Battery electrode plate and battery

Abstract

A battery electrode plate and a battery. The battery electrode plate comprises: a current collector; a first coating disposed on either side or both sides of the current collector; a second coating stacked on the first coating; and at least one recess formed on the second coating. An electrolyte is stored by means of the recess, such that the infiltration effect of the electrolyte on the battery electrode plate is improved and the flow rate of the electrolyte in the battery electrode plate is increased, thereby realizing the increase in the reaction area of an active material on a surface of the battery electrode plate, ameliorating lithium plating on two sides and the middle of the electrode plate and providing an additional space to facilitate ameliorating the expansion effect of the electrode plate, material extrusion, crushing and other conditions, so as to improve the properties of the battery such as cycle and rapid charging and prolong the cycle service life of the battery.

Description

Battery electrode and battery

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on November 16, 2023 with application number 2023231067657 and the Chinese patent application filed with the China Patent Office on November 16, 2023 with application number 2023115355547, the entire contents of the above applications are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of battery technology, and in particular to a battery electrode and a battery. Background Art

[0003] With the rapid development of the new energy era, lithium batteries have also seen rapid growth. In recent years, electronic devices such as mobile phones and tablets have been frequently updated, while hybrid and new energy electric vehicles have become increasingly popular. This has led to higher performance requirements for products in the new energy industry. Consequently, high-performance lithium-ion secondary batteries with large capacity, high energy density, and fast charging and discharging capabilities have attracted widespread attention. However, the resulting safety issues are also of concern, particularly battery fires and explosions, which warrant further attention and resolution. Over the course of long-term battery use, the negative electrode plate expands, causing compression, leading to electrolyte accumulation on both sides of the plate, resulting in lithium deposition at the edges of the negative electrode. This impeded electrolyte backflow can cause the center of the negative electrode plate to burn black due to insufficient electrolyte flow, further impacting the battery's cycling and fast-charging performance. Preventing lithium deposition and reduced capacity retention during cycling and fast-charging due to impeded electrolyte flow within the battery has become a pressing issue. Technical issues

[0004] In order to overcome at least one of the defects described in the above-mentioned prior art, the present application provides a battery electrode to improve the liquid storage capacity of the battery electrode, alleviate the expansion of the battery electrode and lithium deposition on both sides and the middle of the battery electrode, thereby improving the battery cycle and fast charging performance.

[0005] Technical Solution

[0006] In a first aspect, the present application provides a battery electrode, comprising: a current collector; a first coating, the first coating being arranged on any one side or both sides of the current collector; a second coating, the second coating being stacked on the first coating; and at least one groove, the groove being formed on the second coating.

[0007] In this battery electrode, the electrolyte is stored in the groove, which improves the wetting effect of the electrolyte on the battery electrode and the flow rate of the electrolyte in the battery electrode, thereby increasing the reaction area of ​​the active material on the surface of the battery electrode, alleviating lithium deposition on both sides and the middle of the battery electrode, and providing additional space to alleviate the expansion of the electrode and the extrusion and crushing of the material, so as to improve the battery's cycle and fast charging performance, and extend the battery's cycle life.

[0008] In a second aspect, the present application provides a battery comprising the battery electrode as described above. Beneficial effects

[0009] By storing the electrolyte in the grooves, the electrolyte's infiltration effect on the battery pole pieces and the flow rate of the electrolyte in the battery pole pieces are improved, thereby increasing the reaction area of ​​the active material on the surface of the battery pole pieces, alleviating lithium deposition on both sides and the middle of the battery pole pieces, and providing additional space to alleviate the expansion of the pole pieces and the extrusion and crushing of the materials, so as to improve the battery's cycle and fast charging performance and extend the battery's cycle life. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG1 is a schematic structural diagram of a battery electrode in a first embodiment of the present application;

[0011] FIG2 is another structural diagram of the first form of a battery electrode according to an embodiment of the present application;

[0012] FIG3 is a schematic structural diagram of a second type of battery electrode according to an embodiment of the present application;

[0013] FIG4 is a schematic structural diagram of a third type of battery electrode according to an embodiment of the present application;

[0014] FIG5 is a schematic structural diagram of a fourth type of battery electrode according to an embodiment of the present application;

[0015] FIG6 is a schematic structural diagram of a fifth form of a battery electrode according to an embodiment of the present application;

[0016] FIG7 is a schematic structural diagram of a sixth embodiment of a battery electrode sheet according to the present application;

[0017] FIG8 is another structural diagram of a sixth form of a battery electrode according to an embodiment of the present application;

[0018] FIG9 is a schematic structural diagram of a seventh form of a battery electrode according to an embodiment of the present application;

[0019] FIG10 is a schematic structural diagram of the eighth form of the battery electrode according to an embodiment of the present application.

[0020] The meanings of the reference numerals are as follows:

[0021] 1. Current collector; 2. First coating; 3. Second coating; 4. Groove. Modes for Carrying Out the Invention

[0022] In the description of this application, it should be noted that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings. They 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, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limiting this application.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0024] In one embodiment, the areal density of the first coating layer is greater than the areal density of the second coating layer.

[0025] In one embodiment, the compaction density of the first coating layer is greater than the compaction density of the second coating layer.

[0026] In one embodiment, the groove is arranged along the TD direction of the battery electrode sheet or along the MD direction of the battery electrode sheet.

[0027] In one embodiment, the groove is vertically or obliquely arranged along the TD direction of the battery electrode.

[0028] In one embodiment, the inclination angle of the groove is α, and the expression of α is: ;

[0029] Wherein S is the length of the current collector, and L is the width of the active coating.

[0030] In one embodiment, at least two grooves are formed on the second coating layer, and the grooves are cross-distributed or spaced apart.

[0031] In one embodiment, when the groove is constructed by laser etching or layered coating, the depth of the groove on the current collector is d, and the expression of d is: ;

[0032] Wherein a is the length of the groove, b is the width of the groove, d is the depth of the groove on the current collector, P2 is the compaction density of the second coating, w2 is the proportion of active material on the second coating, d2 is the thickness of the second coating, S is the length of the current collector, L is the width of the active coating, d1 is the thickness of the first coating, P1 is the compaction density of the first coating, w1 is the proportion of active material on the first coating, M is the weight of the active material on the active coating, and n is the number of grooves on the current collector.

[0033] In one embodiment, the ratio of active material loss caused by constructing the groove on any side of the current collector is R, and the expression of R is: .

[0034] In one embodiment, when the groove is constructed by rolling, the depth of the groove on the current collector satisfies d≤d2; wherein d is the depth of the groove on the current collector, and d2 is the thickness of the second coating layer.

[0035] In one embodiment, the ratio of active material loss caused by constructing the groove (4) on any side of the current collector (1) is R, and the expression of R is: .

[0036] In one embodiment, 0.01%≤R≤20%.

[0037] In one embodiment, the width of the groove is less than or equal to the width of the active coating.

[0038] In one embodiment, the length of the groove is less than or equal to the length of the current collector.

[0039] Referring to Figures 1 to 10, the present application discloses a battery electrode, which includes a current collector 1, a first coating 2, a second coating 3, and at least one groove 4. In some embodiments, the first coating 2 is provided on any one or both sides of the current collector 1, the second coating 3 is stacked on the first coating 2, and the groove 4 is formed on the second coating 3, wherein both the first coating 2 and the second coating 3 are composed of active materials. Preferably, by providing the groove 4 on the second coating 3, the wettability of the electrolyte to the battery electrode and the liquid storage capacity of the battery electrode are improved, the area of ​​the contact reaction of the active material of the battery electrode is increased, the expansion of the battery electrode and the lithium deposition on the sides and the middle of the battery electrode are alleviated, thereby improving the cycle and fast charging performance of the battery.

[0040] Optionally, one or more grooves 4 are provided on the second coating 3. Optionally, the grooves 4 on the second coating 3 can be determined according to actual conditions. The electrolyte is stored in the grooves 4 to improve the wetting effect of the electrolyte on the battery electrode and the flow rate of the electrolyte in the battery electrode, thereby increasing the reaction area of ​​the active material on the surface of the battery electrode, alleviating lithium deposition on both sides and the middle of the battery electrode, and providing additional space to alleviate the expansion of the electrode and material extrusion, crushing, etc., so as to improve the battery's cycle and fast charging performance, and extend the battery's cycle life.

[0041] Optionally, the first coating layer 2 and the second coating layer 3 are stacked on either side or both sides of the current collector 1 to form an active coating layer. When the first coating layer 2 and the second coating layer 3 are stacked on only one side of the current collector 1, the other side of the current collector 1 may be provided with a corresponding active material to form another active coating layer.

[0042] Optionally, the grooves 4 on the second coating layer 3 can be formed by roller rolling. Preferably, a protrusion is provided on the roller. Optionally, there may be multiple protrusions on the roller. Preferably, the sizes of the multiple protrusions on the roller are different from each other. Further, the setting directions of the multiple protrusions on the roller are different from each other. Optionally, during the coating or cold pressing process, a roller with protrusions of different sizes and different setting directions on the surface is used to roll the second coating layer 3 on the current collector 1 to form multiple grooves 4 of different sizes and different setting directions on the second coating layer 3.

[0043] Optionally, the groove 4 on the second coating 3 can be formed by laser burning. Optionally, after the active material is coated on the current collector 1 and the first coating 2 and the second coating 3 are stacked, the active material on the second coating 3 can be burned by laser to form the groove 4 on the second coating 3; optionally, after the active material coated on the current collector 1 is cold pressed, the active material on the second coating 3 can be burned by laser to form the groove 4 on the second coating 3; optionally, before the current collector 1 stacked with the first coating 2 and the second coating 3 is wound, the active material on the second coating 3 can be burned by laser to form the groove 4 on the second coating 3; further, the active material on the battery pole piece after burning can be adsorbed and removed by equipment such as a dust collector, without the need for an additional process for cleaning the pole piece.

[0044] Optionally, the second coating 3 can be fully coated on the side of the first coating 2 away from the current collector 1, and the groove 4 can be formed on the second coating 3 by laser etching or rolling, that is, the second coating 3 can still exist at the bottom of the groove 4 to reduce the loss of active material; optionally, the second coating 3 can be coated on any area of ​​the side of the first coating 2 away from the current collector 1, and the groove 4 can be directly formed on the second coating 3 by a double-layer coating process, thereby increasing the construction speed of the groove 4 and leaving the bottom of the groove 4 without the second coating 3.

[0045] In some embodiments, the first coating 2 and the second coating 3 are respectively arranged in different areas on the same side of the current collector 1. Optionally, the first coating 2 and the second coating 3 are stacked. Optionally, the first coating 2 is coated on the current collector 1, and the second coating 3 is coated on the first coating 2. Optionally, the surface density of the first coating 2 is greater than the surface density of the second coating 3, and the groove 4 is arranged in the second coating 3 to avoid excessive loss of active material on the current collector 1 after the groove 4 is opened on the second coating 3, which has a great impact on the rated capacity or charge NP ratio of the battery, resulting in low capacity or lithium precipitation and other adverse phenomena, seriously affecting the cycle performance and storage performance of the battery. That is, when the weight of the active material on one side of the current collector 1 is within a preset range, the surface density of the first coating 2 is greater than the surface density of the second coating 3, and the groove 4 is arranged in the second coating 3. The amount of loss of active material caused by setting the groove 4 on the second coating 3 can be reduced, and the impact of setting the groove 4 in the second coating 3 on the cycle performance and storage performance of the battery can be effectively reduced.

[0046] In some embodiments, the battery capacity is positively correlated with the compaction density, that is, the greater the compaction density, the greater the battery capacity. Optionally, the compaction density of the first coating 2 is greater than the compaction density of the second coating 3 to avoid opening the groove 4 on the second coating 3, resulting in a large change in the compaction density of the active material on the current collector 1, resulting in a significant decrease in the battery capacity, thereby reducing the impact of setting the groove 4 on the second coating 3 on the battery capacity.

[0047] In some embodiments, the thickness of the first coating layer 2 is greater than the thickness of the second coating layer 3. Optionally, the first coating layer 2 and the second coating layer 3 are stacked, and the groove 4 is provided in the second coating layer 3 to avoid the formation of the groove 4, which would cause excessive loss of active material on the current collector 1 and affect the cycle performance and storage performance of the battery. That is, by making the thickness of the first coating layer 2 greater than the thickness of the second coating layer 3, the loss of active material caused by providing the groove 4 on the second coating layer 3 is reduced, thereby effectively ensuring the cycle performance and storage performance of the battery after the groove 4 is provided in the second coating layer 3.

[0048] In some embodiments, the first coating 2 and the second coating 3 are respectively arranged in different areas on the same side of the current collector 1. Optionally, the first coating 2 and the second coating 3 are stacked. Optionally, the first coating 2 is coated on the current collector 1, and the second coating 3 is coated on the first coating 2, wherein the surface density of the first coating 2 is greater than the surface density of the second coating 3, and the thickness of the first coating 2 is greater than the thickness of the second coating 3. Furthermore, the compaction density of the first coating 2 is greater than the compaction density of the second coating 3, thereby fully reducing the effect of setting the groove 4 on the second coating 3 on the mass, surface density and compaction density of the active material on the current collector 1, and avoiding a decrease in the capacity, cycle performance and storage performance of the battery due to setting the groove 4 on the second coating 3.

[0049] In some embodiments, the battery pole piece can be a battery positive pole piece. Optionally, the active material can be made of any one or a mixture of lithium ferrous phosphate, ternary materials nickel cobalt manganese, lithium manganate, lithium cobaltate and lithium nickel cobalt aluminum oxide, etc.; optionally, the active material made of any one or a mixture of lithium ferrous phosphate, ternary materials nickel cobalt manganese, lithium manganate, lithium cobaltate and lithium nickel cobalt aluminum oxide, etc. is arranged layer by layer in different areas on the same side of the current collector 1, so that the first coating 2 and the second coating 3 are formed in a stacked manner on the current collector 1.

[0050] In some embodiments, the battery pole piece can be a battery negative pole piece. Optionally, the active material can be made of any one or a mixture of artificial graphite, natural graphite, hard carbon, soft carbon and silicon. Optionally, the active material made of any one or a mixture of artificial graphite, natural graphite, hard carbon, soft carbon and silicon is arranged layer by layer in different areas on the same side of the current collector 1 to form the first coating 2 and the second coating 3 in a stacked arrangement on the current collector 1.

[0051] In some embodiments, the groove 4 on the second coating 3 can be determined according to actual conditions, and the width, length and depth of the groove 4 need to be fully considered to avoid affecting the rated capacity of the battery or the charging N / P ratio as much as possible, where the N / P ratio is the ratio of the negative electrode capacity to the positive electrode capacity of the battery.

[0052] Optionally, the length of the groove 4 is less than or equal to the length of the current collector 1. Optionally, due to the limitations of existing processing technology, the length of the groove 4 is ≥0.005mm, that is, the current minimum value of the length of the groove 4 can be 0.005mm, but with the development of processing technology and corresponding processing equipment, the minimum value of the length of the groove 4 can be further reduced to the range of (0, 0.005mm). Optionally, the maximum value of the length of the groove 4 is equal to the length of the current collector 1, which limits the groove 4 from appearing on the current collector 1 to prevent the phenomenon of pole segment breakage due to uneven tension in subsequent processes such as winding.

[0053] Optionally, the groove 4 is less than or equal to the width of the active coating. Optionally, limited by the existing processing technology, the width of the groove 4 is ≥0.005mm, that is, the current minimum value of the width of the groove 4 can be 0.005mm, but with the development of processing technology and corresponding processing equipment, the minimum value of the width of the groove 4 can be further reduced to the range of (0, 0.005mm). Optionally, the width of the groove 4 can be equal to the width of the active coating, that is, the length of the groove 4 in the MD direction can be equal to the length of the electrode, which also means that the groove 4 can pass through the material area of ​​the battery electrode, but cannot touch the electrode ear. If the electrode ear is damaged, the belt is likely to break during subsequent winding.

[0054] Optionally, the ratio of active material loss caused by constructing the groove 4 on any side of the current collector 1 is R. Preferably, the value range of R is [0.01%, 20%]. The number of the grooves 4 is limited by limiting the amount of active material loss, thereby avoiding excessive loss of active material on the current collector 1, which has a great impact on the rated capacity or charging NP ratio of the battery, resulting in low capacity or lithium precipitation and other adverse phenomena. At the same time, it is avoided that there are too few grooves 4, which cannot effectively store electrolyte, increase the reaction area or alleviate the expansion of the electrode. Preferably, when constructing the groove 4 by laser etching or layered coating process, the loss of active materials that is inevitable in the existing production process affects the opening of the groove 4, so R needs to meet ≥0.01%, and at the same time avoid excessive loss of active materials on the current collector 1, which has a significant impact on the rated capacity or charge NP ratio of the battery, resulting in undesirable phenomena such as low capacity or lithium precipitation, so R needs to meet ≤20%; when constructing the groove 4 by roller pressing process, since the spatial volume of the groove 4 must exist when the roller pressing process is used to construct the groove 4, R needs to meet ≥0.01%. At the same time, the compaction density of the coating at the bottom of the groove 4 will increase during the rolling process, which will affect the rate of lithium deintercalation of the active material in this coating, so R needs to meet ≤20%;

[0055] Optionally, the length and width of the groove 4 on the current collector 1 are set to a and b respectively; the depth of the groove 4 on the current collector 1 is d; the length of the current collector 1 is S; the width of the active coating (that is, the active coating formed by the first coating 2 and the second coating 3) is L; d1 is the thickness of the first coating material area, and d2 is the thickness of the second coating material area; M is the weight of the active material on the active coating; n is the number of grooves 4 on the current collector 1; P1 is the compaction density of the normal area on the current collector 1, that is, the compaction density of the first coating 2; w1 is the proportion of active material on the first coating 2; P2 is the compaction density of the area on the current collector 1 where the groove 4 is provided, that is, the compaction density of the second coating 3, optionally, P1 ≥ P2; w2 is the proportion of active material on the second coating 3;

[0056] Preferably, when the groove 4 is constructed by laser etching or layered coating, the depth d of the groove 4 on the current collector 1 is expressed as follows:

[0057] ;

[0058] When the groove 4 is constructed by rolling, the depth d of the groove 4 on the current collector 1 must satisfy d≤d2, limiting the depth of the groove 4 to prevent the depth from being too large, which may cause the active material at the bottom of the groove 4 to be overly compacted, causing the active material to be "crushed" and unable to normally deintercalate lithium.

[0059] Optionally, referring to FIG3 , the inclination angle of the groove 4 is α;

[0060] Preferably, the expression for the tilt angle α is as follows:

[0061]

[0062] Preferably, when the groove 4 is constructed by laser etching or layered coating, the ratio R of the groove 4 can be expressed as follows:

[0063]

[0064] When the groove 4 is constructed by rolling, the porosity of the material can be ignored, and only the spatial volume of the groove 4 is limited. Therefore, the expression of the ratio R of the groove 4 that can be set is as follows:

[0065]

[0066] In some embodiments, the cross-sectional shape of the groove 4 is not fixed. Optionally, the cross-sectional shape of the groove 4 can be one of a rectangle, a trapezoid, a cone and an arc; optionally, the distribution position of the groove 4 is not fixed. Optionally, the groove 4 is evenly distributed on the second coating 3; optionally, the groove 4 is distributed in a local area of ​​the second coating 3; optionally, the cross-sectional shape of the groove 4 on the same second coating 3 is also not fixed, that is, the cross-sectional shape of the groove 4 on the same second coating 3 can be one or more of a rectangle, a trapezoid, a cone and an arc; optionally, the grooves 4 on the same second coating 3 can be distributed at intervals, that is, the grooves 4 are independent and separated from each other, or the grooves 4 are parallel to each other, or the grooves 4 are cross-distributed. Further, the second coating 3 has both cross-distributed grooves 4 and spaced-distributed grooves 4, that is, the grooves are one or more of cross-distributed and spaced-distributed.

[0067] In some embodiments, a battery includes the battery electrode sheet described above.

[0068] In some embodiments, the form of the battery electrode sheet is as shown in Figures 1 and 2, and the groove 4 on the second coating 3 is vertically arranged along the TD direction of the battery electrode sheet (corresponding to the height direction of the battery), thereby constructing a vertical channel along the TD direction of the battery electrode sheet on the battery electrode sheet, so that the battery electrode sheet can store electrolyte through the vertical channel along the TD direction of the battery electrode sheet, thereby improving the wetting effect of the electrolyte on the battery electrode sheet and the flow rate of the electrolyte in the battery electrode sheet, thereby increasing the reaction area of ​​the active material on the surface of the battery electrode sheet and improving the reaction activity;

[0069] In some embodiments, the second form of the battery electrode is shown in Figure 3, and the groove 4 on the second coating 3 is inclined along the TD direction of the battery electrode (corresponding to the height direction of the battery), thereby constructing an inclined channel along the TD direction of the battery electrode on the battery electrode, so that the battery electrode can greatly increase the reaction area of ​​the active material on the surface of the battery electrode and the ability to store electrolyte through the inclined channel along the TD direction of the battery electrode, thereby improving the wetting effect of the electrolyte on the battery electrode and the flow rate of the electrolyte in the battery electrode, and can also serve as a gas exhaust channel, effectively reducing the pressure inside the battery, improving the safety performance of the battery, and alleviating the occurrence of side reactions between the battery electrodes.

[0070] In some embodiments, form three of the battery electrode is shown in Figure 4, and the groove 4 on the second coating 3 is arranged straight along the MD direction of the battery electrode (corresponding to the width direction of the battery), thereby constructing a straight channel along the MD direction of the battery electrode on the battery electrode, so that the battery electrode can store electrolyte through the straight channel along the MD direction of the battery electrode, thereby improving the wetting effect of the electrolyte on the battery electrode and the flow rate of the electrolyte in the battery electrode, thereby increasing the reaction area of ​​the active material on the surface of the battery electrode and improving the reaction activity, and providing additional space to alleviate the expansion effect of the battery electrode and the extrusion and crushing of the material, while improving the uneven current in the middle and on both sides of the battery electrode.

[0071] In some embodiments, the form of the battery electrode is shown in Figure 5, and the second coating 3 is provided with the groove 4 which is vertically arranged along the TD direction of the battery electrode (corresponding to the height direction of the battery), and the second coating 3 is also provided with the groove 4 which is flatly arranged along the MD direction of the battery electrode (corresponding to the width direction of the battery), thereby constructing a vertical channel along the TD direction of the battery electrode and a flat channel along the MD direction of the battery electrode on the battery electrode. Optionally, the vertical channel and the flat channel are cross-distributed so that the battery electrode can store electrolyte through the channels cross-distributed along the TD direction of the battery electrode and along the MD direction of the battery electrode, thereby improving the wetting effect of the electrolyte on the battery electrode and the flow rate of the electrolyte in the battery electrode, thereby increasing the reaction area of ​​the active material on the surface of the battery electrode and improving the reaction activity, and providing additional space to alleviate the expansion effect of the battery electrode and the extrusion and crushing of the material, and at the same time improving the uneven current in the middle and both sides of the battery electrode.

[0072] In some embodiments, the form of the battery electrode is shown in Figure 6, and the second coating 3 is provided with the groove 4 that is inclined along the TD direction of the battery electrode (corresponding to the height direction of the battery), and the second coating 3 is also provided with the groove 4 that is straight along the MD direction of the battery electrode (corresponding to the width direction of the battery), thereby constructing an inclined channel along the TD direction of the battery electrode and a straight channel along the MD direction of the battery electrode on the battery electrode. Optionally, the inclined channel and the straight channel are cross-distributed so that the battery electrode can pass through the TD direction and the MD direction of the battery electrode. The channels cross-distributed along the MD direction of the battery pole piece greatly increase the reaction area of ​​the active material on the surface of the battery pole piece and the ability to store electrolyte, enhance the wetting effect of the electrolyte on the battery pole piece and the flow rate of the electrolyte in the battery pole piece, improve the battery's cycle and fast charging performance, especially improve the uneven current in the middle and on both sides of the battery pole piece. At the same time, it can also serve as a gas discharge channel, effectively reducing the pressure inside the battery, improving the safety performance of the battery, and can alleviate the occurrence of side reactions between the battery pole pieces. It can further provide additional space to alleviate the expansion of the battery pole piece and the extrusion and crushing of the material.

[0073] In some embodiments, the sixth form of the battery electrode sheet is shown in Figures 7 and 8. The second coating layer 3 is provided with a plurality of grooves 4 vertically arranged along the TD direction of the battery electrode sheet (corresponding to the height direction of the battery), thereby constructing a plurality of vertical channels along the TD direction of the battery electrode sheet on the battery electrode sheet, so that the battery electrode sheet can store electrolyte through the plurality of vertical channels along the TD direction of the battery electrode sheet, thereby improving the infiltration effect of the electrolyte on the battery electrode sheet and the flow rate of the electrolyte in the battery electrode sheet, thereby increasing the reaction area of ​​the active material on the surface of the battery electrode sheet and improving the reaction activity. Furthermore, the plurality of dispersed vertical channels provide additional space to facilitate the alleviation of the expansion effect of the battery electrode sheet and the extrusion and crushing of the material, and can reduce the impedance of the battery electrode sheet;

[0074] Optionally, the second coating 3 is provided with a plurality of grooves 4 arranged in a straight manner along the MD direction of the battery electrode (corresponding to the width direction of the battery), thereby constructing a plurality of straight channels along the MD direction of the battery electrode on the battery electrode, so that the battery electrode can store electrolyte through the plurality of straight channels along the MD direction of the battery electrode, thereby improving the wetting effect of the electrolyte on the battery electrode and the flow rate of the electrolyte in the battery electrode, thereby increasing the reaction area of ​​the active material on the surface of the battery electrode and improving the reaction activity, while improving the battery's cycle and fast charging performance, especially improving the uneven current in the middle and on both sides of the battery electrode. Furthermore, by providing additional space through the dispersed plurality of straight channels, it is convenient to alleviate the expansion effect of the battery electrode and the extrusion and crushing of the material, and can reduce the impedance of the battery electrode.

[0075] In some embodiments, the form of the battery electrode is shown in Figure 9, and the second coating 3 is provided with the groove 4 arranged along the TD direction of the battery electrode (corresponding to the height direction of the battery), and the second coating 3 is also provided with the groove 4 arranged along the MD direction of the battery electrode (corresponding to the width direction of the battery), thereby constructing a channel arranged along the TD direction of the battery electrode and a channel arranged along the MD direction of the battery electrode on the battery electrode. Optionally, the channel arranged along the TD direction of the battery electrode can be independently distributed from the channel arranged along the MD direction of the battery electrode. Optionally, the channel arranged along the TD direction of the battery electrode and the channel arranged along the MD direction of the battery electrode are cross-distributed. Optionally, there is both The channels arranged along the TD direction of the battery electrode can be distributed independently of the channels arranged along the MD direction of the battery electrode, and the channels arranged along the TD direction of the battery electrode and the channels arranged along the MD direction of the battery electrode are cross-distributed, so that the battery electrode can greatly increase the reaction area of ​​the active material on the surface of the battery electrode and the ability to store electrolyte through the channels arranged along the TD direction of the battery electrode and the channels arranged along the MD direction of the battery electrode, improve the wetting effect of the electrolyte on the battery electrode and the flow rate of the electrolyte in the battery electrode, improve the uneven current in the middle and on both sides of the battery electrode, and further provide additional space to alleviate the expansion of the battery electrode and the extrusion and crushing of the material.

[0076] In some embodiments, the form of the battery electrode is shown in Figure 10, and the second coating 3 is provided with the groove 4 arranged along the TD direction of the battery electrode (corresponding to the height direction of the battery), and the second coating 3 is also provided with the groove 4 arranged along the MD direction of the battery electrode (corresponding to the width direction of the battery), wherein the channel arranged along the TD direction of the battery electrode and the channel arranged along the MD direction of the battery electrode are arranged in a cross-distribution, and further, the second coating 3 is also provided with a plurality of channels arranged along the TD direction of the battery electrode and the channels arranged along the MD direction of the battery electrode, which are independent of the cross-distribution. The groove 4 of the channel arranged in the MD direction of the battery electrode is used to construct a cross-distributed channel and a channel independent of the cross-distributed channel on the battery electrode, so that the battery electrode can store electrolyte through the above-mentioned channel, improve the wetting effect of the electrolyte on the battery electrode and the flow rate of the electrolyte in the battery electrode, increase the reaction area of ​​the active material on the surface of the battery electrode, alleviate lithium deposition on both sides and the middle of the electrode, provide additional space to facilitate the alleviation of electrode expansion and material extrusion or crushing, improve the cycle and fast charging performance of the battery, and reduce the impedance of the battery electrode.

Claims

1. A battery electrode, include: current collector(1); A first coating (2), the first coating (2) being arranged on any one side or both sides of the current collector (1); A second coating (3), the second coating (3) being stacked on the first coating (2); At least one groove (4), wherein the groove (4) is formed on the second coating (3).

2. The battery electrode according to claim 1, in: The surface density of the first coating (2) is greater than the surface density of the second coating (3).

3. The battery electrode according to claim 1, in: The compaction density of the first coating (2) is greater than the compaction density of the second coating (3).

4. The battery electrode according to claim 1, in: The groove (4) is arranged along the TD direction of the battery electrode sheet or along the MD direction of the battery electrode sheet.

5. The battery electrode according to claim 4, in: The groove (4) is arranged vertically or obliquely along the TD direction of the battery electrode sheet.

6. The battery electrode according to claim 5, in: The inclination angle of the groove (4) is α, and the expression of α is: ; Wherein S is the length of the current collector (1), and L is the width of the active coating.

7. The battery electrode according to any one of claims 4 to 6, in: At least two grooves (4) are formed on the second coating layer (3), and the grooves (4) are one or more of a cross distribution and an interval distribution.

8. The battery pole piece according to any one of claims 1 to 6, in: When the groove (4) is constructed by laser etching or layered coating, the depth of the groove (4) on the current collector (1) is d, and the expression of d is: ; Wherein a is the length of the groove (4), b is the width of the groove (4), d is the depth of the groove (4) on the current collector (1), and P 2 is the compacted density of the second coating (3), w 2 is the proportion of active material on the second coating (3), d 2 is the thickness of the second coating, S is the length of the current collector (1), L is the width of the active coating, d 1 is the thickness of the first coating, P 1 is the compacted density of the first coating (2), w 1 is the proportion of the active material on the first coating (2), M is the weight of the active material on the active coating, and n is the number of grooves (4) on the current collector (1).

9. The battery electrode according to claim 8, in: The proportion of active material loss caused by constructing the groove (4) on any side of the current collector (1) is R, and the expression of R is: .

10. The battery pole piece according to any one of claims 1 to 6, in: When the groove (4) is formed by rolling, the depth of the groove (4) on the current collector (1) satisfies d≤d 2 ; wherein d is the depth of the groove (4) on the current collector (1), d 2 is the thickness of the second coating.

11. The battery electrode according to claim 10, in: The proportion of active material loss caused by constructing the groove (4) on any side of the current collector (1) is R, and the expression of R is: .

12. The battery pole piece according to claim 9 or 11, in: 0.01%≤R≤20%。 13. The battery electrode according to claim 8, in: The width of the groove (4) is less than or equal to the width of the active coating.

14. The battery electrode according to claim 8, in: The length of the groove (4) is less than or equal to the length of the current collector (1).

15. A battery comprising the battery electrode sheet according to any one of claims 1 to 14.

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