Battery pole piece, battery cell and electrochemical device

Abstract

The embodiment of the utility model provides a battery pole piece, a battery cell and an electrochemical device. The battery pole piece comprises a current collector and a coating, the coating is located on one side of the current collector and comprises a first side face and a second side face, the first side face is located on the side, close to the current collector, of the coating, and the second side face is located on the side, away from the current collector, of the coating; a part of the second side surface is recessed towards the first side surface to form a diffusion channel. The battery pole piece is high in electrolyte infiltration efficiency.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a battery electrode, a battery cell, and an electrochemical device. Background Technology

[0002] Lithium-ion batteries have advantages such as high energy density, high operating voltage, and low self-discharge, and are widely used in consumer electronics, electric vehicles, and energy storage. As new energy sources replace traditional energy sources, higher demands are being placed on the energy density, power density, safety performance, and cost of lithium batteries.

[0003] However, the relevant technologies have the problem of difficulty in wetting the electrolyte from the periphery to the center of the battery electrode, which leads to poor dynamic performance in the middle region of the battery electrode. As a result, the central region of the battery electrode fails first during the entire life cycle of the battery. Utility Model Content

[0004] This application provides a battery electrode, battery cell, and electrochemical device with high electrolyte wetting efficiency.

[0005] The technical solution of this application embodiment is implemented as follows:

[0006] This application provides a battery electrode, which includes:

[0007] current collector;

[0008] The coating is located on one side of the current collector. The coating includes a first side and a second side. The first side is located on the side of the coating close to the current collector, and the second side is located on the side of the coating away from the current collector. A portion of the second side is recessed toward the first side to form a diffusion channel.

[0009] In one embodiment, the porosity of the coating near the first side is less than the porosity of the coating near the second side.

[0010] In one embodiment, the diffusion channel includes a first channel, and in the plane containing the second side, the opening of the first channel extends along a first direction to form a linear opening.

[0011] In one embodiment, the diffusion channel includes a plurality of first channels, each of the first channels being arranged at intervals within the plane containing the second side; and / or,

[0012] The diffusion channel further includes at least one second channel, wherein the opening of the second channel extends along a second direction to form a linear opening in the plane containing the second side.

[0013] In one embodiment, the diffusion channel includes a plurality of third channels. In the plane containing the second side, the openings of the third channels are closed to form point-like openings, and the third channels are arranged at intervals in the plane containing the second side.

[0014] In one embodiment, the diffusion channel includes a plurality of spaced-apart sub-channels;

[0015] Within the plane containing the second side, the opening of the sub-channel extends along the first direction to form a linear opening, and the spacing between adjacent sub-channels is greater than or equal to 0.5 mm and less than or equal to 3 mm; or,

[0016] Within the plane containing the second side, the opening of the sub-channel is closed to form a dotted opening, and the distance between adjacent sub-channels is greater than or equal to 0.3 mm and less than or equal to 3 mm.

[0017] In one embodiment, the recess depth of the diffusion channel is greater than or equal to 10% of the coating thickness and less than or equal to 50% of the coating thickness; and / or,

[0018] The opening width of the diffusion channel on the second side is greater than or equal to 50 μm and less than or equal to 300 μm.

[0019] In one embodiment, along the direction from the second side to the first side, the cross-sectional area of ​​at least a portion of the diffusion channel gradually decreases; and / or,

[0020] From the first side to the second side, the porosity of the coating gradually increases; and / or,

[0021] The porosity of the coating in the region near the first side is greater than or equal to 20% and less than or equal to 30%; and / or,

[0022] The porosity of the coating in the region near the second side is greater than or equal to 35% and less than or equal to 45%.

[0023] In one embodiment, the coating includes a first sub-coating and a second sub-coating. The first sub-coating is located on the side of the coating close to the current collector, and the second sub-coating is located on the side of the first sub-coating away from the current collector. The porosity of the first sub-coating is within a first pore range, and the porosity of the second sub-coating is within a second pore range, wherein the second pore range is greater than the first pore range.

[0024] In one embodiment, the minimum value of the first pore size range is 20%, and the maximum value of the first pore size range is 30%; and / or,

[0025] The difference between the second pore range and the first pore range is greater than or equal to 4% and less than or equal to 6%.

[0026] In one embodiment, the diffusion channel includes a plurality of first channels, each first channel being arranged at intervals in the plane containing the second side, the interval between the first channels being greater than or equal to 1 mm and less than or equal to 2 mm; and / or,

[0027] The recess depth of the first channel is greater than or equal to 30% of the coating thickness and less than or equal to 40% of the coating thickness; and / or,

[0028] The opening width of the first channel on the second side is greater than or equal to 50 μm and less than or equal to 100 μm.

[0029] In one embodiment, the spacing between the third channels is greater than or equal to 0.5 mm and less than or equal to 1 mm; and / or,

[0030] The recess depth of the third channel is greater than or equal to 25% of the coating thickness and less than or equal to 35% of the coating thickness; and / or,

[0031] The opening width of the third channel on the second side is greater than or equal to 50 μm and less than or equal to 100 μm.

[0032] A second aspect of this application provides a battery cell, the battery cell comprising the battery electrodes described in any one of the above embodiments.

[0033] A third aspect of this application provides an electrochemical device, the electrochemical device comprising the battery cell described in any one of the above embodiments.

[0034] The embodiments of this application have the following beneficial effects:

[0035] This application provides a battery electrode, a battery cell, and an electrochemical device. The battery electrode includes a current collector and a coating. The coating is located on one side of the current collector and includes a first side and a second side. The first side is located on the side of the coating closer to the current collector, and the second side is located on the side of the coating away from the current collector. A portion of the second side is recessed towards the first side to form a diffusion channel. This recessed portion of the second side forms a diffusion channel, serving as a rapid diffusion channel for lithium ions within the battery electrode. This rapid diffusion channel reduces the tortuosity of the battery electrode. It not only increases the contact area and contact speed between the electrolyte and the coating, allowing the electrolyte to diffuse rapidly within the coating, but also improves the lithium ion diffusion coefficient, thereby improving the electrolyte wetting efficiency. Simultaneously, it reduces the risk of poor wetting in the central area of ​​the battery electrode and lithium ion diffusion during high-current charging and discharging. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the structure of a battery electrode provided in the first embodiment of this application, showing the distribution of the first channel on the coating;

[0037] Figure 2 This is a schematic diagram of the structure of a battery electrode provided in the second embodiment of this application, showing the distribution of the first channel on the coating;

[0038] Figure 3 This is a schematic diagram of the structure of a battery electrode provided in the third embodiment of this application, showing the distribution of the first channel on the coating;

[0039] Figure 4 This is a schematic diagram of the structure of a battery electrode provided in the fourth embodiment of this application, showing the distribution of the first channel and the second channel on the coating;

[0040] Figure 5 This is a schematic diagram of the structure of a battery electrode provided in the fifth embodiment of this application, showing the distribution of the third channel on the coating;

[0041] Figure 6 This is a cross-sectional view of the coating provided in the sixth embodiment of this application. The figure shows that the cross-sectional area of ​​the diffusion channel gradually decreases linearly from the second side to the first side.

[0042] Figure 7 This is a cross-sectional view of the coating provided in the seventh embodiment of this application. The figure shows that the cross-sectional area of ​​the diffusion channel gradually decreases non-linearly from the second side to the first side.

[0043] Figure 8This is a cross-sectional view of the coating provided in the eighth embodiment of this application, showing that the cross-sectional area of ​​a portion of the diffusion channel gradually decreases along the direction from the second side to the first side;

[0044] Figure 9 This is a schematic diagram of the structure of a battery electrode provided in the ninth embodiment of this application;

[0045] Figure 10 This is a schematic diagram of the structure of a battery electrode provided in the tenth embodiment of this application;

[0046] Figure 11 This is an image showing the electrolyte wetting effect on the shell side of the control group in one embodiment of this application. The orange area in the image represents the area where wetting is complete.

[0047] Figure 12 This is a diagram showing the electrolyte wetting effect in the control group JR in one embodiment of this application. The orange area in the diagram represents the area where wetting is completed.

[0048] Figure 13 This is an image showing the electrolyte wetting effect on the control group JR side in one embodiment of this application. The orange area in the image represents the area where wetting is complete.

[0049] Figure 14 This is a diagram showing the electrolyte wetting effect on the shell side of the experimental group in one embodiment of this application. The orange area in the diagram represents the area where wetting is completed.

[0050] Figure 15 This is a diagram showing the electrolyte wetting effect in experimental group JR in one embodiment of this application. The orange area in the diagram represents the area where wetting is completed.

[0051] Figure 16 This is a diagram showing the electrolyte wetting effect on the JR side of the experimental group in one embodiment of this application. The orange area in the diagram represents the area where wetting is completed.

[0052] Figure 17 This is a comparison chart of the lithium plating rates of experimental group 1, experimental group 2 and control group in one embodiment of this application;

[0053] Figure 18 This is a graph showing the comparison results of the low-temperature capacity retention rates of experimental group 1, experimental group 2, and control group in one embodiment of this application.

[0054] Explanation of reference numerals in the attached figures

[0055] 10. Current collector; 11. Coating; 111. First side surface; 112. Second side surface; 113. Diffusion channel; 113a. First channel; 113b. Second channel; 113c. Third channel; 114. First sub-coating; 115. Second sub-coating; 116. Third sub-coating. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. The described embodiments should not be regarded as limitations on this application. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0057] In the following description, references are made to “some embodiments,” which describe a subset of all possible embodiments. However, it is understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0058] In the description of the embodiments of this application, technical terms such as "first," "second," and "third" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0059] Unless otherwise defined, all technical and scientific terms used in the embodiments of this application have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in the embodiments of this application is for the purpose of describing the embodiments of this application only and is not intended to limit this application.

[0060] One embodiment of this application provides a battery electrode; please refer to [link / reference]. Figure 1 and Figure 9 The battery electrode includes a current collector 10 and a coating 11.

[0061] The coating 11 is located on one side of the current collector 10. The coating 11 includes a first side 111 and a second side 112. The first side 111 is located on the side of the coating 11 close to the current collector 10, and the second side 112 is located on the side of the coating 11 away from the current collector 10. A portion of the second side 112 is recessed toward the first side 111 to form a diffusion channel 113.

[0062] Specifically, battery electrodes refer to components that participate in electrochemical reactions during the charging and discharging process of a battery, enabling the storage and release of energy.

[0063] Current collector 10 refers to a component used to collect and conduct current.

[0064] The material type of the current collector 10 is not limited.

[0065] For example, the material type of the current collector 10 is metal.

[0066] The structure of the current collector 10 is not limited.

[0067] For example, current collector 10 is copper foil.

[0068] Coating 11 refers to the part of the battery electrode used to store electrical energy, which includes active materials, conductive agents, and binders.

[0069] The porosity range of the coating is unlimited.

[0070] For example, the porosity of the region of coating 11 near the first side 111 is less than the porosity of the region of coating 11 near the second side 112. This improves the lithium-ion diffusion rate, thereby enhancing the cell's dynamic performance and achieving a balance between high energy density and fast charging performance.

[0071] The first side 111 refers to the side of the coating 11 that is close to the current collector 10.

[0072] The second side 112 refers to the side of the coating 11 that faces away from the current collector 10.

[0073] Diffusion channel 113 refers to the channel in coating 11 used to provide a path for lithium-ion transport.

[0074] The formation method of diffusion channel 113 is not limited.

[0075] For example, diffusion channels 113 are formed on the second side 112 of the battery electrode by etching.

[0076] The shape of diffusion channel 113 is not limited.

[0077] For example, the opening shape of the diffusion channel 113 is dot-shaped.

[0078] For example, the diffusion channel 113 includes a first channel 113a, and the opening of the first channel 113a extends along a first direction to form a linear opening in the plane of the second side surface 112. This allows the electrolyte to be guided to diffuse directionally along the first direction, preventing disordered diffusion of the electrolyte in the coating 11, thereby improving the diffusion coefficient of lithium ions and thus enhancing the wetting efficiency of the electrolyte.

[0079] Specifically, the linear opening refers to the opening of the first channel 113a on the second side 112 extending in a linear shape.

[0080] The direction of extension of the first direction is not limited.

[0081] For example, when the first direction is parallel to the long side of the battery electrode, the extension direction of the opening of the first channel 113a is parallel to the long side of the battery electrode.

[0082] For example, when the first direction is parallel to the short side of the battery electrode, the extension direction of the opening of the first channel 113a is parallel to the short side of the battery electrode.

[0083] Of course, the first direction can also be other directions.

[0084] In the battery electrode of this embodiment, the coating 11 is located on one side of the current collector 10. The coating 11 includes a first side surface 111 and a second side surface 112. The first side surface 111 is located on the side of the coating 11 closer to the current collector 10, and the second side surface 112 is located on the side of the coating 11 away from the current collector 10. A portion of the second side surface 112 is recessed towards the first side surface 111 to form a diffusion channel 113. Thus, the recessed portion of the second side surface 112 forms a diffusion channel 113, which serves as a rapid diffusion channel 113 for lithium ions within the battery electrode. This rapid diffusion channel 113 reduces the tortuosity of the battery electrode. This not only increases the contact area and contact speed between the electrolyte and the coating 11, allowing the electrolyte to diffuse rapidly within the coating 11, but also improves the lithium ion diffusion coefficient, thereby improving the electrolyte wetting efficiency. Simultaneously, it reduces the risk of poor wetting in the central area of ​​the battery electrode and lithium ion diffusion during high-current charging and discharging.

[0085] In one embodiment, please refer to Figure 1 , Figure 2 and Figure 3 The diffusion channel 113 includes a plurality of first channels 113a, which are spaced apart in the plane of the second side 112. Thus, the spaced arrangement of the plurality of first channels 113a can improve the wetting rate of the battery electrode, and can also make the wetting and ion transport of the entire battery electrode more uniform, improve the consistency of battery performance, and reduce the overall performance degradation of the battery caused by local performance differences.

[0086] Specifically, the spacing between adjacent first channels 113a can be the same or different.

[0087] For example, the spacing between adjacent first channels 113a located in the central region of the battery electrode is smaller than the spacing between adjacent first channels 113a located in the edge region of the battery electrode. This increases the diffusion flux of electrolyte and lithium ions in the central region of the battery electrode, thereby meeting the requirement for rapid diffusion in the central region of the battery electrode.

[0088] In one embodiment, please refer to Figure 4 The diffusion channel 113 further includes at least one second channel 113b, in the plane of the second side 112, the opening of the second channel 113b extends along the second direction to form a linear opening. This further enhances the wetting rate of the electrolyte on the battery electrode.

[0089] Specifically, the direction of extension of the second direction is not limited.

[0090] For example, the extension direction of the second direction is parallel to the extension direction of the first direction.

[0091] For example, the extension direction of the second direction forms an angle with the extension direction of the first direction.

[0092] The number of second channels 113b is unlimited.

[0093] For example, diffusion channel 113 includes a second channel 113b.

[0094] For example, the diffusion channel 113 includes a plurality of second channels 113b, and each second channel 113b is arranged at intervals in the plane on which the second side 112 is located.

[0095] Specifically, the spacing between adjacent second channels 113b can be the same or different.

[0096] In one embodiment, please refer to Figure 5 The diffusion channel includes multiple third channels 113c. Within the plane of the second side surface 112, the openings of the third channels 113c are closed to form point-like openings. The third channels 113c are arranged at intervals within the plane of the second side surface 112. This further reduces the tortuosity of the battery electrode, thereby further improving the effective diffusion coefficient of lithium ions.

[0097] Specifically, the shape of the dotted openings is not limited.

[0098] For example, the shape of a dotted opening is circular.

[0099] For example, the shape of a dotted opening is rectangular.

[0100] Of course, the shape of the dotted opening can also be an irregular shape.

[0101] The direction of the arrangement of each third channel 113c interval is not limited.

[0102] For example, some of the third channels 113c are arranged at intervals along the long side of the battery electrode.

[0103] For example, some of the third channels 113c are arranged at intervals along the short side of the battery electrode.

[0104] For example, the third channel 113c is arranged in an alternating pattern within the plane containing the second side 112.

[0105] In one embodiment, please refer to Figure 1 , Figure 2 , Figure 3 and Figure 4The diffusion channel 113 includes multiple spaced sub-channels. Within the plane of the second side surface 112, the openings of the sub-channels extend along a first direction to form linear openings. The spacing between adjacent sub-channels is greater than or equal to 0.5 mm and less than or equal to 3 mm. For example, the spacing between adjacent sub-channels can be 0.5 mm, 1 mm, 2 mm, or 3 mm. Maintaining the spacing between adjacent sub-channels within the aforementioned range improves the wetting efficiency of the electrolyte on the battery electrode.

[0106] In one embodiment, please refer to Figure 5 The diffusion channel 113 includes multiple spaced sub-channels. Within the plane of the second side surface 112, the openings of the sub-channels are closed to form dotted openings. The spacing between adjacent sub-channels is greater than or equal to 0.3 mm and less than or equal to 3 mm. For example, the spacing between adjacent sub-channels can be 0.3 mm, 0.5 mm, 1 mm, 2 mm, or 3 mm. Maintaining the spacing between adjacent sub-channels within the aforementioned range improves the wetting efficiency of the electrolyte on the battery electrode.

[0107] In one embodiment, please refer to Figure 6 , Figure 7 and Figure 8 The depth of the diffusion channel 113 is greater than or equal to 10% of the thickness of coating 11 and less than or equal to 50% of the thickness of coating 11. For example, the depth of the diffusion channel 113 is 10%, 20%, 30%, 40%, or 50% of the thickness of coating 11. By keeping the depth of the diffusion channel 113 within the above range, the tortuosity of the battery electrode can be reduced and the wetting efficiency of the electrolyte on the battery electrode can be improved.

[0108] Specifically, the recess depth of the diffusion channel 113 refers to the recess depth of a portion of the second side surface 112 in the direction toward the first side surface 111.

[0109] In one embodiment, please refer to Figure 6 , Figure 7 and Figure 8 The opening width of the diffusion channel 113 on the second side 112 is greater than or equal to 50 μm and less than or equal to 300 μm. For example, the opening width of the diffusion channel 113 on the second side 112 is 50 μm, 100 μm, 150 μm, 250 μm, or 300 μm. Therefore, by maintaining the opening width of the diffusion channel 113 on the second side 112 within the above range, the electrolyte can diffuse rapidly in the coating 11 while increasing the diffusion coefficient of lithium ions, thereby improving the wetting efficiency of the electrolyte.

[0110] In one embodiment, please refer to Figure 6 , Figure 7 and Figure 8Along the direction from the second side 112 to the first side 111, the cross-sectional area of ​​at least a portion of the diffusion channel 113 gradually decreases. This effectively guides the transport of lithium ions and increases the diffusion rate of lithium ions.

[0111] Specifically, the cross-sectional area of ​​at least a portion of the diffusion channel 113 may decrease gradually in a linear or non-linear manner.

[0112] The gradual decrease in the cross-sectional area of ​​at least a portion of the diffusion channel 113 can mean that the cross-sectional area of ​​the entire diffusion channel 113 gradually decreases, or that the cross-sectional area of ​​a portion of the diffusion channel 113 gradually decreases.

[0113] In one embodiment, please refer to Figure 9 From the first side 111 to the second side 112, the porosity of the coating 11 gradually increases. This improves the diffusion rate of lithium ions, thereby enhancing the cell's dynamic performance and achieving a balance between high energy density and fast charging performance.

[0114] Specifically, the porosity of coating 11 can increase gradually in a linear relationship or in a non-linear relationship.

[0115] In one embodiment, please refer to Figure 9 The porosity of the region of coating 11 near the first side 111 is greater than or equal to 20% and less than or equal to 30%. For example, the porosity of the region of coating 11 near the first side 111 is 20%, 25%, or 30%. Therefore, maintaining the porosity of the region of coating 11 near the first side 111 within the above range ensures that there is sufficient active material and conductive agent to connect with each other on the side of coating 11 near the current collector 10, maintaining good electronic conductivity. It also provides sufficient transport channels for lithium ions, improving the lithium ion diffusion coefficient.

[0116] In one embodiment, please refer to Figure 9 The porosity of the region of coating 11 near the second side 112 is greater than or equal to 35% and less than or equal to 45%. For example, the porosity of the region of coating 11 near the second side 112 is 35%, 40%, or 45%. Thus, by keeping the porosity of the region of coating 11 near the first side 111 within the above range, the electrolyte can spread rapidly on the surface of coating 11 and penetrate deeply, shortening the wetting time after electrolyte injection into the battery electrode and thereby improving the wetting efficiency of the electrolyte.

[0117] In one embodiment, please refer to Figure 10The coating 11 includes a first sub-coating 114 and a second sub-coating 115. The first sub-coating 114 is located on the side of the coating 11 closer to the current collector 10, and the second sub-coating 115 is located on the side of the first sub-coating 114 away from the current collector 10. The porosity of the first sub-coating 114 is within a first pore range, and the porosity of the second sub-coating 115 is within a second pore range, which is larger than the first pore range. This improves the lithium-ion diffusion rate, thereby enhancing the cell's dynamic performance and achieving a balance between high energy density and fast charging performance.

[0118] Specifically, the first sub-coating 114 refers to the sub-coating 11 on the side of coating 11 closest to the current collector 10.

[0119] The second sub-coating 115 refers to the sub-coating 11 located on the side of the first sub-coating 114 away from the current collector 10.

[0120] The porosity of the first sub-coating 114 is lower than that of the second sub-coating 115.

[0121] The thickness of the first sub-coating 114 and the second sub-coating 115 is not limited.

[0122] For example, the thickness of the first sub-coating 114 is equal to the thickness of the second sub-coating 115.

[0123] For example, the thickness of the first sub-coating 114 is greater than the thickness of the second sub-coating 115.

[0124] For example, the thickness of the first sub-coating 114 is less than the thickness of the second sub-coating 115.

[0125] The material type of the first sub-coating 114 and the second sub-coating 115 is not limited.

[0126] The material type of the first sub-coating 114 and the material type of the second sub-coating 115 can be the same or different.

[0127] For example, the material of the first sub-coating 114 is a material with good conductivity, thereby ensuring efficient transfer of electrons from the current collector 10.

[0128] For example, the material type of the second sub-coating 115 is a material that is conducive to electrolyte wetting and ion conduction, thereby increasing the lithium ion diffusion coefficient and thus improving the electrolyte wetting efficiency.

[0129] In one embodiment, please refer to Figure 10The minimum value of the first porosity range is 20%, and the maximum value of the first porosity range is 30%. For example, the porosity of the first sub-coating 114 is 20%, 25%, or 30%. Thus, maintaining the first porosity within the above range helps to ensure efficient electron conduction between the current collector 10 and the coating 11, and reduces electron transport losses.

[0130] In one embodiment, please refer to Figure 10 The difference between the second pore range and the first pore range is greater than or equal to 4% and less than or equal to 6%. For example, the difference between the second pore range and the first pore range is 4%, 5%, or 6%. This can improve the diffusion rate of lithium ions, thereby improving the cell's dynamic performance and achieving a balance between high energy density and fast charging performance.

[0131] In one embodiment, the coating 11 further includes a third sub-coating 116, which is located on the side of the first sub-coating 114 away from the current collector 10, and a second sub-coating 115 is located on the side of the third sub-coating 116 away from the first sub-coating 114. The porosity of the third sub-coating 116 is within a third pore range, which is greater than the first pore range and the second pore range is greater than the third pore range.

[0132] Specifically, the third sub-coating 116 refers to coating 11 located between the first sub-coating 114 and the second sub-coating 115.

[0133] The porosity of the third sub-coating 116 is lower than that of the second sub-coating 115.

[0134] The porosity of the first sub-coating 114 is lower than that of the third sub-coating 116.

[0135] The thickness of the third sub-coating 116 is unlimited.

[0136] For example, the thickness of the third sub-coating 116 can be the same as or different from the thickness of the first sub-coating 114.

[0137] For example, the thickness of the third sub-coating 116 can be the same as or different from the thickness of the second sub-coating 115.

[0138] The material type of the third sub-coating 116 can be the same as or different from the material type of the first sub-coating 114.

[0139] The material type of the third sub-coating 116 can be the same as or different from that of the second sub-coating 115.

[0140] In one embodiment, the difference between the third pore range and the first pore range is greater than or equal to 4% and less than or equal to 6%, and the difference between the second pore range and the third pore range is greater than or equal to 4% and less than or equal to 6%.

[0141] Specifically, the porosity of the first sub-coating 114, the third sub-coating 116, and the second sub-coating 115 increases progressively, with the difference between adjacent porosities being greater than or equal to 4% and less than or equal to 6%. This improves the diffusion rate of lithium ions, thereby enhancing the cell's dynamic performance and achieving a balance between high energy density and fast charging performance.

[0142] In one embodiment, the diffusion channel 113 includes a plurality of first channels 113a, each of which is arranged at intervals in the plane containing the second side surface 112. The interval between the first channels 113a is greater than or equal to 1 mm and less than or equal to 2 mm. For example, the interval between the first channels 113a is 1 mm, 1.5 mm, or 2 mm. Thus, by maintaining the interval between the first channels 113a within the above-mentioned range, the wetting efficiency of the electrolyte on the battery electrode can be further improved.

[0143] In one embodiment, the recess depth of the first channel 113a is greater than or equal to 30% of the thickness of the coating 11 and less than or equal to 40% of the thickness of the coating 11. For example, the recess depth of the first channel 113a is 30%, 35%, or 40% of the thickness of the coating 11. Thus, by keeping the recess depth of the first channel 113a within the above range, the tortuosity of the battery electrode can be further reduced, and the wetting efficiency of the electrolyte on the battery electrode sheet can be improved.

[0144] In one embodiment, the opening width of the first channel on the second side 112 is greater than or equal to 50 μm and less than or equal to 100 μm. For example, the opening width of the first channel 113a on the second side 112 is 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, or 100 μm. Thus, by maintaining the opening width of the first channel 113a on the second side 112 within the aforementioned range, the electrolyte can rapidly diffuse within the coating 11 while simultaneously increasing the lithium-ion diffusion coefficient, further improving the electrolyte wetting efficiency.

[0145] In one embodiment, the spacing between the third channels 113c is greater than or equal to 0.5 mm and less than or equal to 1 mm. For example, the spacing between the third channels 113c is 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, or 1.0 mm. Therefore, maintaining the spacing between the third channels 113c within the above range can further improve the wetting efficiency of the electrolyte on the battery electrode.

[0146] In one embodiment, the recess depth of the third channel 113c is greater than or equal to 25% of the thickness of the coating 11 and less than or equal to 35% of the thickness of the coating 11. For example, the recess depth of the third channel 113c is 25%, 30%, or 35% of the thickness of the coating 11. Thus, by keeping the recess depth of the third channel 113c within the above range, the tortuosity of the battery electrode can be further reduced, and the wetting efficiency of the electrolyte on the battery electrode sheet can be improved.

[0147] In one embodiment, the opening width of the third channel 113c on the second side surface 112 is greater than or equal to 50 μm and less than or equal to 100 μm. For example, the opening width of the third channel 113c on the second side surface 112 is 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, or 100 μm. Thus, by maintaining the opening width of the third channel 113c on the second side surface 112 within the aforementioned range, the electrolyte can rapidly diffuse within the coating 11 while simultaneously increasing the lithium ion diffusion coefficient, further improving the electrolyte wetting efficiency.

[0148] In one specific embodiment, the battery electrode includes a first channel 113a, and the coating 11 includes a first sub-coating 114 and a second sub-coating 115. The first sub-coating 114 is located on the side of the coating 11 close to the current collector 10, and the second sub-coating 115 is located on the side of the first sub-coating 114 away from the current collector 10. The spacing between adjacent first channels 113a is greater than or equal to 1 mm and less than or equal to 2 mm. The recess depth of the first channel 113a is greater than or equal to 30% of the thickness of the coating 11 and less than or equal to 40% of the thickness of the coating 11. The opening width of the first channel 113a on the second side 112 is greater than or equal to 50 μm and less than or equal to 300 μm. The porosity of the first sub-coating 114 is greater than or equal to 25% and less than or equal to 30%, and the porosity of the second sub-coating 115 is greater than or equal to 28% and less than or equal to 32%. Therefore, by combining the design of the first sub-coating 114, the second sub-coating 115 and the first channel 113a, the dynamic performance of the battery electrode can be improved, the fast charging and low-temperature performance of the cell can be significantly improved, and the requirements of high energy density and high power performance can be taken into account, thereby enabling the cell to achieve optimal performance.

[0149] In one specific embodiment, the battery electrode includes a third channel 113c, and the coating 11 includes a first sub-coating 114 and a second sub-coating 115. The first sub-coating 114 is located on the side of the coating 11 close to the current collector 10, and the second sub-coating 115 is located on the side of the first sub-coating 114 away from the current collector 10. The spacing between adjacent third channels 113c is greater than or equal to 0.5 mm and less than or equal to 1 mm. The recess depth of the third channel 113c is greater than or equal to 25% of the thickness of the coating 11 and less than or equal to 35% of the thickness of the coating 11. The opening width of the third channel 113c on the second side 112 is greater than or equal to 50 μm and less than or equal to 300 μm. The porosity of the first sub-coating 114 is greater than or equal to 25% and less than or equal to 30%, and the porosity of the second sub-coating 115 is greater than or equal to 28% and less than or equal to 32%. Therefore, by combining the design of the first sub-coating 114, the second sub-coating 115 and the third channel 113c, the dynamic performance of the battery electrode can be improved, the fast charging and low temperature performance of the cell can be significantly improved, and the requirements of high energy density and high power performance can be taken into account, thereby enabling the cell to achieve optimal performance.

[0150] The second embodiment of this application provides a battery cell, including the battery electrode of any of the above embodiments.

[0151] The third embodiment of this application provides an electrochemical device, including the battery cell described in the above embodiments.

[0152] Specifically, the electrochemical device includes a housing, a battery cell, and an electrolyte, with the battery cell and electrolyte located inside the housing.

[0153] The material of the shell is not limited.

[0154] For example, the material of the casing is aluminum.

[0155] In one embodiment, please refer to Figure 11 , Figure 12 , Figure 13 , Figure 14 , Figure 15 and Figure 16 The electrode sheets in the experimental group were immersed in electrolyte for 2 hours, and the immersion effect was compared with that of the electrode sheets in the control group.

[0156] Specifically, under the condition that the battery electrode is immersed in the electrolyte for 2 hours, the immersion effect of the experimental group is better than that of the control group, and the immersion area of ​​the experimental group is increased by 30% to 50% compared with that of the control group.

[0157] experimental group

[0158] The battery electrode includes multiple first channels 113a, the spacing between adjacent first channels 113a is 1.0 mm, and the recess depth of the first channel 113a is 30% of the thickness of the coating 11.

[0159] control group

[0160] The first side 111 and the second side 112 of the battery electrode are not recessed, meaning that the battery electrode does not include the diffusion channel 113.

[0161] In one embodiment, please refer to Figure 17 The results of the comparison of lithium plating ratios between experimental group 1, experimental group 2 and the control group were obtained through experiments.

[0162] Specifically, compared with the control group, the average charging rate of experimental group 1 increased by 0.5C, and the average charging rate of experimental group 2 increased by about 0.8C.

[0163] Experimental group 1

[0164] The battery electrode includes multiple first channels 113a, the spacing between adjacent first channels 113a is 1.0 mm, and the recess depth of the first channel 113a is 30% of the thickness of the coating 11.

[0165] Experimental group 2

[0166] The battery electrode includes multiple first channels 113a, the spacing between adjacent first channels 113a is 0.5mm, and the recess depth of the first channel 113a is 50% of the thickness of the coating 11.

[0167] control group

[0168] The first side 111 and the second side 112 of the battery electrode are not recessed, meaning that the battery electrode does not include the diffusion channel 113.

[0169] In one embodiment, please refer to Figure 18 The results of the low-temperature capacity retention rate of experimental group 1, experimental group 2 and control group were compared through experiments.

[0170] Specifically, at -20℃, compared with the control group, the 1C capacity retention rate of experimental group 1 increased by 4.5%, and that of experimental group 2 increased by 10.1%.

[0171] Experimental group 1

[0172] The battery electrode includes multiple first channels 113a, the spacing between adjacent first channels 113a is 1.0 mm, and the recess depth of the first channel 113a is 30% of the thickness of the coating 11.

[0173] Experimental group 2

[0174] The battery electrode includes multiple first channels 113a, the spacing between adjacent first channels 113a is 0.5mm, and the recess depth of the first channel 113a is 50% of the thickness of the coating 11.

[0175] control group

[0176] The first side 111 and the second side 112 of the battery electrode are not recessed, meaning that the battery electrode does not include the diffusion channel 113.

Claims

1. A battery pole piece, characterized by, The battery pole piece comprises: a current collector; a coating layer located on one side of the current collector, the coating layer comprising a first side and a second side, the first side being located on the side of the coating layer close to the current collector, the second side being located on the side of the coating layer away from the current collector, and a part of the second side being recessed towards the first side to form a diffusion channel.

2. The battery pole piece of claim 1, wherein, The porosity of the region of the coating layer close to the first side is less than the porosity of the region of the coating layer close to the second side.

3. The battery pole piece of claim 1 or 2, wherein, The diffusion channel comprises a first channel, and the opening of the first channel extends in a first direction to form a linear opening in the plane in which the second side is located.

4. The battery pole piece of claim 3, wherein, The diffusion channel comprises a plurality of first channels, and each of the first channels is arranged at intervals in the plane in which the second side is located; and / or, The diffusion channel further comprises at least one second channel, and the opening of the second channel extends in a second direction to form a linear opening in the plane in which the second side is located.

5. The battery electrode of any one of claims 1 or 2, wherein, The diffusion channel comprises a plurality of third channels, and the opening of each of the third channels is closed to form a point-like opening in the plane in which the second side is located.

6. The battery pole piece of claim 1 or 2, wherein, The diffusion channel comprises a plurality of sub-channels arranged at intervals; In the plane in which the second side is located, the opening of the sub-channel extends in a first direction to form a linear opening, and the interval distance between adjacent sub-channels is greater than or equal to 0.5 mm and less than or equal to 3 mm; or, In the plane in which the second side is located, the opening of the sub-channel is closed to form a point-like opening, and the interval distance between adjacent sub-channels is greater than or equal to 0.3 mm and less than or equal to 3 mm.

7. The battery pole piece of any one of claims 1-6, wherein, The recess depth of the diffusion channel is greater than or equal to 10% of the thickness of the coating layer and less than or equal to 50% of the thickness of the coating layer; and / or, The opening width of the diffusion channel on the second side is greater than or equal to 50 μm and less than or equal to 300 μm.

8. The battery pole piece of any one of claims 1-7, wherein, In the direction from the second side to the first side, the cross-sectional area of at least a part of the diffusion channel gradually decreases; and / or, From the first side to the second side, the porosity of the coating layer gradually increases; and / or, The porosity of the region of the coating layer close to the first side is greater than or equal to 20% and less than or equal to 30%; and / or, The porosity of the region of the coating layer close to the second side is greater than or equal to 35% and less than or equal to 45%.

9. The battery pole piece of any of claims 1-7, wherein, The coating layer comprises a first sub-coating layer and a second sub-coating layer, the first sub-coating layer is located on the side of the coating layer close to the current collector, the second sub-coating layer is located on the side of the first sub-coating layer away from the current collector, the porosity of the first sub-coating layer is within a first porosity range, the porosity of the second sub-coating layer is within a second porosity range, and the second porosity range is greater than the first porosity range.

10. The battery pole piece of claim 9, wherein, The minimum value of the first porosity range is 20%, and the maximum value of the first porosity range is 30%; and / or, The difference between the second pore size range and the first pore size range is greater than or equal to 4% and less than or equal to 6%.

11. The battery pole piece of claim 3, wherein, The diffusion channel comprises a plurality of the first channels, each of the first channels is arranged at intervals in a plane in which the second side surface is located, the interval distance of the first channels is greater than or equal to 1 mm and less than or equal to 2 mm; and / or, The recess depth of the first channels is greater than or equal to 30% of the thickness of the coating and less than or equal to 40% of the thickness of the coating; and / or, The opening width of the first channels on the second side surface is greater than or equal to 50 μm and less than or equal to 100 μm.

12. The battery pole piece of claim 5, wherein, The interval distance of the third channels is greater than or equal to 0.5 mm and less than or equal to 1 mm; and / or, The recess depth of the third channels is greater than or equal to 25% of the thickness of the coating and less than or equal to 35% of the thickness of the coating; and / or, The opening width of the third channels on the second side surface is greater than or equal to 50 μm and less than or equal to 100 μm.

13. An electric cell characterized by The battery electrode plate comprises the battery electrode plate according to any one of claims 1-12.

14. An electrochemical device, characterized by, The electrochemical device comprises the battery electrode plate according to claim 13.

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