Electrolyte, battery and electric equipment

Abstract

The invention provides an electrolyte, a battery and electric equipment. The electrolyte comprises an additive, and the additive comprises an inorganic mesoporous material; the pH value of the inorganic mesoporous material is 5-10, and the specific surface area of the inorganic mesoporous material is 50 m < 2 > / g-120 m < 2 > / g. According to the invention, gas production of the battery at high temperature can be effectively inhibited, and cycle performance and fast charge performance of the battery are both improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion batteries, and in particular relates to an electrolyte, a battery and an electrical device. Background Art

[0002] The electrolyte plays a vital role in batteries, and electrolyte additives are a key factor in optimizing electrolyte performance, improving battery cycling and fast-charging performance. However, existing technologies are limited by the poor thermal stability of the electrolytes in the electrolyte, which easily decomposes to produce acidic substances. The presence of acidic substances easily corrodes electrode materials and triggers side reactions, leading to problems such as electrolyte decomposition and gas production at high temperatures and obstructed ion transport. As a result, batteries generally suffer from defects such as high gas production at high temperatures and poor cycling and fast-charging performance, which urgently need to be addressed. Summary of the Invention

[0003] The present invention provides an electrolyte, a battery and an electrical device, which can effectively absorb moisture in the electrolyte, inhibit battery gas production, and improve the battery's cycle performance and fast charging performance, effectively overcoming the defects of the existing technology.

[0004] In one aspect of the present invention, an electrolyte is provided, comprising an additive, wherein the additive comprises an inorganic mesoporous material, wherein the pH value of the inorganic mesoporous material is 5-10, and the specific surface area of ​​the inorganic mesoporous material is 50m 2 / g-120m 2 / g.

[0005] According to one embodiment of the present invention, the oil absorption value of the inorganic mesoporous material is 130 ml / 100 g-260 ml / 100 g.

[0006] According to one embodiment of the present invention, the primary particle size of the inorganic mesoporous material is 2 nm-80 nm.

[0007] According to one embodiment of the present invention, the impurity metal element content of the inorganic mesoporous material is less than 100 ppm.

[0008] According to one embodiment of the present invention, the oil absorption value of the inorganic mesoporous material is 150 ml / 100 g-230 ml / 100 g.

[0009] According to one embodiment of the present invention, the primary particle size of the inorganic mesoporous material is 30 nm-70 nm.

[0010] According to one embodiment of the present invention, the impurity metal element content of the inorganic mesoporous material is less than 30 ppm.

[0011] According to one embodiment of the present invention, in the electrolyte, the inorganic mesoporous material exists in the form of secondary particles.

[0012] According to one embodiment of the present invention, the secondary particles are formed by agglomeration of a plurality of primary particles, and the secondary particles of the inorganic mesoporous material have a particle size of 5 μm to 50 μm.

[0013] According to one embodiment of the present invention, the mass percentage of the inorganic mesoporous material in the electrolyte is 0.5%-2%.

[0014] According to one embodiment of the present invention, the inorganic mesoporous material includes one or more of mesoporous alumina, mesoporous silica, mesoporous titania, mesoporous alumina derivatives, mesoporous silica derivatives, and mesoporous titania derivatives.

[0015] Another aspect of the present invention provides a battery comprising the above-mentioned electrolyte.

[0016] Another aspect of the present invention provides an electrical device comprising the battery.

[0017] The present invention provides an electrolyte, a battery and an electrical device. In the electrolyte, the pH value of the inorganic mesoporous material is 5-10, and the specific surface area of ​​the inorganic mesoporous material is 50m 2 / g-120m 2 / g. In this electrolyte composition system, the inorganic mesoporous material has excellent ionic conductivity and adsorption capacity, promoting lithium ion migration, achieving efficient adsorption of water and gas in the electrolyte, and inhibiting side reactions between water and the electrolyte, thereby effectively suppressing battery gas production at high temperatures and improving the battery's fast charging performance and cycle performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a TEM image of the inorganic mesoporous material of Example 1 of the present invention. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below. The specific embodiments listed below are only for describing the principles and features of the present invention. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts are within the scope of protection of the present invention.

[0020] In related technologies, due to the poor thermal stability of the electrolyte in the electrolyte, it is easy to decompose and produce acidic substances. The presence of acidic substances can easily corrode the electrode materials and trigger side reactions, leading to problems such as electrolyte decomposition and gas production, and obstructed ion transmission. As a result, batteries generally have defects such as easy gas production at high temperatures, poor cycle performance and fast charging performance, which need to be solved urgently.

[0021] Taking LiPF6 as an example, LiPF6 has poor thermal stability and easily decomposes to produce acidic substances (such as hydrogen fluoride (HF)). In addition, trace amounts of water in the electrolyte react with LiPF6 to produce HF. HF corrodes the electrode material and triggers side reactions, causing the electrolyte to decompose at high temperatures and produce gas (CO2, H2, etc.), which hinders lithium ion transmission. In addition, side reaction products (such as LiF and Li2CO3) are deposited on the electrode surface, destroying the stability of the SEI film and CEI film, resulting in an increase in interfacial resistance and deteriorating the battery's cycle performance and fast charging performance.

[0022] Under normal circumstances, the water in the electrolyte will undergo a hydrolysis reaction with the lithium salt (such as lithium hexafluorophosphate, LiPF6) in the electrolyte to generate hydrogen fluoride and other by-products. Among them, hydrogen fluoride (HF) is a highly corrosive substance that will corrode the metal current collector and electrode materials inside the battery, resulting in a decrease in battery performance and safety. In addition, HF will also react with the SEI film in the battery (SEI film is usually composed of organic and inorganic components, including lithium carbonate (such as Li2CO3), lithium oxide (such as Li2O), and other lithium salts) to generate gases such as carbon dioxide. The SEI film is destroyed and dissolved, resulting in direct contact between the electrolyte and the negative electrode material, continuous decomposition of the electrolyte, and a significant decrease in the fast charging performance and cycle performance of the battery.

[0023] According to the inventors' long-term research, mesoporous materials are porous structures with pore sizes between 2 and 50 nm. They possess advantages such as adjustable pore size, large specific surface area, uniform and regular pore structure, diverse skeleton composition, and easy surface modification. They have broad application prospects in catalysis, adsorption, separation, energy conversion, and storage. Mesoporous materials have a high specific surface area and unique pore structure, allowing ions to move freely within them. They can effectively adsorb small molecules such as water, carbon dioxide, and hydrogen fluoride, reducing side reactions between water, hydrogen fluoride, and the electrolyte, thereby improving the battery's cycling performance and fast-charging performance.

[0024] According to the inventors' research: 1) Inorganic mesoporous materials with lower pH values ​​will intensify the generation of acidic substances such as HF, destroy the integrity of SEI, and lead to a decrease in the battery's cycle performance; inorganic mesoporous materials with higher pH values ​​accelerate the chemical reaction between the electrolyte and the electrode material, increase gas production, and lead to a decrease in the battery's cycle performance and fast charging performance. 2) If the specific surface area of ​​the inorganic mesoporous material is too small, its electrochemically active area is relatively small, the capacity of the inorganic mesoporous material is high, and the kinetic performance is poor; and if the specific surface area of ​​the inorganic mesoporous material is too large, its electrochemically active area is also relatively large, the capacity of the inorganic mesoporous material is low, and the kinetic performance is good. However, when the specific surface area of ​​the inorganic mesoporous material is too large, its side reactions increase, resulting in increased battery gas production and a decrease in the fractional capacity. Therefore, optimizing the pH value and specific surface area of ​​the inorganic mesoporous material can be used as a direction to inhibit battery gas production while improving the battery's cycle performance and fast charging performance.

[0025] In view of this, an embodiment of the present invention provides an electrolyte, including an additive, wherein the additive includes an inorganic mesoporous material, the pH value of the inorganic mesoporous material is 5-10, and the specific surface area of ​​the inorganic mesoporous material is 50m 2 / g-120m 2 / g.

[0026] Under the above-mentioned electrolyte composition system, when the pH value and specific surface area of ​​the inorganic mesoporous material meet the above-mentioned ranges, the inorganic mesoporous material has excellent ionic conductivity and adsorption capacity, can promote the migration of lithium ions, efficiently adsorb moisture in the electrolyte and gases generated by the battery, avoid side reactions between moisture and gas and the electrolyte, reduce the diffusion impedance of ions, thereby effectively inhibiting the gas production of the battery at high temperature, and improving the cycle performance and fast charging performance of the battery.

[0027] For example, the pH value of the inorganic mesoporous material can be 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5 or 10, etc.

[0028] For example, the specific surface area of ​​the inorganic mesoporous material can be 50 m 2 / g, 60m 2 / g、70m 2 / g、80m 2 / g、90m 2 / g、100m 2 / g、110m 2 / g or 120m 2 / g, etc.

[0029] In an embodiment of the present invention, inorganic mesoporous materials can be obtained by means in the art, for example, they can be purchased commercially or made by conventional methods in the art. For example, inorganic mesoporous materials with preset pH values, specific surface areas and other characteristics can be purchased commercially, or they can be regulated by conventional methods to obtain preset pH values ​​and specific surface areas.

[0030] For example, inorganic mesoporous materials can be prepared by precipitation. Furthermore, taking mesoporous alumina as an example, mesoporous alumina can be synthesized by anion-cation double hydrolysis method. Aluminum salts (such as aluminum sulfate or aluminum chloride) are usually selected as cationic precursors, and alkaline substances (such as ammonia water or sodium hydroxide) are selected as anionic precursors. Aluminum salts are hydrolyzed in water to generate aluminum ions and corresponding acid ions. Alkaline substances dissociate in water to provide hydroxide ions. When the two are mixed, aluminum ions meet hydroxide ions and a double hydrolysis reaction occurs to generate aluminum hydroxide precipitates. Due to the low solubility of aluminum hydroxide, it will precipitate out of the solution. This process breaks the hydrolysis equilibrium and allows the reaction to continue until the reactants are exhausted. The aluminum hydroxide precipitate is then washed, dried, and calcined to obtain mesoporous alumina.

[0031] Generally, the pH value of the inorganic mesoporous material can be adjusted by adjusting the type (such as silicate, aluminate or other metal oxide precursors, etc.) and content of the precursor compound.

[0032] In an embodiment of the present invention, the pH value of the inorganic mesoporous material can be measured by the potentiometric method according to the national standard GB-T 23769-2009. In specific implementation, the inorganic mesoporous material is dispersed in water to form a suspension, and the pH value of the suspension is measured using a pH meter to obtain the pH value of the inorganic mesoporous material.

[0033] The synthesis of inorganic mesoporous materials typically requires the use of a template. The template guides the formation of the pore structure during the synthesis process. The specific surface area of ​​the inorganic mesoporous material can be adjusted using conventional techniques in the art, such as adjusting the type and concentration of the template, as well as the reaction pH and temperature.

[0034] In an embodiment of the present invention, the specific surface area of ​​the inorganic mesoporous material can be measured by BET according to the national standard GB-T 11107-2018. During the specific implementation, the battery can be discharged (i.e., the battery is discharged to 0% state of charge (0% SOC)) to ensure operational safety, and then the battery is disassembled, and the electrolyte is poured into a beaker, and the solvent (such as ethylene carbonate, ethyl methyl carbonate, diethyl carbonate) is dried to obtain a solid residue, and then dimethyl carbonate (DMC) or ethyl methyl carbonate (EMC) is used to wash and dry the solid residue to obtain an inorganic mesoporous material, and the inorganic mesoporous material is degassed under vacuum to remove impurities adsorbed on the surface. At low temperature (usually liquid nitrogen temperature, about 77K), the relative pressure of nitrogen is gradually increased to measure the adsorption amount. The BET equation is then used to fit the adsorption isotherm to calculate the specific surface area of ​​the inorganic mesoporous material.

[0035] According to the inventors' research, when the oil absorption value of the inorganic mesoporous material is too low, its compatibility with the electrolyte is poor, and the electrolyte cannot fully penetrate into the pores of the inorganic mesoporous material, limiting the effective migration path of lithium ions, resulting in a decrease in the battery's cycle performance and fast charging performance. When the oil absorption value of the inorganic mesoporous material is too high, it will adsorb too much electrolyte, resulting in a decrease in the actual available amount of electrolyte in the battery, resulting in a decrease in the battery's cycle performance. In some embodiments, the oil absorption value of the inorganic mesoporous material is 130ml / 100g-260ml / 100g.

[0036] In the embodiment of the present invention, the oil absorption value of the inorganic mesoporous material refers to the number of milliliters of standard oil that can be absorbed by every 100 grams of the inorganic mesoporous material. The standard oil can be any one of dibutyl phthalate (DBP), dioctyl phthalate (DOP), mineral oil, silicone oil, and vegetable oil.

[0037] For example, the oil absorption value of the inorganic mesoporous material (i.e., the DBP oil absorption value of the inorganic mesoporous material) can be 130ml / 100g, 150ml / 100g, 170ml / 100g, 190ml / 100g, 210ml / 100g, 230ml / 100g, 250ml / 100g or 260ml / 100g, etc.

[0038] Generally, the DBP oil absorption value of the inorganic mesoporous material can be adjusted by conventional technical means in the art, such as adjusting the type and concentration of the template, the reaction pH and temperature, and the calcination temperature and time.

[0039] In an embodiment of the present invention, the DBP oil absorption value of the inorganic mesoporous material can be measured according to the national standard GB-T3780.2-2017 by the following method: the battery can be fully discharged (i.e., the battery is discharged to 0% state of charge (0% SOC)) to ensure operational safety, and then the battery is disassembled, the electrolyte is poured into a beaker, and the solvent (such as ethylene carbonate, ethyl methyl carbonate, diethyl carbonate) is dried to obtain a solid residue, and then the solid residue is washed and dried with a solvent to obtain an inorganic mesoporous material, and the inorganic mesoporous material is dried to a constant weight to remove moisture and other volatile substances. A certain amount of inorganic mesoporous material is weighed and placed in a dry mortar. Using a burette or pipette, DBP is added dropwise to the inorganic mesoporous material. Continue to add DBP and mix until the sample forms a uniform paste or reaches a "dry point" (i.e., the sample is no longer powdery, but forms lumps), and the volume of DBP used is recorded.

[0040] According to the inventors' research, inorganic mesoporous materials have smaller primary particle sizes, which means that inorganic mesoporous materials have larger specific surface areas and shorter ion and electron transmission paths, which can significantly improve the kinetic performance of inorganic mesoporous materials, enable batteries to charge and discharge faster, and improve the fast charging performance of batteries. However, the smaller the primary particle size of the inorganic mesoporous material, the more SEI films it generates, and the more side reactions there will be, which will cause the battery's cycle performance to deteriorate and the capacity to decrease. In some embodiments, the primary particle size of the inorganic mesoporous material is 2nm-80nm.

[0041] For example, the primary particle size of the inorganic mesoporous material may be 2 nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm or 80 nm, etc.

[0042] Generally, the primary particle size of the inorganic mesoporous material can be adjusted by conventional technical means in the art, such as adjusting the type and concentration of the template, the reaction pH and temperature, the precursor concentration, the calcination temperature and time.

[0043] In an embodiment of the present invention, the primary particle size of the inorganic mesoporous material can be measured according to national standard GB-T 15445.2-2006 using a laser particle size analyzer or other conventional methods in the art. Specifically, the battery can be fully discharged (i.e., discharged to a 0% state of charge (0% SOC)) to ensure operational safety. The battery is then disassembled, the electrolyte is poured into a beaker, and the solvent (e.g., ethylene carbonate, ethyl methyl carbonate, or diethyl carbonate) is dried to obtain a solid residue. The solid residue is then washed and dried using DMC or EMC to obtain the inorganic mesoporous material. The inorganic mesoporous material is fully dispersed to ensure that the particles do not aggregate. The primary particle size of the inorganic mesoporous material is then measured using a laser particle size analyzer.

[0044] In some embodiments, the secondary particle size of the inorganic mesoporous material is 5 μm-50 μm, which prevents excessively fine particles (<5 μm) from agglomerating due to excessive specific surface area, clogging the pores of the diaphragm, reducing the active sites of side reactions, and preventing excessively large particles (>50 μm) from settling and causing electrolyte stratification, thereby facilitating the uniform dispersion of the inorganic mesoporous material in the electrolyte.

[0045] In an embodiment of the present invention, the secondary particle size of the inorganic mesoporous material can be measured according to the national standard GB-T 15445.2-2006 by conventional methods in the field such as scanning electron microscopy (such as scanning electron microscopy (SEM)). During the test, the inorganic mesoporous material can be scanned by SEM to obtain at least 50 SEM images, and then these SEM images are analyzed by image processing software (such as photoshop (PS)), and the average particle size of the inorganic mesoporous material is measured and counted, which is the secondary particle size of the inorganic mesoporous material.

[0046] For example, the secondary particle size of the inorganic mesoporous material may be 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm or 50 μm, etc.

[0047] In the embodiments of the present invention, the impurity metal elements of the inorganic mesoporous material generally refer to non-target metal elements (such as iron, chromium, nickel, copper, zinc, sodium, etc.) in the inorganic mesoporous material. These impurity metal elements may be introduced during the synthesis process of the inorganic mesoporous material, or come from raw materials, equipment or environment. Furthermore, the impurity metal element content of the inorganic mesoporous material refers to the mass proportion of non-target metal elements in the inorganic mesoporous material, usually expressed as mass percentage (wt%) or mass concentration (ppm).

[0048] In some embodiments, the impurity metal element content of the inorganic mesoporous material is less than 100 ppm, which can effectively prevent the impurity metal elements from dissolving and migrating to the electrode surface during battery operation, reacting with the SEI and CEI membranes, and causing structural damage to the SEI and CEI membranes, thereby improving the cycle performance of the battery.

[0049] Taking mesoporous alumina as an example of an inorganic mesoporous material, the impurity metal element content of mesoporous alumina refers to the mass proportion of non-aluminum metal elements in the mesoporous alumina, usually expressed as mass concentration (ppm).

[0050] Taking silicon oxide as an example of an inorganic mesoporous material, the impurity metal element content of silicon oxide refers to the mass proportion of non-silicon elements in mesoporous silicon oxide, usually expressed as mass concentration (ppm).

[0051] In general, conventional technical means in this field can be used, such as selecting high-purity raw materials, adjusting the pH and temperature of the reaction, and using post-treatment means such as washing and pickling to adjust the impurity metal element content of the inorganic mesoporous material.

[0052] In an embodiment of the present invention, the impurity metal element content of the inorganic mesoporous material can be measured by inductively coupled plasma mass spectrometry (ICP-MS) according to the national standard GB-T 37049-2018. In specific implementations, the battery can be fully discharged (i.e., discharged to 0% state of charge (0% SOC)) to ensure operational safety. The battery is then disassembled, the electrolyte is poured into a beaker, and the solvent (such as ethylene carbonate, ethyl methyl carbonate, or diethyl carbonate) is dried to obtain a solid residue. The solid residue is then washed and dried using DMC or EMC to obtain an inorganic mesoporous material. The inorganic mesoporous material is placed in a container, and an appropriate amount of digestion solution is added to dissolve the inorganic mesoporous material to form a solution. The solution is then introduced into the ICP through an injection system. The sample is atomized and ionized in the high-temperature plasma to form positive ions. The ions are separated and detected by a mass spectrometer based on their mass-to-charge ratio (m / z). ICP-MS can simultaneously detect multiple metal elements and provide their concentration information. The detection signal is converted into metal concentration using a calibration curve to calculate the content of each impurity metal element in the inorganic mesoporous material, usually expressed as mass percentage or ppm.

[0053] For example, the metal impurity content of the inorganic mesoporous material may be 5 ppm, 10 ppm, 20 ppm, 30 ppm, 40 ppm, 50 ppm, 60 ppm, 70 ppm, 80 ppm, 90 ppm or 98 ppm, etc.

[0054] The embodiment of the present invention further screens the oil absorption value, primary particle size and impurity metal element content of the inorganic mesoporous material, which is beneficial to further suppress the gas production of the battery at high temperature and improve the fast charging performance and cycle performance of the battery.

[0055] In some embodiments, the oil absorption value of the inorganic mesoporous material is 150 ml / 100 g-230 ml / 100 g, the primary particle size of the inorganic mesoporous material is 30 nm-70 nm, and the impurity metal element content of the inorganic mesoporous material is <30 ppm.

[0056] For example, the oil absorption value of the inorganic mesoporous material can be 150 ml / 100 g, 160 ml / 100 g, 170 ml / 100 g, 180 ml / 100 g, 190 ml / 100 g, 200 ml / 100 g, 210 ml / 100 g, 220 ml / 100 g or 230 ml / 100 g, etc.

[0057] For example, the primary particle size of the inorganic mesoporous material may be 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm or 70 nm, etc.

[0058] For example, the metal impurity content of the inorganic mesoporous material may be 5 ppm, 10 ppm, 13 ppm, 16 ppm, 19 ppm, 22 ppm, 25 ppm, or 28 ppm, etc.

[0059] According to the inventors' research, excessive content of inorganic mesoporous materials in the electrolyte will increase the overall viscosity of the electrolyte, increase the internal resistance of the battery, reduce the migration speed of ions, and lead to a decrease in the cycle performance of the battery.

[0060] In some embodiments, the mass percentage of the inorganic mesoporous material in the electrolyte is 0.5%-2%, which is beneficial to remove moisture from the electrolyte, further inhibit the gas production of the battery at high temperature, and improve the cycle performance and fast charging performance of the battery.

[0061] For example, the mass percentage of the inorganic mesoporous material in the electrolyte may be 0.5%, 0.8%, 1.1%, 1.4%, 1.7% or 2%, etc.

[0062] In some embodiments, the inorganic mesoporous material includes one or more of mesoporous alumina, mesoporous silica, mesoporous titania, a mesoporous alumina derivative, a mesoporous silica derivative, and a mesoporous titania derivative.

[0063] In some embodiments, derivatives of mesoporous alumina, mesoporous silica, and mesoporous titania are typically obtained by chemically modifying them (such as introducing silicon, titanium, zirconium, magnesium, etc. for doping, introducing organic functional groups, etc.) or compounding them with other materials (such as metals, metal oxides, carbon materials, etc.).

[0064] In some embodiments, the inorganic mesoporous material is in the form of a white powder.

[0065] An embodiment of the present invention further provides a battery, including the above-mentioned electrolyte. The battery has advantages corresponding to the above-mentioned negative electrode sheet, which will not be described in detail.

[0066] In some embodiments, the battery may be a lithium-ion battery.

[0067] Generally speaking, a battery includes an electrolyte, a cell, and a casing that encapsulates the cell. The electrolyte is injected into the cell within the casing, and the cell includes a positive electrode sheet, a negative electrode sheet, and a separator located between the positive and negative electrodes. The cell can be a laminated cell, where the positive electrode sheet, separator, and negative electrode sheet are stacked in an alternating pattern. Alternatively, the cell can be a wound cell, where the positive electrode sheet, separator, and negative electrode sheet are stacked and then wound.

[0068] Specifically, the negative electrode sheet includes a negative electrode collector and a negative electrode active layer located on at least one side surface of the negative electrode collector. Specifically, the negative electrode active layer can be provided on one side surface of the negative electrode collector in the thickness direction, or the negative electrode active layer can be provided on the surfaces of two opposite sides in the thickness direction of the negative electrode collector.

[0069] Specifically, the negative electrode active layer may include a negative electrode active material, a conductive agent, a binder and a thickener. In the negative electrode active layer, the mass percentage of the negative electrode active material may be 70% to 99%, for example, 70%, 75%, 80%, 85%, 90%, 93%, 95%, 97%, 99% or a range consisting of any two thereof, and the mass fraction of the conductive agent may be 0.5% to 15%, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%. , 8%, 10%, 13%, 15% or any two of them, the mass fraction of the binder can be 0.5% to 15%, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 8%, 10%, 13%, 15% or any two of them, the mass fraction of the thickener can be 1% to 3%, for example, 1%, 1.3%, 1.6%, 1.9%, 2.2%, 2.5%, 2.8% or 3%, etc.

[0070] In some embodiments, the negative electrode active material may include one or more of graphite, hard carbon, soft carbon, silicon carbon material, and the like.

[0071] In an embodiment of the present invention, the conductive agent in the negative electrode active layer can be a conventional conductive material in the art. For example, the conductive agent in the negative electrode active layer can include one or more of conductive carbon black, conductive graphite, carbon nanotubes (CNTs), carbon fibers, graphene, acetylene black, and Ketjen black.

[0072] In an embodiment of the present invention, the binder in the negative electrode active layer may be a conventional binding material in the art. For example, the binder in the negative electrode active layer may include one or more of styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), polyvinylidene fluoride, polyvinyl fluoride, polyethylene, polypropylene, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, ethylene oxide-containing polymers, polyvinyl pyrrolidone, polyurethane, and the like.

[0073] In an embodiment of the present invention, the thickener in the negative electrode active layer can be a conventional thickener in the art. For example, the thickener in the negative electrode active layer can include one or more of sodium carboxymethyl cellulose (CMC), sodium polyacrylate (PAA), hydroxypropyl methylcellulose (HPMC), sodium alginate, etc.

[0074] The embodiment of the present invention may use a conventional negative electrode current collector in the art, for example, the negative electrode current collector includes copper foil.

[0075] Specifically, the positive electrode sheet includes a positive electrode collector and a positive electrode active layer located on at least one side surface of the positive electrode collector. Specifically, the positive electrode active layer can be provided on one side surface in the thickness direction of the positive electrode collector, or the positive electrode active layer can be provided on the surfaces of the opposite sides in the thickness direction of the positive electrode collector.

[0076] Specifically, the positive electrode active layer may include a positive electrode active material, a conductive agent and a binder. In the positive electrode active layer, the mass percentage of the positive electrode active material may be 70% to 99%, for example, 70%, 75%, 80%, 85%, 90%, 93%, 95%, 97%, 99% or a range consisting of any two thereof; the mass fraction of the conductive agent may be 0.5% to 15%, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 8%, 10%, 13%, 15% or a range consisting of any two thereof; the mass fraction of the binder may be 0.5% to 15%, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 8%, 10%, 13%, 15% or a range consisting of any two thereof.

[0077] In some embodiments, the positive electrode active material may include LiCoO2, LiNiO2, LiCo x Ni 1-x O2(0≤x≤1), LiCo x Ni 1-x-y Al y O2(0≤x≤1,0≤y≤1), LiMn2O4, LiFe x Mn y Mz O4 (M is one or more of Al, Mg, Ga, Cr, Co, Ni, Cu, Zn or Mo, 0≤x≤1, 0≤y≤1, 0≤z≤1, x+y+z=1), Li 1+x L 1－y－z M y N z O2 (L, M, N is one or more of Li, Co, Mn, Ni, Fe, Al, Mg, Ga, Ti, Cr, Cu, Zn, Mo, F, I, S, B, -0.1≤x≤0.2, 0≤y≤1, 0≤z≤1, 0≤y+z≤1), LiFePO4, Li3V2(PO4)3, Li3V3(PO4)3, LiVPO4F, Li2CuO2, Li5FeO4, and metal sulfides and oxides (such as TiS2, V2S3, FeS, FeS2, LiMS x (M is at least one transition metal element such as Ti, Fe, Ni, Cu, Mo, 1≤x≤2.5), one or more of TiO2, Cr3O8, V2O5, MnO2, etc.

[0078] In an embodiment of the present invention, the conductive agent in the positive electrode active layer can be a conventional conductive material in the art. For example, the conductive agent in the positive electrode active layer can include one or more of conductive carbon black, conductive graphite, carbon nanotubes (CNTs), carbon fibers, graphene, acetylene black, and Ketjen black.

[0079] In an embodiment of the present invention, the binder in the positive electrode active layer may be a conventional binding material in the art. For example, the binder in the positive electrode active layer may include one or more of polyvinylidene fluoride (PVDF), polyvinylidene fluoride, polyvinyl fluoride, polyethylene, polypropylene, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, ethylene oxide-containing polymers, polyvinyl pyrrolidone, polyurethane, and the like.

[0080] The embodiment of the present invention may adopt a conventional positive electrode current collector in the art. For example, the positive electrode current collector includes aluminum foil, and specifically may include carbon-coated aluminum foil.

[0081] In the embodiments of the present invention, the positive electrode sheet can be prepared by conventional methods in the art, such as by a coating method. Specifically, the components used to form the positive electrode active layer, such as the positive electrode active material, the conductive agent, and the binder, can be dispersed in a solvent, such as N-methylpyrrolidone (NMP), to prepare a positive electrode slurry, which is then coated on the surface of the positive electrode current collector. After drying and roller pressing, the positive electrode sheet is prepared. The coating, drying, and roller pressing steps involved are conventional operations for preparing positive electrode sheets using a coating method and are not particularly limited thereto.

[0082] The electrolyte of the embodiment of the present invention can be a conventional electrolyte in the field. For example, the electrolyte is a non-aqueous electrolyte, which may specifically include an organic solvent, an additive and an electrolyte salt. The organic solvent includes, for example, one or more of ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC) and propylene carbonate (PC), the additive includes, for example, fluoroethylene carbonate (FEC), the additive includes, for example, vinylene carbonate (VC), fluoroethylene carbonate (FEC) and methyl methoxydisilane (MMDS), the electrolyte salt may include a lithium salt, and the lithium salt includes, for example, lithium hexafluorophosphate (LiPF6), etc., but is not limited thereto.

[0083] In the embodiment of the present invention, the separator is used to separate the positive electrode sheet and the negative electrode sheet to prevent the positive electrode sheet and the negative electrode sheet from short-circuiting. The embodiment of the present invention can adopt conventional separators in the art without special limitation.

[0084] In the embodiment of the present invention, conventional shell materials in the art may be used to encapsulate the battery cell. The shell may include, for example, a soft packaging material such as an aluminum-plastic film, but is not limited thereto.

[0085] In the embodiment of the present invention, components such as positive electrode sheets, separators and negative electrode sheets can be assembled into a battery by conventional methods in the field. For example, the positive electrode sheets, separators and negative electrode sheets can be stacked in an alternating manner to produce a laminated battery cell (or wound into a wound battery cell); the battery cell is then placed in a shell (outer packaging), and after conventional processes such as liquid injection (i.e., injecting electrolyte) and packaging, the battery is produced.

[0086] In the embodiment of the present invention, the battery may take various forms, including but not limited to a battery pack.

[0087] The battery pack includes a plurality of the above-mentioned batteries, which are connected as single cells to form a battery pack. The batteries can be electrically connected by conventional methods in the art, such as series connection, parallel connection, or a combination of these connection methods, without particular limitation.

[0088] An embodiment of the present invention further provides an electrical device including the above-mentioned battery. The electrical device has advantages corresponding to those of the above-mentioned electrolyte, which will not be described in detail.

[0089] The electrical equipment in the embodiments of the present invention can be conventional electrical equipment in this field, such as power equipment (such as electric vehicles, electric cars), electronic equipment (such as mobile phones, tablets, laptops, digital cameras, etc.), wearable devices (such as watches, bracelets, VR glasses, etc.), energy storage power stations, etc., without special restrictions.

[0090] The present invention is further described below through specific examples.

[0091] Example 1

[0092] 1. Preparation of negative electrode sheet

[0093] The negative electrode active material graphite, the conductive agent carbon black, the thickener CMC and the binder styrene-butadiene rubber (SBR) are mixed in a solid mass ratio of 96:1:1.5:1.5 to obtain a first mixed powder. The first mixed powder is placed in a homogenizer, and deionized water is added as a solvent to mix and stir uniformly to obtain a negative electrode slurry. The negative electrode slurry is coated on the front and back sides of a copper foil with a thickness of 8 μm, and the negative electrode sheet is obtained after drying, rolling and slitting.

[0094] 2. Preparation of positive electrode

[0095] The positive electrode active material lithium iron phosphate, the conductive agent carbon black, and the binder PVDF are mixed in a mass ratio of 97:1.5:1.5 to obtain a second mixed powder. The second mixed powder is placed in a vacuum mixer, and a solvent N-methylpyrrolidone (NMP) is added and stirred evenly to obtain a positive electrode slurry. The positive electrode slurry is coated on the front and back sides of a carbon-coated aluminum foil (the total thickness of the carbon-coated aluminum foil is 17 μm and the thickness of the coating is 2 μm), and the positive electrode sheet is obtained after drying, rolling, and slitting.

[0096] 3. Preparation of electrolyte

[0097] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) are mixed in a mass ratio of 30:40:30 to obtain a mixed solvent, 5 wt% of vinylene carbonate (VC), 2 wt% of fluoroethylene carbonate (FEC), and 1 wt% of methylmethoxydisilane (MMDS) are added to the mixed solvent (the addition amounts of VC, FEC, and MMDS are all based on the mass of the mixed solvent), and then lithium salt LiPF6 and mesoporous alumina are added thereto to prepare an electrolyte with a LiPF6 concentration of 1 mol / L;

[0098] The mass percentage of mesoporous alumina in the electrolyte is 1.5wt%, the pH value of mesoporous alumina is 7.7, and the specific surface area is 91.7m 2 / g, DBP oil absorption value is 202ml / 100g, primary particle size is 54.2nm, metal impurity content is 11ppm, and secondary particle size is 26μm.

[0099] 4. Preparation of lithium-ion batteries

[0100] In a glove box filled with argon, the positive electrode sheet, diaphragm (polyethylene film), and negative electrode sheet are stacked in order to obtain a battery cell; wherein, the diaphragm must completely isolate the positive electrode sheet from the negative electrode sheet. The stacked battery cell is then placed in an aluminum-plastic film soft package and injected with the above-mentioned electrolyte. After vacuum packaging, standing, formation, aging, volume-dividing cutting and sealing, a lithium-ion battery is obtained.

[0101] Example 2

[0102] The difference between this embodiment and embodiment 1 is that during the preparation of the electrolyte, the mass percentage of mesoporous alumina in the electrolyte is 0.5 wt %, the DBP oil absorption value is 210 ml / 100 g, the primary particle size is 65.3 nm, and the secondary particle size is 24 μm.

[0103] Example 3

[0104] The difference between this embodiment and embodiment 1 is that during the preparation of the electrolyte, the mass percentage of mesoporous alumina in the electrolyte is 2 wt %, the DBP oil absorption value is 230 ml / 100 g, the primary particle size is 60.2 nm, and the secondary particle size is 25 μm.

[0105] Example 4

[0106] The difference between this embodiment and embodiment 1 is that during the preparation of the electrolyte, the pH value of the mesoporous alumina is 5.2, the primary particle size is 58.3 nm, and the secondary particle size is 24 μm.

[0107] Example 5

[0108] The difference between this embodiment and embodiment 1 is that during the preparation of the electrolyte, the pH value of the mesoporous alumina is 10 and the specific surface area is 92.3 m 2 / g, DBP oil absorption value is 202ml / 100g, primary particle size is 54.3nm, and secondary particle size is 24μm.

[0109] Example 6

[0110] The difference between this embodiment and embodiment 1 is that during the preparation of the electrolyte, the pH value of the mesoporous alumina is 8.2 and the specific surface area is 50.3 m 2 / g, DBP oil absorption value is 160ml / 100g, and primary particle size is 45.3nm.

[0111] Example 7

[0112] The difference between this embodiment and embodiment 1 is that during the preparation of the electrolyte, the pH value of the mesoporous alumina is 8.4 and the specific surface area is 118.6 m 2 / g, DBP oil absorption value 220ml / 100g, primary particle size 43.2nm, secondary particle size 24μm.

[0113] Example 8

[0114] The difference between this embodiment and embodiment 1 is that during the preparation of the electrolyte, the pH value of the mesoporous alumina is 6.3 and the specific surface area is 86.3 m 2 / g, DBP oil absorption value is 131ml / 100g, primary particle size is 32.1nm, and secondary particle size is 25μm.

[0115] Example 9

[0116] The difference between this embodiment and embodiment 1 is that during the preparation of the electrolyte, the pH value of the mesoporous alumina is 8.2, and the specific surface area is 82.5 m 2 / g, DBP oil absorption value is 258ml / 100g, primary particle size is 38.1nm, and secondary particle size is 24μm.

[0117] Example 10

[0118] The difference between this embodiment and embodiment 1 is that during the preparation of the electrolyte, the specific surface area is 91.3m 2 / g, DBP oil absorption value is 204ml / 100g, primary particle size is 2.3nm, and secondary particle size is 13.2μm.

[0119] Example 11

[0120] The difference between this embodiment and embodiment 1 is that during the preparation of the electrolyte, the specific surface area is 91.8m 2 / g, DBP oil absorption value is 198ml / 100g, primary particle size is 77.9nm, and secondary particle size is 47.2μm.

[0121] Example 12

[0122] The difference between this embodiment and embodiment 1 is that during the preparation of the electrolyte, the specific surface area is 90.7m 2 / g, DBP oil absorption value is 203ml / 100g, primary particle size is 58.1nm, metal impurity content is 28ppm, and secondary particle size is 27μm.

[0123] Example 13

[0124] The difference between this embodiment and embodiment 1 is that during the preparation of the electrolyte, an equal amount of mesoporous alumina is replaced by mesoporous silica, wherein the primary particle size is 53.3 nm, the impurity metal element content is 98 ppm, and the secondary particle size is 28 μm.

[0125] Comparative Example 1

[0126] The difference between this comparative example and Example 1 is that no mesoporous alumina was added during the preparation of the electrolyte.

[0127] Comparative Example 2

[0128] The difference between this comparative example and Example 1 is that during the preparation of the electrolyte, the pH value of the mesoporous alumina is 2.9, and the specific surface area is 92.3 m 2 / g, the primary particle size is 58.3nm, and the secondary particle size is 24μm.

[0129] Comparative Example 3

[0130] The difference between this comparative example and Example 1 is that during the preparation of the electrolyte, the pH value of the mesoporous alumina is 12.5, and the particle size of the secondary particles is 25 μm.

[0131] Comparative Example 4

[0132] The difference between this comparative example and Example 1 is that during the preparation of the electrolyte, the pH value of the mesoporous alumina is 8.1 and the specific surface area is 44.2 m 2 / g, DBP oil absorption value is 208ml / 100g, and secondary particle size is 33μm.

[0133] Comparative Example 5

[0134] The difference between this comparative example and Example 1 is that during the preparation of the electrolyte, the pH value of the mesoporous alumina is 7.9, and the specific surface area is 150.3 m 2 / g, DBP oil absorption value is 199ml / 100g, and secondary particle size is 28μm.

[0135] The batteries of Examples 1-13 and Comparative Examples 1-5 were fully discharged and then disassembled. The electrolyte was poured into a beaker, and the solvent (ethylene carbonate, ethyl methyl carbonate, diethyl carbonate) was dried to obtain a solid residue. The solid residue was then washed and dried with dimethyl carbonate (DMC) or ethyl methyl carbonate (EMC) to obtain an inorganic mesoporous material for testing. The following performance tests were performed on the inorganic mesoporous material for testing:

[0136] 1) pH value of the inorganic mesoporous material: According to the national standard GB-T 23769-2009, the inorganic mesoporous material for the test is dispersed in water to form a suspension, and the pH value of the suspension is measured using a pH meter to obtain the pH value of the inorganic mesoporous material.

[0137] 2) Specific Surface Area of ​​Inorganic Mesoporous Materials: According to the national standard GB-T 11107-2018, the inorganic mesoporous materials used in the above tests were degassed under vacuum to remove surface-adsorbed impurities. At low temperatures (typically liquid nitrogen temperature, approximately 77K), the relative pressure of nitrogen was gradually increased, and the adsorption amount was measured. The adsorption isotherm was then fitted using the BET equation to calculate the specific surface area of ​​the inorganic mesoporous materials.

[0138] 3) DBP Oil Absorption of Inorganic Mesoporous Materials: According to the national standard GB-T 3780.2-2017, weigh a certain amount of the inorganic mesoporous material used in the above test and place it in a dry mortar. Using a burette or pipette, add DBP dropwise to the inorganic mesoporous material. Continue adding DBP and mixing until the inorganic mesoporous material forms a uniform paste or reaches the "drying point" (i.e., the inorganic mesoporous material is no longer powdery but forms clumps), and record the volume of DBP used. The DBP oil absorption value is usually expressed as milliliters of DBP absorbed per 100 grams of inorganic mesoporous material.

[0139] 4) Primary particle size of inorganic mesoporous material: According to the national standard GB-T 15445.2-2006, the inorganic mesoporous material used in the above test was fully dispersed to ensure that the particles did not aggregate, and then the primary particle size of the inorganic mesoporous material was measured using a laser particle size analyzer.

[0140] 5) Secondary particle size of inorganic mesoporous material: According to the national standard GB-T 15445.2-2006, the secondary particle size of the inorganic mesoporous material is measured by a scanning electron microscope (such as a scanning electron microscope (SEM)). During the test, the inorganic mesoporous material can be scanned by SEM to obtain at least 50 SEM images, and then these SEM images are analyzed by image processing software (such as photoshop (PS)). The average particle size of the inorganic mesoporous material is measured and counted, which is the secondary particle size of the inorganic mesoporous material.

[0141] 6) Impurity metal element content of inorganic mesoporous materials: According to the national standard GB-T 37049-2018, the inorganic mesoporous material for the above test is placed in a container, an appropriate amount of digestion solution is added to dissolve the inorganic mesoporous material to form a solution, and then the solution is introduced into the ICP through the injection system. The sample is atomized and ionized in the high-temperature plasma to form positive ions. The ions are separated and detected according to the mass-to-charge ratio (m / z) through the mass spectrometer. ICP-MS is capable of detecting multiple metal elements at the same time and providing their concentration information. The detection signal is converted into metal concentration using a calibration curve, and the content of each impurity metal element in the inorganic mesoporous material is calculated and expressed in ppm.

[0142] 7) TEM image of inorganic mesoporous material: The inorganic mesoporous material used in the test was mixed with epoxy resin and cured at a volume ratio of 3:1. Then, a Pt layer was deposited by electron beam. TEM was used for observation at an accelerating voltage of 300kV. The results are shown in Fig. Figure 1 , Figure 1 It shows that the inorganic mesoporous material exists in the form of secondary particles, which are formed by the aggregation of multiple primary particles.

[0143] The type of inorganic mesoporous material in each embodiment and comparative example, the mass percentage M1 of the inorganic mesoporous material in the electrolyte, the pH value of the inorganic mesoporous material, the specific surface area of ​​the inorganic mesoporous material, the DBP oil absorption value of the inorganic mesoporous material, the primary particle size of the inorganic mesoporous material, the secondary particle size of the inorganic mesoporous material, and the impurity metal element content of the inorganic mesoporous material are summarized in Table 1. Except for the differences shown in Table 1, the other conditions are basically the same.

[0144] Table 1

[0145]

[0146]

[0147] The water content in the electrolytes prepared in Examples 1-13 and Comparative Examples 1-5 was tested using the Karl Fischer method. The results are shown in Table 2. The specific steps are as follows:

[0148] A coulometric Karl Fischer titrator equipped with a fully enclosed titration cell and a double platinum electrode was used, and appropriate amounts of the electrolytes prepared in Examples 1-13 and Comparative Examples 1-5 were added to a coulometric reagent containing iodine, sulfur dioxide, pyridine, and methanol.

[0149] The instrument automatically electrolyzes and records the amount of electricity (Q), and calculates the water content in the electrolyte according to the following formula:

[0150]

[0151] Where Q is the charge (in coulombs) and m is the mass of the electrolyte (in g).

[0152] The lithium ion batteries in Examples 1-13 and Comparative Examples 1-5 were tested as follows:

[0153] 1) 80% SOC cycle number of lithium-ion batteries: At 25°C, charge and discharge three times at 1 / 3C of the theoretical capacity. The discharge capacity of the third cycle is recorded as the battery capacity (C0). Constant current and constant voltage charge and discharge test is performed with the C0 capacity. The cut-off current of constant voltage charging is 0.05C0. Repeat the above charge and discharge cycles, and record the discharge capacity of the battery at the end of each cycle. Calculate the capacity retention rate, that is, the ratio of the discharge capacity of each cycle to the initial capacity C0. Record the number of cycles when the capacity retention rate reaches 80%, which is the 80% SOC cycle number of the lithium-ion battery. The results are shown in Table 2.

[0154] 2) Fast charge time of lithium-ion batteries: The three-electrode method was used to measure the fast charge time of the lithium-ion batteries in Examples 1-13 and Comparative Examples 1-5 at 10% SOC-80% SOC. The specific test method is as follows: Ensure that the battery starts testing at 10% SOC, and charge the battery at different charge rates of 10C, 9.5C, 9C, 8.5C, 8C, 7.5C, 7C, 6.5C, 6C, 5.5C, 5C, 4.5C, 4C, 3.5C, 3C, 2.5C, 2C, 1.5C, 1C, and 0.5C. After each charge, the battery was allowed to stand for 1 hour and discharged at a discharge rate of 1 / 3C to 2V. Record the battery SOC when the negative electrode potential of the three electrodes is 0V at each charge rate, and record the SOC as the SOC value that can be charged at that rate. For example, at 2.5C, the negative electrode voltage is 0V at 70% SOC. This means that at a rate of 2.5C, the battery can be charged to 70% SOC. The time used in this process is (70% SOC-10% SOC) / 2.5C×60=14.4min. During the fast charge cycle test, the battery is charged at a rate from large to small (i.e., from 10C, 9.5C...0.5C). If the battery has 60% SOC when the rate reaches 2.5C, the fast charge time at 2.5C is (70%-60%) / 2.5×60=2.4min. The final fast charge time of the lithium-ion battery is the sum of the charging times at the above different rates. The results are shown in Table 2.

[0155] 3) Gas production of lithium-ion batteries stored at 60°C: The lithium-ion batteries were stored in a 60°C constant temperature box for 28 days. Before the gas production test, the lithium-ion batteries were charged to 100% SOC at a constant current and constant voltage of 0.2C and a cutoff current of 0.05C. After charging, the batteries were left to stand for 2 hours to ensure that the polarization effect inside the battery cell was eliminated. The volume change of the above lithium-ion batteries was measured using the Archimedes principle to estimate the gas production. The specific operation is as follows: The battery is immersed in a liquid (usually a liquid with a known density, such as water or other liquids that do not react with the battery). The amount of liquid discharged before and after the battery is immersed is measured. According to the Archimedes principle, the volume of liquid discharged is equal to the volume change of the battery. By measuring the volume change, the gas production inside the battery can be estimated. The results are shown in Table 2.

[0156] 4) Lithium-ion battery fractional capacity: The lithium-ion battery was charged and discharged at a constant current and constant voltage at 1 / 3C of the theoretical capacity, with a charging cut-off voltage of 4.2V and a cut-off current of 0.05C. The above charge and discharge process was repeated three times (i.e., three cycles). The discharge capacity of the third cycle was recorded as the fractional capacity (C1) of the battery. The fractional capacity (C1) reflects the actual available capacity of the battery under standard test conditions. The results are shown in Table 2.

[0157] Table 2

[0158]

[0159] From the analysis of Table 2, it can be seen that in Comparative Example 1, no mesoporous alumina was added to the electrolyte, the moisture in the electrolyte and the gas production in the battery increased, and the cycle performance and fast charging performance of the battery seriously deteriorated. In Comparative Examples 2-5, although mesoporous alumina was added to the electrolyte, the pH value of the mesoporous alumina in Comparative Example 2 was too small (<5), and the pH value of the mesoporous alumina in Comparative Example 3 was too large (>10), the gas production of the battery increased, and the cycle performance and fast charging performance decreased. The specific surface area of ​​the mesoporous alumina in Comparative Example 4 was too small (<50m 2 / g), the fast charging performance of the battery is reduced; the specific surface area of ​​the mesoporous alumina in Comparative Example 5 is too large (>120m 2 / g), the gas production increases and the cycle performance of the battery deteriorates.

[0160] Compared with Comparative Examples 1 to 5, Examples 1 to 13 add mesoporous alumina to the electrolyte, and control the pH value of the mesoporous alumina in the range of 5-10, and the specific surface area in the range of 50-120 m 2 / g range, it can both inhibit the gas production of the battery at high temperature and improve the battery's cycle performance and fast charging performance.

[0161] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An electrolyte, characterized in that: including an additive, wherein the additive includes an inorganic mesoporous material; The pH value of the inorganic mesoporous material is 5-10, and the specific surface area of ​​the inorganic mesoporous material is 50m 2 / g-120m 2 / g.

2. The electrolyte according to claim 1, characterized in that The oil absorption value of the inorganic mesoporous material is 130 ml / 100 g to 260 ml / 100 g.

3. The electrolyte according to claim 1 or 2, characterized in that The primary particle size of the inorganic mesoporous material is 2nm-80nm.

4. The electrolyte according to any one of claims 1 to 3, characterized in that The impurity metal element content of the inorganic mesoporous material is less than 100 ppm.

5. The electrolyte according to any one of claims 2 to 4, characterized in that The oil absorption value of the inorganic mesoporous material is 150 ml / 100 g-230 ml / 100 g.

6. The electrolyte according to any one of claims 3 to 5, characterized in that The primary particle size of the inorganic mesoporous material is 30nm-70nm.

7. The electrolyte according to any one of claims 4 to 6, characterized in that The impurity metal element content of the inorganic mesoporous material is less than 30 ppm.

8. The electrolyte according to any one of claims 1 to 7, characterized in that In the electrolyte, the inorganic mesoporous material exists in the form of secondary particles.

9. The electrolyte according to claim 8, characterized in that The secondary particles are formed by agglomeration of multiple primary particles, and the particle size of the secondary particles of the inorganic mesoporous material is 5µm-50µm.

10. The electrolyte according to any one of claims 1 to 9, characterized in that The mass percentage of the inorganic mesoporous material in the electrolyte is 0.5%-2%.

11. The electrolyte according to any one of claims 1 to 10, characterized in that The inorganic mesoporous material includes one or more of mesoporous alumina, mesoporous silica, mesoporous titania, mesoporous alumina derivatives, mesoporous silica derivatives, and mesoporous titania derivatives.

12. A battery, characterized in that: The electrolyte comprising the electrolyte according to any one of claims 1 to 11.

13. An electrical device, characterized in that: Including the battery according to claim 12.

Images