Electrode sheet, electrode core, battery, and electrical device

Abstract

An electrode sheet, an electrode core, a battery, and an electrical device. A first coating portion, a second coating portion, and a third coating portion are sequentially arranged on a surface of the electrode sheet in a first direction. A first parameter of the first coating portion and a first parameter of the third coating portion are both larger than a first parameter of the second coating portion. The thicknesses of the first coating portion, the second coating portion, and the third coating portion are the same, and the first parameter is compaction density or surface density.

Description

Electrode sheets, electrode cores, batteries and electrical equipment

[0001] This application claims priority to Chinese Patent Application No. 202420896683.2, filed on April 24, 2024, entitled "Electrode, Electrode Core, Battery and Electrical Equipment", the entire contents of which are incorporated herein by reference.

[0002] This application claims priority to Chinese Patent Application No. 202423267550.8, filed on December 26, 2024, entitled "Electrode, Electrode Core, Battery and Electrical Equipment", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of battery technology, specifically to an electrode sheet, an electrode core, a battery, and an electrical device. Background Technology

[0004] With the development of science and technology, battery-powered devices are becoming increasingly common in daily life. Existing batteries include various types such as lead-acid batteries and lithium batteries. Among them, lithium-ion batteries are widely used in electric vehicles and mobile terminals due to their advantages such as high energy density and environmental friendliness. A lithium-ion battery consists of a positive electrode, a separator, and a negative electrode. The positive and negative electrodes collect electrons generated by the electrochemical reaction and conduct them to an external circuit, thus converting chemical energy into electrical energy. Because the electrodes generate a significant amount of heat at the current collection points, different compaction density coating areas are formed on the electrodes during manufacturing. High compaction density coating areas reduce the heat generated by the electrodes, ensuring uniform heating.

[0005] In existing technologies, uneven temperature exists at different locations on the battery electrodes, which in turn affects battery life. Summary of the Invention

[0006] The purpose of this application is to provide an electrode, electrode core, battery, and electrical device to solve the problem of uneven electrode temperature.

[0007] To achieve the objectives of this application, the following technical solution is provided:

[0008] In a first aspect, this application provides an electrode sheet, wherein 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, wherein the first parameter of the first coating portion and the third coating portion is greater than the first parameter of the second coating portion, wherein 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.

[0009] In conjunction with the first aspect, in one possible implementation, the second coating portion is connected to the first coating portion at its first end in the first direction, the second coating portion is connected to the third coating portion at its second end in the first direction, and the first parameter of the middle portion of the second coating portion in the first direction is smaller than the first parameter of its first end and / or second end.

[0010] In conjunction with the first aspect, in one possible implementation, 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.

[0011] In conjunction with the first aspect, in one possible implementation, the electrode includes a current collector and a tab, wherein 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, and the first coating portion is closer to the tab than the second coating portion.

[0012] In conjunction with the first aspect, in one possible implementation, 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, and a second end of the second region along the first direction is connected to the third coating portion.

[0013] The first parameter of the first region gradually decreases from its first end to its second end, and the compaction density of the second region gradually increases from its first end to its second end.

[0014] In conjunction with the first aspect, in one possible implementation, the second coating portion includes a first region, a second region, and a third region, wherein the first region, the third region, and the second region are arranged sequentially along the first direction, 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 third region along the first direction, a second end of the third region along the first direction is connected to the 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 portion.

[0015] 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.

[0016] In combination with the first aspect, in a possible implementation, the first parameter is the compaction density, and the ratio of the compaction density of the first coating portion to the compaction density of the second coating portion is K1, where 1 < K1 ≤ 1.5, and / or the ratio of the compaction density of the third coating portion to the compaction density of the second coating portion is K2, where 1 < K2 ≤ 1.5.

[0017] In combination with the first aspect, in a possible implementation, the electrode sheet is a positive electrode sheet, the first parameter is the compaction density, and the compaction density range of the first coating portion is 1.8 g / mm 3 ~2.8 g / mm 3 and / or the compaction density range of the second coating portion is 1.8 g / mm 3 ~2.8 g / mm 3 and / or the compaction density range of the third coating portion is 1.8 g / mm 3 ~2.8 g / mm 3 .

[0018] In combination with the first aspect, in a possible implementation, the electrode sheet is a negative electrode sheet, the first parameter is the compaction density, and the compaction density range of the first coating portion is 1.1 g / mm 3 ~1.8 g / mm 3 and / or the compaction density range of the second coating portion is 1.1 g / mm 3 ~1.8 g / mm 3 and / or the compaction density range of the third coating portion is 1.1 g / mm 3 ~1.8 g / mm 3 .

[0019] In combination with the first aspect, in a possible implementation, 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.

[0020] In combination with the first aspect, in a possible implementation, the electrode sheet is a positive electrode sheet, the first parameter is the areal density, and the areal density ranges of the first coating portion, the second coating portion, and the third coating portion are all 200 g / m 2 ~600 g / m 2 .

[0021] In combination with the first aspect, in a possible implementation, the electrode sheet is a negative electrode sheet, the first parameter is the areal density, and the areal density ranges of the first coating portion, the second coating portion, and the third coating portion are all 150 g / m 2 ~250 g / m 2 .

[0022] 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.

[0023] 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.

[0024] 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;

[0025] The third coating portion in one of the two adjacent electrodes covers the first coating portion in the other electrode.

[0026] Thirdly, this application also provides a battery, including a housing and an electrode core according to the second aspect, the electrode core being housed within the housing.

[0027] Fourthly, this application also provides an electrical device, including a frame and a battery according to the third aspect, the battery being disposed on the frame.

[0028] In this application, the first parameter of the first coating portion and the third coating portion on the electrode surface are both greater than the first parameter of the second coating portion. The first parameter is the compaction density or areal density. The higher first parameter of the first coating portion and the third coating portion increases the electrochemical impedance, allowing more current to flow to the second coating portion 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, thus improving the battery life. Attached Figure Description

[0029] To more clearly illustrate the embodiments disclosed in this application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments disclosed in this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0030] Figure 1 is a schematic diagram of the structure of a battery according to one embodiment of this application;

[0031] Figure 2 is a schematic diagram of the structure of the electrode sheet after rolling according to one embodiment of this application;

[0032] Figure 3 is a schematic diagram of the structure of the electrode sheet before rolling in one embodiment of this application;

[0033] Figure 4 is a schematic diagram of the structure of the electrode sheet before rolling in another embodiment of this application;

[0034] Figure 5 is a schematic diagram of the structure of the electrode core according to one embodiment of this application;

[0035] Figure 6 is a schematic diagram of the battery and frame according to one embodiment of this application.

[0036] Explanation of reference numerals in the attached drawings: 100, battery; 110, separator; 120, electrode; 121, current collector; 122, tab; 131, first coating section; 132, second coating section; 132a, first region; 132b, second region; 132c, third region; 133, third coating section; 200, electrical equipment; 210, frame. Detailed Implementation

[0037] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0038] It should be noted that when a component is said to be "fixed" to another component, it can be directly on the other component or it can be in a middle component. When a component is said to be "connected" to another component, it can be directly connected to the other component or it may be in a middle component.

[0039] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terminology used in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used in this application includes any and all combinations of one or more of the associated listed items.

[0040] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0041] This application provides an electrical device, which is a device for converting electrical energy into other forms of energy. The electrical device includes electric vehicles, mobile phones, and computers. The electrical device is powered by a battery to operate. For example, as shown in FIG6, the battery 100 is fixed to the electrical device 200 by a frame 210.

[0042] For electric vehicles, the components include a frame, a battery, and a drive motor, with the battery and drive motor mounted on the frame. The battery, as the vehicle's primary energy source, stores and releases electrical energy. The battery provides power to the drive motor, propelling the vehicle.

[0043] Referring to Figure 1, this application provides a battery 100, which includes a separator 110 and an electrode core. The electrode core includes multiple electrode sheets 120 stacked together, and the separator 110 is disposed between two adjacent electrode sheets 120. The battery 100 also includes a casing and an electrolyte. The casing is used to contain the electrolyte, separator 110, and electrode core, and the electrolyte serves as a medium for ion transfer. One of two adjacent electrode sheets 120 is a positive electrode, and the other is a negative electrode. Electrons generated by the electrochemical reaction are collected and conducted to an external circuit through the positive and negative electrode sheets, thereby realizing the conversion of chemical energy into electrical energy. Because the electrode sheet 120 generates a large amount of heat at the current collection point, during the manufacturing of the electrode sheet 120, coating areas with different compaction densities / area densities are formed on the electrode sheet 120. The coating area with a higher compaction density / area density can increase the electrochemical impedance, allowing more current to flow to the coating area with a lower compaction density / area density, so that the electrode sheet 120 heats up uniformly as a whole.

[0044] In the prior art, electrode sheets with different compaction densities are prone to uneven stress after rolling, causing the battery to deform during charging and discharging.

[0045] Referring to Figures 1, 2 and 3, in this embodiment of the application, the length / width direction of the electrode 120 is taken as the first direction X, and the thickness direction of the electrode is taken as the second direction Y.

[0046] The surface of the electrode 120 is sequentially provided with a first coating portion 131, a second coating portion 132, and a third coating portion 133 along a first direction X. The first parameter of the first coating portion 131 and the third coating portion 133 is greater than the first parameter of the second coating portion 132. The first end of the second coating portion 132 in the first direction X is connected to the first coating portion 131. The thickness of the first coating portion 131, the second coating portion 132, and the third coating portion 133 is the same, and the first parameter is the compaction density or the areal density. In this embodiment, the first coating portion and the third coating portion with higher first parameters increase the electrochemical impedance, allowing more current to flow to the second coating portion in the middle, thereby effectively raising the temperature in the middle of the electrode, resulting in a smaller overall temperature difference and a more uniform temperature distribution on the electrode.

[0047] Specifically, the first coating section 131, the second coating section 132, and the third coating section 133 all contain active materials responsible for storing and releasing energy. In the lithium-ion battery 100, the active material on the positive electrode can be a transition metal oxide, such as lithium cobalt oxide, lithium nickel oxide, or lithium manganese oxide, while the active material on the negative electrode can be graphite, silicon, or tin.

[0048] 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.

[0049] Furthermore, as shown in Figure 2, the fact that the first coating portion 131, the second coating portion 132, and the third coating portion 133 have the same thickness means that after the electrode sheet is rolled, the thickness of the electrode sheet corresponding to the first coating portion 131, the second coating portion 132, and the third coating portion 133 is the same. This results in the areal density or compaction density of the first coating portion 131 and the third coating portion 133 being greater than the areal density or compaction density of the second coating portion 132.

[0050] 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.

[0051] Optionally, the second end of the second coating portion 132 in the first direction X is connected to the third coating portion 133. The first parameter of the middle portion of the second coating portion 132 in the first direction X is smaller than the first parameter of its first end and / or second end. The first parameter is the compaction density or areal density. The first coating portion 131, the second coating portion 132, and the third coating portion 133 are disposed on the same surface of the electrode 120. The middle portion of the second coating portion 132 is the region located between the first end and the second end of the second coating portion 132 in the first direction X. In this embodiment, the first parameter of the middle portion of the second coating portion 132 in the first direction X is smaller than the first parameter of its first end and / or second end, so that the first parameter of the second coating portion 132 in the first direction X changes, thereby making the stress distribution of the electrode 120 more uniform after the electrode 120 is rolled.

[0052] Optionally, the first parameter of the second coating portion 132 gradually increases from the middle of the second coating portion 132 in the first direction X toward its first end and / or second end. By gradually increasing the first parameter of the second coating portion 132 from the middle toward the first end near the first coating portion 131 and / or the second end near the third coating portion 133, the first parameter at the junction of the first coating portion 131 and the second coating portion 132, and at the junction of the second coating portion 132 and the third coating portion 133, smoothly transitions, thereby further improving the uniformity of stress distribution in the electrode 120 after rolling.

[0053] Optionally, the first parameter of the second coating portion 132 increases in gradient from the middle of the second coating portion 132 in the first direction X towards its first end and / or second end. Increasing the gradient of the first parameter of the second coating portion 132 from the middle towards the first end near the first coating portion 131 and / or the second end near the third coating portion 133 facilitates coating between the first coating portion 131 and the second coating portion 132, further reducing the difficulty of the electrode 120 manufacturing process.

[0054] In the electrode 120 provided in this application, the electrode 120 includes a current collector 121 and a tab 122. A first coating portion 131, a second coating portion 132, and a third coating portion 133 are all disposed on the same surface of the current collector 121. The tab 122 is connected to the current collector 121. The first coating portion 131 is closer to the tab 122 than the second coating portion 132. First direction X. The tab 122 is a bridge connecting the current collector 121 and the external circuit to transfer the current inside the battery 100 to the external circuit. The current in the current collector 121 converges towards the tab 122, resulting in a larger heat generation on the current collector 121 near the tab 122. A first coating portion 131 with a high compaction density / area density is provided on the end of the current collector 121 near the tab 122, which increases the electrochemical resistance of the electrode 120 near the tab 122, allowing more current to flow to the middle of the electrode 120, thereby reducing the heat generation on the electrode 120 near the tab 122 and making the temperature difference on the electrode 120 smaller.

[0055] In this application example, the first coating portion 131 is closer to the tab 122 than the second coating portion 132. Specifically, in one embodiment, the first coating portion 131 is at least partially closer to the edge of the current collector 121 where the tab 122 is connected compared to the second coating portion 132. For example, if both the first coating portion 131 and the second coating portion 132 are rectangular, and the length of the first coating portion 131 in the vertical first direction X is the same as the length of the second coating portion 132 in the vertical first direction X, then the first coating portion 131 is generally closer to the edge of the current collector 121 where the tab 122 is connected compared to the second coating portion 132. The first direction X is the arrangement direction of the first coating portion 131 and the second coating portion 132. For example, the first direction X can be the length direction of the electrode 120, or the width direction of the electrode 120. In another embodiment, when the minimum distance from a portion of the edge of the second coating portion 132 to the edge of the current collector 121 connected to the tab 122 is the same as the minimum distance from the first coating portion 131 to the edge of the current collector 121 connected to the tab 122, the first coating portion 131 is disposed directly opposite to the tab 122 in the first direction X, and the second coating portion 132 is U-shaped, surrounding the outer periphery of the first coating portion 131.

[0056] Referring to Figures 2 and 3, in one possible embodiment, the second coating section 132 includes a first region 132a and a second region 132b. The first region 132a is connected to the first coating section 131 at a first end along the first direction X, and the second end of the first region 132a is connected to the first end of the second region 132b along the first direction X. The second end of the second region 132b is connected to the third coating section 133 at a second end along the first direction X. The compaction density / area density of the first region 132a gradually decreases from its first end to its second end, while the compaction density / area density of the second region 132b gradually increases from its first end to its second end. In this embodiment, the middle portion of the second coating section 132 is the junction of the first region 132a and the second region 132b. Specifically, after the electrode 120 is rolled, the dimensions of the first coating section 131, the second coating section 132, and the third coating section 133 are consistent in the second direction Y. The compaction density / area density of the first region 132a of the second coating section 132 is gradually reduced from the end near the first coating section 131 to the end near the second region 132b, and the compaction density / area density of the second region 132b is gradually reduced from the end near the third coating section 133 to the end near the first region 132a. Therefore, before the electrode 120 is rolled, the first coating section 131... The dimensions in the second direction Y are consistent, the dimensions of the third coating section 133 are consistent in the second direction Y, the dimensions of the first region 132a in the second direction Y gradually decrease from the end near the first coating section 131 to the end near the second region 132b, and the height of the second region 132b in the length direction of the electrode 120 gradually decreases from the end near the third coating section 133 to the end near the first region 132a, so that the stress distribution is more uniform after the first coating section 131, the second coating section 132 and the third coating section 133 are rolled to the same height.

[0057] Referring to Figures 2 and 4, in another possible embodiment, the second coating section 132 includes a first region 132a, a third region 132c, and a second region 132b sequentially arranged along a first direction X. The first region 132a is connected to the first coating section 131 at its first end in the first direction X; the first region 132a is connected to the first end of the third region 132c at its second end in the first direction X; the third region 132c is connected to the first end of the second region 132b at its second end in the first direction X; and the second region 132b is connected to the third coating section 133 at its second end in the first direction X. The compaction density of the first region 132a gradually decreases from its first end to its second end, while the compaction density of the second region 132b gradually increases from its first end to its second end. Dividing the second coating section 132 into three regions allows the compaction density at the junctions of the second coating section 132 with the first coating section 131 and the third coating section 133 to gradually change, resulting in a more uniform stress distribution after the electrode 120 is rolled. In this embodiment, the middle part of the second coating section 132 is the third region 132c, which connects the first region 132a and the second region 132b. Before the electrode 120 is rolled, the first coating section 131 has a consistent size in the second direction Y, the third coating section 133 has a consistent size in the second direction Y, the size of the first region 132a in the second direction Y gradually decreases from the end near the first coating section 131 to the end near the third region 132c, the size of the third region 132c is consistent in the second direction Y, and the size of the second region 132b in the second direction Y gradually decreases from the end near the third coating section 133 to the end near the third region 132c. Similarly, this allows for a more uniform stress distribution after the first coating section 131, the second coating section 132, and the third coating section 133 are rolled to the same height.

[0058] Referring to FIGS. 2 and 5, in the electrode core provided in the present application, the electrode core includes a plurality of electrode sheets 120 stacked in the second direction Y. Each electrode sheet 120 includes a current collector 121 and a tab 122. Along the first direction X, a first coating portion 131, a second coating portion 132, and a third coating portion 133 are sequentially provided on each current collector 121. The tab 122 is connected to one end of the current collector 121 close to the first coating portion 131 along the first direction X. The third coating portion 133 in one of the adjacent two electrode sheets 120 covers the first coating portion 131 in the other electrode sheet 120. Specifically, in two adjacent electrode sheets 120 in the second direction Y, the first coating portion 131, the second coating portion 132, and the third coating portion 133 of one electrode sheet 120 respectively cover the third coating portion 133, the second coating portion 132, and the first coating portion 131 of the other electrode sheet 120, so that the current in the adjacent two electrode sheets 120 converges towards the tabs 122 at both ends. The compaction density of the first coating portion 131 and the third coating portion 133 on each current collector 121 is greater than the compaction density of the second coating portion 132, thereby increasing the electrochemical impedance at both ends of each electrode sheet 120 close to the tab 122, causing more current to flow towards the middle of the electrode sheet 120, and making the temperature difference on each electrode sheet 120 smaller.

[0059] Optionally, the first parameter is the compaction density. 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 1 < K1 ≤ 1.5. For example, K1 can be 1.01, 1.02, 1.04, 1. O7, 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. Other unlisted values within the numerical range are equally applicable. Specifically, when the ratio K1 of the compaction density of the first coating portion 131 to the compaction density of the second coating portion 132 ≤ 1.5, it can reduce the difference in dressing thickness between the first coating portion 131 and the second coating portion 132 during coating, thereby increasing the manufacturing difficulty in the actual manufacturing process. At the same time, it reduces the stress difference at different positions of the electrode sheet 120 and reduces the problems of frequent tape breakage and crack generation due to uneven extension and stress distribution during rolling and die-cutting.

[0060] 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, where 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. Other unlisted values within the numerical range are equally 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, it can reduce the excessive difference in dressing thickness between the third coating part 133 and the second coating part 132 during coating, thereby increasing the manufacturing difficulty in the actual manufacturing process. At the same time, it reduces the stress difference at different positions of the electrode sheet 120 and reduces the problems of frequent tape breakage and crack generation due to uneven extension and stress distribution during the roller pressing and die-cutting processes.

[0061] When the electrode sheet 120 is the positive electrode sheet of the electrode 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 compaction density of the third coating part 133 and the compaction density of the second coating part 132 satisfy the ratio K2, the compaction density range of the first coating part 131 is 1.8 g / mm 3 ~2.8 g / mm 3 , for example, it 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. Other unlisted values within the numerical range are equally applicable; the compaction density range of the second coating part 132 is 1.8 g / mm 3 ~2.8 g / mm 3 , for example, it 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 32.05g / mm 3 2.1g / mm 3 2.2g / mm 3 2.25g / mm 3、 2.3g / mm 3 2.4g / mm 3 2.45g / mm 3 2.5g / mm 3 2.65g / mm 3 2.7g / mm 3 2.8g / mm 3 And, but not limited to, the listed values, other unlisted values ​​within the range also apply; the compaction density of the third coating section 133 is 1.8 g / mm². 3 ~2.8g / mm 3 For example, it could be 1.8g / mm 3 1.83g / mm 3 1.85g / mm 3 1.9g / mm 3 2.0g / mm 3 2.05g / mm 3 2.1g / mm 3 2.2g / mm 3 2.25g / mm 3 2.3g / mm 3 2.4g / mm 3 2.45g / mm 3 2.5g / mm 3 2.65g / mm 3 2.7g / mm 3 2.8g / mm 3 And so on, but not limited to the values ​​listed; other unlisted values ​​within the range also apply. This is to improve conductivity while ensuring the migration speed between active material ions in the positive electrode.

[0062] When the electrode 120 is the negative electrode with the electrode core, and ensuring that 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 ratio of the compaction density of the third coating portion 133 to the compaction density of the second coating portion 132 is K2, the compaction density range of the first coating portion 131 is 1.1 g / mm². 3 ~1.8g / mm 3 For example, it could be 1.1 g / mm 3 1.13g / mm 3 1.15g / mm 3 1.2g / mm 31.25g / mm 3 1.3g / mm 3 1.35g / mm 3 1.4g / mm 3 1.45g / mm 3 1.5g / mm 3 1.65g / mm 3 1.7g / mm 3 1.8g / mm 3 And, but not limited to, the listed values, other unlisted values ​​within the range also apply; the compaction density of the second coating section 132 is 1.1 g / mm². 3 ~1.8g / mm 3 For example, it could be 1.1 g / mm 3 1.13g / mm 3 1.15g / mm 3 1.2g / mm 3 1.25g / mm 3 1.3g / mm 3 1.35g / mm 3 1.4g / mm 3 1.45g / mm 3 1.5g / mm 3 1.65g / mm 3 1.7g / mm 3 1.8g / mm 3 And, but not limited to, the listed values, other unlisted values ​​within the range also apply; the compaction density of the third coating section 133 is 1.1 g / mm². 3 ~1.8g / mm 3 For example, it could be 1.1 g / mm 3 1.13g / mm 3 1.15g / mm 3 1.2g / mm 3 1.25g / mm 3 1.3g / mm 3 1.35g / mm 3 1.4g / mm 3 1.45g / mm 3 1.5g / mm 3 1.65g / mm 3 1.7g / mm 3 1.8g / mm 3 And so on, but not limited to the values ​​listed; other unlisted values ​​within the range also apply. This is to improve conductivity while ensuring the migration speed between ions of the active material in the negative electrode.

[0063] In the electrode 120 provided in this application, the compaction density of the first coating portion 131 is the same as that of the third coating portion 133. During the manufacturing process of the electrode 120, the same process can be used to coat the first coating portion 131 and the third coating portion 133 on the current collector 121 to reduce the manufacturing difficulty.

[0064] Optionally, the first parameter is the areal density. When the electrode 120 is the positive electrode with the electrode core, the areal density range of the first coating portion 131, the second coating portion 132, and the third coating portion 133 is all 200 g / m². 2 ~600g / m 2 For example, it could be 200g / m³. 2 210g / m 2 220g / m 2 240g / m 2 280g / m 2 300g / m 2 400g / m 2 450g / m 2 500g / m 2 520g / m 2 580g / m 2 600g / m 2 And, but not limited to, the values ​​listed, other unlisted values ​​within the range also apply. This ensures that there is sufficient active material in the positive electrode while allowing lithium ions to insert and extract smoothly.

[0065] Optionally, the first parameter is the areal density. When the electrode 120 is the negative electrode with the electrode core, the areal density range of the first coating portion 131, the second coating portion 132, and the third coating portion 133 is all 150 g / m². 2 ~250g / m 2 For example, it could be 150g / m³. 2 155g / m 2 160g / m 2 180g / m 2 190g / m 2 200g / m 2 210g / m 2 220g / m 2 230g / m 2 240g / m 2 240g / m 2 250g / m 2 And, but not limited to, the values ​​listed, other unlisted values ​​within the range also apply. This ensures that there is sufficient active material in the negative electrode while allowing lithium ions to intercalate and deintercalate smoothly.

[0066] In the description of the embodiments of this application, it should be noted that the orientation or positional relationship of the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and other indicators are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0067] The above-disclosed embodiments are merely preferred embodiments of this application and should not be construed as limiting the scope of this application. Those skilled in the art will understand that all or part of the processes for implementing the above embodiments and equivalent variations made in accordance with the claims of this application are still within the scope of this application.

Claims

1. An electrode (120), characterized in that, The surface of the electrode (120) is provided with a first coating portion (131), a second coating portion (132) and a third coating portion (133) in sequence along a first direction. The first parameter of the first coating portion (131) and the third coating portion (133) is greater than the first parameter of the second coating portion (132). The first coating portion (131), the second coating portion (132) and the third coating portion (133) have the same thickness, and the first parameter is the compaction density or the areal density.

2. The electrode (120) according to claim 1, characterized in that, The second coating part (132) is connected to the first coating part (131) at its first end in the first direction, and the second coating part (132) is connected to the third coating part (133) at its second end in the first direction. The first parameter of the second coating part (132) at its middle part in the first direction is smaller than the first parameter of its first end and / or second end.

3. The electrode (120) according to claim 2, characterized in that, The first parameter of the second coating portion (132) gradually increases from the middle of the second coating portion (132) in the first direction toward its first end and / or second end.

4. The electrode (120) according to any one of claims 1-3, characterized in that, The electrode (120) includes a current collector (121) and a tab (122). The first coating portion (131), the second coating portion (132) and the third coating portion (133) are all disposed on the same surface of the current collector (121). The tab (122) is connected to the current collector (121). The first coating portion (131) is closer to the tab (122) than the second coating portion (132).

5. The electrode (120) according to claim 4, characterized in that, The second coating section (132) includes a first region (132a) and a second region (132b). The first region (132a) is connected to the first coating section (131) at a first end along the first direction. The second end of the first region (132a) is connected to the first end of the second region (132b) along the first direction. The second end of the second region (132b) is connected to the third coating section (133) at a second end along the first direction. The first parameter of the first region (132a) gradually decreases from its first end to its second end, and the first parameter of the second region (132b) gradually increases from its first end to its second end.

6. The electrode (120) according to claim 4, characterized in that, The second coating section (132) includes a first region (132a), a second region (132b), and a third region (132c). The first region (132a), the third region (132c), and the second region (132b) are arranged sequentially along the first direction. The first end of the first region (132a) along the first direction is connected to the first coating section (131). The second end of the first region (132a) along the first direction is connected to the first end of the third region (132c) along the first direction. The second end of the third region (132c) along the first direction is connected to the first end of the second region (132b) along the first direction. The second end of the second region (132b) along the first direction is connected to the third coating section (133). The first parameter of the first region (132a) gradually decreases from its first end to its second end, and the first parameter of the second region (132b) gradually increases from its first end to its second end.

7. The electrode (120) according to any one of claims 1-6, characterized in that, The first parameter is the compaction density, the ratio of the compaction density of the first coating portion (131) to the compaction density of the second coating portion (132) is K1, 1 < K1 ≤ 1.5, and / or the ratio of the compaction density of the third coating portion (133) to the compaction density of the second coating portion (132) is K2, 1 < K2 ≤ 1.

5.

8. The electrode (120) according to claim 7, characterized in that, The electrode (120) is a positive electrode, the first parameter is the compaction density, and the compaction density of the first coating portion (131) is in the range of 1.8 g / mm². 3 ~2.8g / mm 3 And / or, the compaction density of the second coating portion (132) is in the range of 1.8 g / mm². 3 ~2.8g / mm 3 And / or, the compaction density of the third coating portion (133) is in the range of 1.8 g / mm². 3 ~2.8g / mm 3 .

9. The electrode (120) according to claim 7, characterized in that, The electrode (120) is a negative electrode, the first parameter is the compaction density, and the compaction density of the first coating portion (131) is in the range of 1.1 g / mm². 3 ~1.8g / mm 3 And / or, the compaction density of the second coating portion (132) is in the range of 1.1 g / mm². 3 ~1.8g / mm 3 And / or, the compaction density of the third coating portion (133) is in the range of 1.1 g / mm². 3 ~1.8g / mm 3 .

10. The electrode (120) according to any one of claims 1-9, characterized in that, The first parameter is the compaction density, and the compaction density of the first coating portion (131) is the same as the compaction density of the third coating portion (133).

11. The electrode (120) according to any one of claims 1-10, characterized in that, The electrode (120) is a positive electrode, and the first parameter is the areal density. The areal density range of the first coating part (131), the second coating part (132), and the third coating part (133) is 200 g / m². 2 ~600g / m 2 .

12. The electrode (120) according to any one of claims 1-11, characterized in that, The electrode (120) is a negative electrode, and the first parameter is the areal density. The areal density range of the first coating part (131), the second coating part (132), and the third coating part (133) is 150 g / m². 2 ~250g / m 2 .

13. The electrode (120) according to claim 2 or 3, characterized in that, The first parameter of the second coating portion (132) increases in gradient from the middle of the second coating portion (132) in the first direction towards its first end and / or second end.

14. An electrode core, characterized in that, It includes a plurality of electrode plates (120) according to any one of claims 1-13, and the plurality of electrode plates (120) are stacked or wound.

15. The electrode core according to claim 14, characterized in that, Each electrode plate (120) includes a current collector (121) and a tab (122). On each current collector (121), the first coating portion (131), the second coating portion (132), and the third coating portion (133) are sequentially provided along the first direction, and the tab (122) is connected to one end of the current collector (121) along the first direction close to the first coating portion (131); The third coating portion (133) in one of the adjacent two electrode plates (120) covers the first coating portion (131) in the other electrode plate (120).

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

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

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