Electrode core, battery, and electric device

Abstract

An electrode core, a battery, and an electric device. The electrode core comprises a positive electrode sheet and a negative electrode sheet, wherein the positive electrode sheet comprises a first current collector, a first tab, and a first coating portion and a second coating portion which are arranged 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 relative to 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 third coating portion and a fourth coating portion are provided in sequence on a 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; and the first parameter is a compaction density or an areal density, and the first coating portion and at least part of the second coating portion are located in the orthographic projection of the third coating portion on the positive electrode sheet.

Description

Core, battery and electrical equipment

[0001] This application claims priority to Chinese Patent Application No. 202420866783.0, filed on April 24, 2024, entitled "Core, Battery and Electrical Device", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure relates to the field of battery technology, specifically to an electrode core, a battery, and an electrical device. Background Technology

[0003] 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 positive or negative electrode generates a significant amount of heat at the current collection point, different compaction density coating areas are formed on the positive or negative electrode during manufacturing. High compaction density coating areas can reduce the heat generation of the positive or negative electrode, ensuring uniform heating.

[0004] In existing technologies, electrode cores composed of positive and negative electrode sheets with different compaction density coating areas are prone to lithium plating during charging and discharging. Summary of the Invention

[0005] The purpose of this disclosure is to provide an electrode core, a battery, and an electrical device that solves the problem of lithium plating risk during the charging and discharging process of the electrode core.

[0006] To achieve the objectives of this disclosure, the following technical solutions are provided:

[0007] In a first aspect, this disclosure provides a core, comprising:

[0008] A positive electrode includes a first current collector, a first tab, and a first coating portion and a second coating portion disposed 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. A first parameter of the first coating portion is greater than a first parameter of the second coating portion.

[0009] A negative electrode sheet, wherein a third coating portion and a fourth coating portion are sequentially provided 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;

[0010] Among them, the first parameter is the compaction density or the areal 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 electrode sheet.

[0011] 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.

[0012] 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, 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, 1 < K2 ≤ 1.5.

[0013] 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 the compaction density of the second coating part;

[0014] 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 the compaction density of the fourth coating part.

[0015] In one embodiment, the fifth coating part and at least part of the second coating part are located in the orthographic projection of the sixth coating part on the positive electrode sheet.

[0016] 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;

[0017] 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.

[0018] 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;

[0019] 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 along the first direction.

[0020] In one embodiment, the first parameter is the compaction density, the ratio of the compaction density of the fifth coating portion to the compaction density of the second coating portion is K3, where 1 < K3 ≤ 1.5, and / or the ratio of the compaction density of the sixth coating portion to the compaction density of the fourth coating portion is K4, where 1 < K4 ≤ 1.5.

[0021] In one embodiment, 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 ; the compaction density range of the second coating portion is 1.8 g / mm 3 ~2.8 g / mm 3 ; the compaction density range of the fifth coating portion is 1.8 g / mm 3 3 ; ~2.8 g / mm 3 ;

[0022] and / or, the compaction density range of the third coating portion is 1.1 g / mm 3 ~1.8 g / mm 3 ; the compaction density range of the fourth coating portion is 1. – 1.8 g / mm 3 3 ~1.8 g / mm 3 ; the compaction density range of the sixth coating portion is 3 <00... 3 ~1.8 g / mm 3 .

[0023] In one embodiment, the first parameter is the compaction density, the compaction density of the first coating portion is the same as that of the fifth coating portion, and / or the compaction density of the third coating portion is the same as that of the sixth coating portion.

[0024] In one embodiment, the first parameter is the areal density, and the areal density ranges of the first coating portion, the second coating portion, and the fifth coating portion are all 200 g / m 2 ~600 g / m 2 .

[0025] In one embodiment, the first parameter is the areal density, and the areal density ranges of the third coating portion, the fourth coating portion, and the sixth coating portion are all 150 g / m 2 ~250 g / m 2 .

[0026] In one embodiment, the first parameter is the compaction density. The first coating portion, the second coating portion, and the fifth coating portion are arranged sequentially in a first direction. The third coating portion, the fourth coating portion, and the sixth coating portion are arranged sequentially in a first direction. The compaction density of the second coating portion gradually increases in the first direction from the middle of the second coating portion toward one end near the first coating portion and / or the fifth coating portion.

[0027] And / or, the compaction density of the fourth coating portion gradually increases in the first direction from the middle of the fourth coating portion toward one end near the third coating portion and / or the sixth coating portion.

[0028] Secondly, this disclosure also provides a battery including the electrode core as described in the first aspect.

[0029] Thirdly, this disclosure also provides an electrical device including the battery described in the second aspect.

[0030] In this disclosure, the compaction density of the first coating portion on the surface of the positive electrode is greater than that of the second coating portion, or the areal density of the first coating portion is greater than that of the second coating portion. The second coating portion with a lower compaction density or areal density tends to distribute a higher current, thereby effectively raising the temperature of the positive electrode portion away from the first tab and making the overall temperature difference of the positive electrode portion smaller. The compaction density of the third coating portion on the surface of the negative electrode is greater than that of the fourth coating portion, or the areal density of the third coating portion is greater than that of the fourth coating portion. The fourth coating portion with a lower compaction density or areal density tends to distribute a higher current, thereby effectively raising the temperature of the positive electrode portion away from the first tab and making the overall temperature difference of the negative electrode portion smaller. The first coating portion and at least a portion of the second coating portion are located in the orthogonal projection of the third coating portion on the positive electrode portion, thereby ensuring that the area of ​​the negative electrode portion always exceeds the lithium-ion insertion sites required by the positive electrode, reducing the risk of lithium plating in the electrode core during charging and discharging. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this disclosure or 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 of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 is a schematic diagram of the structure of a battery according to an embodiment of the present disclosure;

[0033] Figure 2 is a schematic diagram of the structure of a positive electrode sheet according to an embodiment of the present disclosure;

[0034] Figure 3 is a schematic diagram of the structure of the positive electrode and the negative electrode according to one embodiment of the present disclosure;

[0035] Figure 4 is a schematic diagram of the structure of an electrical device according to one embodiment of the present disclosure.

[0036] Explanation of reference numerals in the attached drawings: 100, battery; 110, positive electrode; 111, first current collector; 112, first tab; 120, negative electrode; 121, second current collector; 122, second tab; 130, separator; 141, first coating section; 142, second coating section; 143, fifth coating section; 151, third coating section; 152, fourth coating section; 153, sixth coating section; 200, electrical equipment. Detailed Implementation

[0037] The technical solutions of the embodiments of this disclosure 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 disclosure, and not all of them. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[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 disclosure have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terminology used in the specification of this disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of this disclosure. The term "and / or" as used in this disclosure includes any and all combinations of one or more of the associated listed items.

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

[0041] Referring to Figure 4, this disclosure provides an electrical device 200, which is a device for converting electrical energy into other forms of energy. The electrical device 200 includes electric vehicles, mobile phones, and computers, and is powered by a battery 100 to operate the device.

[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 disclosure provides a battery 100, which includes a separator 130 and an electrode core. The electrode core includes a positive electrode 110 and a negative electrode 120, with the separator 130 disposed between the positive electrode 110 and the negative electrode 120. The battery 100 also includes a casing and an electrolyte. The casing is used to contain the electrolyte, the separator 130, and the electrode core, while the electrolyte serves as a medium for ion transfer. Electrons generated by the electrochemical reaction are collected by the positive electrode 110 and the negative electrode 120 and conducted to an external circuit, thereby realizing the conversion of chemical energy into electrical energy. Because the electrode generates a large amount of heat at the current collection point, different compaction density coating areas are formed on the electrode during manufacturing. The high compaction density coating area can reduce the heat generation of the electrode, making the electrode heat generation more uniform.

[0044] In existing technologies, electrode cores composed of positive and negative electrode sheets with different compaction density coating areas are prone to lithium plating during charging and discharging.

[0045] Referring to Figures 1, 2, and 3, this disclosure provides an electrode core, including a positive electrode 110 and a negative electrode 120. The positive electrode 110 includes a first current collector 111, a first tab 112, and a first coating portion 141 and a second coating portion 142 disposed on the same surface of the first current collector 111. The first tab 112 is connected to the first current collector 111. The first coating portion 141 is closer to the first tab 112 than the second coating portion 142. The first parameter of the first coating portion 141 is greater than the first parameter of the second coating portion 142. The negative electrode 120 has a third coating portion 151 and a fourth coating portion 152 sequentially disposed on its surface. The first parameter of the third coating portion 151 is greater than the first parameter of the fourth coating portion 152. The first parameter is the compaction density or the areal density. 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 onto the positive electrode 110.

[0046] The first coating portion 141 and the second coating portion 142 are located on the same surface of the positive electrode 110, and the third coating portion 151 and the fourth coating portion 152 are located on the same surface of the negative electrode 120. Each of the first coating portion 141, the second coating portion 142, the third coating portion 151, and the fourth coating portion 152 contains active material responsible for storing and releasing energy. In the lithium-ion battery 100, the active material on the positive electrode 110 can be a transition metal oxide, such as lithium cobalt oxide, lithium nickel oxide, or lithium manganese oxide; the active material on the negative electrode 120 can be graphite, silicon, or tin. Compacted density refers to the mass of a substance per unit volume, while areal density refers to the mass of a substance per unit area. Compacted density is equal to areal density divided by the thickness of the substance. In the lithium-ion battery 100, the thickness of each coating portion in the positive electrode 110 and the negative electrode is kept as consistent as possible. When the areal density of the first coating portion 141 and the second coating portion 142, and the areal 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.

[0047] In this disclosure, the compaction density of the first coating portion 141 on the surface of the positive electrode 110 is greater than the compaction density of the second coating portion 142, or the areal density of the first coating portion 141 is greater than the areal density of the second coating portion 142. The second coating portion 142 with a lower compaction density or areal density tends to distribute a higher current, thereby effectively raising the temperature of the positive electrode 110 away from the first tab 112, resulting in a smaller overall temperature difference for the positive electrode 110; the compaction density of the third coating portion 151 on the surface of the negative electrode 120 is greater than the compaction density of the fourth coating portion 152, or the third... The areal density of the coating portion 151 is greater than that of the fourth coating portion 152. The fourth coating portion 152, with its lower compaction density or areal density, tends to distribute a higher current, thereby effectively raising the temperature of the positive electrode 110 away from the first tab 112, resulting in a smaller overall temperature difference in the negative electrode 120. The first coating portion 141 and at least a portion of the second coating portion 142 are located in the orthogonal projection of the third coating portion 151 onto the positive electrode 110, thereby ensuring that the area of ​​the negative electrode 120 always exceeds the lithium-ion insertion sites required by the positive electrode, reducing the risk of lithium plating in the electrode core during charging and discharging.

[0048] In this embodiment of the disclosure, the length / width direction of the electrode core is taken as the first direction X, and the thickness direction of the electrode core is taken as the second direction Y.

[0049] In this embodiment, the first coating portion 141 is closer to the first tab 112 than the second coating portion 142. Specifically, in one embodiment, the first coating portion 141 is at least partially closer to the edge of the first current collector 111 where the first tab 112 is connected compared to the edge of the second coating portion 142. For example, if both the first coating portion 141 and the second coating portion 142 are rectangular, and the length of the first coating portion 141 in the perpendicular first direction X is the same as the length of the second coating portion 142 in the perpendicular first direction X, then the first coating portion 141 is generally closer to the edge of the first current collector 111 where the first tab 112 is connected compared to the second coating portion 142. 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 electrode core, or the width direction of the electrode core. In another embodiment, when the minimum distance from a portion of the edge of the second coating portion 142 to the edge of the first current collector 111 connected to the first tab 112 is the same as the minimum distance from the edge of the first coating portion 141 to the edge of the first current collector 111 connected to the first tab 112, the first coating portion 141 is disposed directly opposite to the first tab 112 in the first direction X, and the second coating portion 142 is U-shaped, surrounding the outer periphery of the first coating portion 141.

[0050] The first coating portion 141 and the second coating portion 142 are arranged along the first direction X, and the positive electrode 110 and the negative electrode 120 are stacked in the second direction Y. The negative electrode 120 also includes a second current collector 121 and a second tab 122. The third coating portion 151 and the fourth coating portion 152 are sequentially disposed on the second current collector 121, and the second tab 122 is connected to the end of the second current collector 121 along the first direction X near the third coating portion 151. Specifically, the first tab 112 is a bridge connecting the first current collector 111 and the external circuit, and the second tab 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. The current in the first current collector 111 converges towards the first tab 112 and the second tab 122, and the current in the second current collector 121 converges towards the first tab 112 and the second tab 122, thereby causing heat generation on the first current collector 111 near the first tab 112 and the second tab 122, and on the second current collector 121 near the first tab 112 and the second tab 122. With a relatively large amount of material, a first coating portion 141 and a third coating portion 151 with a high compaction density are respectively provided on the first current collector 111 near the first tab 112 and the second tab 122. This increases the electrochemical resistance of the positive electrode 110 near the first tab 112 and the negative electrode 120 near the second tab 122, allowing more current to flow to the second coating portion 142 of the positive electrode 110 and the fourth coating portion 152 of the negative electrode 120. This reduces the heat generation of the positive electrode 110 near the first tab 112 and the negative electrode 120 near the second tab 122, resulting in a smaller temperature difference between the positive electrode 110 and the negative electrode 120.

[0051] In the electrode core provided in this disclosure, the positive electrode 110 further includes a fifth coating portion 143, wherein the first coating portion 141, the second coating portion 142 and the fifth coating portion 143 are sequentially disposed 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 120 further includes a sixth coating portion 153, wherein the third coating portion 151, the fourth coating portion 152 and the sixth coating portion 153 are sequentially disposed 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 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. The first tab 112 is connected to the end of the first current collector 111 along the first direction X near the first coating section 141, and the second tab 122 is connected to the end of the second current collector 121 along the first direction X near the third coating section 151. That is, the first tab 112 and the second tab 122 are both located at the same end of the electrode core in the first direction X. Alternatively, the first tab 112 is connected to the end of the first current collector 111 along the first direction X near the first coating section 141, and the second tab 122 is connected to the end of the second current collector 121 along the first direction X away from the third coating section 151. That is, the first tab 112 and the second tab 122 are both located at opposite ends of the electrode core in the first direction X.

[0052] Referring to Figure 3, in the first direction X, the orthographic projection of the third coating portion 151 onto the positive electrode 110 covering the second coating portion 142 has a size a ranging from 2 mm to 10 mm. For example, a can be 2 mm, 2.1 mm, 2.5 mm, 3 mm, 4 mm, 5 mm, 6 mm, 8 mm, 10 mm, etc., and is not limited to the listed values; other unlisted values ​​within the range are also applicable. The fifth coating portion 143 and at least a portion of the second coating portion 142 are located within the orthographic projection of the sixth coating portion 153 onto the positive electrode 110. The size b of the orthographic projection of the sixth coating portion 153 onto the positive electrode 110 covering the second coating portion 142 has a size b ranging from 2 mm to 10 mm. For example, b can be 2 mm, 2.1 mm, 2.5 mm, 3 mm, 4 mm, 5 mm, 6 mm, 8 mm, 10 mm, etc., and is not limited to the listed values; other unlisted values ​​within the range are also applicable.

[0053] 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 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 of the negative electrode sheet 120, thereby effectively raising the temperature in the middle 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.

[0054] Optionally, the first parameter is the compaction density. 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. 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 during the rolling and die-cutting processes due to uneven extension and stress distribution.

[0055] 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. 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 during the rolling and die-cutting processes due to uneven extension and stress distribution.

[0056] While ensuring that the ratio of the compaction density of the first coating section 141 to the compaction density of the second coating section 142 is K1, and the ratio of the compaction density of the third coating section 151 to the compaction density of the fourth coating section 152 is K2, the compaction density range of the first coating section 141 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, but not limited to, the listed values, other unlisted values ​​within the range also apply; the compaction density of the second coating section 142 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, but not limited to, the listed values, other unlisted values ​​within the range also apply; the compaction density of the third coating section 151 is 1.1 g / mm². 3 ~1.8g / mm 3For 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 range of the fourth coating section 152 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 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 110 and the negative electrode 120.

[0057] 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.

[0058] 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 the ratio 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 、2.4 \alpha 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 It should be noted that there seems to be an error in the original text where "1.8\alpha g / mm" is written. I translated it as "1.8 \alpha g / mm" according to the rules. If this is incorrect, please check and correct the original text.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 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 110 and the negative electrode 120.

[0059] In one 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 110 and the negative electrode 120, the same process can be used to coat the first coating portion 141 and the fifth coating portion 143 on the first current collector 111, and to coat the third coating portion 151 and the sixth coating portion 153 on the second current collector 121, thereby reducing manufacturing difficulty.

[0060] When the first parameter is areal density, the areal density range of the first coating part 141, the second coating part 142, and the fifth coating part 143 is all 200 g / m³. 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 the positive electrode 110 has sufficient active material while allowing lithium ions to be inserted and extracted smoothly.

[0061] When the first parameter is areal density, the areal density range of the third coating section 151, the fourth coating section 152, and the sixth coating section 153 is 150 g / m³. 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 the negative electrode 120 has sufficient active material while allowing lithium ions to be inserted and extracted smoothly.

[0062] When the first parameter is the compaction density, the first coating portion 141, the second coating portion 142, and the fifth coating portion 143 are arranged sequentially in the first direction X, and the third coating portion 151, the fourth coating portion 152, and the sixth coating portion 153 are arranged sequentially in the first direction X. The compaction density of the second coating portion 142 gradually increases in the first direction X from the middle of the second coating portion 142 toward one end closer to the first coating portion 141 and / or the fifth coating portion 143; and / or, the compaction density of the fourth coating portion 152 gradually increases in the first direction X from the middle of the fourth coating portion 152 toward one end closer to the third coating portion 151 and / or the sixth coating portion 153. This causes the compaction density at the junctions of the first coating section 141 and the second coating section 142, the second coating section 142 and the fifth coating section 143, the third coating section 151 and the fourth coating section 152, and the fourth coating section 152 and the sixth coating section 153 to gradually change, thereby making the stress distribution of the positive electrode 110 and the negative electrode 120 more uniform after the electrode and the negative electrode 120 are rolled.

[0063] In the description of the embodiments of this disclosure, 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 disclosure 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 disclosure.

[0064] The above-disclosed embodiments are merely preferred embodiments of this disclosure and should not be construed as limiting the scope of this disclosure. 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 disclosure, still fall within the scope of this disclosure.

Claims

1. A pole core, comprising: A positive electrode sheet (110), including a first current collector (111), a first tab (112), and a first coating portion (141) and a second coating portion (142) provided on the same surface of the first current collector (111). The first tab (112) is connected to the first current collector (111). The first coating portion (141) is closer to the first tab (112) than the second coating portion (142). A first parameter of the first coating portion (141) is greater than a first parameter of the second coating portion (142); A negative electrode sheet (120), on the surface of which a third coating portion (151) and a fourth coating portion (152) are sequentially provided. A first parameter of the third coating portion (151) is greater than a first parameter of the fourth coating portion (152); Wherein, the first parameter is the compaction density or the areal density. The first coating portion (141) and at least a part of the second coating portion (142) are located in the orthographic projection of the third coating portion (151) on the positive electrode sheet (110).

2. The pole core according to claim 1, comprising, in a first direction, the size range of the orthographic projection of the third coating portion (151) on the positive electrode sheet (110) covering the second coating portion (142) is 2 mm to 10 mm. The first direction is the direction in which the first coating portion (141) and the second coating portion (142) are arranged.

3. The pole core according to claim 1 or 2, comprising, the first parameter is the compaction density. The ratio of the compaction density of the first coating portion (141) to the compaction density of the second coating portion (142) is K1, 1 < K1 ≤ 1.5, and / or, the ratio of the compaction density of the third coating portion (151) to the compaction density of the fourth coating portion (152) is K2, 1 < K2 ≤ 1.

5.

4. The pole core according to any one of claims 1-3, comprising, the first parameter is the compaction density. The positive electrode sheet (110) further includes a fifth coating portion (143). The first coating portion (141), the second coating portion (142), and the fifth coating portion (143) are sequentially provided on the first current collector (111). 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) further includes a sixth coating portion (153) and a second current collector (121). The third coating portion (151), the fourth coating portion (152), and the sixth coating portion (153) are sequentially provided on the second current collector (121). The compaction density of the sixth coating portion (153) is greater than the compaction density of the fourth coating portion (152).

5. The pole core according to claim 4, comprising, the fifth coating portion (143) and at least a 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).

6. The electrode core according to claim 4 or 5, comprising that the first coating part (141) and the second coating part (142) are arranged on the first current collector (111) along a first direction, and the first tab (112) is connected to one end of the first current collector (111) along the first direction close to the first coating part (141); The negative electrode sheet (120) further comprises a second tab (122), the third coating part (151) and the fourth coating part (152) are sequentially arranged on the second current collector (121), and the second tab (122) is connected to one end of the second current collector (121) along the first direction close to the third coating part (151).

7. The electrode core according to any one of claims 4-6, comprising that the first coating part (141) and the second coating part (142) are arranged on the first current collector (111) along a first direction, and the first tab (112) is connected to one end of the first current collector (111) along the first direction close to the first coating part (141); The negative electrode sheet (120) further comprises a second tab (122), the third coating part (151) and the fourth coating part (152) are sequentially arranged on the second current collector (121), and the second tab (122) is connected to one end of the second current collector (121) along the first direction far from the third coating part (151).

8. The electrode core according to any one of claims 5-7, comprising that the first parameter is the compaction density, 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, 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.

9. The electrode core according to any one of claims 5-7, comprising, wherein the first parameter is compaction density, and the compaction density of the first coating portion (141) is in the range of 1.8 g / mm². 3 ~2.8g / mm 3 The compaction density of the second coating portion (142) is in the range of 1.8 g / mm². 3 ~2.8g / mm 3 The compaction density of the fifth coating portion (143) is in the range of 1.8 g / mm². 3 ~2.8g / mm 3 ; And / or, the compaction density of the third coating portion (151) is in the range of 1.1 g / mm². 3 ~1.8g / mm 3 The compaction density of the fourth coating portion (152) is in the range of 1.1 g / mm². 3 ~1.8g / mm 3 The compaction density of the sixth coating section (153) is in the range of 1.1 g / mm². 3 ~1.8g / mm 3 .

10. The electrode core according to any one of claims 5-7, comprising that the first parameter is the compaction density, the compaction density of the first coating part (141) is the same as the compaction density of the fifth coating part (143), and / or the compaction density of the third coating part (151) is the same as the compaction density of the sixth coating part (153).

11. The electrode core according to any one of claims 4-10, comprising, wherein the first parameter is areal density, and the areal density range of the first coating portion (141), the second coating portion (142), and the fifth coating portion (143) is 200 g / m³. 2 ~600g / m 2 .

12. The electrode core according to any one of claims 4-11, comprising, wherein the first parameter is areal density, and the areal density range of the third coating portion (151), the fourth coating portion (152), and the sixth coating portion (153) is 150 g / m³. 2 ~250g / m 2 .

13. The electrode core according to any one of claims 4-12, comprising that the first parameter is the compaction density, the first coating part (141), the second coating part (142) and the fifth coating part (143) are sequentially arranged in the first direction, the third coating part (151), the fourth coating part (152) and the sixth coating part (153) are sequentially arranged in the first direction, and the compaction density of the second coating part (142) gradually increases in the first direction from the middle of the second coating part (142) to one end close to the first coating part (141) and / or the fifth coating part (143); And / or, the compaction density of the fourth coating portion (152) gradually increases in the first direction from the middle of the fourth coating portion (152) toward one end near the third coating portion (151) and / or the sixth coating portion (153).

14. A battery comprising an electrode core according to any one of claims 1-13.

15. An electrical appliance comprising the battery (100) according to claim 14.

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