Pole core, battery and electric equipment

Abstract

The pole core comprises a positive plate and a negative plate, the positive plate comprises a first current collector, a first tab, a first coating part and a second coating part, the first coating part and the second coating part are arranged on the same surface of the first current collector, the first tab is connected to the first current collector, and the first coating part is closer to the first tab than the second coating part. The first parameter of the first coating part is greater than that of the second coating part; a third coating part and a fourth coating part are sequentially arranged on the surface of the negative plate, and the first parameter of the third coating part is greater than that of the fourth coating part; wherein the first parameter is compaction density or surface density, and the first coating part and at least part of the second coating part are located in the orthographic projection of the third coating part on the positive plate. According to the lithium ion battery, the area of the negative plate always exceeds the lithium ion embedding site required by the positive electrode, so that the lithium separation risk of the pole core in the charging and discharging process is reduced.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a pole core, a battery and an electrical device. Background Art

[0002] With the development of science and technology, battery-powered devices are becoming more and more common in life. Existing batteries include various types such as lead-acid batteries and lithium batteries. Among them, lithium-ion batteries have been widely used in electric vehicles, mobile terminals, etc. due to their high energy density and environmental friendliness. Lithium-ion batteries include positive electrodes, diaphragms and negative electrodes. The electrons generated by the electrochemical reaction are collected and conducted to the external circuit through the positive and negative electrodes, thereby realizing the process of converting chemical energy into electrical energy. Because the positive or negative electrode generates a large amount of heat at the current collection point, when making the positive or negative electrode, different compaction density coating areas are formed on the positive or negative electrode. The high compaction density coating area can reduce the heat generation of the positive or negative electrode, so that the positive or negative electrode heats up evenly.

[0003] In the prior art, the electrode core composed of positive and negative electrode sheets with coating areas of different compaction densities is prone to the risk of lithium deposition during the charge and discharge process. Utility Model Content

[0004] The purpose of this application is to provide a pole core, a battery and an electrical device to solve the problem of the risk of lithium plating in the pole core during the charging and discharging process.

[0005] To achieve the purpose of this application, this application provides the following technical solutions:

[0006] In a first aspect, the present application provides a pole core, comprising:

[0007] A positive electrode sheet, comprising a first current collector, a first electrode tab, and a first coating portion and a second coating portion arranged on the same surface of the first current collector, wherein the first electrode tab is connected to the first current collector, the first coating portion is closer to the first electrode tab than the second coating portion, and a first parameter of the first coating portion is greater than a first parameter of the second coating portion;

[0008] A negative electrode sheet, wherein a third coating portion and a fourth coating portion are sequentially disposed on the surface of the negative electrode sheet, and a first parameter of the third coating portion is greater than a first parameter of the fourth coating portion;

[0009] The first parameter is a compaction density or an area density, and the first coating portion and at least a portion of the second coating portion are located in an orthographic projection of the third coating portion on the positive electrode sheet.

[0010] In one embodiment, in the first direction, the size range of the orthographic projection of the third coating part on the positive electrode sheet covering the second coating part is 2 mm to 10 mm, and the first direction is the direction in which the first coating part and the second coating part are arranged.

[0011] In one embodiment, 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, where 1 < K1 ≤ 1.5, and / or the ratio of the compaction density of the third coating part to the compaction density of the fourth coating part is K2, where 1 < K2 ≤ 1.5.

[0012] In one embodiment, the first parameter is the compaction density. The positive electrode sheet further includes a fifth coating part. The first coating part, the second coating part, and the fifth coating part are sequentially arranged on the first current collector, and the compaction density of the fifth coating part is greater than that of the second coating part.

[0013] The negative electrode sheet further includes a sixth coating part and a second current collector. The third coating part, the fourth coating part, and the sixth coating part are sequentially arranged on the second current collector, and the compaction density of the sixth coating part is greater than that of the fourth coating part.

[0014] In one embodiment, the fifth coating part and at least a part of the second coating part are located in the orthographic projection of the sixth coating part on the positive electrode sheet.

[0015] In one embodiment, the first coating part and the second coating part are arranged on the first current collector along the first direction, and the first tab is connected to one end of the first current collector close to the first coating part along the first direction.

[0016] The negative electrode sheet further includes a second tab. The third coating part and the fourth coating part are sequentially arranged on the second current collector, and the second tab is connected to one end of the second current collector close to the third coating part along the first direction.

[0017] In one embodiment, the first coating part and the second coating part are arranged on the first current collector along the first direction, and the first tab is connected to one end of the first current collector close to the first coating part along the first direction.

[0018] The negative electrode sheet further includes a second tab. The third coating part and the fourth coating part are sequentially arranged on the second current collector, and the second tab is connected to one end of the second current collector away from the third coating part along the first direction.

[0019] In one embodiment, the first parameter is the compaction density, and the ratio of the compaction density of the fifth coating part to that of the second coating part is K3, where 1 < K3 ≤ 1.5, and / or the ratio of the compaction density of the sixth coating part to that of the fourth coating part is K4, where 1 < K4 ≤ 1.5.

[0020] In one embodiment, the first parameter is the compaction density, and the compaction density range of the first coating part is 1.8 g / mm 3 ~2.8 g / mm 3 , the compaction density range of the second coating part is 1.8 g / mm 3 ~2.8 g / mm 3 , the compaction density range of the fifth coating part is 1.8 g / mm 3 ~2.8 g / mm 3 ;

[0021] And / or, the compaction density range of the third coating part is 1.1 g / mm 3 ~1.8 g / mm 3 , the compaction density range of the fourth coating part is 1.1 g / mm 3 ~1.8 g / mm 3 , the compaction density range of the sixth coating part is 1.1 g / mm 3 ~1.8 g / mm.

[0022] In one embodiment, the first parameter is the compaction density, and the compaction density of the first coating part is the same as that of the fifth coating part, and / or the compaction density of the third coating part is the same as that of the sixth coating part.

[0023] In one embodiment, the first parameter is the areal density, and the areal density ranges of the first coating part, the second coating part, and the fifth coating part are all 200 g / m 2 ~600 g / m 2 .

[0024] In one embodiment, the first parameter is the areal density, and the areal density ranges of the third coating part, the fourth coating part, and the sixth coating part are all 150 g / m 2 ~250 g / m 2 .

[0025] In one embodiment, the first parameter is a compaction density, the first coating portion, the second coating portion and the fifth coating portion are arranged sequentially in the first direction, the third coating portion, the fourth coating portion and the sixth coating portion are arranged sequentially in the first direction, and the compaction density of the second coating portion gradually increases from the middle of the second coating portion to one end close to the first coating portion and / or the fifth coating portion in the first direction;

[0026] And / or, the compaction density of the fourth coating portion gradually increases from the middle portion of the fourth coating portion toward one end close to the third coating portion and / or the sixth coating portion in the first direction.

[0027] In a second aspect, the present application also provides a battery, comprising the pole core according to the first aspect.

[0028] In a third aspect, the present application further provides an electrical device, comprising the battery according to the second aspect.

[0029] In the present application, the compaction density of the first coating portion on the surface of the positive electrode sheet is greater than the compaction density of the second coating portion, or the surface density of the first coating portion is greater than the surface density of the second coating portion, and the second coating portion with lower compaction density or surface density tends to distribute higher current, thereby effectively pulling the temperature of the positive electrode sheet away from the first pole ear position, so that the overall temperature difference of the positive electrode sheet is smaller; the compaction density of the third coating portion on the surface of the negative electrode sheet is greater than the compaction density of the fourth coating portion, or the surface density of the third coating portion is greater than the surface density of the fourth coating portion, and the fourth coating portion with lower compaction density or surface density tends to distribute higher current, thereby effectively pulling the temperature of the positive electrode sheet away from the first pole ear position, so that the overall temperature difference of the negative electrode sheet is smaller; the first coating portion and at least part of the second coating portion are located in the positive projection of the third coating portion on the positive electrode sheet, so that the area of ​​the negative electrode sheet is always greater than the lithium ion embedding site required by the positive electrode, reducing the risk of lithium plating in the electrode core during charging and discharging. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 This is a schematic diagram of the structure of a battery according to one embodiment of the present application;

[0032] Figure 2 This is a schematic structural diagram of a positive electrode sheet according to an embodiment of the present application;

[0033] Figure 3 A schematic diagram of the structure of a positive electrode sheet and a negative electrode sheet according to an embodiment of the present application.

[0034] Description of reference numerals:

[0035] 100, battery; 110, positive electrode sheet; 111, first current collector; 112, first electrode tab; 120, negative electrode sheet; 121, second current collector; 122, second electrode tab; 130, separator; 141, first coating part; 142, second coating part; 143, fifth coating part; 151, third coating part; 152, fourth coating part; 153, sixth coating part. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0037] 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 there can be a central component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there can be a central component at the same time.

[0038] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in this application and in the specification are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in this application includes any and all combinations of one or more of the related listed items.

[0039] In conjunction with the accompanying drawings, some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0040] The present application provides an electric device, which is a device for converting electrical energy into other forms of energy. The electric device includes electric vehicles, mobile phones and computers. The electric device provides electrical energy through a battery for the operation of the device.

[0041] For electric vehicles, the electric vehicle includes a frame, a battery and a drive motor, and the battery and the drive motor are installed on the frame. The battery is the main energy source of the vehicle and is used to store and release electrical energy. The battery provides electrical energy to the drive motor to drive the vehicle.

[0042] refer to Figure 1 The present application provides a battery 100, the battery 100 includes a diaphragm 130 and a pole core, the pole core includes a positive electrode sheet 110 and a negative electrode sheet 120, and the diaphragm 130 is arranged between the positive electrode sheet 110 and the negative electrode sheet 120. The battery 100 also includes a shell and an electrolyte, the shell is used to contain the electrolyte, the diaphragm 130 and the pole core, and the electrolyte serves as a medium for transferring ions. The electrons generated by the electrochemical reaction are collected by the positive electrode sheet 110 and the negative electrode sheet 120 and conducted to the external circuit, thereby realizing the process of converting chemical energy into electrical energy. Because the pole piece generates a large amount of heat at the current collection point, when making the pole piece, by forming different compaction density coating areas on the pole piece, the high compaction density coating area can reduce the heat generation of the pole piece, so that the pole piece heats evenly.

[0043] In the prior art, the electrode core composed of positive and negative electrode sheets with coating areas of different compaction densities is prone to the risk of lithium deposition during the charge and discharge process.

[0044] refer to Figure 1 , Figure 2 and Figure 3 The present application provides a pole core, including a positive electrode sheet 110 and a negative electrode sheet 120, the positive electrode sheet 110 includes a first current collector 111, a first electrode tab 112, and a first coating portion 141 and a second coating portion 142 arranged on the same surface of the first current collector 111, the first electrode tab 112 is connected to the first current collector 111, the first coating portion 141 is closer to the first electrode tab 112 than the second coating portion 142, and the first parameter of the first coating portion 141 is greater than the first parameter of the second coating portion 142; a negative electrode sheet 120, the surface of the negative electrode sheet 120 is sequentially provided with a third coating portion 151 and a fourth coating portion 152, the first parameter of the third coating portion 151 is greater than the first parameter of the fourth coating portion 152; wherein the first parameter is a compaction density or a surface density, and the first coating portion 141 and at least a portion of the second coating portion 142 are located in the orthographic projection of the third coating portion 151 on the positive electrode sheet 110.

[0045] Among them, the first coating part 141 and the second coating part 142 are located on the same surface of the positive electrode sheet 110, and the third coating part 151 and the fourth coating part 152 are located on the same surface of the negative electrode sheet 120. The first coating part 141, the second coating part 142, the third coating part 151 and the fourth coating part 152 all have active materials responsible for storing and releasing energy. In the lithium-ion battery 100, the active material on the positive electrode sheet 110 can be a transition metal oxide, such as lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, etc.; the active material on the negative electrode sheet 120 can be materials such as graphite, silicon or tin. Compacted density refers to the mass of a substance per unit volume, and surface density refers to the mass of a substance per unit area. The compacted density is equal to the surface density divided by the thickness of the substance. In the lithium-ion battery 100, the thickness of each coating portion in the positive electrode sheet 110 and the negative electrode sheet is kept as consistent as possible. When the surface density of the first coating portion 141 and the second coating portion 142, and the surface density of the third coating portion 151 and the fourth coating portion 152 are different, the compaction density of the first coating portion 141 and the second coating portion 142, and the compaction density of the third coating portion 151 and the fourth coating portion 152 are also different.

[0046] In the present application, the compaction density of the first coating portion 141 on the surface of the positive electrode sheet 110 is greater than the compaction density of the second coating portion 142, or the surface density of the first coating portion 141 is greater than the surface density of the second coating portion 142, and the second coating portion 142 with a lower compaction density or surface density tends to distribute a higher current, thereby effectively raising the temperature of the positive electrode sheet 110 away from the first pole ear 112, so that the overall temperature difference of the positive electrode sheet 110 is smaller; the compaction density of the third coating portion 151 on the surface of the negative electrode sheet 120 is greater than the compaction density of the fourth coating portion 152, or the third The surface density of the coating portion 151 is greater than the surface density of the fourth coating portion 152. The fourth coating portion 152 with lower compaction density or surface density tends to distribute higher current, thereby effectively pulling the temperature of the positive electrode sheet 110 away from the first pole ear 112, so that the overall temperature difference of the negative electrode sheet 120 is smaller; the first coating portion 141 and at least part of the second coating portion 142 are located in the positive projection of the third coating portion 151 on the positive electrode sheet 110, so that the area of ​​the negative electrode sheet 120 is always larger than the lithium ion embedding site required by the positive electrode, reducing the risk of lithium plating in the electrode core during charging and discharging.

[0047] In the embodiment of the present application, the length direction / width direction of the pole core is taken as the first direction X, and the thickness direction of the pole core is taken as the second direction Y.

[0048] In the example of the present application, the first coating portion 141 is closer to the first pole tab 112 than the second coating portion 142. Specifically, in one embodiment, the first coating portion 141 is closer to the edge of the first current collector 111 connected to the first pole tab 112 than at least part of the second coating portion 142. For example, the first coating portion 141 and the second coating portion 142 are both rectangular, and the length of the first coating portion 141 in the vertical first direction X is the same as the length of the second coating portion 142 in the vertical first direction X, then the first coating portion 141 is closer to the edge of the first current collector 111 connected to the first pole tab 112 as a whole than the second coating portion 142, wherein the first direction X is the arrangement direction of the first coating portion 141 and the second coating portion 142, for example, the first direction X can be the length direction of the pole core, and the first direction X can also be the width direction of the pole core. In another embodiment, when the minimum distance from a partial edge of the second coating portion 142 to the edge of the first current collector 111 connected to the first pole ear 112 is the same as the minimum distance from the first coating portion 141 to the edge of the first current collector 111 connected to the first pole ear 112, the first coating portion 141 is arranged opposite to the first pole ear 112 in the first direction X, and the second coating portion 142 is in a "concave" shape, and the second coating portion 142 surrounds the outer periphery of the first coating portion 141.

[0049] The first coating portion 141 and the second coating portion 142 are arranged along the first direction X, and the positive electrode sheet 110 and the negative electrode sheet 120 are stacked in the second direction Y. The negative electrode sheet 120 further includes a second current collector 121 and a second electrode tab 122, and the third coating portion 151 and the fourth coating portion 152 are sequentially arranged on the second current collector 121, and the second electrode tab 122 is connected to one end of the second current collector 121 along the first direction X close to the third coating portion 151. Specifically, the first pole ear 112 is a bridge connecting the first current collector 111 and the external circuit, and the second pole ear 122 is a bridge connecting the second current collector 121 and the external circuit, so as to transfer the current inside the battery 100 to the external circuit, and the current in the first current collector 111 is collected toward the first pole ear 112 and the second pole ear 122, and the current in the second current collector 121 is collected toward the first pole ear 112 and the second pole ear 122, so that the heat generated at the first current collector 111 near the first pole ear 112 and the second pole ear 122 and the heat generated at the second current collector 121 near the first pole ear 112 and the second pole ear 122 are The amount is large, and the first coating part 141 and the third coating part 151 with higher compaction density are respectively arranged at the two ends of the first current collector 111 near the first pole ear 112 and the second pole ear 122, which increases the electrochemical impedance of the positive electrode sheet 110 near the first pole ear 112 and the negative electrode sheet 120 near the second pole ear 122, so that more current flows to the second coating part 142 of the positive electrode sheet 110 and the fourth coating part 152 of the negative electrode sheet 120, thereby reducing the heat generation of the positive electrode sheet 110 near the first pole ear 112 and the negative electrode sheet 120 near the second pole ear 122, so that the temperature difference between the positive electrode sheet 110 and the negative electrode sheet 120 is smaller.

[0050] In the pole core provided in the present application, the positive electrode sheet 110 also includes a fifth coating portion 143, the first coating portion 141, the second coating portion 142 and the fifth coating portion 143 are sequentially arranged on the first current collector 111, and the compaction density of the fifth coating portion 143 is greater than the compaction density of the second coating portion 142; the negative electrode sheet 120 also includes a sixth coating portion 153, the third coating portion 151, the fourth coating portion 152 and the sixth coating portion 153 are sequentially arranged on the second current collector 121, and the compaction density of the sixth coating portion 153 is greater than the compaction density of the fourth coating portion 152. Specifically, the first coating section 141, the second coating section 142 and the fifth coating section 143 are arranged in sequence in the first direction X, the third coating section 151, the fourth coating section 152 and the sixth coating section 153 are arranged in sequence in the first direction X, the first pole tab 112 is connected to one end of the first current collector 111 close to the first coating section 141 along the first direction X, and the second pole tab 122 is connected to one end of the second current collector 121 close to the third coating section 151 along the first direction X, that is, the first pole tab 112 and the second pole tab 122 are both located at the same end of the pole core in the first direction X. Or the first pole tab 112 is connected to one end of the first current collector 111 close to the first coating section 141 along the first direction X, and the second pole tab 122 is connected to one end of the second current collector 121 away from the third coating section 151 along the first direction X, that is, the first pole tab 112 and the second pole tab 122 are both located at both ends of the pole core in the first direction X.

[0051] refer to Figure 3 , in the first direction X, the dimension a of the orthographic projection of the third coating portion 151 on the positive electrode sheet 110 covering the second coating portion 142 is in the range of 2 mm to 10 mm, and a can be, for example, 2 mm, 2.1 mm, 2.5 mm, 3 mm, 4 mm, 5 mm, 6 mm, 8 mm, 10 mm, etc., not limited to the listed values, and other values ​​not listed in the numerical range are also applicable. The fifth coating portion 143 and at least part of the second coating portion 142 are located in the orthographic projection of the sixth coating portion 153 on the positive electrode sheet 110, and the dimension b of the orthographic projection of the sixth coating portion 153 on the positive electrode sheet 110 covering the second coating portion 142 is in the range of 2 mm to 10 mm, and b can be, for example, 2 mm, 2.1 mm, 2.5 mm, 3 mm, 4 mm, 5 mm, 6 mm, 8 mm, 10 mm, etc., not limited to the listed values, and other values ​​not listed in the numerical range are also applicable.

[0052] On the first current collector 111, a first coating portion 141 and a fifth coating portion 143 with relatively high compaction density are respectively provided near the first tab 112 and the second tab 122, increasing the electrochemical impedance of the positive electrode sheet 110 near the first tab 112 and the second tab 122, and causing more current to flow to the middle part of the positive electrode sheet 110; on the second current collector 121, a third coating portion 151 and a sixth coating portion 153 with relatively high compaction density are respectively provided at both ends near the first tab 112 and the second tab 122, increasing the electrochemical impedance of the negative electrode sheet 120 near the first tab 112 and the second tab 122, and causing more current to flow to the middle part of the negative electrode sheet 120, thereby effectively raising the temperature in the middle parts of the positive electrode sheet 110 and the negative electrode sheet 120, and making the overall temperature difference on the positive electrode sheet 110 and the negative electrode sheet 120 smaller.

[0053] Optionally, the first parameter is the compaction density, and the ratio of the compaction density of the first coating portion 141 to the compaction density of the second coating portion 142 is K1, where 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 unlisted values within the numerical range are equally applicable. Specifically, when the ratio K1 of the compaction density of the first coating portion 141 to the compaction density of the second coating portion 142 > 1.5, it will cause too large a difference in the dressing thickness between the first coating portion 141 and the second coating portion 142, resulting in a reduction in the feasibility of the actual manufacturing process. At the same time, too large a difference will cause too large a stress difference at different positions of the electrode sheet, and frequent tape breakage and cracks will occur due to uneven extension and stress distribution during the rolling and die-cutting processes.

[0054] Optionally, the ratio of the compaction density of the third coating portion 151 to the compaction density of the fourth coating portion 152 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, and other unlisted values within the numerical range are equally applicable. Specifically, when the ratio K2 of the compaction density of the third coating portion 151 to the compaction density of the fourth coating portion 152 > 1.5, it will cause too large a difference in the dressing thickness between the third coating portion 151 and the fourth coating portion 152, resulting in a reduction in the feasibility of the actual manufacturing process. At the same time, too large a difference will cause too large a stress difference at different positions of the electrode sheet, and frequent tape breakage and cracks will occur due to uneven extension and stress distribution during the rolling and die-cutting processes.

[0055] Under the condition that the ratio of the compaction density of the first coating part 141 to the compaction density of the second coating part 142 is K1 and the compaction density of the third coating part 151 to the compaction density of the fourth coating part 152 satisfies the ratio K2, the compaction density range of the first coating part 141 is 1.8 g / mm 3 ~2.8g / mm 3 , for example, it can 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 etc., but not limited to the listed values, other values ​​not listed in the numerical range are also applicable; the compaction density range of the second coating portion 142 is 1.8g / mm 3 ~2.8g / mm 3 , for example, it can 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 etc., but not limited to the listed values, other values ​​not listed in the numerical range are also applicable; the compaction density range of the third coating portion 151 is 1.1 g / mm 3 ~1.8g / mm 3, for example, it can 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 etc., but not limited to the listed values, other values ​​not listed in the numerical range are also applicable; the compaction density range of the fourth coating portion 152 is 1.1 g / mm 3 ~1.8g / mm 3 , for example, it can 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 The above values ​​are not limited to the above values, and other values ​​not listed in the above value range are also applicable. This ensures the mobility of active material ions in the positive electrode sheet 110 and the negative electrode sheet 120 while improving the conductivity.

[0056] The ratio of the compaction density of the fifth coating part 143 to the compaction density of the second coating part 142 is K3, where 1 < K3 ≤ 1.5. For example, K3 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. And / or, the ratio of the compaction density of the sixth coating part 153 to the compaction density of the fourth coating part 152 is K4, where 1 < K4 ≤ 1.5. For example, K4 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. The above parameter limitations can ensure that the electrochemical impedance differences between the fifth coating part 143 and the second coating part 142, and between the sixth coating part 153 and the fourth coating part 152 are within a better range, achieving a reduction in the heat generation at the positions of the positive electrode sheet 110 and the negative electrode sheet 120 close to the first pole ear 112 and the second pole ear 122, and making the overall temperature difference on the positive electrode sheet 110 and the negative electrode sheet 120 smaller.

[0057] When ensuring that the ratio of the compaction density of the fifth coating part 143 to the compaction density of the second coating part 142 is K3 and the ratio of the compaction density of the sixth coating part 153 to the compaction density of the fourth coating part 152 satisfies K4, the compaction density range of the fifth coating part 143 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 sixth coating part 153 is 1.1 g / mm 3 ~1.8 g / mm 3, for example, it can 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 The above values ​​are not limited to the above values, and other values ​​not listed in the above value range are also applicable. This ensures the mobility of active material ions in the positive electrode sheet 110 and the negative electrode sheet 120 while improving the conductivity.

[0058] In a possible implementation, the compaction density of the first coating portion 141 is the same as the compaction density of the fifth coating portion 143, and / or the compaction density of the third coating portion 151 is the same as the compaction density of the sixth coating portion 153. During the manufacturing process of the positive electrode sheet 110 and the negative electrode sheet 120, the first coating portion 141 and the fifth coating portion 143 may be coated on the first current collector 111, and the third coating portion 151 and the sixth coating portion 153 may be coated on the second current collector 121 in the same process to reduce the manufacturing difficulty.

[0059] When the first parameter is the surface density, the surface density range of the first coating part 141, the second coating part 142, and the fifth coating part 143 is 200 g / m 2 ~600g / m 2 . For example, it can be 200g / m 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 etc., but not limited to the listed values, other values ​​not listed in the numerical range are also applicable. This ensures that there is sufficient active material in the positive electrode sheet 110 and that lithium ions can be smoothly inserted and removed.

[0060] When the first parameter is the surface density, the surface density range of the third coating part 151, the fourth coating part 152 and the sixth coating part 153 is 150 g / m 2 ~250g / m 2 . For example, it can be 150g / m 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 etc., but not limited to the listed values, other values ​​not listed in the numerical range are also applicable. This ensures that there is sufficient active material in the negative electrode sheet 120 and that lithium ions can be smoothly inserted and removed.

[0061] When the first parameter is the compaction density, the first coating section 141, the second coating section 142 and the fifth coating section 143 are arranged sequentially in the first direction X, and the third coating section 151, the fourth coating section 152 and the sixth coating section 153 are arranged sequentially in the first direction X, and the compaction density of the second coating section 142 gradually increases from the middle of the second coating section 142 to one end close to the first coating section 141 and / or the fifth coating section 143 in the first direction X; and / or, the compaction density of the fourth coating section 152 gradually increases from the middle of the fourth coating section 152 to one end close to the third coating section 151 and / or the sixth coating section 153 in the first direction X. The compaction density at the junction of the first coating part 141 and the second coating part 142, the junction of the second coating part 142 and the fifth coating part 143, the junction of the third coating part 151 and the fourth coating part 152, and the junction of the fourth coating part 152 and the sixth coating part 153 changes gradually, so that after the electrode sheet and the negative electrode sheet 120 are rolled, the stress distribution of the positive electrode sheet 110 and the negative electrode sheet 120 is more uniform.

[0062] In the description of the embodiments of the present application, it should be noted that the orientation or positional relationship of terms such as "center", "up", "down", "left", "right", "vertical", "horizontal", "inside" and "outside" are based on the orientation or positional relationship described in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0063] What is disclosed above is only a preferred embodiment of the present application, and it certainly cannot be used to limit the scope of rights of the present application. Ordinary technicians in this field can understand that all or part of the processes of implementing the above embodiment and equivalent changes made according to the claims of the present application are still within the scope covered by the present application.

Claims

1. A pole core, characterized in that: Comprising: A positive electrode sheet, including a first current collector, a first tab, and a first coating portion and a second coating portion provided on the same surface of the first current collector. The first tab is connected to the first current collector. The first coating portion is closer to the first tab than the second coating portion, and a first parameter of the first coating portion is greater than a first parameter of the second coating portion. A negative electrode sheet, on the surface of which a third coating portion and a fourth coating portion are sequentially provided, and a first parameter of the third coating portion is greater than a first parameter of the fourth coating portion. Wherein, the first parameter is the compaction density or the surface density, and the first coating portion and at least a part of the second coating portion are located in the orthographic projection of the third coating portion on the positive electrode sheet.

2. The pole core according to claim 1, characterized in that: In a first direction, the size range of the orthographic projection of the third coating portion on the positive electrode sheet covering the second coating portion is 2 mm to 10 mm, and the first direction is the direction in which the first coating portion and the second coating portion are arranged.

3. The pole core according to claim 1, characterized in that: The first parameter is the compaction density, the ratio of the compaction density of the first coating portion to the compaction density of the second coating portion is K1, 1 < K1 ≤ 1.5, and / or, the ratio of the compaction density of the third coating portion to the compaction density of the fourth coating portion is K2, 1 < K2 ≤ 1.

5.

4. The pole core according to any one of claims 1 to 3, characterized in that: The first parameter is the compaction density, and the positive electrode sheet further includes a fifth coating portion. The first coating portion, the second coating portion and the fifth coating portion are sequentially provided on the first current collector, and the compaction density of the fifth coating portion is greater than the compaction density of the second coating portion. The negative electrode sheet further includes a sixth coating portion and a second current collector. The third coating portion, the fourth coating portion and the sixth coating portion are sequentially provided on the second current collector, and the compaction density of the sixth coating portion is greater than the compaction density of the fourth coating portion.

5. The pole core according to claim 4, characterized in that: The fifth coating portion and at least a part of the second coating portion are located in the orthographic projection of the sixth coating portion on the positive electrode sheet.

6. The pole core according to claim 4, characterized in that: The first coating portion and the second coating portion are arranged on the first current collector in the first direction, and the first tab is connected to one end of the first current collector close to the first coating portion in the first direction. The negative electrode sheet further includes a second tab. The third coating portion and the fourth coating portion are sequentially provided on the second current collector, and the second tab is connected to one end of the second current collector close to the third coating portion in the first direction.

7. The pole core according to claim 4, characterized in that: The first coating portion and the second coating portion are arranged on the first current collector in the first direction, and the first tab is connected to one end of the first current collector close to the first coating portion in the first direction. The negative electrode sheet further includes a second tab. The third coating portion and the fourth coating portion are sequentially provided on the second current collector, and the second tab is connected to one end of the second current collector away from the third coating portion in the first direction.

8. The pole core according to any one of claims 5 to 7, characterized in that: The first parameter is the compaction density, the ratio of the compaction density of the fifth coating part to the compaction density of the second coating part is K3, 1 < K3 ≤ 1.5, and / or the ratio of the compaction density of the sixth coating part to the compaction density of the fourth coating part is K4, 1 < K4 ≤ 1.

5.

9. The pole core according to any one of claims 5 to 7, characterized in that: The first parameter is the compaction density, and the compaction density range of the first coating portion is 1.8 g / mm 3 ~2.8g / mm 3 The compaction density of the second coating portion is in the range of 1.8 g / mm 3 ~2.8g / mm 3 The compaction density range of the fifth coating portion is 1.8 g / mm 3 ~2.8g / mm 3 ; And / or, the compaction density range of the third coating portion is 1.1 g / mm 3 ~1.8g / mm 3 The compaction density range of the fourth coating portion is 1.1 g / mm 3 ~1.8g / mm 3 The compaction density range of the sixth coating portion is 1.1 g / mm 3 ~1.8g / mm.

10. The pole core according to any one of claims 5 to 7, characterized in that: The first parameter is the compaction density, the compaction density of the first coating part is the same as that of the fifth coating part, and / or the compaction density of the third coating part is the same as that of the sixth coating part.

11. The pole core according to claim 4, characterized in that: The first parameter is the surface density. The surface density ranges of the first coating part, the second coating part, and the fifth coating part are all 200 g / m 2 ~600g / m 2 .

12. The pole core according to claim 4, characterized in that: The first parameter is the surface density. The surface density ranges of the third coating part, the fourth coating part and the sixth coating part are all 150 g / m 2 ~250g / m 2 .

13. The pole core according to claim 4, characterized in that: The first parameter is the compaction density, the first coating part, the second coating part and the fifth coating part are arranged in sequence in the first direction, the third coating part, the fourth coating part and the sixth coating part are arranged in sequence in the first direction, and the compaction density of the second coating part gradually increases in the first direction from the middle of the second coating part towards one end close to the first coating part and / or the fifth coating part; and / or the compaction density of the fourth coating part gradually increases in the first direction from the middle of the fourth coating part towards one end close to the third coating part and / or the sixth coating part.

14. A battery, characterized in that: It includes a pole core according to any one of claims 1-13.

15. An electrical equipment, characterized in that: It includes a battery according to claim 14.

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