Cushion, battery cell, battery, and electric device

Abstract

The application discloses a buffer pad, an electric core, a battery and an electric device. The buffer pad is arranged on a bare electric core and comprises a bonding layer, a slow-release layer and a protective layer. The slow-release layer is arranged on one side of the bonding layer. The material of the slow-release layer comprises porous compressible foam. The protective layer is arranged between the bonding layer and the slow-release layer. The material of the protective layer comprises a heat insulation matrix and ceramic particles dispersed in the heat insulation matrix. The heat insulation matrix provides better heat insulation performance, reduces the risk of thermal failure of the protective layer and the buffer pad, prolongs the service life of the protective layer and the buffer pad, uses the ceramic particles in the protective layer, utilizes the performance that the ceramic particles have a larger dielectric constant, improves the dielectric constant of the protective layer, thereby improves the insulation performance of the protective layer, improves the radiation resistance and corrosion resistance of the protective layer, reduces the accumulation of electric charges in the buffer pad, reduces the risk of failure of the protective layer and the buffer pad, and further improves the service life of the buffer pad.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to cushioning pads, battery cells, batteries, and electrical devices. Background Technology

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

[0003] However, during battery cycling, the shrinkage of the separator and the consumption of electrolyte increase the risk of short circuits between the positive and negative electrodes, generating a large amount of heat. This heat from abnormal cells can transfer to nearby normally functioning cells, leading to thermal runaway of the entire cell. While placing heat insulation pads around the cells can prevent the heat from a single runaway cell from spreading to the surrounding area, this insulation further complicates replenishment when the electrolyte level in the cells is low in the later stages of battery use, thus affecting the cell's lifespan. Summary of the Invention

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

[0005] To achieve the above objectives, embodiments of this application provide a cushioning pad, a battery cell, a battery, and an electrical device.

[0006] In a first aspect, embodiments of this application propose a buffer pad for placement on a bare battery cell, comprising:

[0007] Adhesive layer;

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

[0009] A protective layer is disposed between the adhesive layer and the slow-release layer, and the material of the protective layer includes a heat-insulating matrix and ceramic particles dispersed between the heat-insulating matrix.

[0010] Therefore, in the technical solution of this application embodiment, 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 being disposed on one side of the adhesive layer, the material of the slow-release layer includes porous compressible foam. This allows for easy replenishment of electrolyte through the porous compressible foam in the later stages of battery use, improving electrolyte replenishment performance. Simultaneously, the compressible foam also provides space for the expansion of the battery cell, reducing compression between adjacent bare battery cells and improving the cycle performance of the battery cell. Furthermore, since the lifespan of the buffer pad has a significant impact on the performance of the battery cell during use, buffer pad failure affects its lifespan. One of the main reasons for buffer pad failure is that the buffer pad is located between bare battery cells. When the temperature of adjacent bare battery cells rises, on the one hand, the heat resistance of the protective layer material is affected, leading to thermal failure; on the other hand, charge accumulation inside the buffer pad causes it to fail under prolonged charging conditions. In this application, a protective layer is provided inside the buffer pad, located between the adhesive layer and the slow-release layer. The protective layer is made of a thermal insulation matrix and ceramic particles dispersed between the thermal insulation matrix. This allows the thermal insulation matrix to provide better thermal insulation performance, reducing the risk of thermal failure of the protective layer and the buffer pad, and extending their service life. Furthermore, the use of ceramic particles in the protective layer, which have a high dielectric constant, increases the dielectric constant of the protective layer, thereby improving its insulation performance, radiation resistance, and corrosion resistance. This reduces charge accumulation in the buffer pad, further reducing the risk of failure of the protective layer and the buffer pad, and ultimately extending the lifespan of the buffer pad.

[0011] In any embodiment, the buffer pad further includes a puncture-resistant layer, which is disposed on the side of the protective layer away from the adhesive layer. The puncture-resistant layer is disposed on the side of the protective layer away from the adhesive layer. The service life of the buffer pad has a significant impact on the performance of the battery cell during use. Buffer pad failure affects its service life. One cause of buffer pad failure is external impact, puncture force, and external corrosion. By providing a puncture-resistant 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 increased, the probability of the buffer pad failing due to external force can be reduced, the service life of the buffer pad can be increased, the mechanical damage to the bare battery cell from the external environment 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. Using at least one of these materials can improve the elasticity and resilience of the protective layer, providing space for the expansion of the bare battery cell and improving the cycle performance of the battery cell. Simultaneously, these materials have good thermal insulation properties, which can reduce the risk of thermal runaway of the buffer pad. Specifically, 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 adhesive layer material includes at least one of colloidal silicon, sodium silicate, and aluminum phosphate. Using at least one of these materials allows the buffer pad to be bonded to the bare battery cell, improving adhesion strength. These adhesive layer materials have good compatibility, are not prone to reacting with the electrolyte, and 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 agent filled in the porous compressible foam. The sustained-release agent includes at least one of lithium salt, sodium salt, and film-forming compound. By adding at least one of the sustained-release agent lithium salt, sodium salt, and film-forming compound to the sustained-release layer, lithium salt, sodium salt, and film-forming compound can be released from the buffer layer under the pressure of the bare cell expansion during the later stages of cell cycle use, thereby improving the energy density of the cell and increasing its lifespan.

[0015] In any embodiment, the material of the sustained-release layer comprises a lithium salt filled in a porous compressible foam, wherein the lithium salt includes at least one of a fluorinated lithium salt, a boron-containing lithium salt, and a chloride-containing lithium salt. Using at least one of the above lithium salts allows for the release of lithium salts in the later stages of cell use, improving the high-temperature stability of the cell; and / or,

[0016] The material of the sustained-release layer includes a sodium salt filled in porous compressible foam, wherein the sodium salt includes at least one of fluorine-containing sodium salt, boron-containing sodium salt, and chloride-containing sodium salt. Using at least one of the above sodium salts allows for the release of sodium salts in the later stages of cell use, improving the high-temperature stability of the cell; and / or,

[0017] The material of the sustained-release layer includes a film-forming compound filled in porous compressible foam, wherein the film-forming compound includes at least one of vinylene carbonate, fluoroethylene carbonate, 1,3-propanesulfonate lactone, and lithium difluorophosphate. By using at least one of the above film-forming compounds, the film-forming compound can be released in the later stages of the battery cell's use, 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's cushioning function for the battery cell can be improved, while reducing the space occupied by the battery cell, thereby increasing 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 even better; and / or,

[0019] The thickness of the slow-release layer is 0.5-1.5 mm. Within this range, the buffer pad has a good buffering effect, providing space for the expansion of the battery cell, improving the cycle performance of the battery cell, and reducing the encroachment on the battery cell space, thereby increasing the energy density of the battery cell. Optionally, the thickness of the slow-release layer is 0.5-1 mm. Within this range, the battery cell has a better energy density and better cycle performance.

[0020] In any embodiment, the ceramic particles include at least one of silicon oxide, zirconium oxide, titanium oxide, aluminum oxide, and hafnium oxide. Using at least one of the above ceramic particles can further improve the dielectric constant of the protective layer, thereby improving the insulation of the protective layer, reducing charge accumulation in the protective layer, reducing the probability of buffer pad failure due to internal charge accumulation, improving the dimensional and thermal stability of the protective layer, increasing the service life of the buffer pad, and further improving the service life of the battery cell. Specifically, silicon oxide has a dielectric constant of 4, zirconium oxide has a dielectric constant of 6-10, titanium oxide has a dielectric constant of 80-120, aluminum oxide has a dielectric constant of 9-10, and hafnium oxide has a dielectric constant of 20-30.

[0021] In any embodiment, the thickness of the protective layer is 0.1–2 mm. A protective layer within the 0.1–2 mm range can improve the heat insulation effect of the buffer pad, extend its service life, and reduce encroachment on the internal space of the battery, providing more space for the bare cell and increasing the energy density of the cell. Optionally, the thickness of the protective layer is 1–2 mm; within this range, the heat insulation effect and insulation performance are even 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. This ratio affects the heat insulation effect of the buffer pad. Within this range, the buffer pad has a good heat insulation effect while also providing buffering and heat insulation performance, allowing space for the expansion of the battery cell, improving the cycle performance of the battery cell, and simultaneously improving the insulation performance of the protective layer and the buffer pad, thus extending 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 buffer pad has even better buffering and heat insulation performance, better cycle performance of the battery cell, better insulation performance of the buffer pad, and a longer service life.

[0023] In any embodiment, the tensile strength of the buffer pad is 1–100 MPa. Within this range, the buffer pad has good shape retention capability, thereby improving the cycle performance of the battery cell. Optionally, the tensile strength of the buffer pad is 10–100 MPa. Within this range, the cycle performance of the battery cell is even better. And / or,

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

[0025] The heat resistance temperature of the buffer pad is greater than 400℃. A heat resistance temperature greater than 400℃ can give the buffer pad better heat resistance, improve the thermal stability of the buffer pad, and thus improve the cycle performance of the battery cell. Optionally, the heat resistance temperature of the buffer pad is greater than 500℃. When the heat resistance temperature is greater than 500℃, the thermal stability of the buffer pad is better and the cycle performance of the battery cell is better.

[0026] In any embodiment, the puncture-resistant layer is made of at least one of polyethylene terephthalate, polyethylene, and polypropylene. Using the aforementioned puncture-resistant layer material can improve the puncture resistance of the buffer pad and enhance the cycle performance of the battery cell; and / or,

[0027] The thickness of the puncture-resistant layer is 0.1–2 mm. Within this range, it can improve the puncture resistance of the buffer pad and the cycle performance of the battery cell, while also reducing the space occupied by the puncture-resistant layer on the battery cell, thereby increasing the energy density of the battery cell. Optionally, the thickness of the puncture-resistant layer is 0.5–1.5 mm. Within this range, the puncture resistance is even better, and the cycle performance and energy density of the battery cell are also improved.

[0028] Secondly, embodiments of this application provide a battery cell, including a bare battery cell and a buffer pad of the first aspect of this application bonded to the outside of the bare battery cell.

[0029] By bonding a buffer pad to the outside of the bare battery cell, and by setting a slow-release layer on the buffer pad, with the slow-release layer located on one side of the bonding layer, the material of the slow-release layer includes porous compressible foam. In the later stages of battery use, it is convenient to replenish the electrolyte through the porous compressible foam of the slow-release layer, thereby improving the electrolyte replenishment performance. At the same time, the compressible foam can also provide room for the expansion of the battery cell and reduce the squeezing between adjacent bare battery cells.

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

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

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

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

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

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

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

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

[0038] Thirdly, embodiments of this application propose a battery including the cell of the second aspect of this application.

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

[0040] Fourthly, embodiments of this application provide an electrical device including the battery of the third aspect of this application. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the buffer pad and battery cell structure according to one embodiment of this application;

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

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

[0044] Figure 4 This is a front view of the buffer pad and battery cell structure according to one embodiment of this application;

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

[0046] Figure 6 This is a schematic diagram of a secondary battery according to one embodiment of this application;

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

[0048] Figure 8 This is a schematic diagram of a battery module according to one embodiment of this application;

[0049] Figure 9 This is a schematic diagram of a battery pack according to one embodiment of this application;

[0050] Figure 10 yes Figure 4 An exploded view of a battery pack according to one embodiment of this application is shown;

[0051] Figure 11 This is a schematic diagram of an electrical device that uses a secondary battery as a power source according to one embodiment of this application.

[0052] Explanation of reference numerals in the attached figures:

[0053] 1 Battery pack; 2 Upper housing; 3 Lower housing; 4 Battery module; 5 Secondary battery; 51 Housing; 52 Electrode assembly; 521 Battery cell; 5211 Bare battery cell; 5212 Buffer pad; 52121 Adhesive layer; 52122 Protective layer; 52123 Slow-release layer; 52124 Puncture-resistant layer; 53 Top cover assembly. Detailed Implementation

[0054] The following describes specific embodiments of the buffer pad, battery cell, battery, and power-consuming device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of actually identical structures may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0055] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be combined arbitrarily; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0056] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0057] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0058] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

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

[0060] However, during battery cycling, the shrinkage of the separator and the consumption of electrolyte 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 can be transferred to other nearby normally functioning cells, leading to thermal runaway of the entire cell.

[0061] By placing a heat insulation pad outside the battery cell, the heat of a single runaway battery cell can be prevented from spreading to the surroundings. However, this insulation will further make it difficult to replenish the electrolyte in the battery cell when it is insufficient in the later stages of battery use, thus affecting the life of the battery cell.

[0062] Therefore, numerous technologies have emerged to improve the thermal insulation of bare battery cells. For example, an insulating component, battery cell, battery, and electrical device are described. The insulating component includes a buffer film for bonding the large surface of the bare battery cell, made of a first material; a side film for bonding the sides of the bare battery cell; a bottom film for bonding the bottom of the bare battery cell; and a top film for thermal fusion with a top support. The side, bottom, and top films are made of a second material, and the compression of the first material is greater than that of the second material. The buffer film made of the first material can buffer and limit the expansion of the bare battery cell, preventing it from directly compressing the casing after expansion. This further improves the uniformity of stress on the battery cell body during charging and discharging, improving the battery cell's charging interface and cycle life. Using a second material with a smaller compression to prepare the side, bottom, and top films is beneficial for improving their thermal fusion effect. However, the electrolyte cannot be replenished in the later stages, affecting the cycle performance of the battery cell.

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

[0064] Surprisingly, by directly contacting the bare cells with the buffer pads, no buffer pads are needed between the cells. With a fixed internal space within the module unit, the space originally intended for buffer pads between cells is entirely allocated to the internal space of the cells, improving cell space utilization and assembly efficiency. Furthermore, the buffer pads inside the cells increase their rigidity, thus significantly improving the rigidity and stiffness of the module unit. Simultaneously, the porous foam structure of the slow-release layer improves the cell's liquid retention performance, reduces the difficulty of liquid injection, and utilizes the high dielectric constant of ceramic particles to increase the dielectric constant of the protective layer, thereby improving the insulation performance of the protective layer and enhancing the cell's cycle performance.

[0065] like Figure 1 As shown, in a first aspect, embodiments of this application provide a buffer pad 5212 for placement on a bare battery cell. 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] A protective layer 52122 is disposed between the adhesive layer 52121 and the slow-release layer 52123. The material of the protective layer 52122 includes a heat-insulating matrix and ceramic particles dispersed between the heat-insulating matrix.

[0069] Therefore, in the technical solution of this application embodiment, 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. 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 adhesive layer 52121, the material of the slow-release layer 52123 includes porous compressible foam. In the later stages of battery use, it is convenient to replenish the electrolyte through the porous compressible foam of the slow-release layer 52123, thereby improving the electrolyte replenishment performance. At the same time, the compressible foam can also provide space for the expansion of the battery cell 521, reduce the compression between adjacent bare battery cells 521, and improve the cycle performance of the battery cell. Meanwhile, since the service life of the buffer pad 5212 has a significant impact on the performance of the 521 cell during use, the failure of the 5212 buffer pad 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 located between the bare cells 5211. When the temperature of the adjacent bare cells 5211 rises, on the one hand, the heat resistance of the protective layer 5212 material is affected, leading to thermal failure. On the other hand, there is charge accumulation inside the buffer pad 5212, which causes the buffer pad 5212 to fail under long-term energization. In this application, a protective layer 52122 is provided inside the buffer pad 5212. The protective layer 52122 is disposed between the adhesive layer 52121 and the slow-release layer 52123. The material of the protective layer 52122 includes a heat-insulating matrix and ceramic particles dispersed between the heat-insulating matrix. This allows the heat-insulating matrix to provide better heat insulation performance, reducing the risk of thermal failure of the protective layer 52122 and the buffer pad 5212, and extending the service life of the protective layer 52122 and the buffer pad 5212. On the other hand, the use of ceramic particles in the protective layer 52122, which have a large dielectric constant, increases the dielectric constant of the protective layer 52122, thereby improving the insulation performance of the protective layer 52122, enhancing its radiation resistance and corrosion resistance, reducing charge accumulation in the buffer pad 5212, reducing the risk of failure of the protective layer 52122 and the buffer pad 5212, and thus increasing the service life of the buffer pad 5212.

[0070] It should be noted that the porous compressible foam can be made of a closed-cell foam of polyurethane and acrylic. Inside the battery cell, it improves the battery cell's ability to absorb and retain liquid, reduces the free electrolyte between the bare battery cell and the battery cell shell, and can also improve the battery cell's hardness. Moreover, the porous compressible foam increases the battery cell's electrolyte injection coefficient and extends its lifespan. This is because the longer the battery cell's lifespan, the greater the proportion of the porous compressible foam that is compressed by the expansion of the bare battery cell, and the more electrolyte is squeezed out from the porous compressible foam, allowing for more electrolyte to be added to the bare battery cell later.

[0071] In any embodiment, the material of the thermal insulation matrix includes at least one selected from ethylene-vinyl acetate copolymer, foamed polyurethane, foamed polypropylene, foamed polyethylene, styrene-butadiene rubber, cis-butadiene rubber, polyimide, and silica aerogel. Using at least one of these substances can improve the elasticity and resilience of the protective layer 52122, providing space for the expansion of the bare battery cell 5211 and improving the cycle performance of the battery cell 521. Simultaneously, these materials have good thermal insulation properties, 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, that of foamed polyurethane is 1.2–2.5, that of foamed polypropylene is 1, that of foamed polyethylene is 2.3–3.4, that of styrene-butadiene rubber is 2.7, that of cis-butadiene rubber is 3.0–4.0, that of polyimide is 3.0–4.0, and that of silica aerogel is 1.1–2.5.

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

[0073] In any embodiment, the material of the sustained-release layer 52123 includes a sustained-release agent filled in a porous compressible foam. The sustained-release agent includes at least one of lithium salt, sodium salt, and film-forming compound. By adding at least one of the sustained-release agent lithium salt, sodium salt, and film-forming compound to the sustained-release layer 52123, lithium salt, sodium salt, and film-forming compound can be released from the buffer layer under the pressure of the expansion of the bare cell 5211 in the later stages of the cell 521's cycle life, thereby improving the energy density of the cell 521 and increasing the lifespan of the 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 fluorinated lithium salt, a boron-containing lithium salt, and a chloride-containing lithium salt. By using at least one of the above lithium salts, the lithium salt can be released in the later stages of the use of the battery cell 521, thereby improving the high-temperature stability of the battery cell 521. The fluorinated lithium salt can be at least one of LiPF6, LiFSI, and LiTFSI, and the boron-containing lithium salt can be at least one of the above.

[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 chloride-containing sodium salt. By using at least one of the above sodium salts, the sodium salt can be released in the later stages of the use of the battery cell 521, thereby improving 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 chloride-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-propanesulfonate lactone, and lithium difluorophosphate. By using at least one of the above film-forming compounds, the film-forming compound can be released in the later stages of the 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 pad 5212 can improve the buffering function of the battery cell 521 while reducing the space occupied by the battery cell 521, thereby increasing 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 buffering function of the buffer pad 5212 and the energy density of the battery cell 521 are even better.

[0078] In any embodiment, the thickness of the sustained-release layer 52123 is 0.5-1.5 mm. Within this range, the buffer pad 5212 has a good buffering effect, providing space for the expansion of the battery cell 521, improving the cycle performance of the battery cell 521, and reducing the encroachment on the space of the battery cell 521, thereby increasing the energy density of the battery cell 521. The thickness of the sustained-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 sustained-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 also better.

[0079] like Figure 2As shown, in any embodiment, the buffer pad 5212 further includes a protective layer 52122, which 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 dissipation of the battery cell to the surroundings can be reduced, thereby improving the battery cell's lifespan.

[0080] In any embodiment, the ceramic particles include at least one of silicon oxide, zirconium oxide, titanium oxide, aluminum oxide, and hafnium oxide. Using at least one of the above ceramic particles can further improve the dielectric constant of the protective layer, thereby improving the insulation of the protective layer, reducing charge accumulation in the protective layer, reducing the probability of buffer pad failure due to internal charge accumulation, improving the dimensional and thermal stability of the protective layer, increasing the service life of the buffer pad, and further improving the service life of the battery cell. Specifically, silicon oxide has a dielectric constant of 4, zirconium oxide has a dielectric constant of 6-10, titanium oxide has a dielectric constant of 80-120, aluminum oxide has a dielectric constant of 9-10, and hafnium oxide has a dielectric constant of 20-30.

[0081] In any embodiment, the thickness of the protective layer 52122 is 0.1–2 mm. A protective layer 52122 within the 0.1–2 mm range can improve the heat insulation effect of the buffer pad 5212, extend its service life, and reduce encroachment on the internal space of the battery, providing more space for the bare cell 5211 and increasing the energy density of the 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 even 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 to 0.6):1. This ratio affects the heat insulation effect of the buffer pad 5212. Within this range, the buffer pad 5212 has a good heat insulation effect while also providing adequate buffering and heat insulation performance. This provides space for the expansion of the battery cell 521, improving the cycle performance of the battery cell 521. Simultaneously, it improves the insulation performance of both the protective layer and the buffer pad, extending 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 to 0.5):1. Within this range, the buffer pad 5212 has better buffering and heat insulation performance, the battery cell 521 has better cycle performance, the buffer pad has better insulation performance, and a longer service life.

[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 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 even 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 even better.

[0085] In any embodiment, the heat resistance temperature of the buffer pad 5212 is greater than 400°C. A heat resistance temperature greater than 400°C can give the buffer pad 5212 better heat resistance performance, improve the thermal stability of the buffer pad 5212, and thus 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 puncture-resistant layer 52124 includes at least one of polyethylene terephthalate, polyethylene, and polypropylene. Using the above-mentioned puncture-resistant layer 52124 material can improve the puncture resistance of the buffer pad 5212 and improve the cycle performance of the battery cell 521.

[0087] In any embodiment, the thickness of the puncture-resistant layer 52124 is 0.1–2 mm. Within this range, it can improve both the puncture resistance of the buffer pad 5212 and the cycle performance of the battery cell 521, while also reducing the space occupied by the puncture-resistant layer 52124 on the battery cell 521, thereby increasing the energy density of the battery cell 521. The thickness of the puncture-resistant 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 puncture-resistant layer 52124 is 0.5–1.5 mm. Within this range, the puncture resistance is even better, and the cycle performance and energy density of the battery cell 521 are also improved.

[0088] Secondly, such as Figure 4 , Figure 5 As shown, an embodiment of this application proposes a battery cell 521, including a bare battery cell 5211 and a buffer pad 5212 of the first aspect of this application bonded to the outside of the bare battery cell 5211.

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

[0090] In any embodiment, the bare cell 5211 is a prismatic cell 521 with a wound structure, wherein:

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

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

[0093] In any embodiment, the bare cell 5211 is a prismatic cell 521 with a laminated structure, wherein:

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

[0095] The distance between the edge of the buffer pad 5212 and the edge of the bare cell 5211 in the Y direction is Y2, where 0mm ≤ Y2 ≤ 3mm. Within this range, the space occupied by the buffer pad 5212 can be saved, thereby reducing costs and increasing the energy density of the cell 521.

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

[0097] Thirdly, embodiments of this application propose a battery including the cell of the second aspect of this application.

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

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

[0100] Typically, a secondary battery consists of a positive electrode, a negative electrode, an electrolyte, and a separator. During charging and discharging, active ions move back and forth between the positive and negative electrodes, inserting and releasing. The electrolyte acts as a conductor between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, primarily prevents short circuits while allowing ions to pass through.

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

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

[0103] In some embodiments, the positive 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 substrate and a metal layer formed on at least one surface of the polymer substrate. 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 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 be a positive electrode active material known in the art for lithium-ion batteries. As an example, the positive electrode active material may include at least one of the following materials: lithium phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3O2 (also known as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM811), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05At least one of O2 and its modified compounds. Examples of lithium phosphates with an olivine structure include, but are not limited to, lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

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

[0106] In some embodiments, the positive electrode film may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from 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 by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

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

[0109] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode film layer is disposed on either 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, copper foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer 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 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 be a negative electrode active material known in the art for use in batteries. 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, and 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, this application is not limited to these materials, and other conventional 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 optionally 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 may optionally include a conductive agent. The conductive agent 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 may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0115] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as the negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0116] The electrolyte acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific restrictions on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte can be liquid, gel, or entirely solid.

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

[0118] In some embodiments, the electrolyte salt may 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 difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

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

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

[0121] In some embodiments, the secondary battery also includes a separator. This application does not impose any particular limitation on the type of separator; any known porous separator with good chemical and mechanical stability can be selected.

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

[0123] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

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

[0125] In some embodiments, the outer packaging of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of the secondary battery can also be a soft pack, such as a pouch. The material of the soft pack can be plastic; examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0126] This application does not impose any particular limitation on the shape of the secondary battery; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 6 This is an example of a square-structured secondary battery 5.

[0127] In some implementations, refer to Figure 7The outer packaging may include a housing 51 and a cover plate 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 can be placed over the opening to close the receiving cavity. The positive electrode, negative electrode, and separator can be formed into an electrode assembly 52 through a winding or stacking process. After a buffer pad is attached to one side of the electrode assembly 52, the electrode assembly 52 is encapsulated within the receiving cavity, with one side of the buffer pad abutting against the electrode assembly and the other side close to the cavity wall. Electrolyte is immersed in the electrode assembly 52. ​​The secondary battery 5 may contain one or more electrode assemblies 52, which can be selected by those skilled in the art according to specific practical needs.

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

[0129] Figure 8 This is battery module 4, used as an example. (See reference...) Figure 8 In battery module 4, multiple secondary batteries 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other manner. Furthermore, these multiple secondary batteries 5 can be fixed in place using fasteners.

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

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

[0132] Figure 9 and Figure 10 This is battery pack 1 as an example. (See reference...) Figure 9 and Figure 10 The battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box includes an upper body 2 and a lower body 3, with the upper body 2 covering the lower body 3 to form a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0133] Fourthly, embodiments of this application provide an electrical device including the battery of the third aspect of this application.

[0134] In addition, this application also provides an electrical device, which includes at least one of the secondary battery, battery module, or battery pack provided in this application. The secondary battery, battery module, or battery pack can be used as a power source for the electrical device, or as an energy storage unit for the electrical device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., 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.

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

[0136] Figure 11 This is an example of an electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the secondary battery for this device, a battery pack or battery module can be used.

[0137] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a rechargeable battery as their power source.

[0138] Example

[0139] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0140] The parameters of the buffer pads in Examples 1 to 30 and Comparative Examples 1 to 4 of this application are as specified in Table 1.

[0141]

[0142]

[0143] Performance testing:

[0144] The buffer pads of Examples 1 to 30 and Comparative Examples 1 to 4 were attached to the bare cells and assembled into a stacked secondary battery structure. The following tests were then conducted:

[0145] 1. Secondary battery energy density test

[0146] Each prepared secondary battery was left to stand at 25°C for 30 minutes, then charged at a rate of 1 / 3C to 4.25V, and held at a constant voltage until 0.05C was reached. After standing for 30 minutes, it was discharged at a rate of 1 / 3C to 2.8V. The discharged capacity is C0, and the discharged energy is E0. Based on the formula Battery Energy Density = E0 / Cell Volume, the energy density of the secondary battery was calculated.

[0147] 2. Shallow puncture test

[0148] Each prepared secondary battery was discharged at 25°C at a rate of 1 / 3C to 2.8V, left to stand for 60 minutes, charged at a rate of 1 / 3C to 4.25V, and kept at a constant voltage until 0.05C was reached. After standing for 60 minutes, part of the casing was removed, and the voltage, internal resistance, and weight of the battery cell were recorded at this time.

[0149] A nail penetration test was conducted at 25℃. The nail diameter was 1mm, the speed was 0.1mm / s, and the nail was inserted at a constant speed perpendicular to the direction of the battery plate, with the insertion position close to the geometric center of the punctured surface. The insertion depth was 4mm, and the voltage drop was monitored. The test was observed for 1 hour. If there was no failure, the insertion depth was changed to 5mm, and the above steps were repeated until failure occurred. The voltage, internal resistance, and weight of the cell at the time of failure were recorded.

[0150] 3. Cyclic and expansion force test

[0151] After standing for 10 minutes, charge at 25℃ at a rate of 1 / 3C to 4.25V, and maintain constant voltage until 0.05C is reached; after standing for 10 minutes, discharge at a rate of 1 / 3C to 2.8V, and stand for 10 minutes; cycle to 80% SOH, monitoring the cell expansion force in between.

[0152] 4. External heating plate test

[0153] 1) Assemble the fully charged battery cell and heating plate (1500W) together using a clamp, following the sequence of clamp - heat insulation pad - heating plate - battery cell - heating pad - clamp. (This example uses a built-in buffer pad, so no additional external pad is needed.)

[0154] 2) Arrange temperature sensing wires on the thick cast copper heating plate, turn on the heating plate power supply to heat the battery cell, and control the heating plate temperature at a constant 190℃ until the battery cell goes out of 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] As can be seen from Table 2, through Examples 1 to 30 and Comparative Examples 1 to 4, 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 being located on the side of the protective layer away from the adhesive layer, the material of the slow-release layer includes porous compressible foam. In the later stages of battery use, it is convenient to replenish the electrolyte through the porous compressible foam of the slow-release layer, thereby improving the electrolyte replenishment performance. At the same time, the compressible foam can also provide space for the expansion of the battery cell, reducing the compression between adjacent bare battery cells.

[0160] As can be seen from Examples 1 to 4, different protective layer materials can all achieve the effect of heat insulation.

[0161] As shown in Examples 5 to 9, a protective layer within the range of 0.1 to 2 mm can improve the heat insulation effect of the buffer pad while reducing the encroachment on the internal space of the battery, providing more space for the bare cell and increasing the energy density of the cell. The thickness of the protective layer is 1 to 2 mm; within this range, the heat insulation effect is even better.

[0162] As shown in Examples 10 to 15, the thickness of the slow-release layer is 0.5-1.5 mm. Within this range, the buffer pad has a good buffering effect, providing space for the expansion of the battery cell, improving the cycle performance of the battery cell, and reducing the encroachment on the battery cell space, thereby increasing the energy density of the battery cell. A slow-release layer thickness of 0.5-1 mm results in even better energy density and cycle performance of the battery cell.

[0163] As shown in Examples 16 to 21, the thickness of the puncture-resistant layer is 0.1–2 mm. Within this range, it can improve both the puncture resistance of the buffer pad and the cycle performance of the battery cell, while also reducing the space occupied by the puncture-resistant layer on the battery cell and increasing the energy density of the battery cell. The thickness of the puncture-resistant layer is 0.5–1.5 mm. Within this range, the puncture resistance is even better, and the cycle performance and energy density of the battery cell are also improved.

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

[0165] Comparative Example 1, due to the lack of a buffer pad, has a short heating failure time, making the battery cell prone to failure and affecting its service life.

[0166] The buffer pad in Comparative Example 2 had poor cell cycle performance because it did not contain a slow-release layer.

[0167] The cushioning pad in Comparative Example 3 is at risk of displacement because it does not contain an adhesive layer.

[0168] Because the buffer pad in Comparative Example 4 does not have a protective layer, the heating failure time is short, and charge is easily accumulated inside the battery cell, making the battery cell prone to failure and affecting its service life.

[0169] In summary, the buffer pad proposed in this application, by providing an adhesive layer on the buffer pad, allows it to be directly adhered to the bare battery cell. By providing a slow-release layer on the buffer pad, located on one side of the adhesive layer, and the slow-release layer being made of porous compressible foam, it facilitates electrolyte replenishment through the porous compressible foam in the later stages of battery use, improving electrolyte replenishment performance. Simultaneously, the compressible foam provides space for battery cell expansion, reducing compression between adjacent bare cells and improving battery cell cycle performance. However, since the lifespan of the buffer pad significantly impacts battery cell performance during use, buffer pad failure affects its lifespan. One major cause of buffer pad failure is that, as the buffer pad is located between bare cells, when the temperature of adjacent bare cells rises, the heat resistance of the protective layer material is affected, leading to thermal failure. Furthermore, charge accumulation within the buffer pad causes it to fail under prolonged charging conditions. In this application, a protective layer is provided inside the buffer pad, located between the adhesive layer and the slow-release layer. The protective layer is made of a thermal insulation matrix and ceramic particles dispersed between the thermal insulation matrix. This allows the thermal insulation matrix to provide better thermal insulation performance, reducing the risk of thermal failure of the protective layer and the buffer pad, and extending their service life. Furthermore, the use of ceramic particles in the protective layer, which have a high dielectric constant, increases the dielectric constant of the protective layer, thereby improving its insulation performance, radiation resistance, and corrosion resistance. This reduces charge accumulation in the buffer pad, further reducing the risk of failure of the protective layer and the buffer pad, and ultimately extending the lifespan of the buffer pad.

[0170] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and function as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. An electric cell, characterized by, The buffer pad comprises a bare battery cell and a buffer pad adhered to the outside of the bare battery cell, the buffer pad comprising: a bonding layer; a slow-release layer provided on one side of the bonding layer, the material of the slow-release layer comprising porous compressible foam; and a protective layer provided between the bonding layer and the slow-release layer, the material of the protective layer comprising a heat insulation matrix and ceramic particles dispersed in the heat insulation matrix.

2. The cell of claim 1, wherein, The buffer pad further comprises a puncture-resistant layer provided on the side of the protective layer away from the bonding layer.

3. The cell of claim 1, wherein, The material of the heat insulation matrix comprises at least one of ethylene-vinyl acetate copolymer, foamed polyurethane, foamed polypropylene, foamed polyethylene, styrene butadiene rubber, cis-butadiene rubber, polyimide and silica aerogel; and / or The material of the bonding layer comprises at least one of colloidal silica, sodium silicate and aluminum phosphate; and / or The material of the slow-release layer further comprises a slow-release substance filled in the porous compressible foam, the slow-release substance comprising at least one of lithium salt, sodium salt and film-forming compound.

4. The battery cell of claim 3, wherein The slow-release substance comprises lithium salt, wherein the lithium salt comprises at least one of fluorine-containing lithium salt, boron-containing lithium salt and chlorine-containing lithium salt; and / or The slow-release substance comprises sodium salt, wherein the sodium salt comprises at least one of fluorine-containing sodium salt, boron-containing sodium salt and chlorine-containing sodium salt; and / or The slow-release substance comprises film-forming compound, wherein the film-forming compound comprises at least one of vinylene carbonate, fluoroethylene carbonate, 1,3-propane sulfone lactone and lithium difluorophosphate.

5. The battery cell of claim 1, wherein The thickness of the buffer pad is 0.5-3 mm; and / or The thickness of the slow-release layer is 0.5-1.5 mm.

6. The battery cell of claim 1, wherein The thickness of the buffer pad is 1.5-2.5 mm; and / or The thickness of the slow-release layer is 0.5-1 mm.

7. The cell of claim 1 wherein, The ceramic particles comprise at least one of silicon oxide, zirconium oxide, titanium oxide, aluminum oxide and hafnium oxide.

8. The cell of claim 1 wherein, The thickness of the protective layer is 0.1-2 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 cell of claim 1 wherein, The thickness of the protective layer is 1-2 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 cell of claim 1 wherein, The tensile strength of the buffer pad is 1-100 MPa; and / or The thermal conductivity of the buffer pad at 25°C is 0.03-0.3 W / mK; and / or The heat resistance temperature of the buffer pad is greater than 400°C.

11. The cell of claim 2, wherein, The material of the puncture-resistant layer comprises at least one of polyethylene terephthalate, polyethylene and polypropylene; and / or The thickness of the puncture-resistant layer is 0.1-2 mm.

12. The electrically charged cell of claim 2, wherein, The thickness of the puncture-resistant layer is 0.5-1.5 mm.

13. The electrically charged cell of claim 1, wherein, The bare battery cell is a square cell in a winding structure, wherein: The distance between the edge of the buffer pad and the edge of the bare battery cell in the X direction is X1, 0 mm≤X1≤7 mm; 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≤Rcorner mm, wherein Rcorner=(width of the bare cell-width of the innermost electrode) / 2; The X direction is the height direction of the cell, and the Y direction is the width direction of the cell.

14. The cell of claim 1 wherein, The bare cell is a square can cell in a lamination 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 cell, and the Y direction is the width direction of the cell.

15. A battery, characterized by The battery comprises an electrolyte and the cell according to any one of claims 1 to 14.

16. The battery of claim 15, wherein the cathode comprises a lithium metal oxide. The battery is a lithium ion battery or a sodium ion battery.

17. An electrical device, comprising: The battery according to claim 15 or 16.

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