Cushion pad, battery cell, battery and electric device

Abstract

The invention discloses a cushion pad, a battery cell, a battery and a power utilization device, the cushion pad is used for being arranged on a bare battery cell, the cushion pad comprises a bonding layer, a slow release layer and a protection layer, the slow release layer is arranged on one side of the bonding layer, the slow release layer is made of porous compressible foam, the protection layer is arranged between the bonding layer and the slow release layer, and the protection layer is made of porous compressible foam. And the material of the protective layer comprises heat insulation matrixes and ceramic particles dispersed among the heat insulation matrixes. Wherein the heat insulation matrix provides better heat insulation performance, reduces the risk of thermal failure of the protection layer and the buffer pad and prolongs the service life of the protection layer and the buffer pad, ceramic particles are used in the protection layer, and the dielectric constant of the protection layer is improved by utilizing the performance of larger dielectric constant of the ceramic particles, so that the insulation performance of the protection layer is improved, and the service life of the protection layer is prolonged. The radiation resistance and corrosion resistance of the protection layer are improved, accumulation of charges in the buffer pad is reduced, the risk of failure of the protection layer and the buffer pad is reduced, and the service life of the buffer pad is prolonged.

Description

Technical Field

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

[0002] Lithium-ion batteries and sodium-ion batteries have the advantages of high volumetric energy density and mass energy density, long life, low self-discharge and environmental protection. They are widely used in mobile communication equipment, portable electronic devices such as laptops, and electric vehicles.

[0003] However, during the battery cycle, the shrinkage of the diaphragm and the consumption of electrolyte will increase the risk of short circuit between the positive and negative electrodes, generating a large amount of heat. The heat generated by these abnormal cells will be transferred to other normally working cells nearby, causing thermal runaway of the entire cell. By setting up thermal insulation pads outside the cell, the heat of a single runaway cell can be isolated from spreading to the surrounding area. However, this isolation will further make it difficult to replenish the electrolyte in the cell when the electrolyte is insufficient in the later stage of battery use, thereby affecting the life of the cell. Summary of the invention

[0004] The present application is made in view of the above-mentioned problems, and its purpose is to provide a buffer pad to alleviate the difficulty of refilling the battery in the later stage of use, increase the service life of the buffer pad, and at the same time increase the life of the battery cell.

[0005] In order to achieve the above-mentioned objectives, the embodiments of the present application provide a buffer pad, a battery cell, a battery and an electrical device.

[0006] In a first aspect, an embodiment of the present application provides a buffer pad for being arranged on a bare battery cell, comprising:

[0007] Adhesive layer;

[0008] A sustained-release layer, disposed on one side of the adhesive layer, wherein the material of the sustained-release layer comprises porous compressible foam; and

[0009] The protective layer is arranged between the bonding layer and the sustained-release layer, and the material of the protective layer includes a heat-insulating matrix and ceramic particles dispersed in the heat-insulating matrix.

[0010] Therefore, in the technical solution of the embodiment of the present application, by providing an adhesive layer on the buffer pad, the buffer pad can be directly adhered to the bare battery cell. By providing a slow-release layer on the buffer pad, and the slow-release layer is provided on one side of the adhesive layer, the material of the slow-release layer includes porous compressible foam, which can facilitate fluid replenishment through the porous compressible foam of the slow-release layer in the later stage of battery use, thereby improving the fluid replenishment performance. At the same time, the compressible foam can also provide space for the expansion of the battery cell, reduce the extrusion between adjacent bare batteries, and improve the cycle performance of the battery cell. At the same time, since the service life of the buffer pad has a great influence on the performance of the battery cell during use, the failure of the buffer pad will affect its service life. One of the main reasons for the failure of the buffer pad is that the buffer pad is provided between the bare batteries. When the temperature of the adjacent bare batteries rises, on the one hand, the heat resistance of the protective layer material is affected, resulting in thermal failure. On the other hand, there is charge accumulation inside the buffer pad, resulting in the failure of the buffer pad under long-term charging. In the present application, a protective layer is arranged inside the buffer pad, and the protective layer is arranged between the bonding layer and the sustained-release layer. The material of the protective layer includes a thermal insulation matrix and ceramic particles dispersed in the thermal insulation matrix, so that, on the one hand, the thermal insulation matrix provides better thermal insulation performance, reduces the risk of thermal failure of the protective layer and the buffer pad, and extends the service life of the protective layer and the buffer pad; on the other hand, ceramic particles are used in the protective layer, and the dielectric constant of the protective layer is improved by utilizing the performance of the ceramic particles with a large dielectric constant, thereby improving the insulation performance of the protective layer, improving the radiation resistance and corrosion resistance of the protective layer, reducing the accumulation of charge in the buffer pad, reducing the risk of failure of the protective layer and the buffer pad, and thereby improving the service life of the buffer pad.

[0011] In any embodiment, the buffer pad further comprises an anti-puncture layer, and the anti-puncture layer is arranged on a side of the protective layer away from the adhesive layer. The anti-puncture layer is arranged on a side of the protective layer away from the adhesive layer. The service life of the buffer pad during use has a great influence on the performance of the battery cell, and the failure of the buffer pad will affect its service life. One of the reasons for the failure of the buffer pad is that the buffer pad is subjected to external impact and puncture force as well as external corrosion. By providing an anti-puncture layer on the outermost layer of the buffer pad, the corrosion resistance and insulation of the buffer pad can be improved, the mechanical strength of the buffer pad can be improved, the probability of failure of the buffer pad due to external damage can be reduced, the service life of the buffer pad can be improved, the mechanical damage of the external environment to the bare battery cell can be reduced, and the cycle performance of the battery cell can be improved.

[0012] In any embodiment, the material of the thermal insulation matrix includes at least one of ethylene-vinyl acetate copolymer, foamed polyurethane, foamed polypropylene, foamed polyethylene, styrene-butadiene rubber, butadiene rubber, polyimide and silica aerogel. The use of at least one of the above substances can improve the elasticity and resilience of the protective layer, provide space for the expansion of the bare battery cell, and improve the cycle performance of the battery cell. At the same time, these materials have good thermal insulation properties and can reduce the risk of thermal runaway of the buffer pad. Among them, the dielectric constant of ethylene-vinyl acetate copolymer is 2.9-3.2, the dielectric constant of foamed polyurethane is 1.2-2.5, the dielectric constant of foamed polypropylene is 1, the dielectric constant of foamed polyethylene is 2.3-3.4, the dielectric constant of styrene-butadiene rubber is 2.7, the dielectric constant of butadiene rubber is 3.0-4.0, the dielectric constant of polyimide is 3.0-4.0, and the dielectric constant of silica aerogel is 1.1-2.5; and / or,

[0013] The material of the bonding layer includes at least one of colloidal silicon, sodium silicate and aluminum phosphate. At least one of colloidal silicon, sodium silicate and aluminum phosphate can be used to bond the buffer pad to the bare battery cell to improve the adhesion strength. These bonding layer materials have good compatibility and are not easy to react with the electrolyte, which can improve the stability and cycle performance of the battery cell; and / or,

[0014] The material of the sustained-release layer includes a sustained-release substance filled in the porous compressible foam, and the sustained-release substance includes at least one of lithium salt, sodium salt and film-forming compound. By adding at least one of the sustained-release substances, lithium salt, sodium salt and film-forming compound to the sustained-release layer, the lithium salt, sodium salt and film-forming compound can be released from the buffer layer under the pressure of the expansion of the bare battery cell in the later stage of the battery cell cycle, thereby improving the energy density of the battery cell and increasing the life of the battery cell.

[0015] In any embodiment, the material of the sustained-release layer includes a lithium salt filled in a porous compressible foam, wherein the lithium salt includes at least one of a fluorine-containing lithium salt, a boron-containing lithium salt and a chlorine-containing lithium salt. By using at least one of the above lithium salts, the lithium salt can be released in the later stage of the use of the battery cell, thereby improving the high temperature stability of the battery cell; and / or,

[0016] The material of the sustained-release layer includes a sodium salt filled in a porous compressible foam, wherein the sodium salt includes at least one of a fluorine-containing sodium salt, a boron-containing sodium salt and a chlorine-containing sodium salt. By using at least one of the above sodium salts, the sodium salt can be released in the later stage of the use of the battery cell, thereby improving the high-temperature stability of the battery cell; and / or,

[0017] The material of the sustained-release layer includes a film-forming compound filled in a porous compressible foam, wherein the film-forming compound includes at least one of vinylene carbonate, fluoroethylene carbonate, 1,3-propane sultone and lithium difluorophosphate. By using at least one of the above film-forming compounds, the film-forming compound can be released in the later stage of the use of the battery cell, thereby improving the high-temperature stability of the battery cell.

[0018] In any embodiment, the thickness of the buffer pad is 0.5-3 mm. Within this thickness range, the buffer pad can improve the buffering function of the battery cell and reduce the space occupied by the battery cell, thereby improving the energy density of the battery cell. Optionally, the thickness of the buffer pad is 1.5-2.5 mm. Within this range, the buffering function of the buffer pad and the energy density of the battery cell are better; and / or,

[0019] The thickness of the slow-release layer is 0.5-1.5 mm. Within this range, the cushion has a good cushioning effect, provides space for the expansion of the battery cell, improves the cycle performance of the battery cell, and reduces the occupation of the battery cell space, thereby improving the energy density of the battery cell. Optionally, the thickness of the slow-release layer is 0.5-1 mm. Within this range, the energy density of the battery cell is better and the cycle performance is better.

[0020] In any embodiment, the ceramic particles include at least one of silicon oxide, zirconium oxide, titanium oxide, aluminum oxide and hafnium oxide. By using at least one of the above ceramic particles, the dielectric constant of the protective layer can be further improved, thereby improving the insulation of the protective layer, reducing the accumulation of charges in the protective layer, reducing the probability of failure of the buffer pad due to internal charge accumulation, improving the dimensional stability and thermal stability of the protective layer, improving the service life of the buffer pad, and further improving the service life of the battery core. Among them, the dielectric constant of silicon oxide is 4, the dielectric constant of zirconium oxide is 6 to 10, the dielectric constant of titanium oxide is 80 to 120, the dielectric constant of aluminum oxide is 9 to 10, and the dielectric constant of hafnium oxide is 20 to 30.

[0021] In any embodiment, the thickness of the protective layer is 0.1-2 mm. The protective layer within 0.1-2 mm can improve the heat insulation effect of the buffer pad and increase the service life of the buffer pad, while reducing the occupation of the internal space of the battery, providing more space for the bare battery cell, and improving the energy density of the battery cell. Optionally, the thickness of the protective layer is 1-2 mm. Within this range, the heat insulation effect and insulation performance are better; and / or,

[0022] The ratio of the thickness of the protective layer to the thickness of the buffer pad is (0.3-0.6):1. The ratio of the thickness of the protective layer to the thickness of the buffer pad affects the thermal insulation effect of the buffer pad. Within this range, the buffer pad has a good thermal insulation effect, while taking into account the buffering and thermal insulation performance, providing space for the expansion of the battery cell, improving the cycle performance of the battery cell, and at the same time improving the insulation performance of the protective layer and the buffer pad, thereby increasing the service life of the buffer pad. Optionally, the ratio of the thickness of the protective layer to the thickness of the buffer pad is (0.4-0.5):1. Within this range, the buffering and thermal insulation performance of the buffer pad is better, the cycle performance of the battery cell is better, the insulation performance of the buffer pad is better, and the service life is longer.

[0023] In any embodiment, the tensile strength of the buffer pad is 1 to 100 MPa. Within this range, the buffer pad has a good shape retention ability, thereby improving the cycle performance of the battery cell; optionally, the tensile strength of the buffer pad is 10 to 100 MPa. Within this range, the cycle performance of the battery cell is better; and / or,

[0024] The thermal conductivity of the buffer pad at 25°C is 0.03-0.3 W / mK. Within this range, the thermal stability of the buffer pad can be improved, thereby improving the cycle performance of the battery cell. Optionally, the thermal conductivity of the buffer pad at 25°C is 0.1-0.3 W / mK. Within this range, the cycle performance of the battery cell is better; and / or,

[0025] The heat-resistant temperature of the buffer pad is greater than 400°C. The heat-resistant temperature greater than 400°C can make the buffer pad have better heat resistance, improve the thermal stability of the buffer pad, and further improve the cycle performance of the battery cell; optionally, the heat-resistant temperature of the buffer pad is greater than 500°C. When the heat-resistant temperature is greater than 500°C, the thermal stability of the buffer pad is better and the cycle performance of the battery cell is better.

[0026] In any embodiment, the material of the anti-puncture layer includes at least one of polyethylene terephthalate, polyethylene and polypropylene. The use of the anti-puncture layer material can improve the anti-puncture performance of the buffer pad and improve the cycle performance of the battery core; and / or,

[0027] The thickness of the anti-puncture layer is 0.1-2 mm. Within this range, the anti-puncture performance of the buffer pad and the cycle performance of the battery cell can be improved, and the space occupied by the anti-puncture layer on the battery cell can be reduced, thereby improving the energy density of the battery cell. Optionally, the thickness of the anti-puncture layer is 0.5-1.5 mm. Within this range, the anti-puncture performance is better, and the cycle performance and energy density of the battery cell are better.

[0028] In a second aspect, an embodiment of the present application provides a battery cell, comprising a bare battery cell and a buffer pad according to the first aspect of the present application bonded to the outside of the bare battery cell.

[0029] By bonding a buffer pad to the outside of a bare battery cell, and arranging a slow-release layer on the buffer pad, and the slow-release layer is arranged on one side of the bonding layer, the material of the slow-release layer includes porous compressible foam, so that in the later stage of battery use, fluid replenishment can be facilitated through the porous compressible foam of the slow-release layer, thereby improving the fluid replenishment performance. At the same time, the compressible foam can also provide space for the expansion of the battery cell, thereby reducing the extrusion between adjacent bare battery cells.

[0030] In any embodiment, the bare cell is a square shell cell with a wound structure, wherein:

[0031] The distance between the edge of the buffer pad and the edge of the bare battery cell in the X direction is X1, 0mm≤X1≤7mm. Within this range, the space occupied by the buffer pad can be saved, while saving costs and improving the energy density of the battery cell; optionally, 3mm≤X1≤7mm; and / or,

[0032] The distance between the edge of the buffer pad and the edge of the bare battery cell in the Y direction is Y1, 0mm≤Y1≤R angle mm. Within this range, the space occupied by the buffer pad can be saved, while saving costs and improving the energy density of the battery cell, where R angle = (width of the bare battery cell-width of the innermost electrode) / 2.

[0033] It should be noted that the X direction refers to the direction of the cell height, and the Y direction refers to the direction of the cell width.

[0034] In any embodiment, the bare cell is a square shell cell with a laminated structure, wherein:

[0035] The distance between the edge of the buffer pad and the edge of the bare battery cell in the X direction is X2, 0mm≤X2≤7mm. Within this range, the space occupied by the buffer pad can be saved, while saving costs and improving the energy density of the battery cell; optionally, 3mm≤X2≤7mm; and / or,

[0036] The distance between the edge of the buffer pad and the edge of the bare battery cell in the Y direction is Y2, 0mm≤Y2≤3mm. Within this range, the space occupied by the buffer pad can be saved, while saving costs and improving the energy density of the battery cell.

[0037] It should be noted that the X direction refers to the direction of the cell height, and the Y direction refers to the direction of the cell width.

[0038] In a third aspect, an embodiment of the present application provides a battery, comprising the battery cell of the second aspect of the present application.

[0039] In any embodiment, the battery comprises a lithium ion battery or a sodium ion battery.

[0040] In a fourth aspect, an embodiment of the present application provides an electrical device, comprising the battery of the third aspect of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram of the structure of a buffer pad and a battery cell according to an embodiment of the present application;

[0042] Figure 2 This is a schematic diagram of a buffer pad and a battery cell structure according to another embodiment of the present application;

[0043] Figure 3 is a schematic diagram of a buffer pad and a battery cell structure according to another embodiment of the present application;

[0044] Figure 4 It is a front view schematic diagram of a buffer pad and a battery cell structure according to an embodiment of the present application;

[0045] Figure 5 is a top view of a buffer pad and a battery cell structure according to an embodiment of the present application;

[0046] Figure 6 is a schematic diagram of a secondary battery according to an embodiment of the present application;

[0047] Figure 7 yes Figure 1 An exploded view of a secondary battery according to an embodiment of the present application is shown;

[0048] Figure 8 is a schematic diagram of a battery module according to an embodiment of the present application;

[0049] Fig. 9 is a schematic diagram of a battery pack according to an embodiment of the present application;

[0050] Fig.10 yes Figure 4 An exploded view of a battery pack according to an embodiment of the present application is shown;

[0051] Fig.11 FIG. 1 is a schematic diagram of an electric device using a secondary battery according to an embodiment of the present application as a power source.

[0052] Description of reference numerals:

[0053] 1 battery pack; 2 upper box; 3 lower box; 4 battery module; 5 secondary battery; 51 shell; 52 electrode assembly; 521 battery cell; 5211 bare battery cell, 5212 buffer pad, 52121 adhesive layer, 52122 protective layer, 52123 sustained release layer, 52124 anti-puncture layer, 53 top cover assembly. DETAILED DESCRIPTION

[0054] The following specifically discloses the implementation methods of the buffer pad, battery cell, battery and electrical device of the present application. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structure are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0055] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or not including end values, and can be combined arbitrarily, that is, any lower limit can form a scope with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0056] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0057] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0058] If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0059] Lithium-ion batteries and sodium-ion batteries have the advantages of high volumetric energy density and mass energy density, long life, low self-discharge and environmental protection. They are widely used in mobile communication equipment, portable electronic devices such as laptops, and electric vehicles.

[0060] However, during the battery cycle, the shrinkage of the diaphragm and the consumption of the electrolyte will increase the risk of short-circuiting the positive and negative electrodes, generating a large amount of heat. The heat generated by these abnormal cells will be transferred to other normally working cells nearby, causing thermal runaway of the entire cell.

[0061] By setting a thermal insulation pad outside the battery cell, the heat of a single out-of-control battery cell can be prevented from spreading to the surrounding area. However, this isolation will further make it difficult to replenish the electrolyte in the battery cell when the electrolyte is insufficient in the later stage of battery use, thereby affecting the life of the battery cell.

[0062] Therefore, there are endless technologies for improving the thermal insulation of bare cells, for example, an insulating part, a cell, a battery and an electrical device, wherein the insulating part includes a buffer film for fitting the large surface of the bare cell, the buffer film is made of a first material; a side film for fitting the side of the bare cell; a bottom film for fitting the bottom of the bare cell; a top film for hot-melting with the top bracket; the side film, the bottom film and the top film are made of a second material, and the compression amount of the first material is greater than the compression amount of the second material. The buffer film made of the first material can buffer and limit the expansion of the bare cell, preventing the bare cell from directly squeezing the shell after expansion. Further improve the force uniformity of the cell body during the charging and discharging process, improve the cell filling interface and the cell cycle life. The side film, the bottom film and the top film are prepared using a second material with a smaller compression amount, which is beneficial to improve its hot-melt effect. However, the electrolyte cannot achieve the rehydration function in the later stage, which affects the cycle performance of the cell.

[0063] By providing buffer pads between bare cells, heat transfer between adjacent bare cells can be reduced, thereby reducing the risk of thermal runaway. However, providing buffer pads between bare cells can easily lead to the problem of a short service life of the buffer pads.

[0064] Unexpectedly, by placing the buffer pad in direct contact with the bare battery cell, there is no need to place a buffer pad between the battery cells. When the internal space of the module unit is fixed, the space originally used to place the buffer pad between the battery cells is completely transferred to the internal space of the battery cell, thereby improving the battery cell space utilization and grouping efficiency; and the buffer pad inside the battery cell improves the hardness of the battery cell, thereby significantly improving the hardness and rigidity of the module unit. At the same time, the porous foam structure of the slow-release layer improves the liquid retention performance of the battery cell, reduces the difficulty of liquid injection of the battery cell, and utilizes the performance of the ceramic particles with a large dielectric constant to improve the dielectric constant of the protective layer, thereby improving the insulation performance of the protective layer, which can improve the cycle performance of the battery cell.

[0065] like Figure 1 As shown, in the first aspect, the embodiment of the present application proposes a buffer pad 5212 for being arranged on a bare battery cell, and the buffer pad 5212 includes:

[0066] Adhesive layer 52121;

[0067] A sustained-release layer 52123 is disposed on one side of the adhesive layer 52121, and the material of the sustained-release layer 52123 includes porous compressible foam; and

[0068] The protective layer 52122 is disposed between the bonding layer 52121 and the sustained-release layer 52123 , and the material of the protective layer 52122 includes a heat-insulating matrix and ceramic particles dispersed in the heat-insulating matrix.

[0069] Therefore, in the technical solution of the embodiment of the present application, by providing an adhesive layer 52121 on the buffer pad 5212, the buffer pad 5212 can be directly adhered to the bare battery cell 5211, and by providing a slow-release layer 52123 on the buffer pad 5212, and the slow-release layer 52123 is provided on one side of the adhesive layer 52121, the material of the slow-release layer 52123 includes porous compressible foam, which can facilitate fluid replenishment through the porous compressible foam of the slow-release layer 52123 in the later stage of battery use, thereby improving the fluid replenishment performance. At the same time, the compressible foam can also provide space for the expansion of the battery cell 521, reduce the extrusion between adjacent bare battery cells 521, and improve the cycle performance of the battery cell. At the same time, since the service life of the buffer pad 5212 has a great influence on the performance of the battery cell 521 during use, the failure of the buffer pad 5212 will affect its service life. One of the main reasons for the failure of the buffer pad 5212 is that the buffer pad 5212 is arranged between the bare battery cells 5211. When the temperature of the adjacent bare battery cells 5211 rises, on the one hand, the heat resistance of the protective layer 52122 material is affected, resulting in thermal failure. On the other hand, there is charge accumulation inside the buffer pad 5212, which causes the buffer pad 5212 to fail when charged for a long time. In the present application, a protective layer 52122 is provided inside the buffer pad 5212, and the protective layer 52122 is provided between the bonding layer 52121 and the sustained-release layer 52123. The material of the protective layer 52122 includes a thermal insulation matrix and ceramic particles dispersed in the thermal insulation matrix, so that, on the one hand, the thermal insulation matrix provides better thermal insulation performance, reduces the risk of thermal failure of the protective layer 52122 and the buffer pad 5212, and extends the service life of the protective layer 52122 and the buffer pad 5212; on the other hand, ceramic particles are used in the protective layer 52122, and the dielectric constant of the protective layer 52122 is improved by utilizing the performance of the ceramic particles with a large dielectric constant, thereby improving the insulation performance of the protective layer 52122, improving the radiation resistance and corrosion resistance of the protective layer 52122, reducing the accumulation of charge in the buffer pad 5212, reducing the risk of failure of the protective layer 52122 and the buffer pad 5212, and thereby improving the service life of the buffer pad 5212.

[0070] It should be noted that the porous compressible foam can be made of closed-cell foaming of a mixture of polyurethane and acrylic, which can improve the liquid absorption and liquid retention capabilities of the battery cell itself inside the battery cell, reduce the free electrolyte between the bare battery cell and the battery cell shell, and at the same time improve the hardness of the battery cell; and the porous compressible foam increases the battery cell injection coefficient and increases the life of the battery cell, because the longer the service life of the battery cell, the greater the proportion of the porous compressible foam being compressed by the expansion of the bare battery cell, and the more electrolyte in the porous compressible foam is squeezed out, so that more electrolyte can be replenished for the bare battery cell in the later stage.

[0071] In any embodiment, the material of the heat insulating matrix includes at least one of ethylene-vinyl acetate copolymer, foamed polyurethane, foamed polypropylene, foamed polyethylene, styrene-butadiene rubber, butadiene rubber, polyimide and silica aerogel. Using at least one of the above substances can improve the elasticity and resilience of the protective layer 52122, provide space for the expansion of the bare battery cell 5211, and improve the cycle performance of the battery cell 521. At the same time, these materials have good heat insulation performance, which can reduce the risk of thermal runaway of the buffer pad 5212. It should be noted that the dielectric constant of ethylene-vinyl acetate copolymer is 2.9-3.2, the dielectric constant of foamed polyurethane is 1.2-2.5, the dielectric constant of foamed polypropylene is 1, the dielectric constant of foamed polyethylene is 2.3-3.4, the dielectric constant of styrene-butadiene rubber is 2.7, the dielectric constant of butadiene rubber is 3.0-4.0, the dielectric constant of polyimide is 3.0-4.0, and the dielectric constant of silica aerogel is 1.1-2.5.

[0072] In any embodiment, the material of the bonding layer 52121 includes at least one of colloidal silicon, sodium silicate and aluminum phosphate. The use of at least one of colloidal silicon, sodium silicate and aluminum phosphate can bond the buffer pad 5212 to the bare battery cell 5211 to improve the adhesion strength.

[0073] In any embodiment, the material of the slow-release layer 52123 includes a slow-release substance filled in a porous compressible foam, and the slow-release substance includes at least one of a lithium salt, a sodium salt, and a film-forming compound. By adding at least one of a slow-release substance, a lithium salt, a sodium salt, and a film-forming compound to the slow-release layer 52123, in the later stage of the recycling of the battery cell 521, the lithium salt, the sodium salt, and the film-forming compound can be released from the buffer layer under the pressure of the expansion of the bare battery cell 5211, thereby improving the energy density of the battery cell 521 and increasing the life of the battery cell 521.

[0074] In any embodiment, the material of the sustained-release layer 52123 includes a lithium salt filled in a porous compressible foam, wherein the lithium salt includes at least one of a fluorine-containing lithium salt, a boron-containing lithium salt and a chlorine-containing lithium salt. By using at least one of the above lithium salts, the lithium salt can be released in the later stage of use of the battery cell 521, thereby improving the high-temperature stability of the battery cell 521. The fluorine-containing lithium salt can be at least one of LiPF6, LiFSI and LiTFSI, and the boron-containing lithium salt.

[0075] In any embodiment, the material of the sustained-release layer 52123 includes a sodium salt filled in a porous compressible foam, wherein the sodium salt includes at least one of a fluorine-containing sodium salt, a boron-containing sodium salt and a chlorine-containing sodium salt. By using at least one of the above sodium salts, the sodium salt can be released in the later stage of use of the battery cell 521 to improve the high-temperature stability of the battery cell 521. The fluorine-containing sodium salt can be at least one of NaPF6, NaFSI and NaTFSI, the boron-containing sodium salt can be at least one of NaBF4, NaBOB and NaDFBOB, and the chlorine-containing sodium salt can be NaClO4.

[0076] In any embodiment, the material of the sustained-release layer 52123 includes a film-forming compound filled in a porous compressible foam, wherein the film-forming compound includes at least one of vinylene carbonate, fluoroethylene carbonate, 1,3-propane sultone and lithium difluorophosphate. By using at least one of the above film-forming compounds, the film-forming compound can be released in the later stage of use of the battery cell 521, thereby improving the high-temperature stability of the battery cell 521.

[0077] In any embodiment, the thickness of the buffer pad 5212 is 0.5-3 mm. Within this thickness range, the buffer function of the buffer pad 5212 on the battery cell 521 can be improved, and the space occupied by the battery cell 521 can be reduced, thereby improving the energy density of the battery cell 521. The thickness of the buffer pad 5212 can be 0.5 mm, 1 mm, 1.5 mm, 2.0 mm, 2.5 mm or 3 mm. Optionally, the thickness of the buffer pad 5212 is 1.5-2.5 mm. Within this range, the buffer function of the buffer pad 5212 and the energy density of the battery cell 521 are better.

[0078] In any embodiment, the thickness of the slow-release layer 52123 is 0.5-1.5 mm. Within this range, the buffer pad 5212 has a good buffering effect, provides space for the expansion of the battery cell 521, improves the cycle performance of the battery cell 521, and reduces the space occupied by the battery cell 521, thereby improving the energy density of the battery cell 521. The thickness of the slow-release layer 52123 can be 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm or 1.5 mm. Optionally, the thickness of the slow-release layer 52123 is 0.5-1 mm. Within this range, the energy density of the battery cell 521 is better and the cycle performance is better.

[0079] like Figure 2As shown, in any embodiment, the buffer pad 5212 further includes a protective layer 52122, and the protective layer 52122 is disposed between the adhesive layer 52121 and the slow-release layer 52123. By providing the protective layer 52122 on the buffer pad 5212, the heat diffusion of the battery cell to the surroundings can be reduced, thereby increasing the life of the battery cell.

[0080] In any embodiment, the ceramic particles include at least one of silicon oxide, zirconium oxide, titanium oxide, aluminum oxide and hafnium oxide. By using at least one of the above ceramic particles, the dielectric constant of the protective layer can be further improved, thereby improving the insulation of the protective layer, reducing the accumulation of charges in the protective layer, reducing the probability of failure of the buffer pad due to internal charge accumulation, improving the dimensional stability and thermal stability of the protective layer, improving the service life of the buffer pad, and further improving the service life of the battery core. Among them, the dielectric constant of silicon oxide is 4, the dielectric constant of zirconium oxide is 6 to 10, the dielectric constant of titanium oxide is 80 to 120, the dielectric constant of aluminum oxide is 9 to 10, and the dielectric constant of hafnium oxide is 20 to 30.

[0081] In any embodiment, the thickness of the protective layer 52122 is 0.1-2 mm. The protective layer 52122 within 0.1-2 mm can improve the heat insulation effect of the buffer pad 5212, increase the service life of the buffer pad, and reduce the occupation of the internal space of the battery, provide more space for the bare battery cell 5211, and improve the energy density of the battery cell 521. The thickness of the protective layer 52122 can be 0.1 mm, 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.4 mm, 1.5 mm, 1.8 mm or 2.0 mm. Optionally, the thickness of the protective layer 52122 is 1-2 mm. Within this range, the heat insulation effect and insulation performance are better.

[0082] In any embodiment, the ratio of the thickness of the protective layer 52122 to the thickness of the buffer pad 5212 is (0.3-0.6):1. The ratio of the thickness of the protective layer 52122 to the thickness of the buffer pad 5212 affects the heat insulation effect of the buffer pad 5212. Within this range, the buffer pad 5212 has a good heat insulation effect, while taking into account the buffering and heat insulation performance, providing space for the expansion of the battery cell 521, improving the cycle performance of the battery cell 521, and improving the insulation performance of the protective layer and the buffer pad, thereby increasing the service life of the buffer pad. The ratio of the thickness of the protective layer 52122 to the thickness of the buffer pad 5212 can be 0.3:1, 0.35:1, 0.4:1, 0.45:1, 0.5:1, 0.55:1 or 0.6:1. Optionally, the ratio of the thickness of the protective layer 52122 to the thickness of the buffer pad 5212 is (0.4-0.5):1. Within this range, the buffer pad 5212 has better buffering and heat insulation performance, the cycle performance of the battery cell 521 is better, the insulation performance of the buffer pad is better, and the service life is longer.

[0083] In any embodiment, the tensile strength of the buffer pad 5212 is 1 to 100 MPa. Within this range, the buffer pad 5212 has a good shape retention ability, thereby improving the cycle performance of the battery cell 521; optionally, the tensile strength of the buffer pad 5212 is 10 to 100 MPa. Within this range, the cycle performance of the battery cell 521 is better.

[0084] In any embodiment, the thermal conductivity of the buffer pad 5212 at 25°C is 0.03-0.3 W / mK. Within this range, the thermal stability of the buffer pad 5212 can be improved, thereby improving the cycle performance of the battery cell 521. Optionally, the thermal conductivity of the buffer pad 5212 at 25°C is 0.1-0.3 W / mK. Within this range, the cycle performance of the battery cell 521 is better.

[0085] In any embodiment, the heat resistance temperature of the buffer pad 5212 is greater than 400°C. The heat resistance temperature greater than 400°C can make the buffer pad 5212 have better heat resistance, improve the thermal stability of the buffer pad 5212, and further improve the cycle performance of the battery cell 521; optionally, the heat resistance temperature of the buffer pad 5212 is greater than 500°C. When the heat resistance temperature is greater than 500°C, the thermal stability of the buffer pad 5212 is better and the cycle performance of the battery cell 521 is better.

[0086] In any embodiment, the material of the anti-puncture layer 52124 includes at least one of polyethylene terephthalate, polyethylene and polypropylene. The use of the above-mentioned anti-puncture layer 52124 material can improve the anti-puncture performance of the buffer pad 5212 and improve the cycle performance of the battery cell 521.

[0087] In any embodiment, the thickness of the anti-puncture layer 52124 is 0.1 - 2 mm. Within this range, the anti-puncture performance of the buffer pad 5212 and the cycle performance of the battery cell 521 can be improved, and the occupation of the space of the battery cell 521 by the anti-puncture layer 52124 can be reduced, thereby improving the energy density of the battery cell 521. The thickness of the anti-puncture layer 52124 can be 0.1 mm, 0.3 mm, 0.5 mm, 0.8 mm, 1.0 mm, 1.2 mm, 1.5 mm, 1.8 mm or 2.0 mm. Optionally, the thickness of the anti-puncture layer 52124 is 0.5 - 1.5 mm. Within this range, the anti-puncture performance is better, and the cycle performance and energy density of the battery cell 521 are better.

[0088] In a second aspect, as Figure 4 , Figure 5 shown, an embodiment of the present application provides a battery cell 521, including a bare battery cell 5211 and a buffer pad 5212 of the first aspect of the present application bonded to the outside of the bare battery cell 5211.

[0089] By bonding the buffer pad 5212 to the outside of the bare battery cell 5211, and by providing a slow-release layer 52123 on the buffer pad 5212, and the slow-release layer 52123 is disposed on one side of the bonding layer 52121, the material of the slow-release layer 52123 includes a porous compressible foam. In the later stage of battery use, it is convenient to replenish liquid through the porous compressible foam of the slow-release layer 52123, improving the liquid replenishment performance. At the same time, the compressible foam can also provide a yielding space for the expansion of the battery cell 521, reducing the extrusion between adjacent bare battery cells 5211.

[0090] In any embodiment, the bare battery cell 5211 is a square shell battery cell 521 with a wound structure, where:

[0091] The distance between the edge of the buffer pad 5212 and the edge of the bare battery cell 5211 in the X direction is X1, and 0 mm ≤ X1 ≤ 7 mm. Within this range, the space occupied by the buffer pad 5212 can be saved, the cost can be saved, and the energy density of the battery cell 521 can be improved. The distance between the edge of the buffer pad 5212 and the edge of the bare battery cell 5211 in the height direction of the battery cell 521 can be 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm or 7 mm; optionally, 3 mm ≤ X1 ≤ 7 mm; and / or,

[0092] The distance between the edge of the buffer pad 5212 and the edge of the bare battery cell 5211 in the Y direction is Y1, and 0 mm ≤ Y1 ≤ R corner mm. Within this range, the space occupied by the buffer pad 5212 can be saved, the cost can be saved, and the energy density of the battery cell 521 can be improved, where R corner = (width of the bare battery cell - width of the innermost ring electrode) / 2.

[0093] In any embodiment, the bare battery cell 5211 is a square shell battery cell 521 of a laminated structure, wherein:

[0094] The distance between the edge of the buffer pad 5212 and the edge of the bare battery cell 5211 in the X direction is X2, 0mm≤X2≤7mm. Within this range, the space occupied by the buffer pad 5212 can be saved, while saving costs and improving the energy density of the battery cell 521; the distance between the edge of the buffer pad 5212 and the edge of the bare battery cell 5211 in the height direction of the battery cell 521 can be 1mm, 2mm, 3mm, 4mm, 5mm, 6mm or 7mm. Optionally, 3mm≤X2≤7mm; and / or,

[0095] In the Y direction, the distance between the edge of the buffer pad 5212 and the edge of the bare battery cell 5211 is Y2, 0mm≤Y2≤3mm. Within this range, the space occupied by the buffer pad 5212 can be saved, while saving costs and improving the energy density of the battery cell 521.

[0096] It should be noted that the X direction refers to the direction of the cell height, and the Y direction refers to the direction of the cell width.

[0097] In a third aspect, an embodiment of the present application provides a battery, comprising the battery cell of the second aspect of the present application.

[0098] In any embodiment, the battery comprises a lithium ion battery or a sodium ion battery.

[0099] In one embodiment of the present application, a secondary battery is provided.

[0100] Generally, a secondary battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator. During the battery charging and discharging process, active ions are embedded and released back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte plays the role of conducting ions between the positive electrode sheet and the negative electrode sheet. The separator is set between the positive electrode sheet and the negative electrode sheet, mainly to prevent the positive and negative electrodes from short-circuiting, while allowing ions to pass through.

[0101] The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector, and the positive electrode film layer includes the positive electrode material of the first aspect of the present application or the positive electrode material prepared by the preparation method of the positive electrode material of the second aspect of the present application.

[0102] As an example, the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.

[0103] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0104] In some embodiments, when the secondary battery is a lithium-ion battery, the positive electrode active material may adopt a positive electrode active material for lithium-ion batteries that is well known in the art. As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3O2 (also referred to as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM811), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05O2) and its modified compounds, etc. Examples of lithium-containing phosphates with an olivine structure may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

[0105] In some embodiments, the positive electrode film layer may further optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

[0106] In some embodiments, the positive electrode film layer may further include a conductive agent, which may include, for example, at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0107] In some embodiments, the positive electrode sheet can be prepared in the following manner: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0108] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material.

[0109] As an example, the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.

[0110] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, copper foil may be used. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0111] In some embodiments, the negative electrode active material may adopt the negative electrode active material for the battery known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0112] In some embodiments, the negative electrode film layer may further include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).

[0113] In some embodiments, the negative electrode film layer may further include a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

[0114] In some embodiments, the negative electrode film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0115] In some embodiments, the negative electrode sheet can be prepared in the following manner: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0116] The electrolyte plays the role of conducting ions between the positive electrode and the negative electrode. The present application has no specific restrictions on the type of electrolyte, which can be selected according to needs. For example, the electrolyte can be liquid, gel or all-solid.

[0117] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.

[0118] In some embodiments, the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0119] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane sulfone, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0120] In some embodiments, the electrolyte may further include additives, such as negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.

[0121] In some embodiments, the secondary battery further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical stability and mechanical stability can be selected.

[0122] In some embodiments, the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The isolation membrane can be a single-layer film or a multi-layer composite film, without particular limitation. When the isolation membrane is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0123] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly by a winding process or a lamination process.

[0124] In some embodiments, the secondary battery may include an outer package, which may be used to encapsulate the electrode assembly and the electrolyte.

[0125] In some embodiments, the outer packaging of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the secondary battery may also be a soft package, such as a bag-type soft package. The material of the soft package may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0126] The present application has no particular limitation on the shape of the secondary battery, which may be cylindrical, square or any other shape. Figure 6 The secondary battery 5 is a square structure as an example.

[0127] In some embodiments, reference Figure 7, the outer package may include a shell 51 and a cover plate 53. Among them, the shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation film can form an electrode assembly 52 through a winding process or a lamination process. After the buffer pad is pasted on one side of the electrode assembly 52, the electrode assembly 52 is encapsulated in the receiving cavity, one side of the buffer pad abuts the electrode assembly, and the other side is close to the cavity wall of the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the secondary battery 5 can be one or more, and those skilled in the art can choose according to specific actual needs.

[0128] In some embodiments, secondary batteries may be assembled into a battery module. The number of secondary batteries contained in the battery module may be one or more, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery module.

[0129] Figure 8 4 is an example of a battery module. Figure 8 In the battery module 4, the plurality of secondary batteries 5 may be arranged in sequence along the length direction of the battery module 4. Of course, they may also be arranged in any other manner. Further, the plurality of secondary batteries 5 may be fixed by fasteners.

[0130] Optionally, the battery module 4 may further include a housing having a receiving space, and the plurality of secondary batteries 5 are received in the receiving space.

[0131] In some embodiments, the battery modules described above may also be assembled into a battery pack. The battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery pack.

[0132] Fig. 9 and Fig.10 1 is a battery pack 1 as an example. Fig. 9 and Fig.10 The battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box. The battery box includes an upper box body 2 and a lower box body 3. The upper box body 2 can cover the lower box body 3 and form a closed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0133] In a fourth aspect, an embodiment of the present application provides an electrical device, comprising the battery of the third aspect of the present application.

[0134] In addition, the present application also provides an electrical device, which includes at least one of the secondary battery, battery module, or battery pack provided in the present application. The secondary battery, battery module, or battery pack can be used as a power source for the electrical device, and can also be used as an energy storage unit for the electrical device. The electrical device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited thereto.

[0135] As the electrical device, a secondary battery, a battery module or a battery pack may be selected according to its usage requirements.

[0136] Fig.11 The power consumption device is taken as an example. The power consumption device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. In order to meet the high power and high energy density requirements of the power consumption device for the secondary battery, a battery pack or a battery module can be used.

[0137] Another example of a device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is usually required to be thin and light, and a secondary battery may be used as a power source.

[0138] Example

[0139] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If no specific techniques or conditions are indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0140] The parameters of the cushioning pads of Examples 1 to 30 and Comparative Examples 1 to 4 of the present application are as shown in Table 1.

[0141]

[0142]

[0143] Performance Testing:

[0144] The buffer pads of Examples 1 to 30 and Comparative Examples 1 to 4 were pasted on bare cells to assemble into laminated secondary batteries, and the following tests were performed:

[0145] 1. Secondary battery energy density test

[0146] Each secondary battery was placed at 25°C for 30 minutes, charged to 4.25V at a rate of 1 / 3C, and then discharged to 2.8V at a rate of 1 / 3C. The released capacity is C0, and the released energy is E0. The energy density of the secondary battery was calculated based on the formula battery energy density = E0 / cell volume.

[0147] 2. Shallow puncture test

[0148] The prepared secondary batteries were discharged at 25°C at a rate of 1 / 3C to 2.8V, left standing for 60 minutes, and charged at a rate of 1 / 3C to 4.25V, and the constant voltage was terminated to 0.05C; left standing for 60 minutes, part of the shell was removed, and the voltage, internal resistance and weight of the battery cell were recorded.

[0149] The nail penetration test was carried out at 25°C. The nail diameter was 1mm and the speed was 0.1mm / s. The nail was uniformly penetrated perpendicular to the direction of the battery plate and the penetration position was close to the geometric center of the punctured surface. The penetration depth was 4mm and the voltage drop was monitored. The test environment was observed for 1h. If there was no failure, the penetration depth was changed to 5mm and the above steps were repeated until failure. The voltage, internal resistance and weight of the battery cell at the time of failure were recorded.

[0150] 3. Cycle and expansion force test

[0151] Let stand for 10 minutes, charge to 4.25V at a rate of 1 / 3C at 25℃, and end at constant voltage to 0.05C; let stand for 10 minutes, discharge to 2.8V at a rate of 1 / 3C, and let stand for 10 minutes; cycle to 80% SOH, and monitor the expansion force of the battery cell in the middle.

[0152] 4. External heating plate test

[0153] 1) Assemble the fully charged cell and the heating plate (1500W) together with a clamp, in the order of clamp-insulation pad-heating plate-cell-heating pad-clamp. (The embodiment has a built-in cushion, so no additional external cushion is required)

[0154] 2) Arrange a temperature sensing line on a thick cast copper heating plate, start the power supply of the heating plate to heat the battery cell, and control the temperature of the heating plate at a constant temperature of 190°C until the battery cell loses control; record the failure time.

[0155] The results are shown in Table 2.

[0156] Table 2 Performance test results of Examples 1-29 and Comparative Examples 1-3

[0157]

[0158]

[0159] It can be seen from Table 2 that through Examples 1 to 30 and Comparative Examples 1 to 4, it can be seen that by providing an adhesive layer on the buffer pad, the buffer pad can be directly adhered to the bare battery cell, and by providing a slow-release layer on the buffer pad, and the slow-release layer is provided on the side of the protective layer away from the adhesive layer, the material of the slow-release layer includes porous compressible foam, which can facilitate fluid replenishment through the porous compressible foam of the slow-release layer in the later stage of battery use, thereby improving the fluid replenishment performance. At the same time, the compressible foam can also provide space for the expansion of the battery cell, thereby reducing the extrusion between adjacent bare battery cells.

[0160] It can be seen from Examples 1 to 4 that different protective layer materials can achieve the heat insulation effect.

[0161] From Examples 5 to 9, it can be seen that the protective layer within 0.1 to 2 mm can improve the heat insulation effect of the buffer pad, while reducing the occupation of the internal space of the battery, providing more space for the bare battery cell, and improving the energy density of the battery cell. The thickness of the protective layer is 1 to 2 mm, within this range, the heat insulation effect is better.

[0162] From Examples 10 to 15, it can be seen that the thickness of the slow-release layer is 0.5-1.5 mm. Within this range, the cushion has a good cushioning effect, provides space for the expansion of the battery cell, improves the cycle performance of the battery cell, and reduces the occupation of the battery cell space, thereby improving the energy density of the battery cell. The thickness of the slow-release layer is 0.5-1 mm. Within this range, the energy density of the battery cell is better and the cycle performance is better.

[0163] It can be seen from Examples 16 to 21 that the thickness of the anti-puncture layer is 0.1 to 2 mm. Within this range, the anti-puncture performance of the cushion and the cycle performance of the battery cell can be improved, and the space occupied by the anti-puncture layer on the battery cell can be reduced, thereby improving the energy density of the battery cell. The thickness of the anti-puncture layer is 0.5 to 1.5 mm. Within this range, the anti-puncture performance is better, and the cycle performance and energy density of the battery cell are better.

[0164] It can be seen from Examples 22 to 30 that the slow-release material includes at least one of lithium salt, sodium salt and film-forming compound. By adding at least one of the slow-release material lithium salt, sodium salt and film-forming compound to the slow-release layer, the lithium salt, sodium salt and film-forming compound can be released from the buffer layer under the pressure of the expansion of the bare battery cell in the later stage of the battery cell cycle, thereby improving the energy density of the battery cell and increasing the life of the battery cell.

[0165] In Comparative Example 1, since no buffer pad is provided, the heating failure time is short, the battery cell is prone to failure, and the service life is affected.

[0166] Since the buffer pad of Comparative Example 2 does not contain a sustained-release layer, the cycle performance of the battery cell is poor.

[0167] Since the cushion pad of Comparative Example 3 does not contain an adhesive layer, the cushion pad has the risk of displacement.

[0168] Since the buffer pad of Comparative Example 4 does not contain a protective layer, the heating failure time is short, and charge is easily accumulated inside the battery cell, which makes the battery cell prone to failure and affects its service life.

[0169] In summary, the buffer pad proposed in the present application can be directly adhered to the bare battery cell by arranging an adhesive layer on the buffer pad, and a slow-release layer is arranged on the buffer pad, and the slow-release layer is arranged on one side of the adhesive layer. The material of the slow-release layer includes porous compressible foam, which can facilitate fluid replenishment through the porous compressible foam of the slow-release layer in the later stage of battery use, thereby improving the fluid replenishment performance. At the same time, the compressible foam can also provide space for the expansion of the battery cell, reduce the extrusion between adjacent bare battery cells, and improve the cycle performance of the battery cell. At the same time, since the service life of the buffer pad has a great influence on the performance of the battery cell during use, the failure of the buffer pad will affect its service life. One of the main reasons for the failure of the buffer pad is that the buffer pad is arranged between the bare battery cells. When the temperature of the adjacent bare battery cells rises, on the one hand, the heat resistance of the protective layer material is affected, resulting in thermal failure. On the other hand, there is charge accumulation inside the buffer pad, resulting in the failure of the buffer pad under long-term charging. In the present application, a protective layer is arranged inside the buffer pad, and the protective layer is arranged between the bonding layer and the sustained-release layer. The material of the protective layer includes a thermal insulation matrix and ceramic particles dispersed in the thermal insulation matrix, so that, on the one hand, the thermal insulation matrix provides better thermal insulation performance, reduces the risk of thermal failure of the protective layer and the buffer pad, and extends the service life of the protective layer and the buffer pad; on the other hand, ceramic particles are used in the protective layer, and the dielectric constant of the protective layer is improved by utilizing the performance of the ceramic particles with a large dielectric constant, thereby improving the insulation performance of the protective layer, improving the radiation resistance and corrosion resistance of the protective layer, reducing the accumulation of charge in the buffer pad, reducing the risk of failure of the protective layer and the buffer pad, and thereby improving the service life of the buffer pad.

[0170] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and playing the same role within the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A buffer pad, used to be arranged on a bare battery cell, characterized in that: include: Adhesive layer; A sustained-release layer, the sustained-release layer is disposed on one side of the adhesive layer, and the material of the sustained-release layer comprises porous compressible foam; as well as The protective layer is arranged between the bonding layer and the sustained-release layer, and the material of the protective layer includes a heat-insulating matrix and ceramic particles dispersed in the heat-insulating matrix.

2. The cushioning pad according to claim 1, characterized in that: The buffer pad further comprises an anti-puncture layer, and the anti-puncture layer is arranged on a side of the protective layer away from the bonding layer.

3. The cushioning pad according to claim 1, characterized in that: The material of the heat insulating matrix includes at least one of ethylene-vinyl acetate copolymer, foamed polyurethane, foamed polypropylene, foamed polyethylene, styrene-butadiene rubber, butadiene rubber, polyimide and silica aerogel; and / or, The material of the bonding layer includes at least one of colloidal silicon, sodium silicate and aluminum phosphate; and / or, The material of the sustained-release layer further includes a sustained-release substance filled in the porous compressible foam, and the sustained-release substance includes at least one of a lithium salt, a sodium salt and a film-forming compound.

4. The cushioning pad according to claim 2, characterized in that: The sustained-release material comprises a lithium salt, wherein the lithium salt comprises at least one of a fluorine-containing lithium salt, a boron-containing lithium salt and a chlorine-containing lithium salt; and / or, The sustained-release material comprises a sodium salt, wherein the sodium salt comprises at least one of a fluorine-containing sodium salt, a boron-containing sodium salt and a chlorine-containing sodium salt; and / or, The sustained-release substance includes a film-forming compound, wherein the film-forming compound includes at least one of vinylene carbonate, fluoroethylene carbonate, 1,3-propane sultone and lithium difluorophosphate.

5. The cushioning pad according to claim 1, characterized in that: The thickness of the cushion is 0.5 to 3 mm; and / or, The thickness of the sustained-release layer is 0.5-1.5 mm.

6. The cushioning pad according to claim 1, characterized in that: The thickness of the cushion is 1.5 to 2.5 mm; and / or, The sustained-release layer has a thickness of 0.5-1 mm.

7. The cushioning pad according to claim 1, characterized in that: The ceramic particles include at least one of silicon oxide, zirconium oxide, titanium oxide, aluminum oxide and hafnium oxide.

8. The cushioning pad according to claim 1, wherein: The thickness of the protective layer is 0.1 to 2 mm; and / or, The ratio of the thickness of the protective layer to the thickness of the buffer pad is (0.3-0.6):

1.

9. The cushioning pad according to claim 1, characterized in that: The thickness of the protective layer is 1 to 2 mm; and / or, The ratio of the thickness of the protective layer to the thickness of the buffer pad is (0.4-0.5):

1.

10. The cushioning pad according to claim 1, characterized in that: The tensile strength of the buffer pad is 1 to 100 MPa; and / or, The thermal conductivity of the cushion at 25° C. is 0.03 to 0.3 W / mK; and / or, The heat-resistant temperature of the buffer pad is greater than 400°C.

11. The cushioning pad according to claim 1, characterized in that: The buffer pad further comprises an anti-puncture layer, and the anti-puncture layer is arranged on a side of the sustained-release layer away from the adhesive layer.

12. The cushioning pad according to claim 10, characterized in that: The material of the puncture-resistant layer includes at least one of polyethylene terephthalate, polyethylene and polypropylene; and / or, The thickness of the anti-puncture layer is 0.1-2 mm.

13. The cushioning pad according to claim 10, characterized in that: The thickness of the anti-puncture layer is 0.5 to 1.5 mm.

14. A battery cell, characterized in that: include: A bare battery cell and a buffer pad as claimed in any one of claims 1 to 13 bonded to the outside of the bare battery cell.

15. The battery cell according to claim 14, characterized in that: The bare cell is a square shell cell with a winding structure, wherein: The distance between the edge of the buffer pad and the edge of the bare cell in the X direction is X1, 0mm≤X1≤7mm; and / or, The distance between the edge of the buffer pad and the edge of the bare cell in the Y direction is Y1, 0mm≤Y1≤R angle mm, where R angle = (width of the bare cell - width of the innermost electrode) / 2; The X direction is the height direction of the battery cell, and the Y direction is the width direction of the battery cell.

16. The battery cell according to claim 14, characterized in that: The bare cell is a square shell cell with a laminated structure, wherein: The distance between the edge of the buffer pad and the edge of the bare cell in the X direction is X2, 0mm≤X2≤7mm; and / or, The distance between the edge of the buffer pad and the edge of the bare cell in the Y direction is Y2, 0mm≤Y2≤3mm; The X direction is the height direction of the battery cell, and the Y direction is the width direction of the battery cell.

17. A battery, characterized in that Comprising an electrolyte and the battery cell according to any one of claims 14 to 16.

18. The battery according to claim 17, characterized in that The battery includes a lithium ion battery or a sodium ion battery.

19. An electrical device, characterized in that: Comprising a battery as claimed in claim 17 or 18.

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