Secondary battery and electric equipment

Abstract

The embodiment of the invention discloses a secondary battery and electric equipment, the secondary battery comprises an electrode assembly, the electrode assembly comprises a plurality of first pole pieces and a plurality of second pole pieces, and the secondary battery comprises a first coating; the first coating comprises a plurality of first coating blocks, the plurality of first coating blocks are arranged on the surface, facing the second pole piece, of the first pole piece, a first channel is formed between any two adjacent first coating blocks, the first channel is at least communicated with one edge of the first pole piece, and the first channel exposes at least part of the surface, facing the second pole piece, of the first pole piece; the first coating is melted when the temperature is higher than a first preset temperature and at least partially covers the first channel, the area of the first pole piece covered by the first coating after melting is X1, the area of the first pole piece covered by the first coating before melting is Y1, and X1 is larger than Y1. According to the embodiment of the invention, the area of the first coating after melting is increased, so that heat generated by continuous contact reaction between the active particles of the first pole piece and the electrolyte can be slowed down, and the probability of thermal runaway of the secondary battery is reduced.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of batteries, and in particular, to a secondary battery and an electrical device using the same. Background Art

[0002] A secondary battery refers to a battery that can restore electrical energy through charging and be reused, such as a lithium-ion battery, a nickel-metal hydride battery, or a lead-acid battery, etc. Secondary batteries are widely used in consumer electronic devices or energy storage devices, etc. At present, how to reduce the probability of thermal runaway of secondary batteries has attracted the close attention of researchers. Summary of the Invention

[0003] The inventors of the present application have found through research that during the process of thermal-electrical abuse (such as overcharging or over-discharging), the chemical reactions inside the battery cell of the secondary battery intensify, releasing a large amount of heat. Due to the structural limitations of the battery cell of the secondary battery, the large amount of heat released is difficult to dissipate, and a large amount of heat accumulates inside the battery cell, resulting in an increase in the temperature of the battery cell. However, the increase in the temperature of the battery cell easily promotes a chain reaction inside the battery cell to continue generating heat, resulting in a heat generation cycle inside the battery cell, which is difficult to control. When the heat generation is greater than the heat dissipation, it is easy to cause thermal runaway of the battery cell, leading to potential safety hazards.

[0004] The embodiments of the present application aim to provide a secondary battery and an electrical device using the same, which can reduce the probability of thermal runaway.

[0005] To solve the above technical problems, one technical solution adopted in the embodiments of the present application is: to provide a secondary battery, including an electrode assembly, the electrode assembly includes a plurality of first electrode plates and a plurality of second electrode plates, and the secondary battery further includes a first coating; the first coating includes a plurality of first coating blocks, the plurality of first coating blocks are arranged on the surface of the first electrode plate facing the second electrode plate, a first channel is formed between any two adjacent first coating blocks, the first channel is at least connected to one edge of the first electrode plate, the first channel exposes at least a part of the surface of the first electrode plate facing the second electrode plate, the first coating melts and at least partially covers the first channel when the temperature is higher than a first preset temperature, the area of the first electrode plate covered by the first coating after melting is X1, and the area of the first electrode plate covered by the first coating before melting is Y1, and X1>Y1.

[0006] In the embodiments of the present application, when the temperature is higher than the first preset temperature, the first coating melts and increases the area covering the first electrode sheet, which can slow down the heat generation from the continued contact reaction between the active particles of the first electrode sheet and the electrolyte, and slow down the heat generation from the continued crosstalk reaction of the redox gases between the first electrode sheet and the second electrode sheet. Furthermore, the probability of continued heat generation from the chain reaction occurring inside the secondary battery is reduced, thereby reducing the probability that the heat generation is greater than the heat dissipation, and achieving the purpose of reducing the probability of thermal runaway of the secondary battery. In addition, by providing the first channel, not only can the wetting effect of the electrolyte on the first electrode sheet be maintained when the temperature is lower than the first preset temperature, but also gases and heat can be exported when the temperature is higher than the first preset temperature.

[0007] In some embodiments, the area of the first electrode sheet covered after the first coating melts is equal to the area of the surface of the first electrode sheet facing the second electrode sheet. Setting the area of the first electrode sheet covered after the first coating melts to be equal to the area of the surface of the first electrode sheet facing the second electrode sheet enables the first coating to completely cover the surface of the first electrode sheet facing the second electrode sheet after melting, enhancing the barrier effect, further slowing down the heat generation from the continued contact reaction between the active particles of the first electrode sheet and the electrolyte, and further slowing down the heat generation from the continued crosstalk reaction of the redox gases between the first electrode sheet and the second electrode sheet.

[0008] In some embodiments, the electrode assembly has a stacked structure. The electrode assembly is divided into a first region and two second regions with equal thicknesses along the thickness direction. The two second regions are oppositely arranged on the two outermost sides of the electrode assembly along the thickness direction, and the first region is located between the two second regions; the total area of the first electrode sheet is Q0, the total area of the first electrode sheet in the first region is Q1, and the total area of the first electrode sheet in the two second regions is Q2. Among them, Q1 + Q2 = Q0, 50%Q0 ≤ Q1 ≤ 75%Q0, and 25%Q0 ≤ Q2 ≤ 50%Q0. By providing the first region and the second region and dividing the first region and the second region into a high-temperature region and a low-temperature region, different widths of the first coating blocks and gap widths can be set according to the different temperatures of the first region and the second region.

[0009] In some embodiments, the electrode assembly has a wound structure. The electrode assembly includes a first region and a second region. The first region is located in the central region of the electrode assembly, and the second region is located in the outer peripheral region of the electrode assembly. The first pole piece located in the first region and the first pole piece located in the second region are integrally formed and wound. The connection between the first pole piece located in the first region and the first pole piece located in the second region is the first connection line. The total area of the first pole piece is Q0. From the start end of the winding of the first pole piece to the first connection line, the total area of the first pole piece located in the first region is Q1. From the first connection line to the end of the winding of the first pole piece, the total area of the first pole piece located in the second region is Q2. Wherein, Q1 + Q2 = Q0, 50%Q0 ≤ Q1 ≤ 75%Q0, 25%Q0 ≤ Q2 ≤ 50%Q0. By setting the first region and the second region and dividing the first region and the second region into a high-temperature region and a low-temperature region, the width of the first coating block and the gap width can be set differently according to the different temperatures of the first region and the second region.

[0010] In some embodiments, the width of the gap between any two adjacent first coating blocks located in the first region is M1, the width of the gap between any two adjacent first coating blocks located in the second region is M2, the width of the first coating block located in the first region is N1, and the width of the first coating block located in the second region is N2. The first coating further satisfies at least one of the following conditions:

[0011] 1) 0mm < M1 ≤ 1mm;

[0012] 2) 2mm ≤ M2 ≤ 4mm;

[0013] 3) 7mm ≤ N1 ≤ 10mm;

[0014] 4) 3mm ≤ N2 ≤ 5mm.

[0015] In some embodiments, the material of the first coating includes at least one of the following materials:

[0016] 1) Ethylene propylene random polymer;

[0017] 2) Ethylene propylene rubber;

[0018] 3) Block copolymerized polypropylene;

[0019] 4) Polyisobutylene rubber;

[0020] 5) Thermoplastic rubber;

[0021] 6) Amino-terminated liquid nitrile rubber.

[0022] In some embodiments, the material of the first coating includes an ion conductive agent. By setting the ion conductive agent, the ion transport performance of the first coating can be enhanced.

[0023] In some embodiments, the material of the ionic conductive agent includes at least one of the following materials:

[0024] 1) Polymer electrolyte;

[0025] 2) Inorganic solid electrolyte.

[0026] In some embodiments, the material of the first coating includes an electronic conductive agent. Setting the electronic conductive agent can enhance the electronic transmission performance of the first coating.

[0027] In some embodiments, the material of the electronic conductive agent includes at least one of the following materials:

[0028] 1) Carbon nanotubes;

[0029] 2) Graphene;

[0030] 3) Conductive carbon black.

[0031] In some embodiments, the first preset temperature is 90°C to 170°C. Setting the first preset temperature to 90°C to 170°C can prevent the first coating from melting prematurely and affecting the normal operation of the first electrode, and avoid affecting the normal use of the secondary battery.

[0032] In some embodiments, along the thickness direction of the first electrode, the thickness of the first coating is defined as H, and H satisfies: 0 μm < H ≤ 5 μm. Setting 0 μm < H can prevent the first coating from being too thin and wearing out during long-term use, and H ≤ 5 μm can prevent the first coating from being too thick and reducing the energy density of the secondary battery.

[0033] In some embodiments, the secondary battery further includes a second coating, the second coating includes a plurality of second coating blocks, the plurality of second coating blocks are disposed on the surface of the second electrode facing the first electrode, a second channel is formed between any two adjacent second coating blocks, the second channel at least communicates with one edge of the second electrode, the second channel exposes at least a part of the surface of the second electrode facing the first electrode, the second coating melts and at least partially covers the second channel when the temperature is higher than the second preset temperature, the area of the second electrode covered by the second coating after melting is X2, and the area of the second electrode covered by the second coating before melting is Y2, and X2 > Y2.

[0034] In this embodiment, the first coating and the second coating are melted synchronously and respectively cover the surfaces of the first electrode plate and the second electrode plate, which can slow down the heat generation caused by the continuous contact reaction between the active particles of the first electrode plate and the second electrode plate and the electrolyte, and slow down the heat generation caused by the continuous crosstalk reaction of the redox gases between the first electrode plate and the second electrode plate. It can better reduce the probability of continuous heat generation due to chain reaction inside the secondary battery, and better reduce the probability that the heat generation is greater than the heat dissipation, so as to achieve the purpose of reducing the probability of thermal runaway of the secondary battery. In addition, the first channel and the second channel are provided, which can not only maintain the wetting effect of the electrolyte on the first electrode plate and the second electrode plate when the temperature is lower than the first preset temperature, but also supply the gas and heat to be exported when the temperature is higher than the first preset temperature.

[0035] In some embodiments, the area of the second electrode plate covered by the second coating after melting is equal to the area of the surface of the second electrode plate facing the first electrode plate. Setting the area of the second electrode plate covered by the second coating after melting to be equal to the area of the surface of the second electrode plate facing the first electrode plate can make the second coating completely cover the surface of the second electrode plate facing the first electrode plate after melting, enhance the barrier effect, further slow down the heat generation caused by the continuous contact reaction between the active particles of the second electrode plate and the electrolyte, and further slow down the heat generation caused by the continuous crosstalk reaction of the redox gases between the first electrode plate and the second electrode plate.

[0036] In some embodiments, the first electrode plate includes a first current collector and a first active material. The first active material is disposed on the surface of the first current collector facing the second electrode plate. The first coating is disposed on the surface of the first active material facing away from the first current collector. The first channel exposes at least a part of the surface of the first active material facing away from the first current collector.

[0037] To solve the above technical problems, another technical solution adopted in the embodiments of the present application is: to provide an electrical device including the above secondary battery.

[0038] The beneficial effects of the embodiments of the present application are as follows: Different from the prior art, the embodiments of the present application provide a secondary battery and an electrical device. The secondary battery includes an electrode assembly, and the electrode assembly includes a plurality of first electrode plates and a plurality of second electrode plates. The secondary battery further includes a first coating; the first coating includes a plurality of first coating blocks, and the plurality of first coating blocks are disposed on the surface of the first electrode plate facing the second electrode plate. A first channel is formed between any two adjacent first coating blocks, and the first channel at least communicates with one edge of the first electrode plate. The first channel exposes at least a part of the surface of the first electrode plate facing the second electrode plate. The first coating melts and at least partially covers the first channel when the temperature is higher than the first preset temperature. The area of the first electrode plate covered by the first coating after melting is X1, and the area of the first electrode plate covered by the first coating before melting is Y1, and X1>Y1.

[0039] In the embodiment of the present application, the first coating melts when the temperature is higher than the first preset temperature. Moreover, the area of the first electrode sheet covered after the first coating melts is X1, and the area of the first electrode sheet covered before the first coating melts is Y1, where X1 > Y1. This can slow down the heat generation from the continued contact reaction between the active particles of the first electrode sheet and the electrolyte, and slow down the heat generation from the continued cross-talk reaction of the redox gases between the first electrode sheet and the second electrode sheet. Furthermore, it can reduce the probability of continued heat generation from the chain reaction occurring inside the secondary battery, thereby reducing the probability of thermal runaway of the secondary battery. Description of the Drawings

[0040] To more clearly illustrate the technical solutions in the specific embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0041] Figure 1 is a schematic diagram of the overall structure of the secondary battery provided by the embodiment of the present application;

[0042] Figure 2 is a schematic diagram of the structure of the first electrode sheet and the first coating of the secondary battery provided by the embodiment of the present application;

[0043] Figure 3 is a schematic diagram of a partial structure of the secondary battery provided by the embodiment of the present application;

[0044] Figure 4 is a schematic diagram of the structure of the second electrode sheet and the second coating of the secondary battery provided by the embodiment of the present application.

[0045] Description of the Reference Numerals:

[0046] 1 electrode assembly, 11 first electrode sheet, 12 second electrode sheet, 13 separator;

[0047] 2 first coating, 21 first coating block, 22 first channel;

[0048] 3 second coating, 31 second coating block, 32 second channel;

[0049] 100 secondary battery. Detailed Embodiments

[0050] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following will clearly describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application.

[0051] References to "embodiments" in this application mean that the specific features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of this application. The phrase may not necessarily refer to the same embodiment when it appears in various places in the specification, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments.

[0052] In the description of the embodiments of this application, technical terms such as "first" and "second" are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity, specific order, or primary-secondary relationship of the indicated technical features. In the description of the embodiments of this application, "a plurality of" means more than two, unless otherwise specifically defined.

[0053] In the description of the embodiments of this application, the term "and / or" is merely a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this text generally represents an "or" relationship between the associated objects before and after.

[0054] The term "vertical" is used to describe the ideal state between two components. In the actual production or use state, there can be a state approximately vertical between the two components. For example, in combination with numerical descriptions, vertical can refer to the included angle range between two straight lines being between 90±10°, vertical can also refer to the dihedral angle range between two planes being between 90±10°, and vertical can also refer to the included angle range between a straight line and a plane being between 90±10°. The two components described as "vertical" may not be absolute straight lines or planes, and can also be approximately straight lines or planes. From a macroscopic perspective, as long as the overall extension direction is a straight line or a plane, the components can be considered "straight lines" or "planes".

[0055] The first direction X, the second direction Y, and the third direction Z of this application are two-way directions, that is, the first direction X includes the direction indicated by the arrow in the drawing and its opposite direction, the second direction Y includes the direction indicated by the arrow in the drawing and its opposite direction, and the third direction Z includes the direction indicated by the arrow in the drawing and its opposite direction.

[0056] Without conflict, the different embodiments of this application described below and the technical features involved in the embodiments can be combined with each other.

[0057] During the thermoelectric abuse process (e.g., overcharge or over-discharge), the chemical reactions inside the battery cell intensify, releasing a large amount of heat. Due to the structural limitations of the battery cell, the large amount of heat released is difficult to dissipate, and a large amount of heat accumulates inside the battery cell, resulting in an increase in the temperature of the battery cell. However, the increase in the temperature of the battery cell promotes a chain reaction inside the battery cell to continue generating heat, leading to a heat generation cycle inside the battery cell, which is difficult to control. When the heat generation is greater than the heat dissipation, it is easy to cause thermal runaway of the battery cell, triggering potential safety hazards.

[0058] Based on this, the present application provides an embodiment of a secondary battery 100, which can reduce the probability of thermal runaway and reduce potential safety hazards.

[0059] To facilitate the reader's understanding of the concept of the embodiment of the present application, the specific structure of the secondary battery 100 will be described as follows:

[0060] For the above-mentioned secondary battery 100, please refer to Figure 1 and Figure 2 , the secondary battery 100 includes an electrode assembly 1, the electrode assembly 1 includes a plurality of first electrode plates 11 and a plurality of second electrode plates 12, and the secondary battery 100 further includes a first coating 2; the first coating 2 includes a plurality of first coating blocks 21, the plurality of first coating blocks 21 are arranged on the surface of the first electrode plate 11 facing the second electrode plate 12, a first channel 22 is formed between any two adjacent first coating blocks 21, the first channel 22 at least communicates with one edge of the first electrode plate 11, the first channel 22 exposes at least a part of the surface of the first electrode plate 11 facing the second electrode plate 12, the first coating 2 melts and at least partially covers the first channel 22 when the temperature is higher than a first preset temperature, the area of the first electrode plate 11 covered by the first coating 2 after melting is X1, and the area of the first electrode plate 11 covered by the first coating 2 before melting is Y1, and X1 > Y1.

[0061] In the embodiment of the present application, when the temperature is lower than the first preset temperature, the first coating 2 is not melted, the active particles of the first electrode sheet 11 are in normal contact reaction with the electrolyte, and the oxidative and reductive gas of the first electrode sheet 11 and the second electrode sheet 12 has a normal crosstalk reaction; when the temperature is higher than the first preset temperature, the first coating 2 is melted, and the area of the first electrode sheet 11 covered by the melted first coating 2 is X1, and the area of the first electrode sheet 11 covered by the first coating 2 before melting is Y1, and X1>Y1, that is, the area of the first coating 2 covering the surface of the first electrode sheet 11 facing the second electrode sheet 12 increases, which can slow down the heat generation of the continuous contact reaction between the active particles of the first electrode sheet 11 and the electrolyte, and slow down the heat generation of the continuous crosstalk reaction between the oxidative and reductive gas of the first electrode sheet 11 and the second electrode sheet 12, thereby reducing the probability of continuous heat generation of the chain reaction inside the secondary battery 100, and thus reducing the probability that the heat generation is greater than the heat dissipation, so as to reduce the probability of thermal runaway of the secondary battery 100. In addition, in the embodiment of the present application, by providing the first channel 22, not only can the wetting effect of the electrolyte on the first electrode sheet 11 be maintained when the temperature is lower than the first preset temperature, but also gas and heat can be exported when the temperature is higher than the first preset temperature.

[0062] When the temperature is higher than the first preset temperature, several first coating blocks 21 are melted and flow, so that the first channels 22 between any two adjacent first coating blocks 21 are filled. During this process, if the distances of the first channels 22 between any two adjacent first coating blocks 21 are different, it is easy to cause uneven filling thickness of the first channels 22 between any two adjacent first coating blocks 21, resulting in uneven thickness of the first coating 2 after melting, that is, the first coating 2 is locally too thick or too thin along the thickness direction after melting. Therefore, there are requirements for the distances of the first channels 22 between any two adjacent first coating blocks 21. For example, in some embodiments, several first coating blocks 21 are arranged at equal intervals, so that the distances of the first channels 22 between any two adjacent first coating blocks 21 are the same, which can make the filling thicknesses of the first channels 22 between any two adjacent first coating blocks 21 similar or equal, and reduce the probability of uneven thickness of the first coating 2 after melting, that is, reduce the local excessive thickness or excessive thinness of the first coating 2 along the thickness direction after melting.

[0063] Considering that the area of the first electrode sheet 11 covered after the first coating 2 melts affects the barrier effect of the first coating 2, in order to enable the first coating 2 to have a good barrier effect, there are requirements for the area of the first electrode sheet 11 covered after the first coating 2 melts. For example, in some embodiments, 1.1Y1 ≤ X1 ≤ 1.2Y1, that is, the area of the first electrode sheet 11 covered after the first coating 2 melts increases by 10% to 20% compared with the area of the first electrode sheet 11 covered before melting, reducing the heat generation from the continuous reaction of the active particles of the first electrode sheet 11 with the electrolyte, and reducing the heat generation from the continuous crosstalk reaction of the redox gases between the first electrode sheet 11 and the second electrode sheet 12. In addition, by setting 1.1Y1 ≤ X1 ≤ 1.2Y1, the first channel 22 cannot be completely covered, allowing gas and heat to be exported.

[0064] Furthermore, in order to enable the first coating 2 to have a better barrier effect, there are further requirements for the area of the first electrode sheet 11 covered after the first coating 2 melts. For example, in some embodiments, the area of the first electrode sheet 11 covered after the first coating 2 melts is equal to the area of the surface of the first electrode sheet 11 facing the second electrode sheet 12, so that the first coating 2 completely covers the surface of the first electrode sheet 11 facing the second electrode sheet 12 after melting, further reducing the heat generation from the continuous reaction of the active particles of the first electrode sheet 11 with the electrolyte, and further reducing the heat generation from the continuous crosstalk reaction of the redox gases between the first electrode sheet 11 and the second electrode sheet 12. It should be noted that for the area of the first electrode sheet 11 covered after the first coating 2 melts being equal to the area of the surface of the first electrode sheet 11 facing the second electrode sheet 12, an error of plus or minus 10% is allowed. For example, the area of the first electrode sheet 11 covered after the first coating 2 melts being greater than or less than the area of the surface of the first electrode sheet 11 facing the second electrode sheet 12 by plus or minus 10% can be regarded as equal.

[0065] For the secondary battery 100 described above, in some embodiments, the electrode assembly 1 has a laminated structure. The electrode assembly 1 is divided into a first region and two second regions with equal thicknesses in the thickness direction. The two second regions are relatively arranged on the two outermost sides of the electrode assembly 1 in the thickness direction, and the first region is located between the two second regions. The total area of the first electrode tab 11 is Q0, the total area of the first electrode tab 11 in the first region is Q1, and the total area of the first electrode tab 11 in the two second regions is Q2. Among them, Q1 + Q2 = Q0, 50%Q0 ≤ Q1 ≤ 75%Q0, and 25%Q0 ≤ Q2 ≤ 50%Q0. By setting the first region and the second region, the first region and the second region can be divided into a high-temperature region and a low-temperature region, so that in the first region with a higher temperature, the gap width between any two adjacent first coating blocks is set to be smaller, and the width of the first coating block is set to be larger. And in the second region with a lower temperature, the gap width between any two adjacent first coating blocks is set to be larger, and the width of the first coating block is set to be smaller. Considering that the area ratios of the first region and the second region to the area of the electrode assembly 1 affect the thermal runaway probability of the secondary battery 100, there are requirements for the area ratios of the first region and the second region to the area of the electrode assembly 1. By setting 50%Q0 ≤ Q1 ≤ 75%Q0 and 25%Q0 ≤ Q2 ≤ 50%, the thermal runaway probability of the secondary battery can be controlled at a relatively low level.

[0066] In some embodiments, the electrode assembly 1 has a wound structure. The electrode assembly 1 includes a first region and a second region. The first region is located in the central region of the electrode assembly 1, and the second region is located in the outer peripheral region of the electrode assembly 1. The first pole piece 11 located in the first region and the first pole piece 11 located in the second region are integrally formed and wound. The connection between the first pole piece 11 located in the first region and the first pole piece 11 located in the second region is the first connection line. The total area of the first pole piece 11 is Q0. From the start end of the winding of the first pole piece 11 to the first connection line, the total area of the first pole piece 11 located in the first region is Q1. From the first connection line to the end of the winding of the first pole piece 11, the total area of the first pole piece 11 located in the second region is Q2. Wherein, Q1 + Q2 = Q0, 50%Q0 ≤ Q1 ≤ 75%Q0, 25%Q0 ≤ Q2 ≤ 50%Q0. By setting the first region and the second region, the first region and the second region can be divided into a high-temperature region and a low-temperature region, so that in the first region with a higher temperature, the gap width between any two adjacent first coating blocks is set smaller, the width of the first coating block is set larger, and in the second region with a lower temperature, the gap width between any two adjacent first coating blocks is set larger, and the width of the first coating block is set smaller. Considering that the area ratios of the first region and the second region to the area of the electrode assembly 1 affect the thermal runaway probability of the secondary battery 100, there are requirements for the area ratios of the first region and the second region to the area of the electrode assembly 1. By setting 50%Q0 ≤ Q1 ≤ 75%Q0, 25%Q0 ≤ Q2 ≤ 50%Q0, the thermal runaway probability of the secondary battery can be controlled to be at a relatively low level.

[0067] Considering that the temperature of the first region is higher than that of the second region, the continuous heat generation in the first region should be less than that in the second region. Therefore, there are requirements for the width of the gap between any two adjacent first coating blocks 21 in the first region and the second region, and there are also requirements for the width of the first coating blocks 21 in the first region and the second region. For example, in some embodiments, the width of the gap between any two adjacent first coating blocks 21 located in the first region is M1, the width of the gap between any two adjacent first coating blocks 21 located in the second region is M2, the width of the first coating block 21 located in the first region is N1, the width of the first coating block 21 located in the second region is N2, and the first coating 2 further satisfies at least one of the following conditions: 1) 0mm < M I≤1 mm; 2) 2 mm ≤ M2 ≤ 4 mm; 3) 7 mm ≤ N1 ≤ 10 mm; 4) 3 mm ≤ N2 ≤ 5 mm. By the above method, the gap between any two adjacent first coating blocks 21 in the first region can be made smaller than the gap between any two adjacent first coating blocks 21 in the second region, that is, the gap between any two adjacent first coating blocks 21 in the first region with more heat generation is smaller, and the gap between any two adjacent first coating blocks 21 in the second region with less heat generation is larger. Furthermore, the gap between any two adjacent first coating blocks 21 in the first region is filled faster, so that the barrier effect of the first coating 2 in the first region is better, which helps to make the continuous heat generation in the first region less than that in the second region. In addition, by the above method, the width of the first coating block 21 in the first region can be made larger than the width of the first coating block 21 in the second region, that is, the width of the first coating block 21 in the first region with more heat generation can be made larger, and the width of the first coating block 21 in the second region with less heat generation can be made smaller. Furthermore, the area of the first electrode tab 11 covered by the first coating 2 in the first region is larger, so that the barrier effect of the first coating 2 in the first region is better, which helps to make the continuous heat generation in the first region less than that in the second region. Since the peripheral part of the electrode assembly 1 is weakly bound, the heat dissipation benefit through the gap between the first coating blocks 21 is higher, and the effect of preventing thermal runaway is better. Therefore, the gap in the second region is set relatively large, and the width of the first coating block 21 is relatively small; since the central part of the electrode assembly 1 is strongly bound, the heat generation prevention benefit through the barrier of the first coating blocks 21 is higher, and the effect of preventing thermal runaway is better. Therefore, the width of the first coating blocks 21 in the first region is set relatively large, and the gap in the first region is relatively small.

[0068] For the above-mentioned first coating 2, in order to prevent the first coating 2 from melting prematurely and affecting the normal operation of the first electrode tab 11, thereby affecting the normal use of the secondary battery 100, there are requirements for the melting temperature of the first coating 2. For example, in some embodiments, the first preset temperature is 90°C to 170°C, so that the melting temperature of the first coating 2 is 90°C to 170°C.

[0069] For the above-mentioned first coating 2, considering that the melting temperature of the first coating 2 is 90°C to 170°C, therefore, there are requirements for the material of the first coating 2. For example, in some embodiments, the material of the first coating 2 includes at least one of the following materials: 1) ethylene-propylene random polymer; 2) ethylene-propylene rubber; 3) block copolymerized polypropylene; 4) polyisobutylene rubber; 5) thermoplastic rubber; 6) terminal amino liquid nitrile rubber. Among them, when the material of the first coating 2 is at least one of ethylene-propylene random polymer, ethylene-propylene rubber, block copolymerized polypropylene, polyisobutylene rubber, thermoplastic rubber and terminal amino liquid nitrile rubber, the melting temperature of the first coating 2 can be controlled in the range of 90°C to 170°C by mixing materials.

[0070] For the above-mentioned first coating 2, in order to enhance the ionic conductivity of the first coating 2 and reduce the impact on the normal operation of the first electrode sheet 11, there are further requirements for the material of the first coating 2. For example, in some embodiments, the material of the first coating 2 includes an ionic conductive agent. In the above manner, an ionic conductive agent can be incorporated into the material of the first coating 2, improving the ionic transport performance of the first coating 2 and reducing the impact on the normal operation of the first electrode sheet 11. Further, in some embodiments, the material of the ionic conductive agent includes at least one of the following materials: 1) a polymer electrolyte; 2) an inorganic solid electrolyte.

[0071] In addition, for the above-mentioned first coating 2, in order to enhance the electronic conductivity of the first coating 2 and reduce the impact on the normal operation of the first electrode sheet 11, there are further requirements for the material of the first coating 2. For example, in some embodiments, the material of the first coating 2 includes an electronic conductive agent. In the above manner, an electronic conductive agent can be incorporated into the material of the first coating 2, improving the electronic transport performance of the first coating 2 and reducing the impact on the normal operation of the first electrode sheet 11. Further, in some embodiments, the material of the electronic conductive agent includes at least one of the following materials: 1) carbon nanotubes; 2) graphene; 3) conductive carbon black.

[0072] For the above-mentioned first coating 2, considering that the thickness of the first coating 2 is related to the energy density of the secondary battery 100, therefore, in order to avoid the thickness of the first coating 2 being too thick and reducing the energy density of the secondary battery, there are requirements for the thickness of the first coating 2. For example, in some embodiments, along the thickness direction of the first electrode sheet 11, the thickness of the first coating 2 is defined as H, and H satisfies: 0um < H ≤ 5um. In the above manner, setting 0um < H can avoid the first coating being too thin and causing wear and failure during long-term use, and setting H ≤ 5um can avoid the first coating being too thick and reducing the energy density of the secondary battery.

[0073] For the above-mentioned secondary battery 100, please refer to Figure 1 、 Figure 3 and Figure 4 , the secondary battery 100 further includes a second coating 3. The second coating 3 includes a plurality of second coating blocks 31. The plurality of second coating blocks 31 are disposed on the surface of the second electrode sheet 12 facing the first electrode sheet 11. A second channel 32 is formed between any two adjacent second coating blocks 31. The second channel 32 at least communicates with one edge of the second electrode sheet 12. The second channel 32 exposes at least a part of the surface of the second electrode sheet 12 facing the first electrode sheet 11. The second coating 3 melts and at least partially covers the second channel 32 when the temperature is higher than the second preset temperature. The area of the second electrode sheet 12 covered by the second coating 3 after melting is X2, and the area of the second electrode sheet 12 covered by the second coating 3 before melting is Y2, and X2 > Y2.

[0074] In the embodiment of the present application, when the temperature is lower than the second preset temperature, the second coating 3 is not melted, the active particles of the second electrode sheet 12 are in normal contact reaction with the electrolyte, and the oxidative and reductive gas of the first electrode sheet 11 and the second electrode sheet 12 has a normal crosstalk reaction; when the temperature is higher than the second preset temperature, the second coating 3 is melted, and the area of the second electrode sheet 12 covered by the melted second coating 3 is X2, and the area of the second electrode sheet 12 covered by the second coating 3 before melting is Y2, X2>Y2, that is, the area of the second coating 3 covering the surface of the second electrode sheet 12 facing the first electrode sheet 11 increases, which can slow down the heat generation caused by the continuous contact reaction between the active particles of the second electrode sheet 12 and the electrolyte, and slow down the heat generation caused by the continuous crosstalk reaction of the oxidative and reductive gas of the first electrode sheet 11 and the second electrode sheet 12, thereby reducing the probability of continuous heat generation due to chain reaction inside the secondary battery 100, and thus reducing the probability that heat generation is greater than heat dissipation, achieving the purpose of reducing the probability of thermal runaway of the secondary battery 100. In addition, by providing the first channel and the second channel, not only can the wetting effect of the electrolyte on the first electrode sheet and the second electrode sheet be maintained when the temperature is lower than the first preset temperature, but also gas and heat can be exported when the temperature is higher than the first preset temperature.

[0075] In some embodiments, the first preset temperature is equal to the second preset temperature. When the temperature is higher than the first preset temperature and the second preset temperature, the first coating 2 and the second coating 3 are melted synchronously and cover the surfaces of the first electrode sheet 11 and the second electrode sheet 12 respectively, which can slow down the heat generation caused by the continuous contact reaction between the active particles of the first electrode sheet 11 and the active particles of the second electrode sheet 12 and the electrolyte, and slow down the heat generation caused by the continuous crosstalk reaction of the oxidative and reductive gas of the first electrode sheet 11 and the second electrode sheet 12, better reducing the probability of continuous heat generation due to chain reaction inside the secondary battery 100, and better reducing the probability that heat generation is greater than heat dissipation, achieving the purpose of reducing the probability of thermal runaway of the secondary battery 100.

[0076] Considering that the area of the second electrode sheet 12 covered by the melted second coating 3 affects the barrier effect of the second coating 3, therefore, in order to make the second coating 3 play a good barrier role, there are requirements for the area of the second electrode sheet 12 covered by the melted second coating 3. For example, in some embodiments, 1.1Y2≤X2≤1.2Y2, that is, the area of the second electrode sheet 12 covered by the melted second coating 3 increases by 10% to 20% compared with the area of the second electrode sheet 12 covered before melting, reducing the heat generation caused by the continuous reaction between the active particles of the second electrode sheet 12 and the electrolyte, and reducing the heat generation caused by the continuous crosstalk reaction of the oxidative and reductive gas of the first electrode sheet 11 and the second electrode sheet 12.

[0077] Further, in order for the second coating layer 3 to play a better barrier role, there are further requirements for the area of the second coating layer 3 covering the second electrode sheet 12 after melting. For example, in some embodiments, the area of the second coating layer 3 covering the second electrode sheet 12 after melting is equal to the area of the surface of the second electrode sheet 12 facing the first electrode sheet 11, so that after the second coating layer 3 melts, it completely covers the surface of the second electrode sheet 12 facing the second electrode sheet 12, further reducing the heat generation caused by the continuous reaction of the active particles of the second electrode sheet 12 with the electrolyte, and further reducing the heat generation caused by the continuous cross-talk reaction of the redox gases between the second electrode sheet 12 and the first electrode sheet 11. It should be noted that for the area of the second coating layer 3 covering the second electrode sheet 12 after melting to be equal to the area of the surface of the second electrode sheet 12 facing the first electrode sheet 11, an error of plus or minus ten percent is allowed. For example, if the area of the second coating layer 3 covering the second electrode sheet 12 after melting is greater than or less than plus or minus ten percent of the area of the surface of the second electrode sheet 12 facing the first electrode sheet 11, it can be regarded as equal.

[0078] It should be noted that for the above-mentioned second coating layer 3, the relationship between the gap width between any two adjacent second coating blocks 31 in the first region and the gap width between any two adjacent second coating blocks 31 in the second region can refer to the embodiments of the first coating layer 2 above, and will not be elaborated here one by one. Similarly, for the above-mentioned second coating layer 3, the relationship between the width of the second coating blocks 31 in the first region and the width of the second coating blocks 31 in the second region can refer to the embodiments of the first coating layer 2 above, and will not be elaborated here one by one.

[0079] It should also be noted that for the second preset temperature, material, ion conductive agent, electron conductive agent and thickness of the above-mentioned second coating layer 3, they can all refer to the embodiments of the first coating layer 2 above, and will not be elaborated here one by one.

[0080] For the above-mentioned first electrode sheet 11, the first electrode sheet 11 includes a first current collector and a first active material. The first active material is disposed on the surface of the first current collector facing the second electrode sheet 12. The first coating layer 2 is disposed on the surface of the first active material facing away from the first current collector. The first channel 22 exposes at least a part of the surface of the first active material facing away from the first current collector.

[0081] For the above-mentioned second electrode sheet 12, the second electrode sheet 12 includes a second current collector and a second active material. The second active material is disposed on the surface of the second current collector facing the first electrode sheet 11. The second coating layer 3 is disposed on the surface of the second active material facing away from the second current collector. The second channel 32 exposes at least a part of the surface of the second active material facing away from the second current collector.

[0082] The present application further provides an embodiment of an electrical device, which includes the secondary battery 100 described above. For the specific structure and functions of the secondary battery 100, reference may be made to the above embodiments, and details will not be repeated here.

[0083] The secondary battery 100 of the embodiment of the present application includes an electrode assembly 1. The electrode assembly 1 includes a first electrode tab 11, a second electrode tab 12, and a separator 13. The first electrode tab 11, the separator 13, and the second electrode tab 12 are stacked in sequence. The secondary battery 100 further includes a first coating 2. The first coating 2 includes a plurality of first coating blocks 21. The plurality of first coating blocks 21 are disposed on the surface of the first electrode tab 11 facing the second electrode tab 12. A first channel 22 is formed between any two adjacent first coating blocks 21. The first channel 22 communicates with at least one edge of the first electrode tab 11. The first channel 22 exposes at least a part of the surface of the first electrode tab 11 facing the second electrode tab 12. When the temperature is higher than a first preset temperature, the first coating 2 melts and at least partially covers the first channel 22. The area of the first electrode tab 11 covered by the melted first coating 2 is X1, and the area of the first electrode tab 11 covered by the first coating 2 before melting is Y1, where X1 > Y1. In the embodiment of the present application, when the temperature is higher than the first preset temperature, the first coating 2 melts and increases the area covering the first electrode tab 11, which can slow down the heat generation caused by the continuous contact reaction between the active particles of the first electrode tab 11 and the electrolyte, and slow down the heat generation caused by the continuous cross-talk reaction of the redox gases between the first electrode tab 11 and the second electrode tab 12. Furthermore, the probability of continuous heat generation due to a chain reaction occurring inside the secondary battery is reduced, thereby reducing the probability that the heat generation is greater than the heat dissipation, and achieving the purpose of reducing the probability of thermal runaway of the secondary battery.

[0084] To facilitate the reader's understanding of the concept of the embodiment of the present application, the following is an experimental test on the secondary battery 100:

[0085] Test method for the melting area size of the first coating:

[0086] The first electrode tab coated with the first coating is cut into a 20×20 mm square, fixed to a glass slide with a double-sided high-temperature resistant tape, a grid scale sticker is pasted on the edge of the substrate, and ImageJ software is used for image processing to calculate the area Y1 of the first electrode tab covered before melting;

[0087] The hot air gun is set to the target temperature of 90°C, the vertical distance is maintained at 30 mm, heating is stopped after 10 minutes, and a top view is taken within 10 seconds, keeping the camera parallel to the specimen plane; ImageJ software is used for image processing to calculate the area X1 of the first electrode tab covered after melting.

[0088] High-temperature abuse test:

[0089] 1) After fully charging the secondary battery 100, place it in a thermal chamber;

[0090] 2) Heat the hot box at a rate of 5 ± 0.5 °C / min to increase the temperature of the hot box from room temperature to the safety standard test temperature. For example, the safety standard test temperatures are 130 °C and 135 °C.

[0091] 3) Let the hot box stand still at the safety standard test temperature for 60 min, observe whether the secondary battery 100 catches fire and burns. If it does not burn, it passes. Calculate the ratio of the number of unburned secondary batteries 100 to the total number of secondary batteries 100 to obtain the passing rate of the secondary battery 100 under the condition of the safety standard test temperature.

[0092] The secondary battery 100 is subjected to a high-temperature abuse test, and the test results are shown in Table 1 below:

[0093] Table 1

[0094]

[0095]

[0096]

[0097] According to Table 1 above, in combination with Examples 1 to 23 and Comparative Example 1, the test passing rates in Examples 1 to 23 are all greater than that in Comparative Example 1. That is, the thermal runaway probabilities in Examples 1 to 23 are all less than the thermal runaway probability in Comparative Example 1, indicating that in Examples 1 to 23, setting the first coating can slow down the heat generation caused by the continuous contact reaction between the active particles of the first electrode and the electrolyte, slow down the heat generation caused by the continuous cross-talk reaction of the redox gases between the first electrode and the second electrode, and, through the gaps between the first coating blocks, export heat and gas, thereby reducing the probability of continuous heat generation due to chain reaction inside the secondary battery, and thus reducing the thermal runaway probability of the secondary battery.

[0098] In combination with Examples 1 to 4 and Comparative Example 1, where 0 mm < M I ≤ 1 mm, the test passing rate of the secondary battery is relatively large; when M1 > 1 mm, the gap between the first coating blocks in the first region is large, resulting in a reduction in the total coverage area of the first coating blocks provided on the first electrode in the first region, weakening the barrier effect of the first coating, and the test passing rate of the secondary battery is relatively small. Therefore, in the embodiments of the present application, 0 mm < M I ≤ 1 mm is set to make the barrier and heat dissipation effects of the first coating in the first region better, and reduce the thermal runaway probability of the first region of the electrode assembly.

[0099] Combined with Embodiment 3 and Embodiments 5 to 8, when 2 mm ≤ M2 ≤ 4 mm, the passing rate of the secondary battery test is relatively high; when M1 > 4 mm, the gap between the first coating blocks in the second region is large, resulting in a reduction in the total coverage area of the first coating blocks on the first electrode sheet in the second region, weakening the barrier effect of the first coating, and the passing rate of the secondary battery test is relatively low; when M1 < 2 mm, the gap between the first coating blocks in the second region is small, resulting in the inability to quickly export the gas and heat inside the secondary battery, and the passing rate of the secondary battery test is relatively low. Therefore, in the embodiments of the present application, 2 mm ≤ M2 ≤ 4 mm is set so that the barrier and heat dissipation effects of the first coating in the second region are better, reducing the probability of thermal runaway in the second region of the electrode assembly.

[0100] Combined with Embodiment 6 and Embodiments 9 to 12, when 7 mm ≤ N1 ≤ 10 mm, the passing rate of the secondary battery test is relatively high; when N1 > 10 mm, the width of the first coating blocks in the first region is large, resulting in a small number of gaps between the first coating blocks, and the gas and heat inside the secondary battery cannot be quickly exported, and the passing rate of the secondary battery test is relatively low; when N1 < 2 mm, the width of the first coating blocks in the first region is small, resulting in a reduction in the total coverage area of the first coating blocks on the first electrode sheet in the first region, weakening the barrier effect of the first coating, and the passing rate of the secondary battery test is relatively low. Therefore, in the embodiments of the present application, 7 mm ≤ N1 ≤ 10 mm is set so that the barrier and heat dissipation effects of the first coating in the first region are better, reducing the probability of thermal runaway in the first region of the electrode assembly.

[0101] Combined with Embodiment 10 and Embodiments 13 to 16, when 3 mm ≤ N2 ≤ 5 mm, the passing rate of the secondary battery test is relatively high; when N2 > 5 mm, the width of the first coating blocks in the second region is large, resulting in a small number of gaps between the second coating blocks, and the gas and heat inside the secondary battery cannot be quickly exported, and the passing rate of the secondary battery test is relatively low; when N2 < 3 mm, the width of the first coating blocks in the second region is small, resulting in a reduction in the total coverage area of the first coating blocks on the first electrode sheet in the second region, weakening the barrier effect of the first coating, and the passing rate of the secondary battery test is relatively low. Therefore, in the embodiments of the present application, 3 mm ≤ N2 ≤ 5 mm is set so that the barrier and heat dissipation effects of the first coating in the second region are better, reducing the probability of thermal runaway in the second region of the electrode assembly.

[0102] Combined with Embodiment 14, Embodiments 17 to 20, wherein when 50%Q0 ≤ Q1 ≤ 75%Q0 and 25%Q0 ≤ Q2 ≤ 50%Q0, the passing rate of the secondary battery test is relatively high; when Q1 > 75%Q0 and Q2 < 25%Q0, at this time the coverage area of the second region is small, the heat dissipation effect of the outer peripheral part of the electrode assembly is relatively poor, and the passing rate of the secondary battery test is relatively small; when Q1 < 50%Q0 and Q2 > 50%Q0, at this time the coverage area of the first region is small, the barrier effect of the first coating block in the central part of the electrode assembly is insufficient, and the passing rate of the secondary battery test is relatively small. Therefore, in the embodiments of the present application, 50%Q0 ≤ Q1 ≤ 75%Q0 and 25%Q0 ≤ Q2 ≤ 50% are set so that the barrier and heat dissipation effects of the first coating in the first region and the second region are better, and the probability of thermal runaway of the electrode assembly is reduced.

[0103] Combined with Embodiment 18, Embodiments 21 to 23, wherein when 0um < H ≤ 5um, the passing rate of the secondary battery test is relatively high. When H is continuously increased to H > 5um, the passing rate of the secondary battery test remains unchanged. Therefore, 0um < H ≤ 5um is set to avoid the reduction of the energy density of the secondary battery caused by a large H. Therefore, in the embodiments of the present application, 0um < H ≤ 5um is set.

[0104] The above are only the embodiments of the present application, and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present application.

Claims

1. A secondary battery, comprising an electrode assembly, the electrode assembly including a plurality of first electrode plates and a plurality of second electrode plates, characterized in that, The secondary battery further includes a first coating; The first coating includes a plurality of first coating blocks disposed on the surface of the first electrode sheet facing the second electrode sheet. A first channel is formed between any two adjacent first coating blocks. The first channel communicates with at least one edge of the first electrode sheet. The first channel exposes at least a part of the surface of the first electrode sheet facing the second electrode sheet. The first coating melts and at least partially covers the first channel when the temperature is higher than a first preset temperature. The area of the first electrode sheet covered by the melted first coating is X1, and the area of the first electrode sheet covered by the first coating before melting is Y1, where X1 > Y1.

2. The secondary battery according to claim 1, wherein The area of the first electrode sheet covered by the melted first coating is equal to the area of the surface of the first electrode sheet facing the second electrode sheet.

3. The secondary battery according to claim 1, wherein The electrode assembly is a stacked structure. The electrode assembly is divided into a first region and two second regions with equal thicknesses in the thickness direction. The two second regions are oppositely disposed on the two outermost sides of the electrode assembly in the thickness direction, and the first region is located between the two second regions. The total area of the first electrode sheet is Q0, the total area of the first electrode sheet located in the first region is Q1, and the total area of the first electrode sheet located in the two second regions is Q2, where Q1 + Q2 = Q0, 50%Q0 ≤ Q1 ≤ 75%Q0, 25%Q0 ≤ Q2 ≤ 50%Q0; or The electrode assembly is a wound structure. The electrode assembly includes a first region and a second region. The first region is located in the central region of the electrode assembly, and the second region is located in the outer peripheral region of the electrode assembly. The first electrode sheet located in the first region and the first electrode sheet located in the second region are integrally formed and wound. The connection portion between the first electrode sheet located in the first region and the first electrode sheet located in the second region is a first connection line. The total area of the first electrode sheet is Q0. From the start end of the winding of the first electrode sheet to the first connection line, the total area of the first electrode sheet located in the first region is Q1. From the first connection line to the end of the winding of the first electrode sheet, the total area of the first electrode sheet located in the second region is Q2, where Q1 + Q2 = Q0, 50%Q0 ≤ Q1 ≤ 75%Q0, 25%Q0 ≤ Q2 ≤ 50%Q0.

4. The secondary battery according to claim 3, the width of the gap between any two adjacent first coating blocks located in the first region is M1, the width of the gap between any two adjacent first coating blocks located in the second region is M2, the width of the first coating blocks located in the first region is N1, and the width of the first coating blocks located in the second region is N2. The first coating further satisfies at least one of the following conditions: The first coating further satisfies at least one of the following conditions: 1) 0 mm < M I ≤ 1 mm; 2) 2 mm ≤ M2 ≤ 4 mm; 3) 7 mm ≤ N1 ≤ 10 mm; 4) 3 mm ≤ N2 ≤ 5 mm.

5. The secondary battery according to any one of claims 1-4, characterized in that the material of the first coating comprises at least one of the following materials: 1) ethylene propylene random polymer; 2) ethylene propylene rubber; 3) block copolymerized polypropylene; 4) polyisobutylene rubber; 5) thermoplastic rubber; 6) terminal amino liquid nitrile rubber.

6. The secondary battery according to claim 5, characterized in that the material of the first coating comprises an ion conductive agent.

7. The secondary battery according to claim 6, characterized in that the material of the ion conductive agent comprises at least one of the following materials: 1) polymer electrolyte; 2) inorganic solid electrolyte.

8. The secondary battery according to claim 5, characterized in that the material of the first coating comprises an electron conductive agent.

9. The secondary battery according to claim 8, characterized in that the material of the electron conductive agent comprises at least one of the following materials: 1) carbon nanotube; 2) graphene; 3) conductive carbon black.

10. The secondary battery according to any one of claims 1-4, characterized in that the first preset temperature is 90°C to 170°C.

11. The secondary battery according to any one of claims 1-4, characterized in that along the thickness direction of the first electrode sheet, the thickness of the first coating is defined as H, and H satisfies: 0 μm < H ≤ 5 μm.

12. The secondary battery according to any one of claims 1-4, characterized in that the secondary battery further comprises a second coating, the second coating comprises a plurality of second coating blocks, the plurality of second coating blocks are arranged on the surface of the second electrode sheet facing the first electrode sheet, a second channel is formed between any two adjacent second coating blocks, the second channel is at least communicated with one edge of the second electrode sheet, the second channel exposes at least part of the surface of the second electrode sheet facing the first electrode sheet, the second coating melts and at least partially covers the second channel when the temperature is higher than the second preset temperature, the area of the second electrode sheet covered by the second coating after melting is X2, the area of the second electrode sheet covered by the second coating before melting is Y2, and X2 > Y2.

13. The secondary battery according to claim 12, characterized in that the area of the second electrode sheet covered by the second coating after melting is equal to the area of the surface of the second electrode sheet facing the first electrode sheet.

14. The secondary battery according to any one of claims 1-13, characterized in that the first electrode sheet comprises a first current collector and a first active material, the first active material is arranged on the surface of the first current collector facing the second electrode sheet, the first coating is arranged on the surface of the first active material facing away from the first current collector, and the first channel exposes at least part of the surface of the first active material facing away from the first current collector.

15. An electrical device, characterized in that, A secondary battery comprising the secondary battery according to any one of claims 1-14.

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