and an electrode assembly 10, with at least a portion of the electrode assembly 10 housed within the housing 20.

[0192] The outer shell 20 may be a hollow structure, with an internal space for accommodating the electrode assembly 10 and the electrolyte.

[0193] In some embodiments, the housing 20 may be a metal housing, such as a steel housing, an aluminum housing, a composite metal housing (e.g., a copper-aluminum composite housing), or other metal housings. Alternatively, the housing 20 may also be a non-metallic housing, such as a plastic housing (e.g., polypropylene).

[0194] 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, it serves to protect the electrode assembly, and a sealing bag is included between the housing 20 and the electrode assembly 10 to encapsulate the electrode assembly 10 and the electrolyte. Specifically, the sealing bag can be a bag-shaped insulating component or an aluminum-plastic film. When the housing 20 is a sealed structure, it is used to encapsulate the electrode assembly 10 and components such as the electrolyte.

[0195] As an example, the battery cell 6 can be a square battery cell, a blade-shaped battery cell, etc.

[0196] In some embodiments, the housing 20 includes a housing 21 and an end cap 22, the housing 21 having an opening, and the end cap 22 being connected to the housing 21 and covering the opening.

[0197] The housing 21 is a component used to fit the end cap 22 to form the internal cavity of the battery cell 6. The formed internal cavity can be used to accommodate the electrode assembly 10, electrolyte, and other components.

[0198] The housing 21 and the end cap 22 can be separate components. For example, an opening can be provided on the housing 21, and the end cap 22 can be used to close the opening to form an internal cavity for the battery cell.

[0199] The shell 21 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc.

[0200] The shape of the end cap 22 can be adapted to the shape of the housing 21 to fit the housing 21. The material of the end cap 22 can be the same as or different from the material of the housing 21. Optionally, the end cap 22 can be made of a material with a certain hardness and strength (such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.), so that the end cap 22 is not easily deformed when subjected to compression and impact, so that the battery cell 6 can have higher structural strength and improve reliability.

[0201] The end cap 22 is connected to the housing 21 by welding, bonding, snap-fitting or other means.

[0202] The housing 21 may be open at one end or open at both ends. In some examples, the housing 21 may be a structure with an opening on one side, and one end cap 22 is provided to cover the housing 21. In other examples, the housing 21 may also be a structure with openings on both sides, and two end caps 22 are provided, with the two end caps 22 respectively covering the two openings of the housing 21.

[0203] In some embodiments, the end cap 22 may be provided with functional components such as electrode terminals 30. The electrode terminals 30 can be used to electrically connect with the electrode assembly 10 for outputting or inputting electrical energy from the battery cell 6.

[0204] In some embodiments, the end cap 22 may also be provided with a pressure relief mechanism 221 for releasing internal pressure when the internal pressure or temperature of the battery cell 6 reaches a threshold.

[0205] In some embodiments, an insulating element may be provided on the inner side of the end cap 22. The insulating element can be used to isolate the electrical connection components within the housing 21 from the end cap 22 to reduce the risk of short circuits. For example, the insulating element may be made of plastic, rubber, etc.

[0206] In some embodiments, the housing 21 includes an integrally formed sidewall 212 and endwall 211, the endwall 211 and end cap 22 are opposite each other along the height direction of the battery cell 6, and the end cap 22 is sealed to the sidewall 212.

[0207] Electrode assembly 10 is the component in the battery cell 6 where the electrochemical reaction takes place. Electrode assembly 10 can be entirely housed within housing 20 or partially housed within housing 20. For example, a portion of the tabs of electrode assembly 10 can extend outside housing 20.

[0208] Optionally, the electrode assembly 10 is entirely housed within the housing 20.

[0209] In some embodiments, the electrode assembly 10 includes a positive electrode 11 and a negative electrode 12. During the charging and discharging of the battery cell 6, active ions (e.g., lithium ions) are inserted and extracted back and forth between the positive electrode 11 and the negative electrode 12.

[0210] In some embodiments, the positive electrode 11 may include a positive current collector 111 and a positive active material layer 112 disposed on at least one surface of the positive current collector 111.

[0211] As an example, the positive current collector 111 has two surfaces opposite each other in its own thickness direction, and the positive active material layer 112 is disposed on either or both of the two opposite surfaces of the positive current collector 111.

[0212] As an example, the positive current collector 111 can be made of metal foil, conductive polymer material, carbon material, or composite current collector. For example, as a metal foil, pure metal, alloy, or surface-treated metal can be used, including but not limited to stainless steel, copper, aluminum, nickel, nickel alloy, titanium, or silver. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0213] As an example, the positive electrode active material layer 112 includes a positive electrode active material, which may include at least one of the following materials: lithium phosphate, lithium transition metal oxide, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium phosphate may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.8 Co 0.15 Al 0.05 At least one of O2 and its modified compounds. Modified compounds refer to substances obtained by modification methods such as doping or coating based on the above-mentioned substances.

[0214] In some embodiments, the negative electrode sheet 12 may include a negative electrode current collector 121 and a negative electrode active material layer 122 disposed on at least one surface of the negative electrode current collector 121.

[0215] As an example, the negative electrode current collector 121 has two surfaces opposite each other in its own thickness direction, and the negative electrode active material layer 122 is disposed on either or both of the two opposite surfaces of the negative electrode current collector 121.

[0216] As an example, the negative electrode current collector 121 can be made of metal foil, conductive polymer material, carbon material, or composite current collector. For example, as a metal foil, pure metal, alloy, or surface-treated metal can be used, including but not limited to stainless steel, copper, aluminum, nickel, nickel alloy, titanium, or silver. The composite current collector may include a polymer material substrate and a metal layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0217] As an example, the negative electrode active material may be a negative electrode active material known in the art for use in battery cell 6. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for battery cell 6 may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0218] In some embodiments, the positive current collector 111 may be made of aluminum, and the negative current collector 121 may be made of copper.

[0219] In some embodiments, the electrode assembly 10 further includes a separator 13 disposed between the positive electrode 11 and the negative electrode 12. The separator 13 serves to prevent short circuits between the positive and negative electrodes while allowing active ions to pass through.

[0220] The separator 13 may be partially located between the positive electrode 11 and the negative electrode 12. For example, the separator 13 protrudes from both ends of the positive electrode 11 and the negative electrode 12 along the height direction of the battery cell 6; or the entire separator 13 may be located between the positive electrode 11 and the negative electrode 12.

[0221] In some embodiments, the separator 13 is a separator membrane. The separator membrane of this application can be any known porous structure separator membrane with good chemical and mechanical stability.

[0222] As an example, the main material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride, and ceramic. The separator is a multilayer composite film. When the separator is a multilayer composite film, the materials of each layer can be the same or different. The separator 13 can be a single component located between the positive electrode 11 and the negative electrode 12, or it can be attached to the surface of the positive electrode 11 or the surface of the negative electrode 12. An inorganic particle coating, an organic particle coating, or an organic / inorganic composite coating can also be applied to the surface of the separator.

[0223] In some embodiments, the battery cell 6 further includes an electrolyte that serves to conduct ions between the positive electrode 11 and the negative electrode 12. The electrolyte used in this application can be selected according to requirements.

[0224] In some embodiments, the electrolyte includes an electrolyte salt and a solvent.

[0225] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0226] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent may also be an ether solvent. Ether solvents may include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ethers.

[0227] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain properties of the battery cell 6, such as additives that improve the overcharge / fast charge performance of the battery cell 6, additives that improve the high-temperature performance of the battery cell 6, additives that improve the low-temperature performance of the battery cell 6, etc.

[0228] The electrode assembly 10 can be a wound structure, a stacked structure, or a hybrid structure of wound and stacked.

[0229] In some embodiments, the positive electrode 11, the negative electrode 12, and the separator 13 are wound together.

[0230] The electrode assembly 10 has a wound structure. For example, the positive electrode 11, the separator 13, and the negative electrode 12 are wound into a flat wound structure.

[0231] In some embodiments, the electrode assembly 10 has a stacked structure.

[0232] As an example, multiple positive electrode plates 11 and multiple negative electrode plates 12 can be set, and multiple positive electrode plates 11 and multiple negative electrode plates 12 can be stacked alternately.

[0233] As an example, multiple positive electrode plates 11 can be provided, and negative electrode plates 12 can be folded to form multiple stacked folded segments, with a positive electrode plate 11 sandwiched between adjacent folded segments.

[0234] As an example, both the positive electrode 11 and the negative electrode 12 are folded to form multiple stacked folded segments.

[0235] As an example, multiple separators 13 can be provided, respectively disposed between any adjacent positive electrode 11 or negative electrode 12.

[0236] As an example, the separator 13 can be continuously arranged and disposed between any adjacent positive electrode 11 or negative electrode 12 by means of folding or rolling.

[0237] In some embodiments, the electrode assembly 10 may be flat.

[0238] In some embodiments, the electrode assembly 10 is provided with tabs that can conduct current from the electrode assembly 10. The tabs include a positive tab and a negative tab. The positive tab and the negative tab are electrically connected to two electrode terminals 30, respectively, to realize power output and input.

[0239] Please refer to Figures 10 and 11 together. In some embodiments, a battery cell 6 is provided, which includes a housing 20 and an electrode assembly 10. The housing 20 contains an electrolyte. At least a portion of the electrode assembly 10 is located within the housing 20. The electrode assembly 10 includes a first electrode 14, a separator 13, and a second electrode 15. The first electrode 14 and the second electrode 15 have opposite polarities and are located on opposite sides of the separator 13 along its thickness direction. The first electrode 14 includes a first current collector 141 and a first active material layer 142. At least a portion of at least one surface of 41 along its thickness direction is connected to a first active material layer 142, at least a portion of which is located between the first current collector 141 and the separator 13; the size of the first active material layer 142 is greater than or equal to 150 mm along a first direction, which is parallel to the direction of gravity; the first active material layer 142 has a first surface 1421 facing away from the first current collector 141, and the separator 13 has a second surface 1301 along its thickness direction, and at least one of the first surface 1421 and the second surface 1301 is provided with a groove 16.

[0240] The battery cell 6 is used in the electrical device. The battery cell 6 is installed in the electrical device and serves as an energy storage unit or discharge unit of the electrical device to store or release electrical energy.

[0241] One of the first electrode 14 and the second electrode 15 is the aforementioned positive electrode 11, and the other is the aforementioned negative electrode 12.

[0242] A portion of the spacer 13 is located between the first electrode 14 and the second electrode 15. Alternatively, the entire spacer 13 is located between the first electrode 14 and the second electrode 15.

[0243] The separator 13 can refer to a component used to separate the first electrode 14 and the second electrode 15. The first electrode 14 and the second electrode 15 are located on opposite sides of the separator 13 in the thickness direction. The separator 13 serves to insulate and separate while allowing ions to pass through.

[0244] For example, the first electrode 14 is a negative electrode 12, and the first electrode 14 includes a first current collector 141 and a first active material layer 142. The first current collector 141 is the aforementioned negative current collector 121, and the first active material layer 142 is the aforementioned negative active material layer 122. Alternatively, the first electrode 14 is a positive electrode 11, the first current collector 141 is the aforementioned positive current collector 111, and the first active material layer 142 is the aforementioned positive active material layer 112.

[0245] The first current collector 141 has a first active material layer 142 covering one surface along its thickness direction, or both surfaces of the first current collector 141 along its thickness direction are covered with the first active material layer 142. The thickness direction of the first current collector 141 is parallel to the thickness direction of the first electrode 14.

[0246] The first active material layer 142 may cover a portion of the surface of the first current collector 141, or it may cover the entire surface of the first current collector 141.

[0247] The first active material layer 142 can be directly applied to the first current collector 141. Alternatively, other layer structures, such as a conductive protective layer, can be provided between the first active material layer 142 and the first current collector 141. The conductive protective layer can be made by mixing a conductive agent and a binder. The binder bonds the first active material layer 142 and the first current collector 141, while 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.

[0248] The first direction is parallel to the direction of gravity, where "direction of gravity" can be the direction of gravity of the battery cell 6 when the electrical device is in use or when the battery cell 6 is mounted on the electrical device. For example, when the vehicle 1 is parked on a level surface, the direction of gravity of the battery cell 6 is the height direction of the battery cell 6, and the first direction is parallel to the height direction of the battery cell 6.

[0249] In some examples, when the first electrode 14 is in the unfolded state, the first direction may be parallel to the width direction of the first electrode 14, and the second direction may be the length direction of the first electrode 14.

[0250] Along the first direction, the size of the first active material layer 142 is L, where L ≥ 150 mm.

[0251] Along the first direction, the size of the first active material layer 142 can refer to the distance between two end faces of the first active material layer 142 that are relatively distributed along the first direction.

[0252] In some examples, the value of L can be any value of 150 mm or more; for example, the value of L can be, but is not limited to, 150 mm, 160 mm, 200 mm, 300 mm, 400 mm, 500 mm, 600 mm, 700 mm, etc.; along the first direction, the size L of the first active material layer 142 can be the width or height of the first active material layer 142. A battery cell 6 with L ≥ 150 mm can be referred to as a high-capacity battery cell.

[0253] In some examples, when the spacer 13 is in the unfolded state, the first direction may be parallel to the width direction of the spacer 13, and the second direction may be the length direction of the spacer 13.

[0254] After the first electrode 14, the second electrode 15 and the separator 13 are stacked, the electrode assembly 10 is wound along the second direction to form a wound structure. When the electrode assembly 10 is in the wound state, the second direction is the winding direction of the electrode assembly 10. After the electrode assembly 10 is wound, it can form a columnar structure. The first direction is parallel to the axial direction of the electrode assembly 10. The axial direction of the electrode assembly 10 can be parallel to the height direction of the battery cell 6.

[0255] In some examples, the surface of the first active material layer 142 facing away from the first current collector 141 is a first surface 1421, and a groove 16 is formed on the first surface 1421. The opening formed by the groove 16 on the first surface 1421 is a first opening. A portion of the first active material layer 142 is located between the first current collector 141 and the spacer 13, or the entire first active material layer 142 is located between the first current collector 141 and the spacer 13.

[0256] At least one surface of the separator 13 along its own thickness direction is a second surface 1301, and the second surface 1301 is provided with a groove 16. The opening formed by the groove 16 on the second surface 1301 is a second opening. At least one of the two surfaces of the separator 13 that are relatively distributed along its own thickness direction is provided with a groove 16.

[0257] By adopting the technical solution of this embodiment, for a battery cell 6 with a first active material layer 142 having a dimension greater than or equal to 150 mm along the first direction, during the charging and discharging process of the battery cell 6, ions pass through the separator 13 and are inserted and extracted back and forth between the second electrode 15 and the first electrode 14 via the electrolyte, thereby realizing the electrical energy transfer of the battery cell 6; and the first surface 1421 of the first active material layer 142 and / or the second surface 1301 of the separator 13 are provided with grooves 16, which can be used to store electrolyte or provide flow channels for electrolyte, which is beneficial to improve the wetting effect of electrolyte on electrode assembly 10, improve ion transport rate, improve the cycle performance and fast charging performance of battery cell 6, and better balance the capacity and fast charging performance of battery cell 6.

[0258] In some embodiments, the separator 13 is provided with a groove 16, which makes it easier for the electrolyte to shuttle between the first electrode 14 and the second electrode 15, and increases the climbing path of the electrolyte from the first electrode 14 and the separator 13. When the second electrode 15 does not absorb enough electrolyte, it can rise through the climbing path between the first electrode 14 and the separator 13 and then be supplied to the second electrode 15 through the separator 13. In addition, when the second electrode 15 expels electrolyte, the electrolyte can be partially stored in the groove 16, which improves the electrolyte retention capacity and the electrolyte retention space, shortens the electrolyte return path during the cycle, and increases the return rate, which greatly shortens the return time and greatly suppresses lithium plating caused by insufficient return of electrolyte during the cycle of the high-density battery cell 6.

[0259] In some embodiments, the second electrode 15 includes a second current collector 151 and a second active material layer 152. The second electrode 15 is a negative electrode 12, the second current collector 151 is the aforementioned negative current collector 121, and the second active material layer 152 is the aforementioned negative active material layer 122. Alternatively, the second electrode 15 is a positive electrode 11, the second current collector 151 is the aforementioned positive current collector 111, and the second active material layer 152 is the aforementioned positive active material layer 112. The surface of the second active material layer 152 facing away from the second current collector 151 may or may not have a groove 16.

[0260] The second current collector 151 has a second active material layer 152 covering one surface along its thickness direction, or both surfaces of the second current collector 151 along its thickness direction are covered with the second active material layer 152.

[0261] The second active material layer 152 may cover a portion of the surface of the second current collector 151, or it may cover the entire surface of the second current collector 151.

[0262] 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 provided between the second active material layer 152 and the second current collector 151.

[0263] In some embodiments, the first surface 1421 is provided with a groove 16, and the groove 16 provided on the first active material layer 142 is a first groove 144.

[0264] The groove 16 provided on the first active material layer 142 is the first groove 144. The first groove 144 can refer to the recessed structure formed on the first active material layer 142. The cross-sectional shape of the first groove 144 can be rectangular, arc-shaped, or V-shaped, or other similar shapes.

[0265] When the first electrode 14 is in the unfolded state, the shape of the first groove 144 can be various, such as: straight, curved, wavy, etc.

[0266] In some examples, the first groove 144 is straight in shape, and the first groove 144 is a straight groove.

[0267] For example, the length direction of the first groove 144 is not perpendicular to the first direction. It can be understood that the length direction of the first groove 144 is parallel to or intersects the first direction at an angle.

[0268] For example, the length direction of the first groove 144 is perpendicular to the first direction.

[0269] For example, when the first electrode 14 is in the unfolded state, the number of first grooves 144 can be one or more, and the multiple first grooves 144 can be arranged at intervals along the second direction, or the multiple first grooves 144 can form a grid structure.

[0270] For example, the first groove 144 may be disposed on the lower or upper side of the first active material layer 142, or located in the middle of the first active material layer 142.

[0271] By adopting the technical solution of this embodiment, the first active material layer 142 is provided with a first groove 144. The first groove 144 is used as a storage channel or flow channel for electrolyte, which is beneficial to improve the wetting effect of the first electrode 14, improve the ion transport rate, and improve the cycle performance and fast charging capability of the battery cell 6.

[0272] In some embodiments, the first active material layer 142 includes a first active material portion 1422 and a second active material portion 1423 disposed along a first direction. At least one end of the first active material portion 1422 along the first direction is connected to the second active material portion 1423. The thickness of the second active material portion 1423 is less than the thickness of the first active material portion 1422. The first active material portion 1422 is provided with a first groove 144. Along the first direction, the second active material portion 1423 and the first groove 144 are disposed at intervals.

[0273] The first active material portion 1422 is connected to the second active material portion 1423 at one end along the first direction, or the first active material portion 1422 is connected to the second active material portion 1423 at both ends along the first direction.

[0274] 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 be referred to the thickness transition position of the first active material layer 142. The second active material portion 1423 can be referred to as the thinning region of the first active material layer 142.

[0275] In some examples, the second active material portion 1423 and the first active material portion 1422 may both have a generally equal thickness structure, with the thickness of the second active material portion 1423 being 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.

[0276] In some examples, the first active material portion 1422 may have a generally uniform thickness. Along the direction from the first active material portion 1422 to the second active material portion 1423, the thickness of the second active material portion 1423 decreases from that of the first active material portion 1422, such that the thickness of the second active material portion 1423 is less than the thickness of the first active material portion 1422. The direction from the first active material portion 1422 to the second active material portion 1423 can be seen in the direction indicated by arrow Z in Figure 9.

[0277] Along the first direction, there is a distance between the second active material portion 1423 and the first groove 144, such that the first groove 144 of the first active material portion 1422 does not extend to the second active material portion 1423.

[0278] By adopting the technical solution of this embodiment, the first active material portion 1422 is provided with a first groove 144, which can improve the wetting effect of the first active material portion 1422 and improve the cycle performance of the battery cell 6. The second active material portion 1423 is spaced apart from the first groove 144, which is beneficial to improving the structural strength of the second active material portion 1423 and reducing the risk of powder shedding or even collapse of the second active material portion 1423. This is beneficial to improving the capacity and reliability of the battery cell 6. Therefore, the cycle performance, capacity and reliability of the battery cell 6 can be balanced. In addition, the thickness of the second active material portion 1423 is less than that of the first active material portion 1422. Compared with the first active material portion 1422, the second active material portion 1423 contains less active material. The first groove 144 does not extend to the second active material portion 1423, which reduces the risk of lithium plating and other problems due to the reduction of active material in the second active material portion 1423.

[0279] In some embodiments, along the first direction, the distance between the second active material portion 1423 and the first groove 144 is S1, where 0 mm < S1 ≤ 12 mm.

[0280] S1 can refer to the distance between the interface between the first active material portion 1422 and the second active material portion 1423 and the first opening of the first groove 144.

[0281] In some examples, S1 can be 12mm or any value between 0mm and 12mm. For example, S1 can be 0.1mm, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, or 12mm.

[0282] S1 > 0 mm ensures that the first groove 144 does not extend into the second active material portion 1423, which is beneficial to improving the structural strength of the second active material portion 1423 and reducing the risk of powder shedding or even collapse of the second active material portion 1423. This is beneficial to improving the capacity and reliability of the battery cell 6. The design of S1 ≤ 12 mm ensures that the electrolyte located on the side of the second active material portion 1423 away from the first active material portion 1422 is closer to the first groove 144, allowing the electrolyte to flow better into the first groove 144, improving the wetting effect of the first electrode 14 and improving the cycle performance of the battery cell 6.

[0283] In some embodiments, along the first direction, one end of the first active material portion 1422 is connected to the second active material portion 1423, and the other end of the first active material portion 1422 is not connected to the second active material portion 1423. The surface of the first active material portion 1422 facing away from the first current collector 141 is provided with a first groove 144. Along the first direction, the end face of the first active material portion 1422 facing away from the second active material portion 1423 is spaced apart from the first groove 144.

[0284] Along the first direction, there is a distance between the end face of the first active material portion 1422 facing away from the second active material portion 1423 and the first groove 144, such that the first groove 144 does not penetrate the end face of the first active material portion 1422 facing away from the second active material portion 1423.

[0285] By adopting the technical solution 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 first groove 144, which is beneficial to improve the structural strength of the end face of the first active material part 1422 facing away from the second active material part 1423. This can improve the problem of edge defects caused by the first groove 144 penetrating the end face of the first active material part 1422 facing away from the second active material part 1423, which can lead to tape breakage during processing and edge cracking and cracking of the first electrode 14 during long-term cycling, and even the risk of seriously reduced reliability.

[0286] In some embodiments, the distance between the end face of the first active material portion 1422 facing away from the second active material portion 1423 and the first groove 144 is s, where 1mm≤s≤3mm.

[0287] s can refer to the distance between the end face of the first active material portion 1422 facing away from the second active material portion 1423 and the first opening of the first groove 144.

[0288] In some examples, s can be 1mm, 3mm, or any value between 1mm and 3mm. For example, s can be 1mm, 1.5mm, 2mm, 2.5mm, or 3mm.

[0289] The design of 1mm≤s≤3mm 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 first groove 144 relatively close. The electrolyte located between the end face of the first active material part 1422 facing away from the second active material part 1423 and the outer shell 20 can flow into the first groove 144 more quickly, improving the wetting effect of the first electrode 14 and helping to improve the cycle performance of the battery cell 6.

[0290] In some embodiments, the second active material portion 1423 is located above the first active material portion 1422, and the distance between the first groove 144 and the bottom surface of the first active material portion 1422 is s, where 1mm≤s≤3mm. The setting of 1mm≤s≤3mm allows the bottom end of the first groove 144 to be immersed in the electrolyte, effectively improving the climbing performance of the electrolyte.

[0291] In some cases, the height of the first active material layer 142 is relatively large, making it more difficult for the electrolyte to flow to the top of the first active material layer 142. The wetting effect at the top of the first active material layer 142 is poor, which is not conducive to improving the fast charging performance and cycle performance of the battery cell 6.

[0292] In some embodiments, there are multiple first grooves 144, which extend along a first direction and are spaced apart along a second direction. The first direction is perpendicular to the second direction, and the second direction is perpendicular to the thickness direction of the first current collector 141.

[0293] The first groove 144 extends along the first direction. It can be understood that the first groove 144 extends in a straight line or in a curved manner along the first direction, or extends at an angle relative to the first direction.

[0294] Multiple first grooves 144 are arranged at intervals along the second direction. It can be understood that the multiple first grooves 144 are distributed at equal intervals or at non-equal intervals along the second direction.

[0295] By adopting the technical solution of this embodiment, the first groove 144 extends along the first direction, which is beneficial to improving the climbing ability of the electrolyte along the first direction, improving the wetting effect of the upper part of the first active material layer 142, and improving the fast charging performance and cycle performance of the battery cell 6. In addition, the multiple first grooves 144 are distributed at intervals, so that the electrolyte has multiple flow channels and storage channels in the second direction, which can better improve the climbing ability of the electrolyte, and is beneficial to improving the fast charging performance and cycle performance of the battery cell 6.

[0296] In some cases, the time it takes for the electrolyte to climb from the bottom to the top of the first electrode 14 is directly proportional to the height of the first active material layer 142. The higher the height, the more difficult it is for the electrolyte to climb. In particular, when the height of the first active material layer 142 is large, the time it takes for the electrolyte to climb from the bottom to the top of the first electrode 14 is significantly reduced compared to the shorter first active material layer 142. The first electrode 14 has a first groove 144 extending along the first direction, which can effectively improve the electrolyte climbing rate of the high-density battery cell 6.

[0297] In some examples, the surface of the negative electrode 12 is provided with a first groove 144, which can increase the liquid creep rate by 40%.

[0298] In some examples, the surface of the separator 13 is provided with grooves 16, which can increase the creep rate by 15%.

[0299] In some examples, the surface of the negative electrode 12 is provided with a first groove 144, and the surface of the separator 13 is provided with a groove 16. The two work together to shorten the liquid retention and return distance during the cycle, increase the return speed, and significantly improve the cycle performance of the high-performance battery cell 6.

[0300] In some embodiments, the distance between two adjacent first grooves 144 ranges from 1 mm to 10 mm.

[0301] The distance between two adjacent first grooves 144 can refer to the distance between the first openings of two adjacent first grooves 144. For example, the distance between two adjacent first grooves 144 can refer to the distance between the first openings of two adjacent first grooves 144 in the second direction.

[0302] The distance between two adjacent first grooves 144 is L1, where 1mm≤L1≤10mm.

[0303] In some examples, L1 can be 1mm, 10mm, or any value between 1mm and 10mm. For example, L1 can be 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, or 10mm.

[0304] By adopting the technical solution of this embodiment, the distance between two adjacent first grooves 144 is reasonably designed, which facilitates processing and can also effectively guide the flow of electrolyte in the battery cell 6, improve the wetting effect of the electrode assembly 10, and improve the fast charging performance and cycle performance of the battery cell 6. For example, the reasonable distribution density of the first grooves 144 makes the electrolyte have enough channels, so that it can quickly climb from the bottom to the top of the electrode assembly 10, effectively improving the electrolyte climbing ability.

[0305] Referring to Figure 12, in some embodiments, the first electrode 14 includes two first active material layers 142, which respectively cover two surfaces of the first current collector 141 along its thickness direction. The number of first grooves 144 is multiple, including first grooves 1441 and second grooves 1442 extending along a first direction. In the two first active material layers 142, one is provided with multiple first grooves 1441, and the other is provided with multiple second grooves 1442. Along the thickness direction of the first current collector 141, the first grooves 1441 and the second grooves 1442 are staggered.

[0306] Both first active material layers 142 are provided with first grooves 144, one of which is a first groove 1441 and the other is a second groove 1442.

[0307] The number of first grooves 1441 is multiple, and the number of second grooves 1442 is multiple, in order to improve the wetting effect of the first electrode 14.

[0308] In some examples, along the thickness direction of the first current collector 141, in adjacent first grooves 1441 and second grooves 1442, the projection of the first groove 1441 does not coincide with the projection of the second groove 1442.

[0309] By adopting the technical solution of this embodiment, the two first active material layers 142 are respectively provided with a plurality of first grooves 1441 and a plurality of second grooves 1442, so as to improve the wetting effect of the two first active material layers 142 and improve the cycle performance of the battery cell 6; in addition, the first grooves 1441 and the second grooves 1442 are staggered along the thickness direction of the first current collector 141, which is beneficial to improve the structural strength of the first electrode 14 and improve the reliability of the battery cell 6.

[0310] In some embodiments, a plurality of first grooves 1441 and a plurality of second grooves 1442 are alternately arranged along a second direction, the second direction being perpendicular to the first direction and the thickness direction of the first current collector 141.

[0311] In some examples, the electrode assembly 10 is a wound structure, and when the first electrode 14 is in a wound state, the second direction can be the winding direction of the electrode assembly 10.

[0312] In some examples, when the first electrode 14 is in the unfolded state, the second direction can be the length direction of the first electrode 14.

[0313] For example, a second slot 1442 may be provided between two adjacent first slots 1441.

[0314] By adopting the technical solution of this embodiment, multiple first grooves 1441 and multiple second grooves 1442 can be evenly distributed on two first active material layers 142, which can improve the uniformity of electrolyte distribution in the battery cell 6 and is beneficial to improving the cycle performance of the battery cell 6.

[0315] In some embodiments, along the second direction, the distance between adjacent first groove 1441 and second groove 1442 is C, wherein C ≥ 1.5 mm, optionally 1.8 mm ≤ C ≤ 5 mm, and optionally 2 mm ≤ C ≤ 3 mm.

[0316] In some examples, along the second direction, the distance C between adjacent first slots 1441 and second slots 1442 can refer to the distance between the center plane of the first slot 1441 perpendicular to the second direction and the center plane of the second slot 1442 perpendicular to the second direction.

[0317] 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, and 10mm.

[0318] By adopting the technical solution of this embodiment, the design with C≥1.5mm and the reasonable density setting of the first groove 1441 and the second groove 1442 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 capacity of the battery cell 6 can be taken into account.

[0319] In some embodiments, 1.8mm ≤ C ≤ 5mm.

[0320] With a design of 1.8mm≤C≤5mm, the distance between adjacent first grooves 1441 and second grooves 1442 is reasonably designed, and the first 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 capacity of the battery cell 6 can be taken into account.

[0321] In some embodiments, 2mm≤C≤3mm can better balance the cycle performance, reliability and capacity of the battery cell 6.

[0322] Please refer to Figures 13-16 together. In some embodiments, the first groove 144 includes a plurality of sub-segments 1443, which are spaced apart along a first direction.

[0323] The first groove 144 has a segmented structure, including multiple sub-segments 1443. The multiple sub-segments 1443 are arranged at intervals along the first direction. Adjacent sub-segments 1443 are not connected and there is a distance between them. The multiple sub-segments 1443 can be arranged at equal intervals or at non-equal intervals.

[0324] By adopting the technical solution of this embodiment, the first groove 144 includes multiple segments 1443, which can reduce the removal of active material by grooving the first active material layer 142, reduce the amount of active material loss of the first electrode 14, and help improve the capacity and performance of the battery cell 6. The first active material layer 142 has a large size along the first direction, and the multiple segments 1443 are arranged at intervals along the first direction, which can process the first active material layer 142 in multiple segments at intervals, which helps to reduce the processing difficulty and also reduces processing errors caused by long-distance processing.

[0325] In some examples, the first groove 144 is processed by laser etching. When the size of the first active material layer 142 along the first direction is large, a single laser beam is not enough to process the first groove 144 with a length greater than 200 mm. If the length of the first groove 144 is too long, there may be problems with defocusing and poor dimensions. Therefore, multi-segment processing or multi-beam laser grooving can improve this problem. In addition, if another laser beam starts processing at the end after one laser beam finishes processing, it may cause overlapping processing at the end, resulting in excessive loss of active material at that position, which may lead to risks such as lithium plating caused by excessive loss of active material. This segmented interval processing can reduce the risk of the above problems.

[0326] In some embodiments, the distance between two adjacent segments 1443 is d, where 0.5mm≤d≤2.5mm.

[0327] Segment 1443 forms an opening on the surface of the first active material layer 142 facing away from the first current collector 141. The distance between two adjacent segments 1443 can refer to the distance between the openings of two adjacent segments 1443. For example, the distance between two adjacent segments 1443 can refer to the distance between the openings of two adjacent segments 1443 in a first direction.

[0328] In some examples, d can be 0.5mm, 2.5mm, or any value between 0.5mm and 2.5mm. For example, d can be 0.5mm, 1mm, 1.5mm, 2mm, or 2.5mm.

[0329] By adopting the technical solution of this embodiment, the distance between two adjacent sub-segments 1443 is smaller, and the electrolyte in the lower sub-segment 1443 can easily enter the upper sub-segment 1443, which is beneficial to improving the electrolyte's crawling ability and also facilitates processing and manufacturing.

[0330] In some embodiments, the first groove 144 includes a plurality of segments 1443 extending along a first direction. The plurality of segments 1443 are arranged at intervals along a second direction. In two adjacent segments 1443, the upper end of one segment 1443 and the lower end of the other segment 1443 are projected along the second direction. The second direction is perpendicular to the first direction and the thickness direction of the first current collector 141.

[0331] The first groove 144 includes multiple segments 1443. The segments 1443 extend along a first direction. Adjacent segments 1443 are spaced apart and staggered vertically along a second direction. In the two adjacent segments 1443 distributed vertically, the bottom end of the upper segment 1443 is lower than the top end of the lower segment 1443, forming an interlaced structure.

[0332] By adopting the technical solution of this embodiment, in two adjacent sub-segments 1443, the upper end of one sub-segment 1443 and the lower end of the other sub-segment 1443 are projected along the second direction, so that liquid can be stored or electrolyte can flow at the close position of the two adjacent sub-segments 1443, and the first electrode 14 is more fully wetted; in addition, the close ends of the two adjacent sub-segments 1443 are spaced apart to reduce the risk of processing overlap and reduce the loss of active material.

[0333] In some embodiments, the first current collector 141 includes a first current collector body 1411 and a first electrode 1412. The first electrode 1412 is connected to the upper end of the first current collector body 1411. At least a portion of the first current collector body 1411 is covered with a first active material layer 142, while the first electrode 1412 is not covered with the first active material layer 142. The number of first grooves 144 is plurality of, and the plurality of first grooves 144 are arranged at intervals along a second direction. The first active material layer 142 includes connected first halves 1. 424 and the second half 1425, the first half 1424 is located on the upper side of the second half 1425, the sub-segment 1443 located in the first half 1424 is the first sub-segment 14431, the sub-segment 1443 located in the second half 1425 is the second sub-segment 14432, the depth of at least one first sub-segment 14431 is less than the depth of at least one second sub-segment 14432, and / or, the distance between two adjacent first sub-segments 14431 is less than the distance between two adjacent second sub-segments 14432.

[0334] Along the first direction, the first current collector 141 is divided into two parts. The part located on the lower side and covered with the first active material layer 142 is called the first current collector body 1411, and the part located on the upper side and not covered with the first active material layer 142 is called the first tab 1412. The interface between the first tab 1412 and the first current collector body 1411 is based on the upper end surface of the first active material layer 142. The first tab 1412 is used for electrical connection with the electrode terminal 30 to facilitate the input and output of electrical energy.

[0335] In some examples, the first current collector 1411 may be completely covered by the first active material layer 142 or partially covered by the first active material layer 142. For example, the side of the first current collector 1411 facing away from the first tab 1412 is not covered by the first active material layer 142.

[0336] Along the first direction, the first active material layer 142 is divided into two parts: the upper part is the first half 1424, and the lower part is the second half 1425.

[0337] In some examples, the first active material layer 142 is divided equally in a first direction to form a first half 1424 and a second half 1425, wherein the dimension a1 of the first half 1424 in the first direction is equal to the dimension a2 of the second half 1425 in the first direction.

[0338] The sub-segment 1443 located in the first half 1424 is the first sub-segment 14431, and the sub-segment 1443 located in the second half 1425 is the second sub-segment 14432. There can be one or more first sub-segments 14431, and there can be one or more second sub-segments 14432.

[0339] By adopting the technical solution of this embodiment, the first tab 1412 is located on the upper side, the current density of the first half 1424 is greater than the current density of the second half 1425, and the first half 1424 requires more active material to improve the charging window compared to the second half 1425. The design that at least one first segment 14431 has a depth less than the second segment 14432 helps reduce the amount of active material removed from the first half 1424, thereby allowing the first half 1424 to retain more active material to improve the charging window; while the adjacent two first... The distance between segments 14431 is smaller than the distance between two adjacent second segments 14432. The distribution of segments 1443 in the first half 1424 is denser than that in the second half 1425, providing more channels for electrolyte creep and improving the creep effect of the electrode assembly 10. The second half 1425 has a lower current density, and the second segments 14432 are deeper and more sparsely distributed, which can take into account the differences in charging needs in different areas caused by uneven current density, and help the battery cell 6 achieve better performance.

[0340] In some embodiments, the depth range of at least one first segment 14431 is 10 μm to 15 μm; and / or, the depth range of at least one second segment 14432 is 15 μm to 20 μm.

[0341] The depth of the first sub-segment 14431 is h1, where 10μm≤h1≤15μm.

[0342] In some examples, h1 can be 10μm, 15μm, or any value between 10μm and 15μm. For example, h1 can be 10μm, 11μm, 12μm, 13μm, 14μm, or 15μm.

[0343] The depth of the second sub-segment 14432 is h2, 15μm≤h2≤20μm.

[0344] In some examples, h2 can be 15μm, 20μm, or any value between 15μm and 20μm. For example, h2 can be 15μm, 16μm, 17μm, 18μm, 19μm, or 20μm.

[0345] By adopting the technical solution of this embodiment, the depth of at least one first segment 14431 is set within the above-mentioned range. The depth of the first segment 14431 is reasonable and convenient for processing and manufacturing. The first segment 14431 can also guide the electrolyte to rise well while taking into account the charging requirements. The depth of at least one second segment 14432 is set within the above-mentioned range. The depth of the second segment 14432 is reasonable and convenient for processing and manufacturing. The second segment 14432 can also guide the electrolyte to rise well while taking into account the performance of the battery cell 6.

[0346] In some embodiments, the distance between two adjacent first segments 14431 is in the range of 0.5mm to 2mm; and / or, the distance between two adjacent second segments 14432 is in the range of 2.5mm to 6mm.

[0347] The distance between two adjacent first sub-segments 14431 is w1, where 0.5mm≤w1≤2mm.

[0348] In some examples, w1 can be 0.5mm, 2mm, or any value between 0.5mm and 2mm. For example, w1 can be 0.5mm, 1mm, 1.5mm, or 2mm.

[0349] The distance between two adjacent second sub-segments 14432 is w2, where 2.5mm≤w2≤6mm.

[0350] In some examples, w2 can be 2.5mm, 6mm, or any value between 2.5mm and 6mm. For example, w2 can be 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, or 6mm.

[0351] By adopting the technical solution of this embodiment, the distance between two adjacent first segments 14431 is set within the above-mentioned range, the distance between two adjacent first segments 14431 is reasonable, the first half 1424 has more segments 1443, and more channels to guide the electrolyte to climb, while the first half 1424 can also retain more active material to improve the charging window; the distance between two adjacent second segments 14432 is set within the above-mentioned range, the distance between two adjacent second segments 14432 is reasonable, the second half 1425 has more segments 1443, and more channels to guide the electrolyte to climb.

[0352] In some embodiments, the second half 1425 includes a first half 14251 and a second half 14252 connected to each other. The first half 14251 is located on the upper side of the second half 14252. The ratio of the dimension of the second half 14252 along the first direction to the dimension of the first active material layer 142 along the first direction is 0.2. The depth of at least one second segment 14432 located in the second half 14252 is less than the depth of at least one second segment 14432 located in the first half 14251.

[0353] Along the first direction, the second half 1425 is divided into two parts: the upper part is the first half 14251, and the lower part is the second half 14252. The ratio of the dimension b1 of the second half 14252 along the first direction to the dimension L of the first active material layer 142 along the first direction is 0.2.

[0354] In some cases, during charging, the first active material layer 142 has a larger dimension L along the first direction. The first half 1424 is closer to the first tab 1412, resulting in a shorter current path, lower resistance, higher current density, and faster charging speed. The second half 1425 is farther from the tab, resulting in a longer current path, higher resistance, and lower current density. Consequently, the State of Charge (SOC) of the second half 1425 is significantly lower than that of the first half 1424 during the initial charging phase. When the first half 1424 is nearly fully charged (e.g., SOC ≥ 90%), the charging current preferentially flows to the still-uncharged second half 14252, especially the second half 14252, because it is closer to the bottom, has the longest current path, and experiences the lowest SOC during the initial charging phase. At this time, most of the end charging current will be concentrated in the second half 14252, which requires this part to absorb a large amount of charge quickly. Therefore, the depth of at least one second segment 14432 in the second half 14252 is less than the depth of at least one second segment 14432 in the first half 14251. The second half 14252 adopts a shallower second segment 14432, which can retain more active material and improve the charging capacity of the second half 14252. This allows the voltage of the second half 14252 to be stabilized within the preset charging window, thereby suppressing lithium plating and improving cycle life.

[0355] In some embodiments, the depth range of at least one second segment 14432 located in the second half 14252 is 5 μm to 15 μm.

[0356] The depth of at least one second segment 14432 located in the second half of the second sub-part 14252 is h3, 5μm≤h3≤15μm.

[0357] In some examples, h3 can be 5μm, 15μm, or any value between 5μm and 15μm. For example, h3 can be 5μm, 7μm, 9μm, 11μm, 13μm, or 15μm.

[0358] By adopting the technical solution of this embodiment, the depth of at least one second segment 14432 located in the second half 14252 is set within the above-mentioned range. The depth of at least one second segment 14432 located in the second half 14252 is reasonable and convenient for processing and manufacturing. At least one second segment 14432 of the second half 14252 can also meet the charging requirements.

[0359] Please refer to Figures 5, 17, and 18. In some embodiments, the electrode assembly 10 is a wound structure. The first electrode 14 is wound to form a plurality of first electrode winding coils 143. The first current collector 141 includes a first current collector winding coil 1431 located in the first electrode winding coil 143. The first active material layer 142 includes a first active winding coil 1432 located in the first electrode winding coil 143. The first surface 1421 includes a first winding surface 1433 located in the first electrode winding coil 143. In this embodiment, at least one first winding surface 1433 of the first electrode winding coil 143 is provided with a first groove 144.

[0360] In some examples, the first electrode 14, the second electrode 15, and the spacer 13 are stacked along the thickness direction of the first current collector 141, and then wound from one end of the first electrode 14 to the other end along the second direction to form a wound structure.

[0361] The electrode assembly 10 has a winding structure. The first electrode 14 is wound multiple times along the winding direction of the electrode assembly 10. The first electrode 14 has a first winding start end A1 and a first winding end A2. The first winding start end A1 can refer to the end of the first electrode 14 located on the inner side, and the first winding end A2 can refer to the end of the first electrode 14 located on the outer side.

[0362] The first current collector 141 is also wound multiple times along the winding direction of the electrode assembly 10. The starting end of the winding of the first current collector 141 can refer to the end of the first current collector 141 located on the inner side, and the ending end of the winding of the first current collector 141 can refer to the end of the first current collector 141 located on the outer side.

[0363] The first active material layer 142 is also wound multiple times along the winding direction of the electrode assembly 10. The starting end of the winding of the first active material layer 142 can refer to the end of the first active material layer 142 located on the inner side, and the ending end of the winding of the first active material layer 142 can refer to the end of the first active material layer 142 located on the outer side.

[0364] The surface of the first active material layer 142 facing away from the first current collector 141 is the first surface 1421, and the first surface 1421 is wound multiple times along the winding direction of the electrode assembly 10.

[0365] From the starting end of the first active material layer 142 to the ending end of the first active material layer 142, the first electrode 14 is wound into multiple first electrode winding loops 143. The innermost first electrode winding loop 143 is the first first electrode winding loop 143. From the first to the second to last first electrode winding loop 143, they are all full loop structures. The last first electrode winding loop 143 can be a full loop structure or a structure of less than one loop, such as 1 / 2 loop, 1 / 3 loop or 1 / 4 loop.

[0366] For example, a plane M is drawn through the end face of the first active material layer 142 at the starting end of the winding. The plane M extends from the end face of the first active material layer 142 at the starting end of the winding to the outer side of the electrode assembly 10. The plane M intersects with the first electrode 14 and divides the first electrode 14 into multiple first electrode winding loops 143 according to the intersection point of the plane M and the first electrode 14. The portion of the first electrode 14 located between two adjacent intersection points forms a complete loop structure of the first electrode winding loop 143. If the winding end of the first active material layer 142 intersects the plane M exactly, the penultimate first electrode winding loop 143 is also a complete loop structure. If the winding end of the first active material layer 142 does not intersect the plane M, the portion of the first electrode 14 located between the outermost intersection point and the winding end of the first active material layer 142 forms the penultimate first electrode winding loop 143, which is a structure of less than one loop.

[0367] The first electrode winding ring 143 is divided based on the winding start end and winding end end of the first active material layer 142, so that each first electrode winding ring 143 includes a first current collector winding ring 1431 and a first active winding ring 1432.

[0368] For example, in the opposite direction to the winding direction of the electrode assembly 10, the winding start end of the first current collector 141 extends beyond the winding start end of the first active material layer 142, and the portion of the first current collector 141 that extends beyond the first active material layer 142 does not belong to the first first electrode winding loop 143. In this case, the winding start end of the first current collector 141 can be the first winding start end A1.

[0369] For example, along the winding direction of the electrode assembly 10, the winding end of the first current collector 141 extends beyond the winding end of the first active material layer 142. The portion of the first current collector 141 that extends beyond the first active material layer 142 does not belong to the penultimate first electrode winding loop 143. In this case, the winding end of the first current collector 141 can be the first winding end A2.

[0370] For example, the starting end of the winding of the first current collector 141 is aligned with the starting end of the winding of the first active material layer 142, the ending end of the winding of the first current collector 141 is aligned with the ending end of the winding of the first active material layer 142, the starting end of the winding of the first current collector 141 and the starting end of the winding of the first active material layer 142 together form the first winding starting end A1, and the ending end of the winding of the first current collector 141 and the ending end of the winding of the first active material layer 142 together form the first winding ending end A2.

[0371] The portion of the first current collector 141 located on the first electrode winding 143 is the first current collector winding 1431, the portion of the first active material layer 142 located on the first electrode winding 143 is the first active winding 1432, and the portion of the first surface 1421 located on the first electrode winding 143 is the first winding surface 1433.

[0372] If the two surfaces of the first current collector 141 along its own thickness direction are covered with a first active material layer 142, each first electrode winding coil 143 includes a first current collector winding coil 1431 and two first active winding coils 1432, with the two first active winding coils 1432 located on the inner and outer sides of the first current collector 141, respectively.

[0373] If a first active material layer 142 is covered on one surface of the first current collector 141 along its own thickness direction, each first electrode winding 143 includes a first current collector winding 1431 and a first active winding 1432, with the first active winding 1432 located on one side of the first current collector winding 1431.

[0374] The first active winding 1432 is located between the first current collector winding 1431 and the separator 13, so that ions can pass through the separator 13 and be inserted or extracted from the first active winding 1432, thereby realizing the charging and discharging of the battery cell 6.

[0375] The first active winding 1432 has a first winding surface 1433 facing away from the corresponding first current collector winding 1431. Here, "the corresponding first current collector winding 1431" refers to the first current collector winding 1431 located in the same first electrode winding 143 as the first active winding 1432. The surface of the first active winding 1432 facing away from the first current collector winding 1431 connected to it is the first winding surface 1433. The separator 13 is located between the second electrode 15 and the first winding surface 1433. During the expansion of the electrode assembly 10, the distance between the second electrode 15 and the first winding surface 1433 decreases, thereby squeezing out the electrolyte between the second electrode 15 and the first winding surface 1433.

[0376] At least one first electrode winding coil 143 has at least one first groove 144 on its first winding surface 1433. For example, the number of first electrode winding coils 143 with the first groove 144 may be one or more. The first winding surface 1433 may have one or more first grooves 144. The cross-sectional shape of the first groove 144 may be rectangular, trapezoidal, arc-shaped, or V-shaped, etc. The first groove 144 may be processed on the surface of the first active winding coil 1432 using methods such as laser processing or mechanical cutting.

[0377] For example, one or more first electrode windings 143 near the inner side of the electrode assembly 10 do not have the first groove 144; or, one or more first electrode windings 143 near the outer side of the electrode assembly 10 do not have the first groove 144; or, one or more first electrode windings 143 located in the middle of the electrode assembly 10 do not have the first groove 144.

[0378] For example, all the first electrode windings 143 are provided with a first groove 144.

[0379] By adopting the technical solution of this embodiment, the electrode assembly 10 is wound and the gap between the first electrode 14 and the second electrode 15 is small. The returned electrolyte is not easy to enter between the first electrode 14 and the second electrode 15, which is not conducive to improving the cycle performance of the battery cell 6. On the other hand, the first winding surface 1433 of at least one first electrode winding ring 143 is provided with at least one first groove 144. On the one hand, the electrolyte can flow into the first groove 144 for storage. The stored electrolyte can wet the first electrode 14 and provide a transport path for ions, reducing the ion transport resistance and improving the cycle performance of the battery cell 6. On the other hand, the first groove 144 can also provide a channel for the return of electrolyte, reducing the difficulty of electrolyte return, reducing the ion transport resistance, improving the wetting effect of the first electrode 14, and also helping to improve the cycle performance of the battery cell 6.

[0380] In some embodiments, there are multiple first grooves 144, the first grooves 144 extend along a first direction, and the multiple first grooves 144 are spaced apart along a second direction, the second direction being the winding direction of the electrode assembly 10.

[0381] By adopting the technical solution of this embodiment, the first groove 144 extends along the first direction, which is conducive to the electrolyte climbing upward along the first groove 144 and improving the electrolyte climbing ability; in addition, multiple first grooves 144 are spaced apart along the winding direction of the electrode assembly 10, so that the electrolyte can be distributed along the winding direction of the electrode assembly 10, which can effectively improve the climbing ability of the electrode assembly 10.

[0382] In some embodiments, the electrode assembly 10 includes a flat region E1 and two bending regions E2, the two bending regions E2 being located at both ends of the flat region E1; the first active winding 1432 includes a first active bending portion 1434 located in the bending region E2 and a first active flat portion 1435 located in the flat region E1; at least one first active flat portion 1435 of the first active winding 1432 is provided with a first groove 144; and / or, at least one first active bending portion 1434 of the first active winding 1432 is provided with a first groove 144.

[0383] The flat region E1 is the area of ​​the electrode assembly 10 with a flat structure. The portions of the first electrode 14 and the second electrode 15 located within the flat region E1 are both arranged in a basically flat manner. The portion of the first electrode winding 143 located within the flat region E1 is also arranged in a basically flat manner.

[0384] The bending region E2 is the area of ​​the electrode assembly 10 with a bent structure. The portion of the first electrode 14 located in the bending region E2 and the portion of the second electrode 15 located in the bending region E2 are both bent. The portion of the first electrode winding 143 located in the bending region E2 is also bent.

[0385] In some examples, the portion of the first electrode 14 located in the bending region E2 and the portion of the second electrode 15 located in the bending region E2 are both arc-shaped, and the portion of the first electrode winding 143 located in the bending region E2 is also arc-shaped.

[0386] The portion of the first active winding 1432 located in the bending region E2 is the first active bending portion 1434, and the portion of the first active winding 1432 located in the straight region E1 is the first active straight portion 1435.

[0387] In some examples, the first active flat portion 1435 of a first active winding 1432 is provided with a first groove 144, or the first active flat portions 1435 of a plurality of first active windings 1432 are provided with first grooves 144.

[0388] For example, the first active straight portion 1435 of all the first active windings 1432 is provided with a first groove 144.

[0389] In some examples, the first active bend 1434 of a first active winding 1432 is provided with a first groove 144, or the first active bend 1434 of a plurality of first active windings 1432 is provided with a first groove 144.

[0390] For example, all the first active bends 1434 of the first active windings 1432 are provided with first grooves 144.

[0391] By adopting the technical solution of this embodiment, the first active straight portion 1435 of at least one first active winding 1432 is provided with a first groove 144, which is beneficial to improve the wetting effect of the straight area E1 and improve the cycle performance of the battery cell 6; the first active bending portion 1434 of at least one first active winding 1432 is provided with a first groove 144, which is beneficial to improve the wetting effect of the bending area E2 and improve the cycle performance of the battery cell 6.

[0392] In some embodiments, the first active straight portion 1435 of all the first active windings 1432 is provided with a first groove 144, and the first active bent portion 1434 of all the first active windings 1432 is not provided with a first groove 144.

[0393] By adopting the technical solution of this embodiment, the bending of the first active bending portion 1434 in the bending region E2 increases the risk of powder shedding from the first active bending portion 1434. However, the first active bending portions 1434 of all the first active windings 1432 are not provided with the first groove 144, which is beneficial to improving the structural strength of the first active bending portion 1434, reducing the risk of powder shedding in the bending region E2, and improving the capacity and reliability of the battery cell 6. Compared with the bending region E2, the gap between the first electrode 14 and the second electrode 15 in the flat region E1 is small, making electrolyte reflux difficult. However, by providing the first groove 144 for all the first active flat portions 1435, the first groove 144 can be used to store electrolyte or provide a reflux channel for electrolyte, which is beneficial to improving the wetting effect of the flat region E1, thereby effectively improving the cycle performance of the battery cell 6.

[0394] 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 a first groove 144 at the end face corresponding to the end face of the first winding end A2; and / or, the last two first electrode winding coils 143 are not provided with a first groove 144 at the end face corresponding to the end face of the second winding end B2.

[0395] The second electrode 15 has a second winding end B2 and a second winding start end B1. Along the winding direction of the electrode assembly 10, of the two oppositely distributed ends of the second electrode 15, the end located inside the electrode assembly 10 is the second winding start end B1, and the end located outside the electrode assembly 10 is the second winding end B2. Along the winding direction of the electrode assembly 10, of the two oppositely distributed end faces of the second electrode 15, the end face located inside the electrode assembly 10 is the end face of the second winding start end B1, and the end face located outside the electrode assembly 10 is the end face of the second winding end B2.

[0396] In some examples, along the winding direction of the electrode assembly 10, after the second electrode 15 is wound, the first electrode 14 continues to be wound forward for a distance and for less than one turn, so that the last two first electrode winding turns 143 can completely cover the second winding end B2, and the second winding end B2 is located between the last two first electrode winding turns 143.

[0397] The first groove 144 is not provided at the position corresponding to the end face of the second to last first electrode winding coil 143 and the end face of the first winding end A2. It can be understood that the first groove 144 is not provided at the position corresponding to the end face of the first winding end A2 and the second to last first electrode winding coil 143.

[0398] The first groove 144 is not provided at the position corresponding to the end face of the second to last first electrode winding coil 143 and the end face of the second winding end B2. It can be understood that the first groove 144 is not provided at the position corresponding to the end face of the second to last first electrode winding coil 143 and the end face of the second winding end B2 is not provided at the position corresponding to the end face of the first to last first electrode winding coil 143.

[0399] During the expansion of the electrode assembly 10, the second-to-last first electrode winding coil 143 presses against the last first electrode winding coil 143. During this process, the edge of the end face of the first winding termination end A2 presses against the second-to-last first electrode winding coil 143, and the end face of the second winding termination end B2 is sandwiched between the two last first electrode winding coils 143. The edge of the end face of the second winding termination end B2 presses against both the last first electrode winding coil 143 and the second-to-last first electrode winding coil 143. If a first groove 144 is provided at the position corresponding to the end face of the first winding termination end A2, the first... The end face of the winding termination end A2 is opposite to and presses against the first groove 144. The structural strength of the first groove 144 is poor, and the end face of the first winding termination end A2 is at risk of cutting off the last two first electrode winding coils 143. Similarly, if the last two first electrode winding coils 143 are provided with the first groove 144 at the position corresponding to the end face of the second winding termination end B2, and the end face of the second winding termination end B2 is opposite to and presses against the first groove 144, the structural strength of the first groove 144 is poor, and the end face of the second winding termination end B2 is at risk of cutting off the last two first electrode winding coils 143.

[0400] In some examples, 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 a first groove 144 at the end face corresponding to the first winding end A2.

[0401] For example, the second to last first electrode winding loop 143 does not have a first groove 144 at the position corresponding to the end face of the first winding end A2.

[0402] During the expansion of the electrode assembly 10, the positions corresponding to the end faces of the last two first electrode winding coils 143 and the first winding end A2 are not provided with the first groove 144. The structural strength at the positions corresponding to the end faces of the last two first electrode winding coils 143 and the first winding end A2 is good, which reduces the risk of the last two first electrode winding coils 143 being sheared by the end face of the first winding end A2 and improves the reliability of the battery cell 6.

[0403] In some examples, 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 position corresponding to the end face of the last two first electrode winding coils 143 and the second winding end B2 is not provided with a first groove 144.

[0404] For example, the first groove 144 is not provided at the position corresponding to the end face of the first electrode winding 143 to the second winding end B2; the first groove 144 is not provided at the position corresponding to the end face of the second electrode winding 143 to the second winding end B2.

[0405] During the expansion of the electrode assembly 10, the first groove 144 is not provided at the position corresponding to the end face of the second winding end B2 of the last two first electrode windings 143. The structural strength at the position corresponding to the end face of the second winding end B2 of the last two first electrode windings 143 is good, which reduces the risk of the last two first electrode windings 143 being sheared by the end face of the second winding end B2 and improves the reliability of the battery cell 6.

[0406] In some examples, 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 do not have a first groove 144 at the end face corresponding to the end face of the first winding end A2; the last two first electrode winding coils 143 do not have a first groove 144 at the end face corresponding to the end face of the second winding end B2.

[0407] For example, the first groove 144 is not provided at the position corresponding to the end face of the first electrode winding 143 to the second winding end B2; the first groove 144 is not provided at the position corresponding to the end face of the second electrode winding 143 to the second winding end B2; and the first groove 144 is not provided at the position corresponding to the end face of the second electrode winding 143 to the first winding end A2.

[0408] During the expansion of the electrode assembly 10, the positions corresponding to the end faces of the second to last first electrode winding coils 143 and the end faces of the first winding end A2 and the second winding end B2 are not provided with the first groove 144. The structural strength at the positions corresponding to the end faces of the second to last first electrode winding coils 143 and the end faces of the first winding end A2 and the second winding end B2 is good, which reduces the risk of the second to last first electrode winding coils 143 being sheared by the end faces of the first winding end A2 and the second winding end B2, and improves the reliability of the battery cell 6.

[0409] In some embodiments, the second to last first electrode winding coil 143 is provided with a first groove 144, and the first groove 144 is offset from at least one of the end face of the first winding end A2 and the end face of the second winding end B2.

[0410] The last two first electrode windings 143 are provided with a first groove 144. It can be understood that at least one of the last first electrode winding 143 or the last second first electrode winding 143 is provided with the first groove 144. The first groove 144 in the last two first electrode windings 143 can improve the wetting effect of the last two first electrode windings 143 and improve the cycle performance of the battery cell 6.

[0411] In some examples, the last two first electrode windings 143 are provided with a first groove 144, which is offset from the end face of the first winding end A2.

[0412] For example, the second-to-last first electrode winding 143 is provided with a first groove 144, which is offset from the end face of the first winding termination A2. The penultimate first electrode winding 143 may or may not have a first groove 144.

[0413] The first groove 144 of the last two first electrode windings 143 is not opposite to the end face of the first winding end A2, which reduces the risk that the last two first electrode windings 143 will be cut by the end face of the first winding end A2 and improves the reliability of the battery cell 6.

[0414] In some examples, the last two first electrode windings 143 are provided with a first groove 144, which is offset from the end face of the second winding end B2.

[0415] For example, the penultimate first electrode winding 143 is provided with a first groove 144, while the penultimate first electrode winding 143 is not provided with a first groove 144. The first groove 144 of the penultimate first electrode winding 143 is offset from the end face of the second winding end B2.

[0416] For example, the second to last first electrode winding 143 is provided with a first groove 144, the first to last first electrode winding 143 is not provided with a first groove 144, and the first groove 144 of the second to last first electrode winding 143 is offset from the end face of the second winding end B2.

[0417] For example, the penultimate first electrode winding coil 143 and the penultimate first electrode winding coil 143 are provided with a first groove 144, and the first groove 144 of the penultimate first electrode winding coil 143 and the first groove 144 of the penultimate first electrode winding coil 143 are both offset from the end face of the second winding end B2.

[0418] The first groove 144 of the last two first electrode windings 143 is not opposite to the end face of the second winding end B2, which reduces the risk that the last two first electrode windings 143 will be cut by the end face of the second winding end B2 and improves the reliability of the battery cell 6.

[0419] In some examples, the last two first electrode windings 143 are provided with a first groove 144, which is offset from the end face of the first winding end A2 and the end face of the second winding end B2.

[0420] For example, the penultimate first electrode winding 143 is provided with a first groove 144, while the penultimate first electrode winding 143 is not provided with a first groove 144. The first groove 144 of the penultimate first electrode winding 143 is offset from the end face of the second winding end B2.

[0421] For example, the second to last first electrode winding 143 is provided with a first groove 144, while the first to last first electrode winding 143 is not provided with a first groove 144. The first groove 144 of the second to last first electrode winding 143 is offset from the end face of the first winding end A2 and the end face of the second winding end B2.

[0422] For example, the penultimate first electrode winding coil 143 and the penultimate first electrode winding coil 143 are provided with a first groove 144. The first groove 144 of the penultimate first electrode winding coil 143 and the first groove 144 of the penultimate first electrode winding coil 143 are both offset from the end face of the second winding end B2, and the first groove 144 of the penultimate first electrode winding coil 143 is offset from the end face of the first winding end A2.

[0423] The first groove 144 of the last two first electrode windings 143 is not opposite to the end face of the second winding end B2, and the first groove 144 of the last two first electrode windings 143 is not opposite to the end face of the first winding end A2. This reduces the risk that the last two first electrode windings 143 will be cut by the end face of the first winding end A2 and the end face of the second winding end B2, and improves the reliability of the battery cell 6.

[0424] In some embodiments, the last two first electrode windings 143 are not provided with the first groove 144.

[0425] The penultimate first electrode winding coil 143 and the penultimate first electrode winding coil 143 do not have a first groove 144.

[0426] By adopting the technical solution of this embodiment, the last two first electrode winding coils 143 are not provided with the first groove 144. On the one hand, the structural strength of the last two first electrode winding coils 143 is improved. On the other hand, the risk of the last two first electrode winding coils 143 being cut by the end face of the first winding end A2 and the end face of the second winding end B2 is reduced, thereby improving the reliability of the battery cell 6.

[0427] In some embodiments, the first electrode 14 has a first winding start end A1, the second electrode 15 has a second winding start end B1, the innermost first electrode winding coil 143 is the first first electrode winding coil 143, and the second winding start end B1 is located between the first two first electrode winding coils 143; the first two first electrode winding coils 143 are not provided with a first groove 144 at the end face corresponding to the end face of the first winding start end A1; and / or, the first two first electrode winding coils 143 are not provided with a first groove 144 at the end face corresponding to the end face of the second winding start end B1.

[0428] In some examples, along the winding direction of the electrode assembly 10, the second electrode 15 begins to be wound only after the first electrode 14 has been wound for a certain distance, and the first electrode 14 is wound less than one turn before the second electrode 15 is wound, so that the first two first electrode 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 electrode winding turns 143.

[0429] The first two first electrode winding coils 143 do not have a first groove 144 at the position corresponding to the end face of the first winding start end A1. It can be understood that the end face of the first winding start end A1 does not have a first groove 144 at the position corresponding to the second first electrode winding coil 143.

[0430] The first two first electrode winding coils 143 do not have a first groove 144 at the position corresponding to the end face of the second winding start end B1. It can be understood that the end face of the second winding start end B1 does not have a first groove 144 at the position opposite to the second first electrode winding coil 143, and the end face of the second winding start end B1 does not have a first groove 144 at the position opposite to the first first electrode winding coil 143.

[0431] During the expansion of the electrode assembly 10, the first first electrode winding 143 compresses the second first electrode winding 143, and the edge of the end face of the first winding starting end A1 compresses the second first electrode winding 143. The end face of the second winding starting end B1 is sandwiched between the first two first electrode windings 143, and the edge of the end face of the second winding starting end B1 compresses the first and second first electrode windings 143. If the first two first electrode windings 143 are provided with a first groove 144 corresponding to the end face of the first winding starting end A1, the first winding starting end A1... The end face of the first winding start end A1 is opposite to and presses against the first groove 144. The structural strength of the first groove 144 is poor, and the end face of the first winding start end A1 is at risk of cutting off the first two first electrode winding coils 143. Similarly, if the first two first electrode winding coils 143 are provided with the first groove 144 at the position corresponding to the end face of the second winding start end B1, the end face of the second winding start end B1 is opposite to and presses against the first groove 144. The structural strength of the first groove 144 is poor, and the end face of the second winding start end B1 is at risk of cutting off the first two first electrode winding coils 143.

[0432] In some examples, the first electrode 14 has a first winding start end A1, the second electrode 15 has a second winding start end B1, the innermost first electrode winding coil 143 is the first first electrode winding coil 143, and the second winding start end B1 is located between the first two first electrode winding coils 143; the first groove 144 is not provided at the position corresponding to the end face of the first two first electrode winding coils 143 and the first winding start end A1.

[0433] For example, the second first electrode winding 143 does not have a first groove 144 at the position corresponding to the end face of the first winding start end A1.

[0434] During the expansion of the electrode assembly 10, the first groove 144 is not provided at the position corresponding to the end face of the first winding start end A1 of the first two first electrode winding coils 143. The structural strength at the position corresponding to the end face of the first winding start end A1 of the first two first electrode winding coils 143 is good, which reduces the risk that the first two first electrode winding coils 143 will be sheared by the end face of the first winding start end A1 and improves the reliability of the battery cell 6.

[0435] In some examples, the first electrode 14 has a first winding start end A1, the second electrode 15 has a second winding start end B1, the innermost first electrode winding coil 143 is the first first electrode winding coil 143, and the second winding start end B1 is located between the first two first electrode winding coils 143; the first groove 144 is not provided at the position corresponding to the end face of the first two first electrode winding coils 143 and the second winding start end B1.

[0436] For example, the first groove 144 is not provided at the position corresponding to the end face of the first first electrode winding 143 and the end face of the second winding starting end B1; the first groove 144 is not provided at the position corresponding to the end face of the second first electrode winding 143 and the end face of the second winding starting end B1.

[0437] During the expansion of the electrode assembly 10, the first groove 144 is not provided at the position corresponding to the end face of the first two first electrode windings 143 and the end face of the second winding start end B1. The structural strength at the position corresponding to the end face of the first two first electrode windings 143 and the end face of the second winding start end B1 is good, which reduces the risk that the first two first electrode windings 143 will be sheared by the end face of the second winding start end B1 and improves the reliability of the battery cell 6.

[0438] In some examples, the first electrode 14 has a first winding start end A1, the second electrode 15 has a second winding start end B1, the innermost first electrode winding coil 143 is the first first electrode winding coil 143, and the second winding start end B1 is located between the first two first electrode winding coils 143; the first two first electrode winding coils 143 do not have a first groove 144 at the end face corresponding to the end face of the first winding start end A1; the first two first electrode winding coils 143 do not have a first groove 144 at the end face corresponding to the end face of the second winding start end B1.

[0439] For example, the first electrode winding 143 does not have a first groove 144 at the position corresponding to the end face of the second winding start end B1; the second electrode winding 143 does not have a first groove 144 at the position corresponding to the end face of the second winding start end B1, and the second electrode winding 143 does not have a first groove 144 at the position corresponding to the end face of the first winding start end A1.

[0440] During the expansion of the electrode assembly 10, the first groove 144 is not provided at the position corresponding to the end face of the first winding start end A1 and the end face of the second winding start end B1 of the first two first electrode winding coils 143. The structural strength at the position corresponding to the end face of the first winding start end A1 and the end face of the second winding start end B1 of the first two first electrode winding coils 143 is good, which reduces the risk that the first two first electrode winding coils 143 will be sheared by the end face of the first winding start end A1 and the end face of the second winding start end B1, and improves the reliability of the battery cell 6.

[0441] In some embodiments, the first two first electrode winding coils 143 are provided with a first groove 144, which is offset from 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.

[0442] The first two first electrode windings 143 are provided with first grooves 144. It can be understood that at least one of the first first electrode windings 143 or the second first electrode winding 143 is provided with the first groove 144. The first groove 144 provided in the first two first electrode windings 143 can improve the wetting effect of the first two first electrode windings 143 and improve the cycle performance of the battery cell 6.

[0443] In some examples, the first two first electrode windings 143 are provided with first grooves 144, which are offset from the end face of the first winding start end A1.

[0444] For example, the second first electrode winding 143 is provided with a first groove 144, which is offset from the end face of the first winding starting end A1. The first first electrode winding 143 may or may not be provided with the first groove 144.

[0445] The first grooves 144 of the first two first electrode windings 143 are not opposite to the end face of the first winding start end A1, which reduces the risk that the first two first electrode windings 143 will be cut by the end face of the first winding start end A1 and improves the reliability of the battery cell 6.

[0446] In some examples, the first two first electrode windings 143 are provided with first grooves 144, which are offset from the end face of the second winding start end B1.

[0447] For example, the first first electrode winding 143 is provided with a first groove 144, and the second first electrode winding 143 is not provided with a first groove 144. The first groove 144 of the first first electrode winding 143 is offset from the end face of the second winding start end B1.

[0448] For example, the second first electrode winding 143 is provided with a first groove 144, the first first electrode winding 143 is not provided with a first groove 144, and the first groove 144 of the second first electrode winding 143 is offset from the end face of the second winding starting end B1.

[0449] For example, the first first electrode winding coil 143 and the second first electrode winding coil 143 are provided with a first groove 144, and the first groove 144 of the first first electrode winding coil 143 and the first groove 144 of the second first electrode winding coil 143 are both offset from the end face of the second winding starting end B1.

[0450] The first groove 144 of the first two first electrode windings 143 is not opposite to the end face of the second winding start end B1, which reduces the risk that the first two first electrode windings 143 will be cut by the end face of the second winding start end B1 and improves the reliability of the battery cell 6.

[0451] In some examples, the first two first electrode winding coils 143 are provided with first grooves 144, which are offset from the end face of the first winding start end A1 and the end face of the second winding start end B1.

[0452] For example, the first first electrode winding 143 is provided with a first groove 144, and the second first electrode winding 143 is not provided with a first groove 144. The first groove 144 of the first first electrode winding 143 is offset from the end face of the second winding start end B1.

[0453] For example, the second first electrode winding 143 is provided with a first groove 144, the first first electrode winding 143 is not provided with a first groove 144, and the first groove 144 of the second first electrode winding 143 is offset from the end face of the first winding start end A1 and the end face of the second winding start end B1.

[0454] For example, the first first electrode winding coil 143 and the second first electrode winding coil 143 are provided with a first groove 144. The first groove 144 of the first first electrode winding coil 143 and the first groove 144 of the second first electrode winding coil 143 are both offset from the end face of the second winding starting end B1, and the first groove 144 of the second first electrode winding coil 143 is offset from the end face of the first winding starting end A1.

[0455] The first grooves 144 of the first two first electrode windings 143 are not opposite to the end face of the second winding start end B1, and the first grooves 144 of the first two first electrode windings 143 are not opposite to the end face of the first winding start end A1. This reduces the risk that the first two first electrode windings 143 will be cut by the end face of the first winding start end A1 and the end face of the second winding start end B1, and improves the reliability of the battery cell 6.

[0456] In some embodiments, the first two first electrode windings 143 are not provided with the first groove 144.

[0457] The first electrode winding 143 and the second electrode winding 143 do not have a first groove 144.

[0458] By adopting the technical solution of this embodiment, the first two first electrode winding coils 143 are not provided with the first groove 144. On the one hand, the structural strength of the first two first electrode winding coils 143 is improved. On the other hand, the risk of the first two first electrode winding coils 143 being sheared by the end face of the first winding start end A1 and the end face of the second winding start end B1 is reduced, thereby improving the reliability of the battery cell 6.

[0459] In some embodiments, the electrode assembly 10 has a stacked structure.

[0460] By adopting the technical solution of this embodiment, the first electrode 14 is provided with a first groove 144, which can serve as a storage channel and flow channel for electrolyte, which is beneficial to improving the wetting effect of the first electrode 14 and improving the fast charging capability and cycle performance of the large-size stacked battery cell 6.

[0461] In some embodiments, the first groove 144 extends along a first direction.

[0462] By adopting the technical solution of this embodiment, the first groove 144 extends along the first direction, which is beneficial to improve the climbing ability of the electrolyte, improve the wetting effect of the top of the electrode assembly 10, and effectively improve the fast charging capability and cycle performance of the large-size stacked battery cell 6.

[0463] In some embodiments, the first current collector 141 includes a first current collector body 1411 and a first tab 1412 arranged and connected along a first direction, wherein at least a portion 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; or, the first current collector 141 includes a first current collector body 1411 and a first tab 1412 arranged and connected along a second direction, wherein at least a portion 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, wherein the second direction is perpendicular to the first direction and the thickness direction of the first current collector 141.

[0464] The first tab 1412 can be disposed on one side of the first electrode 14 along the first direction, or on one side of the first electrode 14 along the second direction. That is, the first electrode 14 is provided with a first groove 144, which can be flexibly applied to battery cells 6 with different stacked structures.

[0465] Referring to Figure 5, in some embodiments, the ratio of the groove depth of the first groove 144 to the thickness of the first active material layer 142 ranges from 0.15 to 0.7.

[0466] The groove depth of the first groove 144 can refer to the distance between the bottom surface of the first groove 144 and the first opening.

[0467] The thickness of the first active material layer 142 can refer to the distance between two surfaces of the first active material layer 142 that are relatively distributed along its own thickness direction.

[0468] The groove depth of the first groove 144 is h, and the thickness of the first active material layer 142 is H, where 0.15≤h / H≤0.7.

[0469] In some examples, the value of h / H can be 0.15, 0.7, or any value between 0.15 and 0.7. For example, the value of h / H can be, but is not limited to, 0.15, 0.2, 0.3, 0.4, 0.5, and 0.7.

[0470] With a design of 0.15≤h / H≤0.7, the groove depth h of the first groove 144 is reasonable relative to the thickness H of the first active material layer 142, and the distance between the bottom surface of the first groove 144 and the first current collector 141 is also reasonable. This allows the electrolyte in the first groove 144 to flow quickly to the first current collector 141, improving the wetting effect of the first electrode 14 and enhancing the fast charging performance and cycle performance of the battery cell 6.

[0471] In some embodiments, the groove depth of the first groove 144 is h, where 10μm≤h≤40μm.

[0472] In some examples, the value of h can be 10 μm, 40 μm, or any value between 10 and 40 μm. For example, the value of h can be, but is not limited to, 10 μm, 20 μm, 30 μm, or 40 μm.

[0473] With a design of 10μm≤h≤40μm, the groove depth h of the first groove 144 is reasonable, enabling the first groove 144 to store electrolyte and guide electrolyte flow, improving the wetting effect of the first electrode 14 and enhancing the cycle performance of the battery cell 6. Furthermore, reducing the amount of active material removed by the grooves in the first active material layer 142 helps increase the active material capacity of the first electrode 14 and reduces the risk of performance degradation in the battery cell 6 due to insufficient active material capacity. Therefore, both the cycle performance and overall performance of the battery cell 6 can be balanced.

[0474] In some embodiments, the groove width of the first groove 144 is w, where 70μm≤w≤170μm.

[0475] The width of the first groove 144 is the same as the width of the first opening.

[0476] In some examples, the value of w can be 70 μm, 170 μm, or any value between 70 μm and 170 μm. For example, the value of w can be, but is not limited to, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, and 170 μm.

[0477] The design of 70μm≤w≤170μm enables the first groove 144 to have a capillary effect, which effectively improves the flow of electrolyte, improves the wetting of electrode assembly 10, and improves the fast charging performance and cycle performance of battery cell 6. It also makes the active material removed by the groove of the first active material layer 142 reasonable, reducing the risk of the battery cell 6's performance deteriorating due to insufficient active material capacity of the first electrode 14.

[0478] In some embodiments, the cross-section of the first groove 144 is V-shaped, the bottom surface of the first groove 144 is smaller than the size of the first opening of the first groove 144, the bottom surface of the first groove 144 is approximately a straight line, and the side surface of the first groove 144 is inclined, which can provide more embedding positions for ions and reduce the risk of lithium plating; and the V-shaped groove makes the surface area of ​​the first active material layer 142 larger, making it easier for ions to embed into the first electrode 14, which is beneficial to improving the fast charging performance of the battery cell 6.

[0479] In some embodiments, along the first direction, the size of the first 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.

[0480] Along the first direction, the size of the first groove 144 can refer to the distance between the two side lines of the first opening that are relatively distributed along the first direction.

[0481] 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.

[0482] The design of 0.8≤l / L≤1 ensures that the size l of the first groove 144 and the size L of the first active material layer 142 are not much different or the same along the first direction. The height of the first groove 144 is high, which is beneficial to improving the electrolyte creeping ability. In addition, the two ends of the first groove 144 along the first direction are relatively close to the two ends of the first active material layer 142, which allows the electrolyte squeezed out from the two ends of the electrode assembly 10 to flow back quickly along the first direction, which can effectively improve the wetting effect of the first electrode 14 and improve the cycle performance of the battery cell 6.

[0483] In some embodiments, 0.9 ≤ l / L ≤ 0.98 can better improve the cycle performance of the battery cell 6.

[0484] In some embodiments, the first electrode 14 is the negative electrode 12, and the second electrode 15 is the positive electrode 11.

[0485] The negative electrode 12 is provided with a first groove 144, which allows the negative electrode 12 to be better wetted and improves the performance of the battery cell 6. In addition, the active material of the negative electrode 12 has a redundancy. After the groove is cut to remove part of the active material, the impact on the capacity of the battery cell 6 is small, which is conducive to balancing the capacity and cycle performance of the battery cell 6.

[0486] In some embodiments, along the first direction, the size of the first active material layer 142 is L, where 160mm ≤ L ≤ 500mm.

[0487] In some examples, the value of L can be 160mm, 500mm or any value between 160mm and 500mm. For example, the value of L can be, but is not limited to, 160mm, 165mm, 170mm, 180mm, 190mm, 200mm, 300mm, 350mm, 400mm, and 500mm.

[0488] By adopting the technical solution of this embodiment, with a design of 160mm≤L≤500mm, the size of the first active material layer 142 is larger along the first direction, and the first active material layer 142 can accommodate more active material, thereby improving the capacity of the battery cell 6. At the same time, combined with the first groove 144, it can better improve the wetting problem of the first electrode 14, and can better balance the capacity of the battery cell 6 and the fast charging performance.

[0489] In some embodiments, 165mm≤L≤350mm can better balance the capacity of high-capacity battery cells and fast charging performance.

[0490] Please refer to Figures 19-22. In some embodiments, the second surface 1301 is provided with a groove 16, and the groove 16 provided on the spacer 13 is the second groove 1321.

[0491] The groove 16 provided on the spacer 13 is a second groove 1321. The second groove 1321 can refer to a recessed structure provided on the spacer 13. The cross-sectional shape of the second groove 1321 can be rectangular, arc-shaped, V-shaped, or other similar shapes. At least one of the two surfaces of the spacer 13 that are relatively distributed along its own thickness direction is provided with the second groove 1321.

[0492] In some examples, the surface of the separator 13 facing the first electrode 14 is provided with a second groove 1321.

[0493] In some examples, the surface of the separator 13 facing the second electrode 15 is provided with a second groove 1321.

[0494] In some examples, the surface of the separator 13 facing the first electrode 14 and the surface facing the second electrode 15 are provided with second grooves 1321, that is, the separator 13 is provided with second grooves 1321 on both sides.

[0495] When the spacer 13 is in the unfolded state, the shape of the second groove 1321 can be various, such as straight, curved, or wavy. The cross-sectional shape of the second groove 1321 can be rectangular, arc-shaped, or V-shaped.

[0496] When the isolation member 13 is in the unfolded state, the shape of the second groove 1321 is straight, and the second groove 1321 is a straight groove.

[0497] In some examples, when the spacer 13 is in the unfolded state, the first direction may be the length direction of the spacer 13 and the second direction may be the width direction of the spacer 13; or, the first direction may be the width direction of the spacer 13 and the second direction may be the length direction of the spacer 13.

[0498] In some examples, the number of second grooves 1321 may be one or more. The multiple second grooves 1321 may be arranged at intervals along the first direction or at intervals along the second direction. The multiple second grooves 1321 may be arranged in a grid along the first direction and the second direction.

[0499] For example, multiple second grooves 1321 may be arranged at intervals along the second direction, the second grooves 1321 may also be arranged at an angle to the first direction, or the second grooves 1321 may be parallel to the first direction.

[0500] By adopting the technical solution of this embodiment, the separator 13 is provided with a second groove 1321. The second groove 1321 is used as a storage channel or flow channel for electrolyte, which is beneficial to improve the wetting effect of the electrode assembly 10, improve the ion transport rate, and improve the cycle performance and fast charging capability of the battery cell 6.

[0501] In some embodiments, the separator 13 includes a base film 131 and a coating 132, wherein at least one surface of the base film 131 along the thickness direction of the separator 13 is covered with the coating 132; a second surface 1301 is formed on the surface of the coating 132 facing away from the base film 131, and at least a portion of the second groove 1321 is located on the coating 132.

[0502] The separator 13 has a multi-layer structure, and the base film 131 is the main part of the separator 13. The base film 131 serves to separate the first electrode 14 and the second electrode 15. The base film 131 can also provide support for the coating 132. The base film 131 can be made of at least one of the following materials: glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic. The coating 132 can refer to the coating structure coated on the surface of the base film 131. The coating 132 can be the above-mentioned inorganic particle coating, organic particle coating, or organic / inorganic composite coating.

[0503] The base film 131 and the coating 132 are stacked along the thickness direction of the separator 13. At least one of the two surfaces of the base film 131 that are relatively distributed along the thickness direction of the separator 13 is covered with the coating 132. The thickness direction of the base film 131 is parallel to the thickness direction of the separator 13. At least one of the two surfaces of the base film 131 that are relatively distributed along its own thickness direction is covered with the coating 132.

[0504] In some examples, a coating 132 is provided between the base film 131 and the first electrode 14; or, a coating 132 is provided between the base film 131 and the second electrode 15; or, a coating 132 is provided between both the base film 131 and the first electrode 14 and between the base film 131 and the second electrode 15. The coating 132 may cover the entire surface of the base film 131 or a portion of the surface of the base film 131.

[0505] The coating 132 can be a single-layer structure or a multi-layer structure.

[0506] The second groove 1321 can refer to a recessed structure formed on the separator 13. The opening formed by the second groove 1321 on the surface of the coating 132 facing away from the base film 131 (i.e., the second surface 1301) is called the second opening. The second opening facilitates the entry of the electrolyte between the first electrode 14 and the second electrode 15 into the second groove 1321 for storage or flow. The coating 132 can be coated intermittently, laser etched, or otherwise formed to create the second groove 1321.

[0507] At least a portion of the second groove 1321 is located in the coating 132. It is understood that a portion of the second groove 1321 is located in the coating 132 and another portion is located in the base film 131, that is, the second groove 1321 penetrates at least a portion of the coating 132 and the base film 131; or, the entire second groove 1321 is located in the coating 132, the second groove 1321 penetrates the coating 132 but does not extend into the interior of the base film 131, that is, the second groove 1321 only penetrates the coating 132; or, the second groove 1321 does not penetrate the coating 132, that is, the second groove 1321 exists only inside the coating 132.

[0508] By adopting the technical solution of this embodiment, it is convenient to manufacture the second groove 1321.

[0509] In some embodiments, the second groove 1321 does not penetrate the coating 132 along the thickness direction of the separator 13.

[0510] The groove depth of the second groove 1321 can refer to the distance between the bottom surface of the second groove 1321 and the second opening.

[0511] The thickness of coating 132 can refer to the distance between the surface of coating 132 facing away from the base film 131 and the base film 131.

[0512] The groove depth t1 of the second groove 1321 is less than the thickness T1 of the coating 132. The second groove 1321 exists in the coating 132 and is recessed from the surface of the coating 132 away from the base film 131 toward the base film 131, but does not reach the contact surface between the coating 132 and the base film 131. Some coating material is still retained at the bottom.

[0513] By adopting the technical solution of this embodiment, the second groove 1321 that does not penetrate the coating 132 can provide a certain liquid storage space, and because the coating material is retained at the bottom, it can improve the overall structural integrity and mechanical strength of the coating 132, which is beneficial to improving the performance of the separator 13.

[0514] In some embodiments, coating 132 includes a first coating 1323 and a second coating 1324 made of different materials. The first coating 1323 includes a plurality of coating portions 1322. The second coating 1324 continuously covers the surface of the base film 131. The plurality of coating portions 1322 are spaced apart on the surface of the second coating 1324 facing away from the base film 131. Two adjacent coating portions 1322 and the second coating 1324 surround each other to form a second groove 1321.

[0515] The materials of the first coating 1323 and the second coating 1324 are different. It can be understood that the composition of the first coating 1323 and the second coating 1324 is different, or the composition of the first coating 1323 and the second coating 1324 is the same, but the content of the components is different.

[0516] In some examples, the main components in the first coating 1323 and the second coating 1324 are different, and the main component may refer to the component with the highest content in coating 132.

[0517] The coating 132 is a double-layer composite coating. The first coating 1323 and the second coating 1324 are stacked along the thickness direction of the separator 13. The layer closer to the base film 131 is the second coating 1324, and the layer farther away from the base film 131 is the first coating 1323. The second coating 1324 is located between the first coating 1323 and the base film 131. The second coating 1324 is a monolithic structure and continuously covers the surface of the base film 131. The first coating 1323 is a multi-part partitioned structure, each part forming a coating part 1322. Multiple coating parts 1322 are spaced apart and cover the surface of the second coating 1324. The areas of the second coating 1324 that are not covered by coating parts 1322 form a second groove 1321.

[0518] By adopting the technical solution of this embodiment, the coating 132 adopts a two-layer structure, and the performance of the coating 132 can be flexibly set to meet different usage requirements.

[0519] In some embodiments, coating 132 includes a first coating 1323 and a second coating 1324 made of different materials. The first coating 1323 includes a plurality of coating portions 1322 covering the surface of the base film 131. The second coating 1324 includes a plurality of filling portions 13241 covering the surface of the base film 131. The plurality of coating portions 1322 and the plurality of filling portions 13241 are alternately distributed along a second direction, which is perpendicular to the first direction and the thickness direction of the separator 13. Two adjacent coating portions 1322 and the filling portions 13241 located between two adjacent coating portions 1322 together form a second groove 1321.

[0520] The coating 132 is a single-layer composite coating. The first coating 1323 and the second coating 1324 are both directly covered on the surface of the base film 131. Along the thickness direction of the separator 13, the first coating 1323 and the second coating 1324 have no obvious upper and lower layer relationship and belong to different areas distributed in the same plane.

[0521] The first coating 1323 includes a plurality of discrete coating portions 1322, each coating portion 1322 directly covering the surface of the base film 131; the second coating 1324 includes a plurality of discrete filling portions 13241, each filling portion 13241 also directly covering the surface of the base film 131; the plurality of coating portions 1322 and the plurality of filling portions 13241 are arranged alternately along a second direction, forming a periodic distribution of coating portion 1322-filling portion 13241-coating portion 1322-filling portion 13241. A filling portion 13241 is sandwiched between two adjacent coating portions 1322, and the thickness of the coating portion 1322 is greater than the thickness of the filling portion 13241, so that two adjacent coating portions 1322 and the filling portion 13241 located between the two adjacent coating portions 1322 form a second groove 1321. The opposite sides of adjacent coating portions 1322 form the two side walls 212 of the second groove 1321, the surface of the filling portion 13241 forms the bottom surface of the second groove 1321, and the second opening of the second groove 1321 is located on the side of the coating 132 facing away from the base film 131.

[0522] The second direction can refer to the thickness direction perpendicular to the spacer 13 and the first direction; for example, when the spacer 13 is in the unfolded state, the first direction is the width direction of the spacer 13 and the second direction is the length direction of the spacer 13.

[0523] By adopting the technical solution of this embodiment, the first coating 1323 and the second coating 1324 form a single-layer composite structure, which is beneficial to reduce the thickness of the separator 13 and improve the volumetric energy density of the battery cell 6; the multiple coating parts 1322 and the multiple filling parts 13241 are arranged alternately in the second direction, the overall structure is regular, and it is convenient to manufacture the coating 132.

[0524] In some embodiments, the first coating 1323 is a polymer coating 13202, and the second coating 1324 is a ceramic coating 13201.

[0525] Ceramic coating 13201 can refer to an inorganic ceramic material coating. Ceramic coating 13201 can be a CCS (Ceramic Coated Separator) coating. The main components of ceramic coating 13201 are ceramic materials such as alumina and boehmite, and it also includes auxiliary components such as dispersants, thickeners, binders, and wetting agents. The dispersant is generally one or more of carboxymethyl cellulose, polyacrylic acid, and their copolymers; the thickener can be carboxymethyl cellulose, xanthan gum, carrageenan, etc.; the binder is usually a heat-resistant binder such as polyimide, inorganic adhesive, or silicone; and the wetting agent is one or more of polyethers and alcohols.

[0526] Polymer coating 13202 can refer to a polymer material coating, and polymer coating 13202 can be a PCS (Polymer Coating Separator) coating.

[0527] The main components of polymer coating 13202 are polymer particles such as polyvinylidene fluoride (PVDF), and water-based thickeners such as BI-4 or CMC-Na (sodium carboxymethyl cellulose) and binders such as FA-3 (polyacrylate emulsion) are usually added.

[0528] The polymer ceramic coating 13201 can be a coating structure formed by mixing ceramic materials and polymer materials. The polymer ceramic coating 13201 combines the advantages of both ceramic coating 13201 and polymer coating 13202, possessing the good heat resistance and puncture resistance of ceramic coating 13201, and the excellent adhesion and flexibility of polymer coating 13202. This significantly improves the overall performance of the battery cell 6, such as cycle performance and reliability.

[0529] By adopting the technical solution of this embodiment, the first coating 1323 adopts a polymer coating 13202, which is beneficial to improve the adhesion between the separator 13 and the first electrode 14 and / or the second electrode 15, and reduce the risk of interlayer delamination during battery cell 6 cycling; the first coating 1323 adopts a polymer ceramic coating 13201, which can significantly improve the overall performance of battery cell 6; the second coating 1324 adopts a ceramic coating 13201, which has heat resistance and insulation properties, which is beneficial to improve the high temperature resistance and insulation performance of the separator 13, and improve the reliability of battery cell 6.

[0530] In some embodiments, the ratio of the groove depth of the second groove 1321 to the thickness of the coating 132 ranges from 0.3 to 0.9.

[0531] The groove depth of the second groove 1321 is t1, and the thickness of the coating 132 is T1; 0.3≤t1 / T1≤0.9.

[0532] In some examples, the value of t1 / T1 can be 0.3, 0.9, or any value between 0.3 and 0.9. For example, the value of t1 / T1 can be, but is not limited to, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, and 0.9.

[0533] With a design of 0.3 ≤ t1 / T1 ≤ 0.9, the ratio of the groove depth of the second groove 1321 to the thickness of the coating 132 is within this range. The second groove 1321 can serve as a good wetting channel for the electrolyte. The bottom of the second groove 1321 has a portion of the coating material to ensure that the separator 13 has good performance. For example, the bottom of the second groove 1321 has a ceramic coating 13201 of a certain thickness to improve the heat resistance of the separator 13.

[0534] In some embodiments, the thickness of the coating 132 ranges from 1 μm to 3.5 μm, and the groove depth of the second groove 1321 ranges from 0.2 μm to 3 μm.

[0535] The value of T1 can be 1 μm, 3.5 μm, or any value between 1 μm and 3.5 μm. For example, the value of T1 can be, but is not limited to, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, and 3.5 μm.

[0536] The value of t1 can be 0.2μm, 3μm, or any value between 0.2μm and 3μm. For example, the value of t1 can be, but is not limited to, 0.2μm, 0.5μm, 0.8μm, 1μm, 1.5μm, 2μm, 2.5μm, and 3μm.

[0537] By adopting the technical solution of this embodiment, the groove depth of the second groove 1321 is reasonable relative to the thickness of the coating 132, the second groove 1321 can serve as a good wetting channel for the electrolyte, and the bottom of the second groove 1321 has a portion of the coating material so that the separator 13 has good performance.

[0538] Please refer to Figures 23 and 24 together. In some embodiments, the second groove 1321 penetrates the coating 132 along the thickness direction of the spacer 13.

[0539] Along the thickness direction of the separator 13, the second groove 1321 penetrates the coating 132, wherein the second groove 1321 may partially extend to the base film 131, and the surface of the base film 131 forms a recessed structure, which is part of the second groove 1321. The groove depth t1 of the second groove 1321 is greater than the thickness T1 of the coating 132. The second groove 1321 does not extend to the base film 131, the surface of the base film 131 is flat, and the groove depth t1 of the second groove 1321 is equal to the thickness T1 of the coating 132.

[0540] By adopting the technical solution of this embodiment, the second groove 1321 penetrates the coating 132. The second groove 1321 has a relatively deep depth, which can accommodate more electrolyte, which is conducive to electrolyte reflux, improves the wetting effect of the electrode assembly 10, and improves the fast charging performance and cycle performance of the battery cell 6. In addition, the second groove 1321 can penetrate the coating 132 along the thickness direction of the separator 13, and the base film 131 is exposed. The base film 131 can be directly dissipated by the second groove 1321, reducing the thermal load of the separator 13 and improving the performance of the battery cell 6.

[0541] In some embodiments, the groove depth t1 of the second groove 1321 is equal to the thickness T1 of the coating 132.

[0542] By adopting the technical solution of this embodiment, the second groove 1321 penetrates through the coating 132 and terminates at the surface of the base film 131. The base film 131 has good structural strength, which is beneficial to improving the structural strength of the separator 13 and improving the reliability of the battery cell 6. Using the coating 132 to make the second groove 1321 is also beneficial to reduce the manufacturing cost of the separator 13 and the manufacturing cost of the battery cell 6.

[0543] In some embodiments, the coating 132 includes a plurality of coating portions 1322, which are spaced apart, and two adjacent coating portions 1322 and the base film 131 surround each other to form a second groove 1321.

[0544] The second groove 1321 divides the coating 132 into multiple sections. The portion of the coating 132 located on the side of the second groove 1321 forms a coating section 1322. Multiple coating sections 1322 are spaced apart. The sides of two adjacent coating sections 1322 facing each other and the surface of the base film 131 surround the second groove 1321.

[0545] The second groove 1321 is located between two adjacent coating portions 1322. The coating 132 can be applied to the base film 131 by intermittent coating. The area where the coating is applied to the base film 131 forms the coating portion 1322, and the area where the coating is not applied forms the second groove 1321. For example, the coating 132 can be a zebra stripe structure, with each stripe being a coating portion 1322. For example, the coating 132 can also be a dot matrix structure, with each dot being a coating portion 1322.

[0546] By adopting the technical solution of this embodiment, it is easy to form the second groove 1321.

[0547] In some embodiments, coating 132 is a ceramic coating 13201.

[0548] By adopting the technical solution of this embodiment, the ceramic coating 13201 can improve the heat resistance of the separator 13, enhance the puncture resistance of the separator 13, reduce the self-discharge of the battery cell 6 during use, thereby improving the yield of the battery cell 6.

[0549] In some embodiments, coating 132 is a polymer coating 13202.

[0550] By adopting the technical solution of this embodiment, the polymer coating 13202 can enhance the adhesion between the separator 13 and the first electrode 14 and / or the second electrode 15, reduce the deformation of the battery cell 6 during the cycle process, and improve the hardness of the battery cell 6. At the same time, it can also improve the wettability of the separator 13, enhance liquid absorption, and improve cycle life.

[0551] In some embodiments, coating 132 is a polymer ceramic coating 13201.

[0552] By adopting the technical solution of this embodiment, the polymer ceramic coating 13201 combines the advantages of ceramic coating 13201 and polymer coating 13202. It has the good heat resistance and puncture resistance of ceramic coating 13201, and the excellent adhesion and flexibility of polymer coating 13202. It can significantly improve the overall performance of battery cell 6, such as cycle performance and reliability.

[0553] In some embodiments, there are multiple second grooves 1321, the second grooves 1321 extend along a first direction, and the multiple second grooves 1321 are spaced apart along a second direction, the second direction being perpendicular to the first direction and the thickness direction of the spacer 13.

[0554] The second groove 1321 extends along the first direction. It can be understood that the second groove 1321 extends in a straight line or in a curved manner along the first direction, or extends at an angle relative to the second direction.

[0555] In some examples, the second groove 1321 is a straight groove, the third direction is the length direction of the second groove 1321, the second direction is the length direction of the spacer 13, and the third direction can be the width direction of the spacer 13. In this case, the second groove 1321 extends straight along the width direction of the spacer 13, and the coating portion 1322 is arranged at intervals along the length direction of the spacer 13.

[0556] In some examples, the second groove 1321 is a straight groove, the third direction is the length direction of the second groove 1321, the second direction is the length direction of the spacer 13, and the third direction forms an angle of 30°, 45° or 60° with the length direction of the spacer 13. In this case, the second groove 1321 extends obliquely, and the coating portion 1322 is arranged at intervals along the length direction of the spacer 13.

[0557] Multiple coating portions 1322 are spaced apart along a second direction and cover the surface of the base film 131, and multiple second grooves 1321 are spaced apart along the second direction. For example, the coating 132 can be formed by intermittent coating.

[0558] By adopting the technical solution of this embodiment, the second groove 1321 extends along the first direction, which can guide the electrolyte to climb up in the first direction, which is beneficial to improving the electrolyte climbing performance of the high-performance battery cell 6.

[0559] In some embodiments, the distance between two adjacent second grooves 1321 ranges from 0.5 mm to 10 mm.

[0560] The distance between two adjacent second grooves 1321 is L2, 0.5mm≤L2≤10mm.

[0561] In some examples, L2 can be 0.5mm, 10mm, or any value between 0.5mm and 10mm. For example, L2 can be 0.5mm, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, or 10mm.

[0562] By adopting the technical solution of this embodiment, the distance between two adjacent second grooves 1321 is set within the above-mentioned range, which facilitates processing and can also effectively guide the flow of electrolyte in the battery cell 6, improve the wetting effect of the electrode assembly 10, and improve the fast charging performance and cycle performance of the battery cell 6. For example, the reasonable distribution density of the second grooves 1321 provides sufficient channels for the electrolyte to quickly climb from the bottom to the top of the electrode assembly 10, effectively improving the electrolyte's crawling ability and improving the fast charging performance and cycle performance of the battery cell 6.

[0563] In some embodiments, the second groove 1321 penetrates the coating 132 along the first direction.

[0564] The second groove 1321 penetrates the coating 132 along the opposite two ends of the coating in the first direction and forms an opening.

[0565] In some examples, the second groove 1321 is parallel to and perpendicular to the first direction, penetrating the opposite end faces of the coating 132 along the first direction.

[0566] In some examples, the second groove 1321 is inclined relative to the first direction, and the second groove 1321 is inclined through the opposite end faces of the coating 132 along the first direction.

[0567] In some cases, after the electrode assembly 10 expands, the electrolyte is squeezed out from both ends of the electrode assembly 10, and after the electrode assembly 10 is wound, the distance between the first electrode 14 and the second electrode 15 is small, making it difficult for the electrolyte to flow back between the first electrode 14 and the second electrode 15.

[0568] By adopting the technical solution of this embodiment, the electrolyte located at the opposite two end faces of the separator 13 along the first direction can flow directly into the second groove 1321 for reflux, which is beneficial to improve the wetting effect of the electrode assembly 10 and improve the cycle performance of the battery cell 6.

[0569] In some embodiments, the groove width of the second groove 1321 ranges from 0.5 mm to 12 mm.

[0570] The width of the second groove 1321 is the same as the width of the second opening.

[0571] The width of the second groove 1321 is W, 0.5mm≤W≤12mm.

[0572] In some examples, the value of W can be 0.5mm, 12mm, or any value between 0.5mm and 12mm. For example, the value of W can be, but is not limited to, 0.5mm, 1mm, 2mm, 4mm, 6mm, 8mm, 10mm, or 12mm.

[0573] By adopting the technical solution of this embodiment, the groove width of the second groove 1321 is set within the above range, so that the second groove 1321 has a capillary effect, which effectively improves the flow of electrolyte, improves the wetting of electrode assembly 10, and improves the fast charging performance and cycle performance of battery cell 6.

[0574] Please refer to Figures 25 and 26 together. In some embodiments, the second groove 1321 is a straight groove, and the length direction of the second groove 1321 is not perpendicular to the first direction.

[0575] When the isolation member 13 is in the unfolded state, the shape of the second groove 1321 is straight, and the second groove 1321 is a straight groove.

[0576] The length direction of the second groove 1321 is not perpendicular to the first direction. It can be understood that the length direction of the second groove 1321 is parallel to or intersects the first direction at an angle.

[0577] In some examples, when the spacer 13 is in the deployed state, the first direction may be parallel to the width direction of the spacer 13.

[0578] By adopting the technical solution of this embodiment, the second groove 1321 is a straight groove, and the length direction of the second groove 1321 is not perpendicular to the first direction, so that the second groove 1321 can guide the electrolyte to diffuse upward, improve the climbing ability of the electrolyte, improve the wetting effect of the electrode assembly 10, reduce the ion transmission resistance, improve the distribution uniformity of the electrolyte, and improve the cycle performance of the battery cell 6.

[0579] In some embodiments, the angle between the length direction of the second groove 1321 and the first direction ranges from 0° to 45°.

[0580] In some examples, the groove 16 extending from one side of the coating 132 along the first direction to the other side is a second groove 1321. The second groove 1321 is a straight groove, and the angle between the length direction of the second groove 1321 and the first direction is α1, where 0°≤α1≤45°. The value of α1 can be 0°, 45°, or any value between 0° and 45°. For example, the value of α1 can be 0°, 2°, 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, or 45°.

[0581] In some examples, α1 equals 0, and the second groove 1321 is vertically positioned. When the electrolyte flows along the second groove 1321, the upward path is shorter, the flow resistance is lower, and the electrolyte's climbing effect is better. The closer α1 is to 0°, the closer the length direction of the second groove 1321 is to vertically upward. When the electrolyte flows along the second groove 1321, the upward path is straighter, and the flow resistance is lower. In this case, the electrolyte accumulated at the bottom can quickly flow to the top of the electrode assembly 10 through the second groove 1321, reducing losses during the flow process. This is suitable for scenarios where it is necessary to quickly fill the electrolyte gap in the upper part of the electrode assembly 10.

[0582] α1 is located between 0° and 45°. The second groove 1321 is inclined but close to vertical. The second groove 1321 can effectively guide the electrolyte to climb upward. At the same time, the second groove 1321 can also guide the electrolyte to diffuse in the horizontal direction, which is beneficial to improving the overall wetting uniformity of the surface of the first electrode 14 and / or the second electrode 15.

[0583] By adopting the technical solution of this embodiment, the angle between the length direction of the second groove 1321 and the first direction is set within the above range, and the length direction of the second groove 1321 is parallel to or nearly parallel to the vertical direction. The electrolyte at the bottom can quickly climb up along the second groove 1321, thereby improving the wetting effect of the upper part of the electrode assembly 10, and thus effectively improving the cycle performance of the battery cell 6.

[0584] In some embodiments, the angle between the length direction of the second groove 1321 and the first direction ranges from 0° to 30°.

[0585] 0°≤α1≤30°.

[0586] By adopting the technical solution of this embodiment, the cycle performance and fast charging performance of the battery cell 6 can be better improved.

[0587] In some embodiments, the spacer 13 has a second groove 1321 on each of its opposite sides along its thickness direction.

[0588] In some examples, the base film 131 has coatings 132 on both sides of the opposite side along the thickness direction of the separator 13, and the coatings 132 on both sides are provided with second grooves 1321.

[0589] By adopting the technical solution of this embodiment, the separator 13 has a second groove 1321 on both sides, which can better wet the first electrode 14 and the second electrode 15, reduce the ion transport resistance, and help improve the cycle performance of the battery cell 6.

[0590] In some embodiments, along the thickness direction of the spacer 13, the projections of the second grooves 1321 located on both sides of the spacer 13 along its own thickness direction intersect.

[0591] It is understandable that after the spacer 13 is unfolded, when the projection is observed from the thickness direction of the spacer 13, there is an intersection between the projection of the second groove 1321 of the spacer 13 facing the first pole piece 14 and the projection of the second groove 1321 facing the second pole piece 15. For example, the projection of multiple second grooves 1321 along the thickness direction of the spacer 13 forms a grid-like structure.

[0592] By adopting the technical solution of this embodiment, the projections of the second grooves 1321 located on both sides of the separator 13 along its thickness direction intersect, which is beneficial to improving the structural stability of the separator 13 and the reliability of the battery cell 6. Furthermore, since the electrolyte can pass through the separator 13, the electrolyte in the second groove 1321 opposite to the first electrode 14 can pass through the separator 13 to wet the second electrode 15, and the electrolyte in the second groove 1321 opposite to the second electrode 15 can pass through the separator 13 to wet the first electrode 14. Since the projections of the second grooves 1321 on both sides of the separator 13 intersect, both the first electrode 14 and the second electrode 15 on both sides of the separator 13 receive more sufficient electrolyte wetting in the projection areas of the second grooves 1321, improving the uniformity of electrolyte distribution and enhancing the cycle performance of the battery cell 6.

[0593] In some embodiments, the battery cell 6 is a prismatic battery cell.

[0594] By adopting the technical solution of this embodiment, the first electrode 14 and / or the separator 13 are provided with grooves 16, which is beneficial to improving the cycle performance and fast charging performance of the high-square-shell battery cell.

[0595] Please refer to Figures 27-29. In some embodiments, the outer casing 20 includes a housing 21 and an end cap 22. The electrode assembly 10 is located inside the housing 21, and the end cap 22 covers the opening of the housing 21. The surface with the largest area of ​​the electrode assembly 10 is the third surface 101. The housing 21 has a first sidewall 2121, which is disposed opposite to the third surface 101. The thickness of the first sidewall 2121 ranges from 0.1 mm to 0.8 mm.

[0596] The third surface 101 may refer to the surface with the largest area of ​​the electrode assembly 10. For example, the third surface 101 may refer to the surface of the electrode assembly 10 that is perpendicular to its own thickness direction.

[0597] The first sidewall 2121 can refer to the outer wall of the housing 21 that is parallel to or abuts against the third surface 101. The third surface 101 can directly abut against the first sidewall 2121, or it can abut against the first sidewall 2121 through intermediate components.

[0598] For example, the first sidewall 2121 may refer to the outer wall of the sidewall 212 in the direction perpendicular to the thickness of the housing 21.

[0599] The thickness of the first sidewall 2121 is c1, 0.1mm≤c1≤0.8mm. It can be understood that the value of c1 can be 0.1mm, 0.8mm, or any value between 0.1mm and 0.8mm. For example, the value of c1 can be 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, or 0.8mm.

[0600] During charge-discharge cycles, the expansion force of the electrode assembly 10 is typically along its thickness direction. Therefore, the expansion of the electrode assembly 10 mainly occurs on the third surface 101, which compresses the first sidewall 2121. During this expansion, the electrolyte between the first electrode 14 and the second electrode 15 is squeezed out. In this embodiment, the thickness of the first sidewall 2121 is set within the aforementioned range. The relatively small thickness of the first sidewall 2121 allows for easy deformation, thereby providing the electrode assembly 10 with... The expansion space reduces the amount of electrolyte squeezed out between the first electrode 14 and the second electrode 15, which helps to improve the wetting effect of the electrode assembly 10 and improve the cycle performance and fast charging performance of the battery cell 6. At the same time, the expansion space provided by the first sidewall 2121 helps to reduce the degree of compression between the first electrode 14 and the second electrode 15 during expansion, which facilitates the return of electrolyte to the space between the first electrode 14 and the second electrode 15, and also facilitates the return of electrolyte into the groove 16. This also helps to improve the wetting effect of the electrode assembly 10 and improve the cycle performance and fast charging performance of the battery cell 6.

[0601] In some embodiments, the housing 20 includes a housing 21 and an end cap 22. The electrode assembly 10 is located inside the housing 21, and the end cap 22 covers the opening of the housing 21. The surface with the largest area of ​​the electrode assembly 10 is the third surface 101. The housing 21 has a first sidewall 2121, a second sidewall 2122, and a third sidewall 2111. The first sidewall 2121 and the second sidewall 2122 are disposed opposite to each other, and the first sidewall 2121 and the third surface 101 are disposed opposite to each other. The third surface 101 is located between the first sidewall 2121 and the second sidewall 2122. The third sidewall 2111 is connected between the first sidewall 2121 and the second sidewall 2122. The thickness of the first sidewall 2121 is less than the thickness of the third sidewall 2111.

[0602] The second sidewall 2122 can refer to the outer wall of the housing 21 that is disposed opposite to the first sidewall 2121. For example, the first sidewall 2121 and the second sidewall 2122 can refer to the two outer walls of the housing 21 that are disposed opposite to each other along its own thickness direction. The third sidewall 2111 can refer to the outer wall of the housing 21 that is connected between the first sidewall 2121 and the second sidewall 2122.

[0603] For example, the third sidewall 2111 can refer to the outer wall of the sidewall 212 that is perpendicular to the height direction of the battery cell 6, such as the bottom wall.

[0604] For example, the third sidewall 2111 can also be the endwall 211 described above.

[0605] The thickness of the third sidewall 2111 is c2, where c2 > c1.

[0606] By adopting the technical solution of this embodiment, the thickness of the first sidewall 2121 is less than the thickness of the third sidewall 2111. The first sidewall 2121 is more easily deformed relative to the third sidewall 2111, thereby providing expansion space for the electrode assembly 10, reducing the amount of electrolyte squeezed out between the first electrode 14 and the second electrode 15, which is beneficial to improving the wetting effect of the electrode assembly 10 and improving the cycle performance and fast charging performance of the battery cell 6. At the same time, the expansion space provided by the first sidewall 2121 is beneficial to reducing the degree of compression between the first electrode 14 and the second electrode 15 during expansion, facilitating the return of electrolyte between the first electrode 14 and the second electrode 15, and also facilitating the return of electrolyte into the groove 16, which is also beneficial to improving the wetting effect of the electrode assembly 10 and improving the cycle performance and fast charging performance of the battery cell 6.

[0607] In some embodiments, the battery device 2 includes a plurality of the aforementioned battery cells 6.

[0608] The battery device 2 is used to be installed in the electrical device. The battery device 2 serves as an energy storage device or a discharge device for the electrical device, for storing or releasing electrical energy.

[0609] The first direction is parallel to the direction of gravity of the battery device 2 when the electrical device is in use or when the battery device 2 is mounted on the electrical device. For example, when the vehicle 1 is parked on a level surface, the direction of gravity of the battery device 2 is the height direction of the battery device 2, and the first direction is parallel to the height direction of the battery device 2.

[0610] By adopting the technical solution of this embodiment, the battery cell 6 has high capacity and good fast charging performance, which is beneficial to improving the performance of the battery device 2.

[0611] In some embodiments, the electrical device includes the battery cell 6 or the battery device 2 described above, which are used to store or provide electrical energy.

[0612] By adopting the technical solution of this embodiment, the battery cell 6 has high capacity and good fast charging performance, and the battery device 2 has good performance, which is conducive to improving the performance of the power device.

[0613] In some embodiments, this application provides a battery cell 6, which includes a housing 20, an electrode assembly 10, and electrode terminals 30.

[0614] The outer casing 20 includes a housing 21 and an end cap 22. The housing 21 includes an integrally formed side wall 212 and an end wall 211. The end wall 211 and the end cap 22 are opposite each other along the height direction of the battery cell 6. The end cap 22 is welded to the side wall 212.

[0615] The electrode assembly 10 is housed within the housing 20. The electrode assembly 10 includes a first electrode 14, a second electrode 15, and a spacer 13, which are wound together. The spacer 13 is used to isolate the second electrode 15 and the first electrode 14.

[0616] The first electrode 14 includes a first current collector 141 and a first active material layer 142 covering the surface of the first current collector 141. The second electrode 15 includes a second current collector 151 and a second active material layer 152 covering the surface of the second current collector 151. The portion of the first current collector 141 not covered by the first active material layer 142 forms a first tab 1412, which is electrically connected to the electrode terminal 30 on the end cap 22.

[0617] The first electrode 14 and the second electrode 15 are located on opposite sides of the separator 13 along its own thickness direction; the first active material layer 142 has a first surface 1421 facing away from the first current collector 141, the separator 13 has a second surface 1301 along its own thickness direction, and at least one of the first surface 1421 and the second surface 1301 is provided with a groove 16.

[0618] The description of the various embodiments above tends to emphasize the differences between the various embodiments. The similarities or similarities between them can be referred to, and for the sake of brevity, they will not be repeated here.

[0619] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This 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, wherein, The battery cell includes: The outer casing contains the electrolyte; An electrode assembly, at least partially located within the housing, includes a first electrode, an isolator, and a second electrode. The first and second electrodes have opposite polarities and are located on opposite sides of the isolator along its thickness direction. The first electrode includes a first current collector and a first active material layer. At least a portion of at least one surface of the first current collector along its thickness direction is connected to the first active material layer, and at least a portion of the first active material layer is located between the first current collector and the isolator. The size of the first active material layer is greater than or equal to 150 mm along a first direction, which is parallel to the direction of gravity. The first active material layer has a first surface facing away from the first current collector, and the separator has a second surface along its own thickness direction. At least one of the first surface and the second surface is provided with a groove.

2. The battery cell according to claim 1, wherein: The first surface is provided with the groove, and the groove provided in the first active material layer is the first groove.

3. The battery cell according to claim 2, wherein: The first active material layer includes a first active material portion and a second active material portion disposed along the first direction. At least one end of the first active material portion along the first direction is connected to the second active material portion. The thickness of the second active material portion is less than the thickness of the first active material portion. The first active material portion is provided with the first groove. Along the first direction, the second active material portion is disposed at a distance from the first groove.

4. The battery cell of claim 3, wherein: Along the first direction, the distance between the second active material portion and the first groove is S1, where 0mm < S1 ≤ 12mm.

5. The battery cell of claim 3 or 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 surface of the first active material portion facing away from the first current collector is provided with the first groove. Along the first direction, the end face of the first active material portion facing away from the second active material portion is spaced apart from the first groove.

6. The battery cell according to claim 5, wherein: The distance between the end face of the first active material portion facing away from the second active material portion and the first groove is s, where 1mm≤s≤3mm.

7. The battery cell according to any one of claims 2 to 6, wherein: The number of the first grooves is multiple, the first grooves extend along the first direction, and the multiple first grooves are spaced apart along the second direction. The first direction is perpendicular to the second direction, and the second direction is perpendicular to the thickness direction of the first current collector.

8. The battery cell according to claim 7, wherein: The distance between two adjacent first grooves ranges from 1mm to 10mm.

9. The battery cell of any one of claims 2-8, wherein: The first pole piece includes two first active material layers, each of which covers two surfaces of the first current collector along the thickness direction of the first current collector, the number of the first grooves is multiple, and the multiple first grooves include first grooves and second grooves extending along the first direction; in the two first active material layers, one 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 alternately.

10. The battery cell of claim 9, wherein: Along the second direction, the multiple first grooves and the multiple second grooves are arranged alternately, and the second direction is perpendicular to the first direction and the thickness direction of the first current collector.

11. The battery cell of claim 10, wherein: Along the second direction, the distance between adjacent first grooves and second grooves is C, wherein C≥1.5mm, optionally, 1.8mm≤C≤5mm, optionally, 2mm≤C≤3mm.

12. The battery cell of any one of claims 2-11, wherein: The first groove includes multiple subsegments, and the multiple subsegments are distributed along the first direction.

13. The battery cell of claim 12, wherein: The distance between adjacent two subsegments is d, and 0.5mm≤d≤2.5mm.

14. The battery cell according to any one of claims 2 to 13, wherein: The first groove includes multiple subsegments extending along the first direction, and the multiple subsegments are arranged along the second direction, wherein the upper end of one of the adjacent two subsegments coincides with the projection of the lower end of the other subsegment along the second direction, and the second direction is perpendicular to the first direction and the thickness direction of the first current collector.

15. The battery cell of any one of claims 12-14, wherein: The first current collector includes a first current collector body and a first tab, the first tab is connected to the upper end of the first current collector body, 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 number of the first grooves is multiple, and the multiple first grooves are arranged along the second direction; the first active material layer includes a first half and a second half connected to each other, the first half is located on the upper side of the second half, the first half is located on the upper side of the second half, the subsegment located in the first half is a first subsegment, the subsegment located in the second half is a second subsegment, the depth of at least one first subsegment is less than the depth of at least one second subsegment, and / or the distance between adjacent two first subsegments is less than the distance between adjacent two second subsegments.

16. The battery cell according to claim 15, wherein: The depth of at least one first subsegment ranges from 10μm to 15μm; and / or the depth of at least one second subsegment ranges from 15μm to 20μm.

17. The battery cell according to claim 15 or 16, wherein: The distance between adjacent two first subsegments ranges from 0.5mm to 2mm; and / or the distance between adjacent two second subsegments ranges from 2.5mm to 6mm.

18. The battery cell according to any one of claims 15 to 17, wherein: The second half includes a first half subsegment and a second half subsegment connected to each other, the ratio of the size of the second half subsegment along the first direction to the size of the first active material layer along the first direction is 0.2, and the depth of at least one second subsegment located in the second half subsegment is less than the depth of at least one second subsegment located in the first half subsegment.

19. The battery cell according to claim 18, wherein: The depth range of at least one second segment located in the second half of the second sub-part is 5 μm to 15 μm.

20. The battery cell according to any one of claims 2 to 19, wherein: The electrode assembly is a wound structure, the first electrode is wound to form a plurality of first electrode winding rings, the first current collector includes a first current collector winding ring located in the first electrode winding ring, the first active material layer includes a first active winding ring located in the first electrode winding ring, and the first surface includes a first winding surface located in the first electrode winding ring; wherein, at least one of the first winding surfaces of the first electrode winding ring is provided with the first groove.

21. The battery cell according to claim 20, wherein: The number of the first grooves is multiple, the first grooves extend along the first direction, and the multiple first grooves are spaced apart along the second direction, which is the winding direction of the electrode assembly.

22. The battery cell according to claim 20 or 21, wherein: The electrode assembly includes a flat region and two bending regions, the two bending regions being located at both ends of the flat region; the first active winding includes a first active bending portion located in the bending region and a first active flat portion located in the flat region; at least one of the first active windings has the first active flat portion having the first groove; and / or, at least one of the first active windings has the first active bending portion having the first groove.

23. The battery cell according to claim 22, wherein: The first active straight portion of all the first active windings is provided with the first groove, while the first active bent portion of all the first active windings is not provided with the first groove.

24. The battery cell according to any one of claims 20 to 23, wherein: The first electrode has a first winding end, the second electrode has a second winding end, the innermost first electrode winding is the first first electrode winding, and the second winding end is located between the last two first electrode windings; the last two first electrode windings do not have the first groove at the position corresponding to the end face of the first winding end; and / or, the last two first electrode windings do not have the first groove at the position corresponding to the end face of the second winding end.

25. The battery cell according to claim 24, wherein: The last two first electrode windings are provided with the first groove, and the first groove is offset from at least one of the end faces of the first winding end and the second winding end; or, the last two first electrode windings are not provided with the first groove.

26. The battery cell according to any one of claims 20 to 25, wherein: The first electrode has a first winding start end, the second electrode has a second winding start end, the innermost first electrode winding ring is the first first electrode winding ring, and the second winding start end is located between the first two first electrode winding rings; the first groove is not provided at the position corresponding to the end face of the first two first electrode winding rings and the first winding start end; and / or, the first groove is not provided at the position corresponding to the end face of the second winding start end of the first two first electrode winding rings.

27. The battery cell of claim 26, wherein: The first two first electrode windings are provided with the first groove, and the first groove is offset from at least one of the end face of the first winding start end and the end face of the second winding start end; or, the first two first electrode windings are not provided with the first groove.

28. The battery cell of any one of claims 2-19, wherein: The electrode assembly has a stacked structure.

29. The battery cell of claim 28, wherein: The first groove extends along the first direction.

30. The battery cell of claim 29, wherein: The first current collector includes a first current collector body and a first electrode connected and arranged along the first direction, wherein at least a portion of the first current collector body is covered with the first active material layer, and the first electrode is not covered with the first active material layer; or, the first current collector includes a first current collector body and a first electrode connected and arranged along a second direction, wherein at least a portion of the first current collector body is covered with the first active material layer, and the first electrode is not covered with the first active material layer, wherein the second direction is perpendicular to the first direction and the thickness direction of the first current collector.

31. The battery cell of any one of claims 2-30, wherein: The ratio of the groove depth to the thickness of the first active material layer ranges from 0.15 to 0.

7.

32. The battery cell of any one of claims 2-31, wherein: The groove depth of the first groove is h, where 10μm≤h≤40μm.

33. The battery cell of any one of claims 2-32, wherein: The width of the first groove is w, where 70μm≤w≤170μm.

34. The battery cell of any one of claims 2-33, wherein: Along the first direction, the size of the first groove is l, and the size of the first active material layer is L, 0.8≤l / L≤1; optionally, 0.9≤l / L≤0.

98.

35. The battery cell of any one of claims 2-34, wherein: The first electrode is the negative electrode, and the second electrode is the positive electrode.

36. The battery cell of any one of claims 1-35, wherein: Along the first direction, the size of the first active material layer is L, 160mm≤L≤500mm, or optionally, 165mm≤L≤350mm.

37. The battery cell of any one of claims 1-36, wherein: The second surface is provided with the groove, and the groove provided on the separator is the second groove.

38. The battery cell of claim 37, wherein: The separator includes a base film and a coating, wherein at least one surface of the base film along the thickness direction of the separator is covered with the coating; the surface of the coating opposite to the base film forms a second surface, and at least a portion of the second groove is located in the coating.

39. The battery cell of claim 38, wherein: Along the thickness direction of the separator, the second groove does not penetrate the coating.

40. The battery cell of claim 39, wherein: The coating includes a first coating and a second coating made of different materials. The first coating includes a plurality of coating portions. The second coating continuously covers the surface of the base film. The plurality of coating portions are spaced apart on the surface of the second coating facing away from the base film. Two adjacent coating portions and the second coating surround to form the second groove.

41. The battery cell of claim 40, wherein: The coating includes a first coating and a second coating made of different materials, wherein the first coating includes a plurality of coating portions covering the surface of the base film; The second coating includes a plurality of filling portions covering the surface of the base film. The plurality of coating portions and the plurality of filling portions are alternately distributed along the second direction, which is perpendicular to the first direction and the thickness direction of the separator. Two adjacent coating portions and the filling portion located between two adjacent coating portions together form the second groove.

42. The battery cell of claim 40 or 41, wherein: The first coating is a polymer coating or a polymer-ceramic coating, and the second coating is a ceramic coating.

43. The battery cell of any one of claims 38-42, wherein: The ratio of the groove depth to the coating thickness of the second groove ranges from 0.3 to 0.

9.

44. The battery cell of any one of claims 38-43, wherein: The thickness of the coating ranges from 1 μm to 3.5 μm, and the depth of the second groove ranges from 0.2 μm to 3 μm.

45. The battery cell of claim 38, wherein: The second groove penetrates the coating along the thickness direction of the separator.

46. The battery cell of any one of claims 38, 39, and 45, wherein: The coating is a ceramic coating, a polymer coating, or a polymer-ceramic coating.

47. The battery cell of any one of claims 38-46, wherein: Along the first direction, the second groove penetrates the coating.

48. The battery cell of any one of claims 37-46, wherein: The number of the second grooves is multiple, the second grooves extend along the first direction, and the multiple second grooves are spaced apart along the second direction, which is perpendicular to the first direction and the thickness direction of the separator.

49. The battery cell of any one of claims 37-47, wherein: The width of the second groove ranges from 0.5mm to 12mm.

50. The battery cell of any one of claims 37-49, wherein: The second groove is a straight groove, and the length direction of the second groove is not perpendicular to the first direction.

51. The battery cell of claim 50, wherein: The angle between the length direction of the second groove and the first direction is in the range of 0° to 45°; optionally, the angle between the length direction of the second groove and the first direction is in the range of 0° to 30°.

52. The battery cell of any one of claims 37-51, wherein: The isolation member has the second groove on both sides along its thickness direction.

53. The battery cell of claim 52, wherein: Along the thickness direction of the separator, the projections of the second grooves located on both sides of the separator along its own thickness direction intersect.

54. The battery cell of any one of claims 1-53, wherein: The battery cell is a prismatic battery cell.

55. The battery cell of any one of claims 1-54, wherein: The housing includes a shell and an end cap. The electrode assembly is located inside the shell. The end cap covers the opening of the shell. The surface with the largest area of ​​the electrode assembly is the third surface. The shell has a first sidewall, which is disposed opposite to the third surface. The thickness of the first sidewall ranges from 0.1 mm to 0.8 mm.

56. The battery cell of any one of claims 1-55, wherein: The housing includes a shell and an end cap. The electrode assembly is located inside the shell. The end cap covers the opening of the shell. The surface with the largest area of ​​the electrode assembly is the third surface. The shell has a first sidewall, a second sidewall, and a third sidewall. The first sidewall and the second sidewall are disposed opposite each other. The first sidewall and the third surface are disposed opposite each other. The third surface is located between the first sidewall and the second sidewall. The third sidewall is connected between the first sidewall and the second sidewall. The thickness of the first sidewall is less than the thickness of the third sidewall.

57. A battery device, wherein: It includes multiple battery cells according to any one of claims 1 to 56.

58. An electrical device, comprising: Includes a battery cell according to any one of claims 1 to 56 or a battery device according to claim 57, wherein the battery cell or the battery device is used to store or provide electrical energy.

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