Battery and electronic device

Abstract

The invention discloses a battery and an electronic device, the battery comprises an electrode, a diaphragm and an electrolyte, the electrode comprises a current collector, a bonding layer, a foaming layer and an active layer which are stacked in sequence, and the bonding layer comprises a first polymer and a conductive agent; the foaming layer comprises a foaming agent, a conductive agent and a second polymer, the melting point of the second polymer is T DEG C, and 90 < = T < = 150; the active layer includes an electrode active material. The safety performance of the battery is improved by using the bonding layer and controlling the melting point of the second polymer.

Description

Technical Field

[0001] The present application relates to the field of energy storage technology, and more specifically, to a battery and an electronic device. Background Art

[0002] The safety performance of a battery refers to the ability of the battery to avoid harm to personal safety, health, the environment, and equipment during use, storage, and transportation. It is one of the important indicators for measuring battery quality, especially in scenarios involving high energy density, frequent use, or special environmental applications, where safety performance is particularly important. Overcharging and short circuiting of batteries may cause thermal runaway of the battery, causing the temperature inside the battery to rise sharply, leading to fire or explosion. Therefore, overcharging and short circuiting of batteries will cause the safety performance of the battery to drop sharply. Among them, battery overcharging refers to the phenomenon that during the charging process of the battery, the charging current or voltage exceeds the safe charging range specified by the battery, causing the chemical reaction inside the battery to run away or excessively. Battery short circuits are divided into external short circuits and internal short circuits. When the positive and negative poles of the battery are directly connected by an external conductor (such as a metal tool, a wire, etc.), an external short circuit occurs; while an internal short circuit refers to a short circuit between the positive and negative poles inside the battery, which may be caused by damage to the diaphragm inside the battery, aging of the electrode material, or manufacturing defects.

[0003] Therefore, it is of great significance to develop a battery with high safety performance. Summary of the invention

[0004] In view of the above problems in the prior art, an object of the present application is to provide a battery and an electronic device, which have high safety performance under extreme conditions.

[0005] The first aspect of the present application provides a battery, including an electrode, a separator and an electrolyte, the electrode including a current collector, an adhesive layer, a foaming layer and an active layer stacked in sequence, the adhesive layer including a first polymer and a conductive agent; the foaming layer including a foaming agent, a conductive agent and a second polymer, the melting point of the second polymer is T℃, 90≤T≤150; the active layer includes an electrode active material.

[0006] The present application can better bond the current collector and the foaming layer by using an adhesive layer, which can not only reduce the probability of demolding during battery processing, but also the conductive agent inside can reduce the resistance, and can also increase the possibility of the foaming layer fully blocking the current collector and the active layer when the battery is overcharged and / or short-circuited, thereby improving the safety performance of the battery.

[0007] In addition, the present application requires the use of a second polymer with a specific melting point. Because when the melting point of the second polymer is higher than 150°C, it will not melt at high temperature or melt late when the battery is overcharged and / or short-circuited, resulting in the inability of the foaming agent in the foaming layer to play a foaming role, unable to block the current collector and the active layer, so that the circuit is still connected, and a large current passes and generates a lot of heat to cause thermal runaway, thereby causing the safety performance of the battery to decrease; when the melting point of the second polymer is lower than 90°C, the second polymer is easy to melt at the normal operating temperature of the battery, causing the electrode to lose its function, and increasing the internal resistance of the battery, so that the battery cannot work normally.

[0008] In some embodiments, the thickness of the foaming layer is D1 μm, 0.1≤D1≤20. In some embodiments, 1≤D1≤2. When D1 is within the above range, it will not affect the energy density of the battery, and the foaming layer can fully play its role when the battery is overcharged and / or short-circuited, and can better block the current collector and the active layer, thereby further improving the safety performance of the battery.

[0009] In some embodiments, the thickness of the bonding layer is D2 μm, 0.05≤D2≤0.2. When D2 is within the above range, it will not affect the energy density of the battery, and it can better bond the current collector and the foaming layer, thereby further improving the safety performance of the battery.

[0010] In some embodiments, the thickness of the foaming layer is D1 μm, the thickness of the adhesive layer is D2 μm, and D1>D2. When D1>D2, the probability of the foaming layer being damaged during the electrode and battery processing can be reduced, so that the foaming layer can fully play its role when the battery is overcharged and / or short-circuited, and can better block the current collector and the active layer, thereby helping to further improve the safety performance of the battery.

[0011] In some embodiments, based on the mass of the bonding layer, the mass percentage of the first polymer is Q1%, based on the mass of the foaming layer, the mass percentage of the second polymer is Q2%, and Q1≥Q2. When Q1≥Q2, the current collector and the foaming layer can be better bonded, which is beneficial to further improve the safety performance of the battery.

[0012] In some embodiments, based on the mass of the foaming layer, the mass percentage of the foaming agent is 5% to 10%, the mass percentage of the conductive agent is 5% to 30%, and the mass percentage of the second polymer is 60% to 85%. When the mass percentages of the foaming agent, the conductive agent, and the second polymer in the foaming layer are within the above ranges, it is beneficial to further improve the safety performance of the battery.

[0013] In some of the embodiments, the first polymer includes at least one of polyethylene, polyvinylidene fluoride, sodium carboxymethyl cellulose, styrene-butadiene rubber, polyacrylic acid, polytetrafluoroethylene, polyurethane, and polypropylene.

[0014] In some embodiments, the foaming agent includes at least one of an azo compound, a sulfonylhydrazide compound, a nitroso compound, sodium carbonate, and sodium bicarbonate.

[0015] In some of the embodiments, the second polymer includes at least one of polyethylene, polyvinylidene fluoride, sodium carboxymethyl cellulose, styrene-butadiene rubber, polyacrylic acid, polytetrafluoroethylene, polyurethane, and polypropylene.

[0016] In some of the embodiments, the conductive agent includes at least one of conductive carbon black, acetylene black, graphite, graphene, carbon nanotubes, carbon nanofibers, and conductive polymers, and the conductive polymer includes at least one of polythiophene, polypyrrole, polyaniline, polyacetylene, polyparaphenylene, and polyfluorene.

[0017] In some of these embodiments, the first polymer and the second polymer are the same.

[0018] In some of the embodiments, the electrode active material is selected from at least one of lithium cobalt oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium nickel manganese oxide, and lithium-rich manganese-based materials.

[0019] In some of the embodiments, the electrode active material is selected from at least one of graphite, artificial graphite, hard carbon, soft carbon, silicon carbon, silicon oxide, lithium metal, lithium titanate, metal alloy, metal sulfide, and graphene.

[0020] A second aspect of the present application provides an electronic device, comprising the battery according to the first aspect.

[0021] Compared with the prior art, the beneficial effects of this application are:

[0022] The present application can better bond the current collector and the foaming layer by using an adhesive layer, which can not only reduce the probability of demolding during battery processing, but also the conductive agent inside can reduce the resistance, and can also increase the possibility of the foaming layer fully blocking the current collector and the active layer when the battery is overcharged and / or short-circuited, thereby improving the safety performance of the battery.

[0023] In addition, the present application requires the use of a second polymer with a specific melting point. When the melting point of the second polymer is higher than 150°C, it will not melt at high temperature or will melt later when the battery is overcharged and / or short-circuited, causing the foaming agent in the foaming layer to be unable to play a foaming role, unable to block the current collector and the active layer, so that the circuit is still connected, and a large current passes through and generates a large amount of heat to cause thermal runaway, thereby causing the safety performance of the battery to decrease; when the melting point of the second polymer is lower than 90°C, it is easy to melt at the normal operating temperature of the battery, causing the electrode to lose its function, and increasing the internal resistance of the battery, so that the battery cannot work normally.

[0024] Additional aspects and advantages of the embodiments of the present application will be described, shown, or explained in part in the subsequent description through implementation of the embodiments of the present application. DETAILED DESCRIPTION

[0025] For simplicity, this application only specifically discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an undefined range; and any lower limit can be combined with other lower limits to form an undefined range, and any upper limit can be combined with any other upper limit to form an undefined range. In addition, each separately disclosed point or single value can itself be combined as a lower limit or upper limit with any other point or single value or with other lower limits or upper limits to form an undefined range.

[0026] Unless otherwise specified, the terms used in this application have the commonly known meanings generally understood by those skilled in the art. Unless otherwise specified, the numerical values ​​of the various parameters mentioned in this application can be measured using various measurement methods commonly used in the art (for example, they can be tested according to the methods given in the examples of this application).

[0027] A list of items connected by the terms "at least one of," "at least one of," "at least one of," or other similar terms may mean any combination of the listed items. For example, if items A and B are listed, the phrase "at least one of A and B" means only A; only B; or A and B. In another example, if items A, B, and C are listed, the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may contain a single component or multiple components. Item B may contain a single component or multiple components. Item C may contain a single component or multiple components.

[0028] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0029] 1. Battery

[0030] The first aspect of the present application provides a battery, including an electrode, a separator and an electrolyte, the electrode including a current collector, an adhesive layer, a foaming layer and an active layer stacked in sequence, the adhesive layer including a first polymer and a conductive agent; the foaming layer including a foaming agent, a conductive agent and a second polymer, the melting point of the second polymer is T℃, 90≤T≤150; the active layer includes an electrode active material.

[0031] The present application can better bond the current collector and the foaming layer by using an adhesive layer, which can not only reduce the probability of demolding during battery processing, but also the conductive agent inside can reduce the resistance, and can also increase the possibility of the foaming layer fully blocking the current collector and the active layer when the battery is overcharged and / or short-circuited, thereby improving the safety performance of the battery.

[0032] In addition, the present application requires the use of a second polymer with a specific melting point. Because when the melting point of the second polymer is higher than 150°C, it will not melt at high temperature or melt late when the battery is overcharged and / or short-circuited, resulting in the inability of the foaming agent in the foaming layer to play a foaming role, unable to block the current collector and the active layer, so that the circuit is still connected, and a large current passes and generates a lot of heat to cause thermal runaway, thereby causing the safety performance of the battery to decrease; when the melting point of the second polymer is lower than 90°C, it is easy to melt at the normal operating temperature of the battery, causing the electrode to lose its function, and increasing the internal resistance of the battery, so that the battery cannot work normally.

[0033] In some embodiments, T is 90, 92, 95, 97, 100, 102, 105, 107, 110, 112, 115, 117, 120, 121, 122, 125, 127, 130, 132, 135, 137, 140, 142, 145, 147, 150 or a range consisting of any two of these values. In some embodiments, 110≤T≤125.

[0034] In some embodiments, the thickness of the foaming layer is D1 μm, and D1 is 0.1, 0.2, 0.5, 0.7, 1, 1.2, 1.5, 1.7, 2, 2.2, 2.5, 2.7, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 or a range consisting of any two of these values. In some embodiments, 0.1≤D1≤20. In some embodiments, 1≤D1≤2. When D1 is within the above range, it will not only not affect the energy density of the battery, but also enable the foaming layer to fully play its role when facing overcharge and / or short circuit of the battery, and can better block the current collector and the active layer, thereby helping to further improve the safety performance of the battery.

[0035] In some embodiments, the thickness of the bonding layer is D2 μm, and D2 is 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, or a range consisting of any two of these values. In some embodiments, 0.05≤D2≤0.2. When D2 is within the above range, it will not affect the energy density of the battery, and it can better bond the current collector and the foaming layer, thereby helping to further improve the safety performance of the battery.

[0036] In some embodiments, the thickness of the foaming layer is D1 μm, the thickness of the adhesive layer is D2 μm, and D1>D2. When D1>D2, the probability of the foaming layer being damaged during the electrode and battery processing can be reduced, so that the foaming layer can fully play its role when the battery is overcharged and / or short-circuited, and can better block the current collector and the active layer, thereby helping to further improve the safety performance of the battery.

[0037] In some embodiments, based on the mass of the bonding layer, the mass percentage of the first polymer is Q1%, based on the mass of the foaming layer, the mass percentage of the second polymer is Q2%, and Q1≥Q2. When Q1≥Q2, the current collector and the foaming layer can be better bonded, which is beneficial to further improve the safety performance of the battery.

[0038] In some embodiments, Q1 is 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90 or a range consisting of any two of these values. In some embodiments, 70≤Q1≤90. In some embodiments, 75≤Q1≤80. In some embodiments, based on the mass of the adhesive layer, the mass percentage of the conductive agent is 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30% or a range consisting of any two of these values. In some embodiments, the mass percentage of the conductive agent is 10% to 30%. In some embodiments, the mass percentage of the conductive agent is 15% to 20%. When the mass percentages of the first polymer and the conductive agent in the adhesive layer are within the above range, it is beneficial to further improve the safety performance of the battery.

[0039] In some embodiments, based on the mass of the foaming layer, the mass percentage of the foaming agent is 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10% or a range consisting of any two of these values, and the mass percentage of the conductive agent is 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15%, 15.5%, 16%, 16.5%, 17%, 17.5%, 18%, 18.5%, 19%, 19.5%, 20%, 20.5%, 21%, 21.5%, 22%, 22.5%, 23%, 23.5%, 24%, 24.5%, 25%, 25.5%, 26%, 26.5%, 27%, 27.5%, %, 28%, 28.5%, 29%, 29.5%, 30% or a range consisting of any two of these values, and the mass percentage of the second polymer is 60%, 60.5%, 61%, 61.5%, 62%, 62.5%, 63%, 63.5%, 64%, 64.5%, 65%, 65.5%, 66%, 66.5%, 67%, 67.5%, 68%, 68.5%, 69%, 69.5%, 70%, 70.5%, 71.5%, 72.5%, 73.5%, 74.5%, 75.5%, 76.5%, 77.5%, 78.5%, 79.5%, 80.5%, 81.5%, 82.5%, 83.5%, 84.5%, 85.5%, 86.5%, 87.5%, 88.5%, 8 ...% %, 71%, 71.5%, 72%, 72.5%, 73%, 73.5%, 74%, 74.5%, 75%, 75.5%, 76%, 76.5%, 77%, 77.5%, 78%, 78.5%, 79%, 79.5%, 80%, 80.5%, 81%, 81.5%, 82%, 82.5%, 83%, 83.5%, 84%, 84.5%, 85% or a range consisting of any two of these values. When the mass percentages of the foaming agent, the conductive agent and the second polymer in the foaming layer are within the above ranges, it is beneficial to further improve the safety performance of the battery.

[0040] In some of the embodiments, the first polymer includes at least one of polyethylene, polyvinylidene fluoride, sodium carboxymethyl cellulose, styrene-butadiene rubber, polyacrylic acid, polytetrafluoroethylene, polyurethane, and polypropylene. In some of the embodiments, polyethylene includes at least one of low-density polyethylene, high-density polyethylene, medium-density polyethylene, and linear low-density polyethylene. In some of the embodiments, polypropylene includes at least one of homopolymer polypropylene and copolymer polypropylene. In some of the embodiments, copolymer polypropylene includes at least one of random copolymer polypropylene and block copolymer polypropylene. In some of the embodiments, polyurethane includes but is not limited to thermoplastic polyurethane.

[0041] In some embodiments, the foaming agent includes at least one of an azo compound, a sulfonylhydrazide compound, a nitroso compound, sodium carbonate, and sodium bicarbonate. The present application has no particular limitation on the types of azo compounds, sulfonylhydrazide compounds, and nitroso compounds, as long as the purpose of the present application can be achieved. For example, the azo compound may include but is not limited to at least one of azodicarbonamide, azobisisobutyronitrile, diisopropyl azodicarboxylate, barium azodicarboxylate, diethyl azodicarboxylate, and azoaminobenzene; the sulfonylhydrazide compound may include but is not limited to at least one of benzenesulfonylhydrazide, p-toluenesulfonylhydrazide, 4-chlorobenzenesulfonylhydrazide, 4-nitrobenzenesulfonylhydrazide, 4,4'-oxidized bisbenzenesulfonylhydrazide, 3,3'-disulfonylhydrazide diphenyl sulfone, 1,3-benzenedisulfonylhydrazide, p-toluenesulfonylsemicarbazide, 4,4',-oxybis(benzenesulfonylsemicarbazide), and diphenyl ether sulfonylhydrazide; the nitroso compound may include but is not limited to at least one of N,N'-dimethyl-N,N'-dinitrosoterephthalamide and dinitrosopentamethylenetetramine.

[0042] In some of the embodiments, the second polymer includes at least one of polyethylene, polyvinylidene fluoride, sodium carboxymethyl cellulose, styrene-butadiene rubber, polyacrylic acid, polytetrafluoroethylene, polyurethane, and polypropylene. In some of the embodiments, polyethylene includes at least one of low-density polyethylene, high-density polyethylene, medium-density polyethylene, and linear low-density polyethylene. In some of the embodiments, polypropylene includes at least one of homopolymer polypropylene and copolymer polypropylene. In some of the embodiments, copolymer polypropylene includes at least one of random copolymer polypropylene and block copolymer polypropylene. In some of the embodiments, polyurethane includes but is not limited to thermoplastic polyurethane.

[0043] In some of the embodiments, the conductive agent includes at least one of conductive carbon black, acetylene black, graphite, graphene, carbon nanotubes, carbon nanofibers, and conductive polymers, and the conductive polymer includes at least one of polythiophene, polypyrrole, polyaniline, polyacetylene, polyparaphenylene, and polyfluorene.

[0044] In some of these embodiments, the first polymer and the second polymer are the same.

[0045] In some embodiments, the battery includes a positive electrode and a negative electrode. At least one of the positive electrode and the negative electrode adopts any of the electrodes described above in the present application. In other words, the electrode can be used as at least one of the positive electrode and the negative electrode of the battery.

[0046] <Positive electrode>

[0047] In some embodiments, when the electrode is a positive electrode, the current collector is a positive electrode current collector. The present application has no particular restrictions on the positive electrode current collector, as long as the purpose of the present application can be achieved. For example, it may include but is not limited to at least one of aluminum foil, aluminum alloy foil, composite current collector, carbon cloth, and carbon paper. In some embodiments, the composite current collector may include but is not limited to an aluminum-carbon composite current collector.

[0048] In some embodiments, when the electrode is a positive electrode, the active layer is a positive electrode active layer, and the electrode active material is a positive electrode active material. The present application has no particular restrictions on the positive electrode active material, as long as the purpose of the present application can be achieved. For example, it may include but is not limited to at least one of lithium cobalt oxide, lithium manganese oxide, nickel cobalt manganese oxide, nickel cobalt aluminum oxide, lithium iron phosphate, lithium nickel manganese oxide, and lithium-rich manganese-based materials. The chemical formula of the lithium-rich manganese-based material is γLi2MnO3·(1-γ)LiGO2, 0<γ<1, and G is a transition metal such as nickel, cobalt or iron. In some embodiments, the nickel cobalt manganese oxide includes at least one of NCM811, NCM622, NCM523, and NCM111. In the present application, the surface of the positive electrode active material may be attached with a substance having a different composition from the positive electrode active material. For example, the substance attached to the surface may include, but is not limited to, at least one of aluminum oxide, silicon dioxide, titanium dioxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, bismuth oxide, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, aluminum sulfate, lithium carbonate, calcium carbonate, magnesium carbonate, and carbon. By attaching the above substances to the surface of the positive electrode active material, the oxidation reaction of the electrolyte on the surface of the positive electrode active material can be suppressed, and the service life of the electrochemical device can be improved.

[0049] In some embodiments, when the electrode is a positive electrode, the active layer is a positive electrode active layer, and the positive electrode active layer further includes at least one of a conductive agent, a binder, and a thickener; the present application has no particular restrictions on the conductive agent and the binder, as long as the purpose of the present application can be achieved. For example, the conductive agent may include but is not limited to at least one of a carbon-based material, a metal-based material, and a conductive polymer. In some embodiments, the carbon-based material may include but is not limited to at least one of natural graphite, artificial graphite, carbon black, acetylene black, Super-P, Ketjen black, carbon fiber, carbon nanotubes, graphene, and amorphous carbon. In some embodiments, the metal-based material may include but is not limited to at least one of metal powder and metal fiber, and the metal may include but is not limited to at least one of copper, nickel, aluminum, and silver. In some embodiments, the conductive polymer may include but is not limited to at least one of polyphenylene derivatives, polythiophene, polypyrrole, polyaniline, polyacetylene, polyparaphenylene, and polyfluorene. For another example, the binder may include, but is not limited to, at least one of polyvinyl alcohol, hydroxypropyl cellulose, sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride (PVDF), polyethylene, polypropylene, polyolefin esters, polyolefin alcohols, polyacrylic acid, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resins, and nylon. For another example, the thickener may include, but is not limited to, at least one of carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, and their salts.

[0050] In some of the embodiments, the structure of the positive electrode is a positive electrode structure known in the art and can be used in batteries.

[0051] In some embodiments, the preparation method of the positive electrode is a method known in the art that can be used for preparing the positive electrode of a battery. For example, the positive electrode can be obtained by the following method:

[0052] S1. Mixing the components of the adhesive layer in a solvent to obtain an adhesive layer slurry for standby use;

[0053] S2. Mixing the components of the foaming layer in a solvent to obtain a foaming layer slurry for standby use;

[0054] S3. Mixing the components of the positive electrode active layer (active layer) in a solvent to obtain a positive electrode active layer slurry for standby use;

[0055] S4. Sequentially coat and / or spray the bonding layer slurry, the foaming layer slurry and the positive electrode active layer slurry on the positive electrode current collector to obtain the positive electrode.

[0056] In some embodiments, in step S1 and / or S2 and / or S3, the solvent may include but is not limited to at least one of water, toluene, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, trimethyl phosphate, acetone, and dipropylene glycol dimethyl ether. In some embodiments, step S3 may heat the thickener (one of the optional components of the positive electrode active layer) before use as needed. In some embodiments, step S4 may perform a drying operation after each coating and / or spraying of a slurry to facilitate coating and / or spraying of the next slurry.

[0057] It is understandable that when the positive electrode of the battery adopts any of the electrodes described above in the present application, the negative electrode of the battery may adopt negative electrodes of other structures, such as negative electrodes commonly used in the art.

[0058] <Negative electrode>

[0059] In some embodiments, when the electrode is a negative electrode, the current collector is a negative electrode current collector. The present application has no particular restrictions on the negative electrode current collector, as long as the purpose of the present application can be achieved. For example, it may include but is not limited to at least one of copper foil, aluminum foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, foam nickel, foam copper, and composite current collector. In some embodiments, the composite current collector may include but is not limited to at least one of a carbon copper composite current collector, a nickel copper composite current collector, and a titanium copper composite current collector.

[0060] In some embodiments, when the electrode is a negative electrode, the active layer is a negative electrode active layer, and the electrode active material is a negative electrode active material. The present application has no particular restrictions on the negative electrode active material, as long as the purpose of the present application can be achieved. For example, it may include but is not limited to at least one of graphite, artificial graphite, hard carbon, soft carbon, silicon carbon, silicon dioxide, lithium metal, lithium titanate, metal alloy, metal sulfide, and graphene. Metal alloys include but are not limited to at least one of Li-Sn alloy, Li-Sn-O alloy, and Li-Al alloy. Silicon dioxide is SiO x (0.5 <x<1.6)。

[0061] In some embodiments, when the electrode is a negative electrode, the active layer is a negative electrode active layer, and the negative electrode active layer further includes at least one of a conductive agent, a binder, and a thickener; the present application has no particular restrictions on the conductive agent and the binder, as long as the purpose of the present application can be achieved. For example, the conductive agent may include but is not limited to at least one of a carbon-based material, a metal-based material, and a conductive polymer. In some embodiments, the carbon-based material may include but is not limited to at least one of natural graphite, artificial graphite, carbon black, acetylene black, Super-P, Ketjen black, carbon fiber, carbon nanotubes, graphene, and amorphous carbon. In some embodiments, the metal-based material may include but is not limited to at least one of metal powder and metal fiber, and the metal may include but is not limited to at least one of copper, nickel, aluminum, and silver. In some embodiments, the conductive polymer may include but is not limited to at least one of polyphenylene derivatives, polythiophene, polypyrrole, polyaniline, polyacetylene, polyparaphenylene, and polyfluorene. For another example, the binder may include, but is not limited to, at least one of polyvinyl alcohol, hydroxypropyl cellulose, sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride (PVDF), polyethylene, polypropylene, polyolefin esters, polyolefin alcohols, polyacrylic acid, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resins, and nylon. For another example, the thickener may include, but is not limited to, at least one of carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, and their salts.

[0062] In some of the embodiments, the structure of the negative electrode is a negative electrode structure known in the art and can be used in batteries.

[0063] In some embodiments, the preparation method of the negative electrode is a method known in the art that can be used for preparing the negative electrode of a battery. For example, the negative electrode can be obtained by the following method:

[0064] S1. Mixing the components of the adhesive layer in a solvent to obtain an adhesive layer slurry for standby use;

[0065] S2. Mixing the components of the foaming layer in a solvent to obtain a foaming layer slurry for standby use;

[0066] S3. Mixing the components of the negative electrode active layer (active layer) in a solvent to obtain a negative electrode active layer slurry for standby use;

[0067] S4. Sequentially coating and / or spraying the adhesive layer slurry, the foaming layer slurry and the negative electrode active layer slurry on the negative electrode current collector to obtain the negative electrode.

[0068] In some embodiments, in step S1 and / or S2 and / or S3, the solvent may include but is not limited to at least one of water, toluene, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, trimethyl phosphate, acetone, and dipropylene glycol dimethyl ether. In some embodiments, step S3 may heat the thickener (one of the optional components of the negative electrode active layer) before use as needed. In some embodiments, step S4 may perform a drying operation after each coating and / or spraying of a slurry to facilitate coating and / or spraying of the next slurry.

[0069] It is understandable that when the negative electrode of the battery adopts any of the electrodes described above in the present application, the positive electrode of the battery may adopt positive electrodes of other structures, such as positive electrodes commonly used in the art.

[0070] <Electrolyte>

[0071] The present application has no particular limitation on the electrolyte, as long as the purpose of the present application can be achieved. The electrolyte used in the present application can be an electrolyte known in the prior art. For example, the electrolyte can be divided into an aqueous electrolyte and a non-aqueous electrolyte. Compared with an aqueous electrolyte, an electrochemical device (battery) using a non-aqueous electrolyte can operate in a wider voltage window, thereby achieving a higher energy density.

[0072] In some embodiments, the non-aqueous electrolyte includes an organic solvent and an electrolyte.

[0073] In some of the embodiments, the present application has no particular restrictions on the organic solvent, as long as the purpose of the present application can be achieved, the organic solvent used in the present application can be an organic solvent known in the prior art, for example, the organic solvent can include but is not limited to at least one of carbonate compounds, carboxylate compounds, ether compounds, and other organic solvents. Wherein, the carbonate compound can include but is not limited to at least one of a linear carbonate compound, a cyclic carbonate compound, and a fluorinated carbonate compound. The linear carbonate compound can include but is not limited to at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), and ethyl methyl carbonate (EMC). Cyclic carbonates can include but are not limited to at least one of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), and vinyl ethylene carbonate (VEC). Fluorinated carbonate compounds may include, but are not limited to, at least one of fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-difluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene carbonate, and trifluoromethylethylene carbonate. Carboxylate compounds may include, but are not limited to, at least one of methyl formate, methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ-butyrolactone, decalactone, valerolactone, and caprolactone. The ether compound may include, but is not limited to, at least one of dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, 1,2-dimethoxyethane, 1,2-diethoxyethane, 1-ethoxy-1-methoxyethane, 2-methyltetrahydrofuran, and tetrahydrofuran. Other organic solvents may include, but are not limited to, at least one of dimethyl sulfoxide, 1,3-dioxolane, cyclopentane, methyl cyclopentane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, and trioctyl phosphate.

[0074] In some embodiments, the electrolyte may include but is not limited to at least one of an inorganic lithium salt, a fluorine-containing organic lithium salt, and a dicarboxylic acid complex-containing lithium salt. Among them, the inorganic lithium salt may include but is not limited to at least one of LiClO4, LiAsF6, LiPF6, LiBF4, LiSbF6, LiSO3F, LiPO2F2, and LiN(FSO2)2. Fluorine-containing organic lithium salts may include, but are not limited to, at least one of LiCF3SO3, LiN(FSO2)(CF3SO2), LiN(CF3SO2)2, LiN(C2F5SO2)2, cyclic 1,3-hexafluoropropane disulfonyl imide lithium, cyclic 1,2-tetrafluoroethane disulfonyl imide lithium, LiPF4(CF3)2, LiN(CF3SO2)(C4F9SO2), LiC(CF3SO2), LiPF4(CF3SO2)2, LiPF4(C2F5)2, LiPF4(C2F5SO2)2, LiBF2(CF3)2, LiBF2(C2F5)2, LiBF2(CF3SO2)2, and LiBF2(C2F5SO2)2. The lithium salt containing a dicarboxylic acid complex may include, but is not limited to, at least one of lithium bis(oxalato)borate, lithium difluorooxalatoborate [LiBF2(C2O4)], lithium tris(oxalato)phosphate, lithium difluorobis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate.

[0075] In some embodiments, the concentration of the electrolyte is 0.1mol / L, 0.2mol / L, 0.5mol / L, 0.7mol / L, 1mol / L, 1.2mol / L, 1.5mol / L, 1.7mol / L, 2mol / L, 2.2mol / L, 2.5mol / L, 2.7mol / L, 3mol / L, 3.2mol / L, 3.5mol / L, 3.7mol / L, 4mol / L, 4.2mol / L, 4.5mol / L, 4.7mol / L, 5mol / L or a range consisting of any two of these values. In some embodiments, the concentration of the electrolyte is 0.5mol / L to 3mol / L.

[0076] In some embodiments, the non-aqueous electrolyte further includes an additive.

[0077] In some embodiments, the present application has no particular restrictions on additives, as long as the purpose of the present application can be achieved, and the additives used in the present application can be additives known in the prior art, for example, the additives can include but are not limited to at least one of polynitrile compounds, sulfur-containing additives, fluoroethylene carbonate (FEC), 1,3-propane sultone (PS), and 1,4-butane sultone. Among them, the polynitrile compound includes at least one of a dinitrile compound and a trinitrile compound. The dinitrile compound is a compound containing two cyano groups (-CN), and may include, but is not limited to, malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimelonitrile, suberonitrile, azelaic acid dinitrile, methyl malononitrile, ethyl malononitrile, isopropyl malononitrile, tert-butyl malononitrile, methyl succinonitrile, 2-methylene glutaronitrile, 1,4-dicyano-3-butene, 2,2-dimethylsuccinonitrile, 2,3-dimethylsuccinonitrile, 2,3,3-trimethylsuccinonitrile, 2,2,3,3-tetramethylsuccinonitrile, 2,3-diethyl-2,3-dimethylsuccinonitrile, 2,2-diethyl-3,3-dimethylsuccinonitrile, dicyclohexyl-1,1-dicarbonitrile, dicyclohexyl-2,2-dicarbonitrile, dicyclohexyl-3,3-dicarbonitrile, 2,5-dimethyl-2,5-hexane dicarbonitrile, 2 ,3-diisobutyl-2,3-dimethylsuccinonitrile, 2,2-diisobutyl-3,3-dimethylsuccinonitrile, 2-methylglutaronitrile, 2,3-dimethylglutaronitrile, 2,4-dimethylglutaronitrile, 2,2,3,3-tetramethylglutaronitrile, 2,2,4,4-tetramethylglutaronitrile, 2,2,3,4-tetramethylglutaronitrile, 2,3,3,4-tetramethylglutaronitrile, 1, At least one of 4-dicyanopentane, 2,6-dicyanoheptane, 2,7-dicyanooctane, 2,8-dicyanononane, 1,6-dicyanodecane, 1,2-dicyanobenzene, 1,3-dicyanobenzene, 1,4-dicyanobenzene, 3,3'-(ethylenedioxy)dipropionitrile, 3,3'-(ethylenedisulfide)dipropionitrile, 1,4-dicyano-2-butene, and butylene dinitrile. The trinitrile compound is a compound containing three cyano groups (-CN).

[0078] In some embodiments, the preparation method of the electrolyte is a method for preparing an electrolyte that can be used in a battery and is well known in the art. For example, the electrolyte can be obtained by the following method: mixing the components of the electrolyte [including an organic solvent, an electrolyte, and optional additives, etc.].

[0079] <Diaphragm>

[0080] The present application has no particular restrictions on the diaphragm, as long as the purpose of the present application can be achieved. The diaphragm used in the present application can be a diaphragm known in the prior art. For example, the type of the diaphragm can include but is not limited to at least one of a woven membrane, a non-woven membrane, a microporous membrane, a composite membrane, a rolled membrane, and a spun membrane. The material of the diaphragm can include but is not limited to at least one of polyethylene (PE), polypropylene (PP)-based polyolefins (PO), polyester, cellulose, polyimide (PI), polyamide (PA), spandex, and aramid. Polyester can include but is not limited to polyethylene terephthalate (PET) film.

[0081] In some embodiments, the diaphragm includes a substrate layer. The substrate layer may include, but is not limited to, at least one of a non-woven fabric, a film, and a composite film having a porous structure. The material of the substrate layer may include, but is not limited to, at least one of polyethylene, polypropylene, polyethylene terephthalate, and polyimide. In some embodiments, the substrate layer may include, but is not limited to, at least one of a polypropylene porous film, a polyethylene porous film, a polypropylene non-woven fabric, a polyethylene non-woven fabric, and a polypropylene-polyethylene-polypropylene porous composite film.

[0082] In some of the embodiments, the diaphragm further comprises a surface treatment layer disposed on at least one surface of the substrate layer. The surface treatment layer may include but is not limited to at least one of a polymer layer, an inorganic layer, and a layer formed by a mixed polymer and an inorganic substance. The polymer layer includes a polymer. The present application has no particular restrictions on the polymer, as long as the purpose of the present application can be achieved. For example, the polymer includes at least one of polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinyl pyrrolidone, polyvinyl ether, polyvinylidene fluoride, and poly (vinylidene fluoride-hexafluoropropylene). The inorganic layer includes inorganic particles and a binder. The present application has no particular restrictions on inorganic particles and binders, as long as the purpose of the present application can be achieved. For example, the inorganic particles may include but are not limited to aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, and barium sulfate. For another example, the binder may include but is not limited to at least one of the binders used in the above-mentioned positive electrode material layer or negative electrode material layer.

[0083] In some of the embodiments, the present application has no particular limitation on the thickness of the diaphragm, as long as the purpose of the present application can be achieved. For example, the thickness of the diaphragm is 1 μm to 500 μm.

[0084] <Packaging bag>

[0085] In some embodiments, the battery further includes a packaging bag for containing electrodes (including positive electrodes and negative electrodes), a separator and an electrolyte, and other components of the battery known in the art, and the present application has no particular restrictions on other components. The present application has no particular restrictions on the packaging bag, as long as the purpose of the present application can be achieved, and the packaging bag used in the present application can be a packaging bag known in the prior art, for example, the packaging bag can include but is not limited to an aluminum-plastic film packaging bag.

[0086] <Battery Preparation Method>

[0087] The preparation method of the battery is well known to those skilled in the art. The present application does not particularly limit the preparation method of the battery, as long as the purpose of the present application can be achieved. For example, the preparation method of the battery may include but is not limited to the following steps: stacking electrodes (including positive electrodes and negative electrodes) and separators in order, and winding and folding them as needed to obtain an electrode assembly of a wound structure, placing the electrode assembly in a packaging bag, injecting an electrolyte into the packaging bag and sealing it to obtain a battery; or stacking electrodes (including positive electrodes and negative electrodes) and separators in order, and then fixing the four corners of the entire stacked structure with tape to obtain an electrode assembly of a stacked structure, placing the electrode assembly in a packaging bag, injecting an electrolyte into the packaging bag and sealing it to obtain a battery. In addition, overcurrent protection elements, guide plates, etc. may also be placed in the packaging bag as needed.

[0088] 2. Electronic Devices

[0089] A second aspect of the present application provides an electronic device, comprising the battery according to the first aspect.

[0090] The present application has no particular restrictions on electronic devices, as long as the purpose of the present application can be achieved. The electronic devices used in the present application can be electronic devices known in the prior art. For example, the electronic devices can include but are not limited to laptop computers, pen-input computers, mobile computers, e-book players, portable phones, portable fax machines, portable copiers, portable printers, head-mounted stereo headphones, video recorders, LCD televisions, portable cleaners, portable CD players, mini CDs, transceivers, electronic notepads, calculators, memory cards, portable recorders, radios, backup power supplies, motors, cars, motorcycles, power-assisted bicycles, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries, and at least one of lithium-ion capacitors.

[0091] 3. Embodiment

[0092] The present application is further clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those skilled in the art based on the present application belong to the scope of protection of the present application.

[0093] It should be noted that in the specific implementation manner of the present application, a lithium-ion battery is used as an example of a battery to explain the present application, but the battery of the present application is not limited to a lithium-ion battery.

[0094] In the following examples and comparative examples, the reagents, materials and instruments used are all commercially available unless otherwise specified. In addition, "part" and "%" are by mass unless otherwise specified.

[0095] Test methods and equipment:

[0096] (1) Melting point test of the first or second polymer:

[0097] The melting point test uses an aluminum crucible. After the sample crucible is stable and cleared at room temperature, take it out, add 10 mg of sample (first polymer or second polymer or polymer layer or diaphragm) into the crucible, and buckle the edge of the crucible. Gently place the crucible with the sample on the bracket, call the latest calibration baseline → enter the sample number, sample name, sample weight according to the software process → edit the heating rate and heating range → save the file name, confirm that the input parameters are correct, and click Start. The instrument starts the heating test. Among them, the heating rate is 10℃ / min, and the test temperature is RT400℃. Open the raw data of the completed test with the X-axis as the reference temperature, unit: ℃, and the Y-axis as the heat flow power caused by the unit weight sample at a certain temperature, unit: mW / mg. The X-axis value at the highest point of the peak is the melting point of the sample (first polymer or second polymer or polymer layer or diaphragm).

[0098] (2) Test of the content of each component in the electrolyte:

[0099] The battery was discharged at a constant current of 0.5C to 3.0V and then disassembled to collect the electrolyte. The removed positive electrode sheet, negative electrode sheet and diaphragm were centrifuged, and the liquid obtained after centrifugation was evenly mixed with the above electrolyte. Then, the battery was tested using a gas chromatography-mass spectrometer (instrument model: Agilent 8890) and an ion chromatography (instrument model: AQUION ion chromatography) to obtain the components in the electrolyte and test their contents.

[0100] (3) Battery safety performance test:

[0101] The safety performance of the battery of the present application is characterized by overcharge test, puncture test and impedance test. The degree of improvement of the battery impedance can be known through the impedance test. Batteries with low impedance generate less heat and have a low risk of thermal runaway, which is conducive to improving the safety performance of the battery. When the battery not only shows a high pass rate in the overcharge test and puncture test, but also shows low impedance in the impedance test, it means that the battery has high safety performance.

[0102] A. Overcharge test:

[0103] The battery is charged to 4.5V at a constant current of 0.5C, and then charged to 0.02C at a constant voltage of 4.5V to fully charge the battery. Then, it is charged to 10V at a constant current of 0.5C and maintained at 10V for 3h. If the battery does not catch fire or explode, it is considered to have passed the test. The experiment is repeated 10 times, and the pass rate = number of passes / 10.

[0104] B. Acupuncture test:

[0105] The battery is charged at a constant current of 0.5C to 4.5V, and then charged at a constant voltage of 4.5V to 0.02C to fully charge the battery. Then a 3mm diameter steel needle is used to pierce the battery at a speed of 10cm / s. If the battery does not catch fire or explode within 1h, it is considered to have passed the test. The experiment is repeated 10 times, and the pass rate = number of passes / 10.

[0106] C. Impedance test:

[0107] An electrochemical workstation (Bio-Logic, France) was used to test the electrochemical impedance spectroscopy (EIS) to characterize the impedance of the battery. The specific test method was to measure the ratio of the disturbance signal X and the response signal Y with a frequency of 10 μHz to 1 MHz, and obtain the real part Z', imaginary part Z", modulus |Z| and phase angle of the impedance at different frequencies. Then the EIS impedance spectrum of the battery is obtained, and the EIS impedance spectrum is curve fitted using EIS analysis software to obtain the impedance of the battery.

[0108] Example 1

[0109] 1. Preparation of positive electrode

[0110] S1. In N-methylpyrrolidone, the mass ratio of the first polymer polyvinylidene fluoride and the conductive agent acetylene black component in the adhesive layer is mixed at 80:20 to obtain an adhesive layer slurry for standby use;

[0111] S2. Mixing a foaming layer in toluene in a mass ratio of 10:20:70 of azodicarbonamide, a conductive agent acetylene black and a second polymer low-density polyethylene to obtain a foaming layer slurry for standby use;

[0112] S3. Mixing the positive electrode active material (i.e., electrode active material) lithium cobalt oxide, conductive agent acetylene black, conductive agent carbon nanotube CNT, and binder polyvinylidene fluoride PVDF in a mass ratio of 97:1:0.5:1.5 in N-methylpyrrolidone to obtain a positive electrode active layer slurry for standby use;

[0113] S4. Coating the adhesive layer slurry on one surface of the positive electrode current collector aluminum foil, drying, coating the foaming layer slurry, drying, and then coating the positive electrode active layer slurry, drying, to obtain a positive electrode coated with the slurry on one side; repeating the above steps on the other surface of the positive electrode current collector aluminum foil to obtain a positive electrode coated with the slurry on both sides; cold pressing, cutting, slitting and drying to obtain a positive electrode with a specification of 74mm×867mm;

[0114] Wherein, the melting point of the second polymer low-density polyethylene is T°C, T=110°C;

[0115] The positive electrode comprises a positive electrode current collector, an adhesive layer, a foaming layer and a positive electrode active layer which are stacked in sequence, the thickness of the foaming layer is D1 μm, D1=2, the thickness of the adhesive layer is D2 μm, D2=0.2; based on the mass of the adhesive layer, the mass percentage of the first polymer polyvinylidene fluoride is Q1%, Q1=80, and the mass percentage of the conductive agent acetylene black is 20%; based on the mass of the foaming layer, the mass percentage of the foaming agent azodicarbonamide is 10%, the mass percentage of the conductive agent acetylene black is 20%, and the mass percentage of the second polymer low-density polyethylene is Q2%, Q2=70, Q1>Q2;

[0116] 2. Preparation of negative electrode

[0117] Mixing artificial graphite, a conductive agent, acetylene black, a binder, styrene-butadiene rubber, and a thickener, of a negative electrode active material (i.e., an electrode active material) in a mass ratio of 97:1:1:1 in solvent water to prepare a negative electrode active layer slurry, and coating the negative electrode active layer slurry on one surface of a negative electrode current collector copper foil, and drying to obtain a negative electrode coated with the slurry on one side; repeating the above steps on the other surface of the negative electrode current collector copper foil to obtain a negative electrode coated with the slurry on both sides; and drying after cold pressing, cutting, slitting, and then obtaining a negative electrode with a specification of 78 mm×875 mm;

[0118] The negative electrode includes a negative electrode current collector and a negative electrode active layer stacked in sequence, and the thickness of the negative electrode active layer is 2 μm;

[0119] 3. Preparation of electrolyte

[0120] In a dry argon atmosphere glove box, ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed uniformly at a mass ratio of EC:PC:EMC:DEC=10:30:30:30, and then fluoroethylene carbonate (FEC) and 1,3-propane sultone (PS) were added, dissolved and fully stirred, and then inorganic lithium salt LiPF6 was added and mixed uniformly to obtain an electrolyte;

[0121] Among them, based on the mass of the electrolyte, the mass proportion of fluoroethylene carbonate (FEC) is 2%, the mass proportion of 1,3-propane sultone (PS) is 2%; the concentration of LiPF6 (electrolyte) is 1 mol / L;

[0122] 4. Diaphragm

[0123] A polyethylene porous membrane with a thickness of 15 μm was used as the separator;

[0124] 5. Preparation of batteries

[0125] The positive electrode and negative electrode prepared as above are respectively connected to the electrode ears, the positive electrode, separator, and negative electrode are stacked in order, and they are wound, folded, and the like as needed to obtain an electrode assembly with a wound structure, the electrode assembly is placed in an aluminum-plastic film packaging bag, the electrolyte is injected into the packaging bag and the bag is sealed, and the battery is allowed to stand, formed (charged at a constant current of 0.2C for 120s, then charged at a constant current of 1C for 180s, and finally charged to 4.6V at a constant current of 1.5C), degassed, and trimmed to obtain a battery.

[0126] Example 2

[0127] 1. Preparation of positive electrode

[0128] The positive electrode active material (i.e., electrode active material) lithium cobalt oxide, conductive agent acetylene black, conductive agent carbon nanotube CNT, and binder polyvinylidene fluoride PVDF are mixed in N-methylpyrrolidone in a mass ratio of 97:1:0.5:1.5 to prepare a positive electrode active layer slurry, and the positive electrode active layer slurry is coated on one surface of the positive electrode current collector aluminum foil, and dried to obtain a positive electrode coated with the slurry on one side; the above steps are repeated on the other surface of the positive electrode current collector aluminum foil to obtain a positive electrode coated with the slurry on both sides; after cold pressing, cutting, slitting, and drying, a positive electrode with a specification of 74 mm×867 mm is obtained;

[0129] The positive electrode includes a positive electrode current collector and a positive electrode active layer stacked in sequence, and the thickness of the positive electrode active layer is 2 μm;

[0130] 2. Preparation of negative electrode

[0131] S1. In N-methylpyrrolidone, the mass ratio of the first polymer polyvinylidene fluoride and the conductive agent acetylene black component in the adhesive layer is mixed at 80:20 to obtain an adhesive layer slurry for standby use;

[0132] S2. Mixing a foaming layer in toluene in a mass ratio of 10:20:70 of azodicarbonamide, a conductive agent acetylene black and a second polymer low-density polyethylene to obtain a foaming layer slurry for standby use;

[0133] S3. Mixing the negative electrode active layer (active layer) in water in a mass ratio of 97:1:1:1 negative electrode active material (ie, electrode active material) artificial graphite, conductive agent acetylene black, binder styrene butadiene rubber, thickener sodium hydroxymethyl cellulose to obtain a negative electrode active layer slurry for standby use;

[0134] S4. Coating the adhesive layer slurry on one surface of the negative electrode current collector copper foil, drying, coating the foaming layer slurry, drying, and then coating the negative electrode active layer slurry, drying, to obtain a negative electrode coated with the slurry on one side; repeating the above steps on the other surface of the negative electrode current collector aluminum foil to obtain a negative electrode coated with the slurry on both sides; after cold pressing, cutting, slitting and drying, a negative electrode with a specification of 78mm×875mm is obtained;

[0135] Wherein, the melting point of the second polymer low-density polyethylene is T°C, T=110°C;

[0136] The negative electrode comprises a negative electrode current collector, an adhesive layer, a foaming layer and a negative electrode active layer which are stacked in sequence, the thickness of the foaming layer is D1 μm, D1=2, the thickness of the adhesive layer is D2 μm, D2=0.2; based on the mass of the adhesive layer, the mass percentage of the first polymer polyvinylidene fluoride is Q1%, Q1=80, and the mass percentage of the conductive agent acetylene black is 20%; based on the mass of the foaming layer, the mass percentage of the foaming agent azodicarbonamide is 10%, the mass percentage of the conductive agent acetylene black is 20%, and the mass percentage of the second polymer low-density polyethylene is Q2%, Q2=70, Q1>Q2;

[0137] 3. Preparation of electrolyte

[0138] Consistent with Example 1;

[0139] 4. Diaphragm

[0140] Consistent with Example 1;

[0141] 5. Preparation of batteries

[0142] The same as Example 1.

[0143] Example 3

[0144] 1. Preparation of positive electrode

[0145] Consistent with Example 1;

[0146] 2. Preparation of negative electrode

[0147] Consistent with Example 2;

[0148] 3. Preparation of electrolyte

[0149] Consistent with Example 1;

[0150] 4. Diaphragm

[0151] Consistent with Example 1;

[0152] 5. Preparation of batteries

[0153] The same as Example 1.

[0154] Comparative Example 1

[0155] The difference between Comparative Example 1 and Example 1 is that no bonding layer slurry is used in the preparation process of the positive electrode, that is, the positive electrode of Comparative Example 1 has no bonding layer, and only includes a positive electrode current collector, a foaming layer and a positive electrode active layer stacked in sequence, and the rest is consistent with Example 1.

[0156] Comparative Example 2

[0157] The difference between Comparative Example 2 and Example 2 is that no adhesive layer slurry is used in the preparation process of the negative electrode, that is, the negative electrode of Comparative Example 2 has no adhesive layer, and it only includes a negative electrode current collector, a foaming layer and a negative electrode active layer stacked in sequence, and the rest is consistent with Example 2.

[0158] Comparative Example 3

[0159] The difference between Comparative Example 3 and Example 3 is that no bonding layer slurry is used in the preparation process of the positive electrode and the negative electrode, that is, the positive electrode and the negative electrode of Comparative Example 3 have no bonding layer, the positive electrode only includes a positive electrode collector, a foaming layer and a positive electrode active layer stacked in sequence, and the negative electrode only includes a negative electrode collector, a foaming layer and a negative electrode active layer stacked in sequence, and the rest is consistent with Example 3.

[0160] Table 1 Test results of Examples 1 to 3 and Comparative Examples 1 to 3

[0161]

[0162]

[0163] It can be seen from Table 1 that the battery provided in the present application not only shows a high pass rate in the overcharge test and the puncture test, but also shows a low impedance in the impedance test, which means that the risk of thermal runaway of the battery is reduced and the safety performance of the battery is improved.

[0164] Examples 4 to 6 and Comparative Examples 4 to 5

[0165] Except for adjusting the melting point T°C of the second polymer according to Table 2, the rest is the same as Example 1. The melting point T°C of the second polymer can be as shown in Table 2 by using different types of second polymers.

[0166] Table 2 Condition parameters and test results of Example 1, Examples 4 to 6 and Comparative Examples 4 to 5

[0167]

[0168] It can be seen from Table 2 that when the present application uses an adhesive layer and the value of the melting point T of the second polymer is within the range of the present application, the battery not only shows a high pass rate in the overcharge test and the puncture test, but also shows a low impedance in the impedance test, which means that the risk of thermal runaway of the battery is reduced and the safety performance of the battery is improved.

[0169] Examples 7 to 11

[0170] Except for adjusting the thickness of the foaming layer D1 μm and the thickness of the adhesive layer D2 μm according to Table 3, the rest is the same as Example 1.

[0171] Table 3 Condition parameters and test results of Example 1, Examples 7 to 11

[0172]

[0173] As can be seen from Table 3, when the thickness D1 of the foaming layer and / or the thickness D2 of the adhesive layer is within the range of this application, the battery not only shows a high pass rate in the overcharge test and the puncture test, but also shows a low impedance in the impedance test, which means that the risk of thermal runaway of the battery is reduced and the safety performance of the battery is improved. In particular, when 1≤D1≤2 is further adjusted, the safety performance of the battery can be further improved.

[0174] Examples 12 to 14

[0175] Except for adjusting the mass percentage of each substance in the adhesive layer and the foaming layer according to Table 4, the rest is consistent with Example 1. The application amount of each substance in the adhesive layer and / or the foaming layer can be adjusted by any means known in the art so that the mass percentage of each substance in the adhesive layer and / or the foaming layer is as shown in Table 4. Based on the mass of the adhesive layer, the mass percentage of the first polymer polyvinylidene fluoride is Q1%, and the mass percentage of the conductive agent acetylene black is W1%. Based on the mass of the foaming layer, the mass percentage of the second polymer low-density polyethylene is Q2%, the mass percentage of the conductive agent acetylene black is W2%, and the mass percentage of the foaming agent azodicarbonamide is Y%.

[0176] Table 4 Condition parameters and test results of Example 1, Examples 12 to 14

[0177]

[0178] As can be seen from Table 4, when the mass percentage of each substance in the adhesive layer and the foaming layer is within the scope of this application, the battery not only shows a high pass rate in the overcharge test and the puncture test, but also shows a low impedance in the impedance test, which means that the risk of thermal runaway of the battery is reduced and the safety performance of the battery is improved. In particular, when Q1≥Q2 is further adjusted, the safety performance of the battery can be further improved.

[0179] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application rather than to limit the scope of protection of the present application. Although the present application has been described in detail with reference to the preferred embodiments, ordinary technicians in this field should understand that the technical solution of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present application.

Claims

1. A battery comprising an electrode, a separator and an electrolyte, characterized in that: The electrode comprises a current collector, an adhesive layer, a foaming layer and an active layer which are stacked in sequence, wherein the adhesive layer comprises a first polymer and a conductive agent; the foaming layer comprises a foaming agent, a conductive agent and a second polymer, wherein the melting point of the second polymer is T°C, 90≤T≤150; and the active layer comprises an electrode active material.

2. The battery according to claim 1, characterized in that: Satisfy at least one of the following conditions (a)-(b): (a) the thickness of the foaming layer is D1 μm, 0.1≤D1≤20; (b) The thickness of the adhesive layer is D2 μm, 0.05≤D2≤0.

2.

3. The battery according to claim 2, characterized in that: 1≤D1≤2 。 4. The battery according to claim 1, characterized in that: The thickness of the foaming layer is D1 μm, the thickness of the adhesive layer is D2 μm, and D1>D2.

5. The battery according to claim 1, characterized in that: Based on the mass of the adhesive layer, the mass percentage of the first polymer is Q1%, and based on the mass of the foaming layer, the mass percentage of the second polymer is Q2%, and Q1≥Q2.

6. The battery according to claim 1, characterized in that: Based on the mass of the foaming layer, the mass percentage of the foaming agent is 5% to 10%, the mass percentage of the conductive agent is 5% to 30%, and the mass percentage of the second polymer is 60% to 85%.

7. The battery according to claim 1, characterized in that: Satisfy at least one of the following conditions (a)-(d): (a) the first polymer includes at least one of polyethylene, polyvinylidene fluoride, sodium carboxymethyl cellulose, styrene-butadiene rubber, polyacrylic acid, polytetrafluoroethylene, polyurethane, and polypropylene; (b) the foaming agent comprises at least one of an azo compound, a sulfonylhydrazide compound, a nitroso compound, sodium carbonate, and sodium bicarbonate; (c) the second polymer comprises at least one of polyethylene, polyvinylidene fluoride, sodium carboxymethyl cellulose, styrene-butadiene rubber, polyacrylic acid, polytetrafluoroethylene, polyurethane, and polypropylene; (d) The conductive agent includes at least one of conductive carbon black, acetylene black, graphite, graphene, carbon nanotubes, carbon nanofibers, and conductive polymers; and the conductive polymer includes at least one of polythiophene, polypyrrole, polyaniline, polyacetylene, polyparaphenylene, and polyfluorene.

8. The battery according to claim 1, characterized in that: The first polymer and the second polymer are the same.

9. The battery according to claim 1, characterized in that: The electrode active material satisfies at least one of the following conditions (a)-(b): (a) the electrode active material is selected from at least one of lithium cobalt oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium nickel manganese oxide, and lithium-rich manganese-based materials; (b) The electrode active material is selected from at least one of graphite, artificial graphite, hard carbon, soft carbon, silicon carbon, silicon oxide, lithium metal, lithium titanate, metal alloy, metal sulfide, and graphene.

10. An electronic device, characterized in that: Comprising a battery as claimed in any one of claims 1 to 9.

Images