Pole piece, pole core, battery and electric equipment

Abstract

According to the pole piece, the pole core, the battery and the electric equipment, a first coating part, a second coating part and a third coating part are sequentially arranged on the surface of the pole piece in the first direction, the first parameter degree of the first coating part and the first parameter degree of the third coating part are both larger than the first parameter degree of the second coating part, and the first coating part, the second coating part and the third coating part are the same in thickness. The first parameter is compaction density or surface density. In the application, the first coating part and the third coating part with higher first parameters increase the electrochemical impedance, so that more current flows to the second coating part in the middle, thereby effectively increasing the temperature of the middle of the pole piece, and enabling the overall temperature difference of the pole piece to be smaller and the temperature distribution of the pole piece to be uniform.

Description

[0001] The present application claims priority to the Chinese patent application No. 202420896683.2, filed on April 24, 2024, entitled "Pole piece, pole core, battery and electric device", the whole content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the technical field of batteries, in particular to a pole piece, a pole core, a battery and an electric device. BACKGROUND

[0003] With the development of science and technology, devices powered by batteries are becoming more and more common in life. Existing batteries include lead-acid batteries, lithium batteries and various types. Among them, lithium-ion batteries have been widely used in electric vehicles, mobile terminals and other fields due to their high energy density, environmental friendliness and other advantages. Lithium-ion batteries include positive pole pieces, separators and negative pole pieces. The electrons generated by the electrochemical reaction are collected by the positive pole pieces and the negative pole pieces and are guided to the external circuit, thereby realizing the process of converting chemical energy into electrical energy.

[0004] In the prior art, the temperature of the pole pieces of the battery is not uniform at different positions, which affects the service life of the battery. UTILITY MODEL CONTENT

[0005] The purpose of the present application is to provide a pole piece, a pole core, a battery and an electric device to solve the problem of uneven temperature of the pole piece.

[0006] To achieve the purpose of the present application, the present application provides the following technical solutions:

[0007] In a first aspect, the present application provides a pole piece, the surface of the pole piece is provided with a first coating part, a second coating part and a third coating part in sequence along a first direction, the first parameter of the first coating part and the third coating part is greater than the first parameter of the second coating part, wherein the thickness of the first coating part, the second coating part and the third coating part is the same, and the first parameter is the compaction density or the area density.

[0008] In combination with the first aspect, in a possible implementation manner, the first end of the second coating part in the first direction is connected with the first coating part, the second end of the second coating part in the first direction is connected with the third coating part, and the first parameter of the middle part of the second coating part in the first direction is less than the first parameter of the first end and / or the second end thereof.

[0009] In combination with the first aspect, in a possible implementation manner, the first parameter of the second coating part gradually increases from the middle part of the second coating part in the first direction to the first end and / or the second end thereof.

[0010] With reference to the first aspect, in a possible implementation manner, the pole piece includes a current collector and a tab, the first coating part, the second coating part and the third coating part are all arranged on a same surface of the current collector, and the tab is connected to the current collector, and the first coating part is closer to the tab relative to the second coating part.

[0011] With reference to the first aspect, in a possible implementation manner, the second coating part includes a first region and a second region, a first end of the first region along the first direction is connected to the first coating part, a second end of the first region along the first direction is connected to a first end of the second region along the first direction, and a second end of the second region along the first direction is connected to the third coating part.

[0012] A first parameter of the first region gradually decreases from the first end to the second end, and a compaction density of the second region gradually increases from the first end to the second end.

[0013] With reference to the first aspect, in a possible implementation manner, the second coating part includes a first region, a second region and a third region, the first region, the third region and the second region are sequentially arranged along the first direction, a first end of the first region along the first direction is connected to the first coating part, a second end of the first region along the first direction is connected to a first end of the third region along the first direction, a second end of the third region along the first direction is connected to a first end of the second region along the first direction, and a second end of the second region along the first direction is connected to the third coating part.

[0014] A first parameter of the first region gradually decreases from the first end to the second end, and a first parameter of the second region gradually increases from the first end to the second end.

[0015] With reference to the first aspect, in a possible implementation manner, the first parameter is a compaction density, a ratio of the compaction density of the first coating part to the compaction density of the second coating part is K1,1 < K1 ≤ 1.5, and / or a ratio of the compaction density of the third coating part to the compaction density of the second coating part is K2,1 < K2 ≤ 1.5.

[0016] With reference to the first aspect, in a possible implementation manner, the pole piece is a positive pole piece, the first parameter is a compaction density, a range of the compaction density of the first coating part is 1.8 g / mm 3 ~ 2.8 g / mm 3 , and / or a range of the compaction density of the second coating part is 1.8 g / mm 3 ~ 2.8 g / mm 3And / or, the compaction density of the third coating portion is in the range of 1.8 g / mm². 3 ~2.8g / mm 3 .

[0017] In conjunction with the first aspect, in one possible implementation, the electrode is a negative electrode, the first parameter is the compaction density, and the compaction density of the first coated portion is in the range of 1.1 g / mm². 3 ~1.8g / mm 3 And / or, the compaction density of the second coating portion is in the range of 1.1 g / mm². 3 ~1.8g / mm 3 And / or, the compaction density of the third coating portion is in the range of 1.1 g / mm². 3 ~1.8g / mm 3 .

[0018] In conjunction with the first aspect, in one possible implementation, the first parameter is the compaction density, and the compaction density of the first coating portion is the same as the compaction density of the third coating portion.

[0019] In conjunction with the first aspect, in one possible implementation, the electrode is a positive electrode, the first parameter is areal density, and the areal density range of the first coating portion, the second coating portion, and the third coating portion is all 200 g / m². 2 ~600g / m 2 .

[0020] In conjunction with the first aspect, in one possible implementation, the electrode is a negative electrode, the first parameter is areal density, and the areal density range of the first coating portion, the second coating portion, and the third coating portion is all 150 g / m². 2 ~250g / m 2 .

[0021] In conjunction with the first aspect, the first parameter of the second coating portion increases in gradient from the middle of the second coating portion in the first direction toward its first end and / or second end.

[0022] Secondly, this application provides an electrode core, including the electrode sheet as described in the first aspect, wherein a plurality of the electrode sheets are stacked or wound together.

[0023] In conjunction with the second aspect, in one possible implementation, each electrode includes a current collector and a tab, and each current collector is provided with a first coating portion, a second coating portion and a third coating portion in sequence along the first direction, and the tab is connected to one end of the current collector near the first coating portion along the first direction;

[0024] The third coating part in one of the two adjacent pole pieces covers the first coating part in the other pole piece.

[0025] In a third aspect, the application further provides a battery comprising a shell and the pole core according to the second aspect, wherein the pole core is accommodated in the shell.

[0026] In a fourth aspect, the application further provides a power consumption device comprising a frame and the battery according to the third aspect, wherein the battery is arranged on the frame.

[0027] In the application, the first parameter of the first coating part and the third coating part on the surface of the pole piece is greater than the first parameter of the second coating part, and the first parameter is the compaction density or the area density. The first coating part and the third coating part with higher first parameter increase the electrochemical impedance, so that more current flows to the second coating part in the middle, thereby effectively raising the temperature in the middle of the pole piece, making the overall temperature difference of the pole piece smaller, and the temperature distribution of the pole piece uniform, thereby improving the service life of the battery, and the thickness of the first coating part, the second coating part and the third coating part is limited to be the same, so as to reduce the manufacturing process and manufacturing difficulty of the pole piece. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0029] Figure 1 Structure schematic diagram of the battery of one embodiment of the application;

[0030] Figure 2 Structure schematic diagram of the pole piece after rolling of one embodiment of the application;

[0031] Figure 3 Structure schematic diagram of the pole piece before rolling of one embodiment of the application;

[0032] Figure 4 Structure schematic diagram of the pole piece before rolling of another embodiment of the application;

[0033] Figure 5 Structure schematic diagram of the pole core of one embodiment of the application.

[0034] Explanation of reference signs:

[0035] 100, battery; 110, separator; 120, electrode sheet; 121, current collector; 122, tab; 131, first coating part; 132, second coating part; 132a, first region; 132b, second region; 132c, third region; 133, third coating part. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be clearly and completely described in combination with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0037] It should be noted that when a component is referred to as being "fixed" to another component, it can be directly on the other component or there can be an intervening component. When a component is referred to as being "connected" to another component, it can be directly connected to the other component or there can be an intervening component.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The use of the terms "and / or" includes a combination of one or more of the associated listed items.

[0039] Some embodiments of the present application are described in detail below with reference to the accompanying drawings. The following examples and features in the examples can be combined with each other in the case of no conflict.

[0040] The present application provides a power-using device, which is a device for converting electrical energy into other forms of energy. The power-using device includes an electric vehicle, a mobile phone and a computer. The power-using device is powered by a battery to operate the device. The battery is fixed to the power-using device by a frame.

[0041] For an electric vehicle, the electric vehicle includes a vehicle frame, a battery and a drive motor. The battery and the drive motor are mounted on the vehicle frame. The battery serves as the main energy source of the vehicle and is used to store and release electrical energy. The battery provides electrical energy for the drive motor to drive the vehicle to travel.

[0042] Reference Figure 1The battery 100 includes a diaphragm 110 and a pole core, the pole core includes a plurality of pole pieces 120 arranged in a stack, and the diaphragm 110 is arranged between two adjacent pole pieces 120. The battery 100 further includes a shell and an electrolyte, the shell is used to accommodate the electrolyte, the diaphragm 110 and the pole core, and the electrolyte is used as a medium for transferring ions. One of the two adjacent pole pieces 120 is a positive pole piece, and the other is a negative pole piece. The electrons generated by the electrochemical reaction are collected through the positive pole piece and the negative pole piece and led to the external circuit, thereby realizing the process of converting chemical energy into electrical energy. Because the pole piece 120 generates a large amount of heat at the current collection point, when the pole piece 120 is manufactured, a coating area with different compaction densities / surface densities is formed on the pole piece 120. The coating area with high compaction density / surface density can increase the electrochemical impedance, so that more current flows to the coating area with low compaction density / surface density, so that the overall heat generation of the pole piece 120 is uniform.

[0043] With reference to Figure 1 、 Figure 2 and Figure 3 , in the embodiment of the present application, the length direction / width direction of the pole piece 120 is the first direction X, and the thickness direction of the pole piece is the second direction Y.

[0044] The surface of the pole piece 120 is sequentially provided with a first coating part 131, a second coating part 132 and a third coating part 133 along the first direction X, the first parameters of the first coating part 131 and the third coating part 133 are both greater than the first parameter of the second coating part 132, and the first end of the second coating part 132 in the first direction X is connected with the first coating part 131. In this embodiment, the first coating part and the third coating part with higher first parameters increase the electrochemical impedance, so that more current flows to the second coating part in the middle, thereby effectively raising the temperature in the middle of the pole piece, so that the overall temperature difference of the pole piece is small and the temperature distribution of the pole piece is uniform.

[0045] Specifically, the first coating part 131, the second coating part 132 and the third coating part 133 all have active materials, which are responsible for storing and releasing energy. In the lithium ion battery 100, the active material on the positive pole piece can be a transition metal oxide, such as lithium cobaltate, lithium nickelate, lithium manganate, etc., and the active material on the negative pole piece can be graphite, silicon or tin, etc.

[0046] It should be noted that compaction density refers to the mass of a substance per unit volume, while areal density refers to the mass of a substance per unit area. Compaction density equals areal density divided by the thickness of the substance. In lithium-ion batteries, the thickness of each coating portion in the positive and negative electrode sheets is kept as consistent as possible. When the areal densities of the first coating portion 131 and the second coating portion 132, and the second coating portion 132 and the third coating portion 133 are different, the compaction densities of the first coating portion 131 and the second coating portion 132, and the second coating portion 132 and the third coating portion 133 will also be different.

[0047] In addition, such as Figure 2 As shown, the fact that the first coating section 131, the second coating section 132, and the third coating section 133 have the same thickness means that after the electrode sheet is rolled, the thickness of the electrode sheet corresponding to the first coating section 131, the second coating section 132, and the third coating section 133 is the same. This results in the areal density or compaction density of the first coating section 131 and the third coating section 133 being greater than that of the second coating section 132. Specifically, having the same thickness for the first coating section 131, the second coating section 132, and the third coating section 133 can reduce the manufacturing process and difficulty of the electrode sheet. For example, having the same thickness for the first coating section 131, the second coating section 132, and the third coating section 133, i.e., the same electrode sheet thickness, makes it easier to stack or wind multiple electrodes, reducing the overall process and manufacturing difficulty.

[0048] In this application, the first parameters of the first coating portion 131 and the third coating portion 133 on the surface of the electrode 120 are both greater than the first parameter of the second coating portion 132, and the thicknesses of the first coating portion, the second coating portion and the third coating portion are the same. The first parameter is the compaction density or the areal density. The higher first parameter of the first coating portion 131 and the third coating portion 133 increases the electrochemical impedance, allowing more current to flow to the second coating portion 132 in the middle, thereby effectively raising the temperature in the middle of the electrode, making the overall temperature difference of the electrode smaller and the temperature distribution of the electrode more uniform, so as to improve the battery life.

[0049] Optionally, the second end of the second coating part 132 in the first direction X is connected with the third coating part 133, and the first parameter of the middle part of the second coating part 132 in the first direction X is less than the first parameter of the first end and / or the second end of the second coating part 132, the first parameter being the compaction density or the areal density, wherein the first coating part 131, the second coating part 132 and the third coating part 133 are arranged on the same surface of the pole piece 120, and the middle part of the second coating part 132 is the region between the first end and the second end of the second coating part 132 in the first direction X. In this embodiment, the first parameter of the middle part of the second coating part 132 in the first direction X is less than the first parameter of the first end and / or the second end of the second coating part 132, so that the first parameter of the second coating part 132 in the first direction X changes, thereby making the stress distribution of the pole piece 120 more uniform after the pole piece 120 is rolled.

[0050] Optionally, the first parameter of the second coating part 132 gradually increases from the middle part of the second coating part 132 in the first direction X to the first end and / or the second end of the second coating part 132. The first parameter of the second coating part 132 gradually increases from the middle part to the first end close to the first coating part 131 and / or the second end close to the third coating part 133, so that the first parameter of the junction between the first coating part 131 and the second coating part 132 and the junction between the second coating part 132 and the third coating part 133 is smoothly transitioned, thereby further improving the uniformity of the stress distribution of the pole piece 120 after the pole piece 120 is rolled.

[0051] Optionally, the first parameter of the second coating part 132 gradually increases from the middle part of the second coating part 132 in the first direction X to the first end and / or the second end of the second coating part 132. The first parameter of the second coating part 132 gradually increases from the middle part to the first end close to the first coating part 131 and / or the second end close to the third coating part 133, so that the first parameter of the junction between the first coating part 131 and the second coating part 132 and the junction between the second coating part 132 and the third coating part 133 is smoothly transitioned, thereby further improving the uniformity of the stress distribution of the pole piece 120 after the pole piece 120 is rolled.

[0052] In the tab 120 provided in the present application, the tab 120 comprises a current collector 121 and a tab 122, the first coating part 131, the second coating part 132 and the third coating part 133 are all arranged on the same surface of the current collector 121, the tab 122 is connected to the current collector 121, and the first coating part 131 is closer to the tab 122 than the second coating part 132. The first direction X. The tab 122 is a bridge connecting the current collector 121 and the external circuit to transmit the current inside the battery 100 to the external circuit. The current in the current collector 121 converges towards the tab 122, so that the heat generation at the end of the current collector 121 close to the tab 122 is larger. The first coating part 131 with higher compaction density / surface density is arranged at the end of the current collector 121 close to the tab 122, which increases the electrochemical impedance of the end of the tab 120 close to the tab 122, so that more current flows to the middle of the tab 120, thereby reducing the heat generation at the end of the tab 120 close to the tab 122, and the temperature difference on the tab 120 is smaller.

[0053] In the examples of the present application, the first coating part 131 is closer to the tab 122 than the second coating part 132. Specifically, in one embodiment, the first coating part 131 is closer to the edge of the current collector 121 connected with the tab 122 than at least part of the second coating part 132. For example, the first coating part 131 and the second coating part 132 are both rectangular, and the length of the first coating part 131 perpendicular to the first direction X is the same as the length of the second coating part 132 perpendicular to the first direction X, then the first coating part 131 is closer to the edge of the current collector 121 connected with the tab 122 than the second coating part 132 as a whole, wherein the first direction X is the arrangement direction of the first coating part 131 and the second coating part 132, for example, the first direction X can be the length direction of the tab 120, and the first direction X can also be the width direction of the tab 120. In another embodiment, the minimum distance from part of the edge of the second coating part 132 to the edge of the current collector 121 connected with the tab 122 is the same as the minimum distance from the first coating part 131 to the edge of the current collector 121 connected with the tab 122, the first coating part 131 is arranged opposite to the tab 122 in the first direction X, the second coating part 132 is in the shape of "concave", and the second coating part 132 surrounds the outer periphery of the first coating part 131.

[0054] The first direction X is referred to Figure 2 And Figure 3In a possible implementation, the second coating part 132 includes a first region 132a and a second region 132b, the first region 132a is connected with the first coating part 131 at a first end of the first region 132a along the first direction X, the first region 132a is connected with the second region 132b at a second end of the first region 132a along the first direction X and a first end of the second region 132b along the first direction X, and the second region 132b is connected with the third coating part 133 at a second end of the second region 132b along the first direction X; the compaction density / surface density of the first region 132a gradually decreases from the first end to the second end of the first region 132a, and the compaction density / surface density of the second region 132b gradually increases from the first end to the second end of the second region 132b. In this implementation, the middle part of the second coating part 132 is the joint position of the first region 132a and the second region 132b. Specifically, after the pole piece 120 is rolled, the sizes of the first coating part 131, the second coating part 132, and the third coating part 133 in the second direction Y are consistent; the compaction density / surface density of the first region 132a of the second coating part 132 gradually decreases from one end close to the first coating part 131 to one end close to the second region 132b, and the compaction density / surface density of the second region 132b gradually decreases from one end close to the third coating part 133 to one end close to the first region 132a, so that, before the pole piece 120 is rolled, the size of the first coating part 131 in the second direction Y is consistent, the size of the third coating part 133 in the second direction Y is consistent, the size of the first region 132a in the second direction Y gradually decreases from one end close to the first coating part 131 to one end close to the second region 132b, and the height of the second region 132b in the length direction of the pole piece 120 gradually decreases from one end close to the third coating part 133 to one end close to the first region 132a, so that the stress distribution is more uniform after the first coating part 131, the second coating part 132, and the third coating part 133 are rolled to the same height.

[0055] Reference Figure 2 and Figure 4In another possible implementation, the second coating part 132 comprises a first region 132a, a third region 132c and a second region 132b arranged in sequence along the first direction X, the first region 132a is connected with the first coating part 131 at a first end of the first direction X, the first region 132a is connected with a first end of the third region 132c at a second end of the first direction X, the third region 132c is connected with a first end of the second region 132b at a second end of the first direction X, and the second region 132b is connected with the third coating part 133 at a second end of the first direction X; the compaction density of the first region 132a gradually decreases from the first end to the second end, and the compaction density of the second region 132b gradually increases from the first end to the second end. The second coating part 132 is divided into three regions to gradually change the compaction density at the connection positions of the second coating part 132 with the first coating part 131 and the third coating part 133, so that the stress distribution of the pole piece 120 after rolling is more uniform. In this embodiment, the middle part of the second coating part 132 is the third region 132c, and the third region 132c connects the first region 132a and the second region 132b. Before the pole piece 120 is rolled, the size of the first coating part 131 in the second direction Y is consistent, the size of the third coating part 133 in the second direction Y is consistent, the size of the first region 132a in the second direction Y gradually decreases from one end close to the first coating part 131 to one end close to the third region 132c, the size of the third region 132c in the second direction Y is consistent, the size of the second region 132b in the second direction Y gradually decreases from one end close to the third coating part 133 to one end close to the third region 132c, and the stress distribution of the first coating part 131, the second coating part 132 and the third coating part 133 after rolling to the same height is more uniform.

[0056] Reference Figure 2 and Figure 5In the pole core provided in the present application, the pole core comprises a plurality of pole pieces 120 stacked along a second direction Y, each pole piece 120 comprising a current collector 121 and a tab 122, each current collector 121 sequentially comprising a first coating part 131, a second coating part 132 and a third coating part 133 along a first direction X, and the tab 122 being connected to one end of the current collector 121 close to the first coating part 131 along the first direction X; the third coating part 133 in one of the two adjacent pole pieces 120 covers the first coating part 131 in the other. Specifically, in the two adjacent pole pieces 120 along the second direction Y, the first coating part 131, the second coating part 132 and the third coating part 133 of one pole piece 120 cover the third coating part 133, the second coating part 132 and the first coating part 131 of the other pole piece 120 respectively, so that the current in the two adjacent pole pieces 120 converges to the direction of the tabs 122 at both ends, the compaction density of the first coating part 131 and the third coating part 133 on each current collector 121 is greater than that of the second coating part 132, thereby increasing the electrochemical impedance of each pole piece 120 close to the tabs 122 at both ends, making more current flow to the middle part of the pole piece 120, and making the temperature difference on each pole piece 120 smaller.

[0057] Optionally, the first parameter is the compaction density, and the ratio of the compaction density of the first coating part 131 to the compaction density of the second coating part 132 is K1, 1 < K1≤ 1.5, for example, K1 can be 1.01, 1.02, 1.04, 1.07, 1.09, 1.12, 1.15, 1.18, 1.2, 1.3, 1.4, 1.5, etc., but is not limited to the listed values, and other values not listed in the value range are also applicable. Specifically, when the ratio K1 of the compaction density of the first coating part 131 to the compaction density of the second coating part 132 is less than or equal to 1.5, the difference in coating thickness between the first coating part 131 and the second coating part 132 during coating can be reduced, thereby improving the manufacturing difficulty in the actual manufacturing process, and at the same time, reducing the stress difference at different positions of the pole piece 120, and reducing the problems of frequent belt breaking and cracking due to uneven distribution of extension and stress during roll pressing and die cutting.

[0058] Optionally, the ratio of the compaction density of the third coating part 133 to the compaction density of the second coating part 132 is K2, 1 < K2 ≤ 1.5, for example, K2 can be 1.01, 1.02, 1.04, 1.07, 1.09, 1.12, 1.15, 1.18, 1.2, 1.3, 1.4, 1.5, etc., but is not limited to the listed values, and other values not listed in the value range are also applicable. When the ratio K2 of the compaction density of the third coating part 133 to the compaction density of the second coating part 132 is ≤ 1.5, the difference in the coating thickness of the third coating part 133 and the second coating part 132 during coating can be reduced, thereby improving the manufacturing difficulty in the actual manufacturing process, and at the same time, reducing the stress difference at different positions of the pole piece 120, and reducing the problem of frequent belt breakage and cracks due to uneven distribution of extension and stress during rolling and die cutting.

[0059] When the pole piece 120 is a positive pole piece of a pole core, and the ratio of the compaction density of the first coating part 131 to the compaction density of the second coating part 132 is K1, and the ratio of the compaction density of the third coating part 133 to the compaction density of the second coating part 132 is K2, the compaction density of the first coating part 131 ranges from 1.8 g / mm 3 to 2.8 g / mm 3 , for example, can be 1.8 g / mm 3 , 1.83 g / mm 3 , 1.85 g / mm 3 , 1.9 g / mm 3 , 2.0 g / mm 3 , 2.05 g / mm 3 , 2.1 g / mm 3 , 2.2 g / mm 3 , 2.25 g / mm 3 , 2.3 g / mm 3 , 2.4 g / mm 3 , 2.45 g / mm 3 , 2.5 g / mm 3 , 2.65 g / mm 3 , 2.7 g / mm 3 , 2.8 g / mm 3 , etc., but is not limited to the listed values, and other values not listed in the value range are also applicable; the compaction density of the second coating part 132 ranges from 1.8 g / mm 3 to 2.8 g / mm 3 , for example, can be 1.8 g / mm 3 , 1.83 g / mm 3 , 1.85 g / mm 3 , 1.9 g / mm 3, 2.0 g / mm 3 , 2.05 g / mm 3 , 2.1 g / mm 3 , 2.2 g / mm 3 , 2.25 g / mm 3、 2.3 g / mm 3 , 2.4 g / mm 3 , 2.45 g / mm 3 , 2.5 g / mm 3 , 2.65 g / mm 3 , 2.7 g / mm 3 , 2.8 g / mm 3 and the like, but are not limited to the listed values, and other values not listed in the value range are also applicable; the compaction density of the third coating portion 133 ranges from 1.8 g / mm 3 to 2.8 g / mm 3 , and can be, for example, 1.8 g / mm 3 , 1.83 g / mm 3 , 1.85 g / mm 3 , 1.9 g / mm 3 , 2.0 g / mm 3 , 2.05 g / mm 3 , 2.1 g / mm 3 , 2.2 g / mm 3 , 2.25 g / mm 3 , 2.3 g / mm 3 , 2.4 g / mm 3 , 2.45 g / mm 3 , 2.5 g / mm 3 , 2.65 g / mm 3 , 2.7 g / mm 3 , 2.8 g / mm 3 and the like, but are not limited to the listed values, and other values not listed in the value range are also applicable. The conductive performance is improved while ensuring the ion movement speed of the active material in the positive electrode sheet.

[0060] In the case where the electrode sheet 120 is a negative electrode sheet, and the ratio of the compaction density of the first coating portion 131 to the compaction density of the second coating portion 132 is K1, and the compaction density of the third coating portion 133 to the compaction density of the second coating portion 132 satisfies the ratio K2, the compaction density of the first coating portion 131 ranges from 1.1 g / mm 3 to 1.8 g / mm 3 , and can be, for example, 1.1 g / mm 3 , 1.13 g / mm 31.1 g / mm 3 1.2 g / mm 3 1.25 g / mm 3 1.3 g / mm 3 1.35 g / mm 3 1.4 g / mm 3 1.45 g / mm 3 1.5 g / mm 3 1.65 g / mm 3 1.7 g / mm 3 1.8 g / mm 3 and the like, but are not limited to the listed values, and other, non-listed values within the numerical range are equally applicable; the second coated portion 132 has a range of compacted densities of 1.1 g / mm 3 1.8 g / mm 3 , for example, can be 1.1 g / mm 3 1.13 g / mm 3 1.15 g / mm 3 1.2 g / mm 3 1.25 g / mm 3 1.3 g / mm 3 1.35 g / mm 3 1.4 g / mm 3 1.45 g / mm 3 1.5 g / mm 3 1.65 g / mm 3 1.7 g / mm 3 1.8 g / mm 3 and the like, but are not limited to the listed values, and other, non-listed values within the numerical range are equally applicable; the third coated portion 133 has a range of compacted densities of 1.1 g / mm 3 1.8 g / mm 3 , for example, can be 1.1 g / mm 3 1.13 g / mm 3 1.15 g / mm 3 1.2 g / mm 3 1.25 g / mm 3 1.3 g / mm 3 1.35 g / mm 3 1.4 g / mm 3 1.45 g / mm 3 1.5 g / mm 3 1.65 g / mm 3 1.7 g / mm 3 1.8 g / mm3 but are not limited to the recited numerical values, and other unrecited numerical values within the numerical range are also applicable. The purpose is to ensure the movement speed of active material ions in the negative electrode sheet while improving the conductivity.

[0061] In the electrode sheet 120 provided in the present application, the compaction density of the first coating part 131 is the same as the compaction density of the third coating part 133. In the manufacturing process of the electrode sheet 120, the first coating part 131 and the third coating part 133 can be coated on the current collector 121 by using the same process, so as to reduce the manufacturing difficulty.

[0062] Optionally, the first parameter is the area density, and when the electrode sheet 120 is a positive electrode sheet of the electrode core, the area density of the first coating part 131, the second coating part 132 and the third coating part 133 ranges from 200 g / m 2 to 600 g / m 2 . For example, it can be 200 g / m 2 , 210 g / m 2 , 220 g / m 2 , 240 g / m 2 , 280 g / m 2 , 300 g / m 2 , 400 g / m 2 , 450 g / m 2 , 500 g / m 2 , 520 g / m 2 , 580 g / m 2 , 600 g / m 2 , etc., but are not limited to the recited numerical values, and other unrecited numerical values within the numerical range are also applicable. The purpose is to ensure that the positive electrode sheet has sufficient active material while making the lithium ions smoothly embedded and extracted.

[0063] Optionally, the first parameter is the area density, and when the electrode sheet 120 is a negative electrode sheet of the electrode core, the area density of the first coating part 131, the second coating part 132 and the third coating part 133 ranges from 150 g / m 2 to 250 g / m 2 . For example, it can be 150 g / m 2 , 155 g / m 2 , 160 g / m 2 , 180 g / m 2 , 190 g / m 2 , 200 g / m 2 , 210 g / m 2 , 220 g / m 2 , 230 g / m 2 , 240 g / m 2 , 240 g / m2 250 g / m 2 but are not limited to the recited numerical values, and other unrecited numerical values within the numerical range are also applicable. This is to ensure that there is sufficient active material in the negative electrode sheet while allowing lithium ions to smoothly intercalate and deintercalate.

[0064] In the description of the embodiments of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the drawings described, and are merely intended to facilitate the description of the present application and simplify the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0065] The above only discloses one preferred embodiment of the present application, and of course cannot limit the scope of the present application. Those skilled in the art can understand that all or part of the processes described above can be implemented, and equivalent changes made in accordance with the claims of the present application, still fall within the scope of the present application.

Claims

1. An electrode sheet, characterized in that, The surface of the electrode sheet is provided with a first coating portion, a second coating portion and a third coating portion in sequence along a first direction. The first parameter of the first coating portion and the third coating portion is greater than the first parameter of the second coating portion. The first coating portion, the second coating portion and the third coating portion have the same thickness, and the first parameter is the compaction density or the areal density.

2. The electrode sheet according to claim 1, characterized in that, The second coating portion is connected to the first coating portion at its first end in the first direction, and the second coating portion is connected to the third coating portion at its second end in the first direction. The first parameter of the middle part of the second coating portion in the first direction is smaller than the first parameter of its first end and / or second end.

3. The electrode sheet according to claim 2, characterized in that, The first parameter of the second coating portion gradually increases from the middle of the second coating portion in the first direction toward its first end and / or second end.

4. The electrode sheet according to claim 1, characterized in that, The electrode includes a current collector and a tab. The first coating portion, the second coating portion, and the third coating portion are all disposed on the same surface of the current collector. The tab is connected to the current collector. The first coating portion is closer to the tab than the second coating portion.

5. The electrode sheet according to claim 4, characterized in that, The second coating portion includes a first region and a second region. A first end of the first region along the first direction is connected to the first coating portion. A second end of the first region along the first direction is connected to the first end of the second region along the first direction. A second end of the second region along the first direction is connected to the third coating portion. The first parameter of the first region gradually decreases from its first end to its second end, and the first parameter of the second region gradually increases from its first end to its second end.

6. The electrode sheet according to claim 4, characterized in that, The second coating section includes a first region, a second region, and a third region. The first region, the third region, and the second region are arranged sequentially along the first direction. The first end of the first region along the first direction is connected to the first coating section. The second end of the first region along the first direction is connected to the first end of the third region along the first direction. The second end of the third region along the first direction is connected to the first end of the second region along the first direction. The second end of the second region along the first direction is connected to the third coating section. The first parameter of the first region gradually decreases from its first end to its second end, and the first parameter of the second region gradually increases from its first end to its second end.

7. The electrode sheet according to claim 1, characterized in that, The first parameter is the compaction density, the ratio of the compaction density of the first coating part to the compaction density of the second coating part is K1, 1 < K1 ≤ 1.5, and / or, the ratio of the compaction density of the third coating part to the compaction density of the second coating part is K2, 1 < K2 ≤ 1.

5.

8. The electrode sheet according to claim 7, characterized in that, The electrode is a positive electrode, the first parameter is the compaction density, and the compaction density of the first coated portion is in the range of 1.8 g / mm². 3 ~2.8g / mm 3 And / or, the compaction density of the second coating portion is in the range of 1.8 g / mm². 3 ~2.8g / mm 3 And / or, the compaction density of the third coating portion is in the range of 1.8 g / mm². 3 ~2.8g / mm 3 .

9. The electrode sheet according to claim 7, characterized in that, The electrode is a negative electrode, the first parameter is the compaction density, and the compaction density of the first coated portion is in the range of 1.1 g / mm². 3 ~1.8g / mm 3 And / or, the compaction density of the second coating portion is in the range of 1.1 g / mm². 3 ~1.8g / mm 3 And / or, the compaction density of the third coating portion is in the range of 1.1 g / mm². 3 ~1.8g / mm 3 .

10. The electrode sheet according to claim 1, characterized in that, The first parameter is the compaction density, and the compaction density of the first coating portion is the same as that of the third coating portion.

11. The electrode sheet according to claim 1, characterized in that, The electrode is a positive electrode, and the first parameter is the areal density. The areal density range of the first coating portion, the second coating portion, and the third coating portion is all 200 g / m³. 2 ~600g / m 2 .

12. The electrode sheet according to claim 1, characterized in that, The electrode is a negative electrode, and the first parameter is the areal density. The areal density range of the first coating portion, the second coating portion, and the third coating portion is 150 g / m³. 2 ~250g / m 2 .

13. The electrode sheet according to claim 2 or 3, characterized in that, The first parameter of the second coating portion increases in gradient from the middle of the second coating portion in the first direction to its first end and / or second end.

14. An electrode core, characterized in that, It includes a plurality of electrodes according to any one of claims 1-13, wherein the plurality of electrodes are stacked or wound together.

15. The electrode core according to claim 14, characterized in that, Each electrode includes a current collector and a tab. Each current collector is provided with a first coating portion, a second coating portion and a third coating portion in sequence along the first direction. The tab is connected to one end of the current collector near the first coating portion along the first direction. The third coating portion in one of the two adjacent electrodes covers the first coating portion in the other electrode.

16. A battery, characterized in that, It includes a housing and an electrode core according to claim 14 or 15, wherein the electrode core is housed within the housing.

17. An electrical appliance, characterized in that, It includes a frame and a battery according to claim 16, wherein the battery is disposed on the frame.

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