Electrolyte, battery and preparation method thereof, and electric device

Abstract

The application provides an electrolyte, a battery and a preparation method thereof, and a power utilization device. The electrolyte comprises a singlet oxygen quencher, and the singlet oxygen quencher contains an aromatic group, and the aromatic group comprises one or more of a phenyl group, a furan group and an imidazole group. Through the preparation of the battery by using the electrolyte, the problem of battery gas production caused by singlet oxygen in the battery can be effectively solved, and the cycle stability, safety and service life of the battery are improved.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, and in particular to an electrolyte, a battery, a method for preparing the same, and an electrical device thereof. Background Technology

[0002] Lithium-ion batteries, as the cornerstone of modern energy storage technology, are widely used in portable electronic devices, electric vehicles, and renewable energy systems. Their high energy density, long cycle life, and excellent electrochemical performance make them an indispensable energy solution. However, under conditions of high temperature, high pressure, or overcharging, the battery components of lithium-ion batteries may undergo decomposition or oxidation reactions, leading to the formation of singlet oxygen. For example, lithium supplements release reactive oxygen species during decomposition, with singlet oxygen (¹O2) being particularly prominent; in ternary batteries, when the cathode material is over-oxidized, some oxygen can escape from the material structure, forming the aforementioned singlet oxygen.

[0003] Singlet oxygen is a highly reactive oxygen species with extremely high reactivity. It can react with organic solvents in the electrolyte to generate gases (such as H2, CO2, and CO) and byproducts (such as peroxides and organic acids). This increases the internal pressure of the battery, leading to battery seal failure, electrolyte leakage, and affecting battery performance and safety. Furthermore, the generated gases can cause the battery casing to expand. This expansion not only affects the battery's physical structure but may also prevent the battery from being installed in existing equipment, affecting its normal operation. In addition, the singlet oxygen quenchers added to address the high battery expansion rate can reduce battery capacity, resulting in the current widespread problem of high volume expansion and low capacity in batteries.

[0004] Therefore, there is an urgent need for an electrolyte that can effectively control the generation of singlet oxygen, solve the gas generation problem caused by the decomposition or oxidation of lithium-ion battery components to produce singlet oxygen, reduce the volume expansion rate of the battery, and not lead to a decrease in battery capacity. Summary of the Invention

[0005] The main objective of this invention is to provide an electrolyte that can capture singlet oxygen in battery components, thereby solving the problems of high battery expansion rate and reduced battery capacity caused by battery gas production, and thus improving the cycle stability, safety and lifespan of the battery.

[0006] The present invention also provides a battery comprising the above-mentioned electrolyte, which exhibits excellent chemical stability, no obvious gas generation, and high cycle stability and service life.

[0007] The present invention also provides a method for preparing a battery, wherein the battery is prepared by using the above-mentioned electrolyte, and the prepared battery has high cycle stability and service life.

[0008] The present invention also provides an electrical device including the battery as described above, which is capable of maintaining its intended function during long-term operation without performance degradation or failure due to power fluctuations.

[0009] In a first aspect, the present invention provides an electrolyte comprising a singlet oxygen quencher, the singlet oxygen quencher containing an aromatic group, the aromatic group comprising one or more of phenyl, furanyl, and imidazolyl groups.

[0010] The electrolyte as described above, wherein the singlet oxygen quencher further includes at least one of amino, tertiary amino, and hydroxyl groups.

[0011] The electrolyte as described above, wherein the singlet oxygen quencher includes at least one of triphenylamine, furfuryl alcohol, and histidine.

[0012] In the electrolyte as described above, the singlet oxygen quencher has a mass percentage content of 1 to 10% in the electrolyte.

[0013] In the electrolyte as described above, the singlet oxygen quencher has a mass percentage content of 3-10% in the electrolyte.

[0014] The electrolyte as described above further includes a solvent, a film-forming additive, and a lithium salt.

[0015] The electrolyte as described above, wherein the solvent comprises at least one selected from ethylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, dimethoxyethane, trimethyl phosphate, and methyl formate; and / or,

[0016] The film-forming additive includes at least one selected from vinylene carbonate, fluoroethylene carbonate, propylene carbonate, vinyl sulfate, acrylate, and dimethyl vinyl sulfate; and / or,

[0017] The lithium salt includes at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium nitrate, and lithium chloride.

[0018] A second aspect of the present invention provides a battery comprising the electrolyte as described above.

[0019] The battery as described above includes a positive electrode sheet, the positive electrode sheet includes a positive electrode active layer, and the positive electrode active layer includes a lithium supplement.

[0020] In the battery described above, the positive electrode active layer of the battery further includes a positive electrode active material, and the mass ratio of the positive electrode active material to the lithium replenishing agent is (19~1000):1.

[0021] The battery as described above, wherein,

[0022] The areal density of the positive electrode sheet of the battery is 330~340 g / m³. 2 The compaction density of the positive electrode is 2.2~2.6 g / cm³. 3 ;

[0023] And / or, the areal density of the negative electrode sheet of the battery is 160~164 g / m³. 2 The compaction density of the negative electrode sheet is 1.1~1.5 g / cm³. 3 .

[0024] A third aspect of the present invention provides a method for preparing the battery as described above, comprising the following steps:

[0025] After the battery cell is wetted with the first electrolyte, the battery cell is then subjected to formation treatment and aging treatment in sequence to obtain the battery cell precursor;

[0026] The battery is obtained by wetting the cell precursor with a second electrolyte; wherein the second electrolyte includes the electrolyte as described above.

[0027] The battery manufacturing method described above, wherein the process of impregnating the battery cell with a first electrolyte includes impregnating the battery cell with a first electrolyte at a first injection coefficient, wherein the first injection coefficient is 3.0~4.5 g / Ah;

[0028] And / or, the process of wetting the cell precursor with a second electrolyte includes wetting the battery with a second electrolyte at a second injection coefficient of 2.0~3.5 g / Ah.

[0029] In the battery preparation method described above, the battery cell includes a positive electrode sheet, and the positive electrode sheet includes a lithium replenishing agent.

[0030] The battery preparation method described above further includes, after the aging treatment, sequentially subjecting the aged cell precursor to a first lithium replenishing agent decomposition treatment, a second lithium replenishing agent decomposition treatment, and a third lithium replenishing agent decomposition treatment to obtain a battery precursor after lithium replenishing agent decomposition treatment.

[0031] The battery is obtained by wetting the battery precursor after lithium replenishment agent decomposition treatment with the second electrolyte;

[0032] The charging rate of the first lithium replenishment agent decomposition treatment is greater than that of the second lithium replenishment agent decomposition treatment;

[0033] The charging rate of the second lithium replenishing agent decomposition treatment is greater than that of the third lithium replenishing agent decomposition treatment.

[0034] In the battery manufacturing method described above, the first lithium replenishment agent decomposition treatment includes constant current charging of the cell precursor to 3.9-4.2V at a rate of 0.1-0.3C.

[0035] And / or, the second lithium replenishment decomposition treatment includes constant current charging of the cell precursor to 3.9-4.2V at a rate of 0.1-0.2C;

[0036] And / or, the third lithium replenishment decomposition treatment includes constant current charging of the cell precursor to 3.9-4.2V at a rate of 0.01-0.05C;

[0037] And / or, after the first lithium replenishment agent decomposition treatment, the cell precursor is further subjected to a standing period of 2 to 10 minutes;

[0038] And / or, after the second lithium replenishment agent decomposition treatment, the cell precursor is further subjected to a standing period of 2 to 10 minutes.

[0039] A fourth aspect of the present invention provides an electrical device comprising a battery as described above or a battery obtained by a method for preparing a battery as described above.

[0040] The electrolyte provided by this invention, by adding a singlet oxygen quencher comprising one or more aromatic groups including phenyl, furanyl, and imidazole groups, can rapidly capture and neutralize singlet oxygen, thereby inhibiting its destructive effect on battery components. This not only slows down the rate of battery capacity decay but also reduces battery gas generation problems caused by singlet oxygen accumulation, lowers the battery volume expansion rate, and does not lead to a reduction in battery capacity, thus enhancing the stability and safety of the entire battery system. Attached Figure Description

[0041] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0042] Figure 1 This is a schematic diagram of the gas production measurement method provided by the present invention.

[0043] Explanation of reference numerals in the attached figures:

[0044] 201: Balance scale;

[0045] 202: Stent;

[0046] 203: Table;

[0047] 204: Bucket:

[0048] 205: Battery.

[0049] The accompanying drawings have illustrated specific embodiments of the invention, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0051] During the charging and discharging process of lithium-ion batteries, reactive oxygen species, especially singlet oxygen, are often generated. Singlet oxygen leads to gas formation in the battery, causing serious damage to the battery components. Currently, adding singlet oxygen quenchers to the cathode material can alleviate the gas formation problem caused by reactive oxygen species to some extent. However, these singlet oxygen quenchers are usually small molecules that dissolve from the electrode into the electrolyte. Not only is their ability to improve gas formation limited, but they also alter the properties of the electrolyte, leading to a decrease in battery performance.

[0052] Therefore, there is an urgent need for a singlet active oxygen quencher that can not only effectively neutralize the singlet oxygen generated during the operation of lithium-ion batteries, but also does not affect the properties of the electrolyte. This can effectively solve the problem of gas generation in batteries, thereby improving the cycle stability, safety and lifespan of batteries.

[0053] Based on this, embodiments of the present invention provide an electrolyte comprising a singlet oxygen quencher containing aromatic groups, including one or more of phenyl, furanyl, and imidazole groups. The inventors have found that when the singlet oxygen quencher includes these groups, its electron-rich properties effectively promote electron transfer during the electrochemical process of the battery. For example, furanyl groups, due to the presence of their oxygen atoms and the conjugation effect of the aromatic system, can effectively disperse and stabilize the local charge density changes induced by singlet oxygen, thereby inhibiting further oxidative degradation. Imidazole groups, with their unique nitrogen heterocyclic structure and abundant electron cloud distribution, can not only efficiently capture singlet oxygen but also convert it into a harmless form through rapid electron or energy transfer mechanisms, exhibiting excellent antioxidant properties. Imidazole groups can react with singlet oxygen through energy transfer or direct addition reactions to generate relatively stable compounds, thereby reducing the damage of singlet oxygen to the internal components of the battery. Therefore, by using a singlet oxygen quencher containing the above-mentioned groups to prepare the electrolyte, the present invention can effectively suppress the problem of singlet oxygen generation and improve the stability and safety of the battery.

[0054] The singlet oxygen quencher in this invention embodiment further includes at least one of amino, tertiary amino, and hydroxyl groups. Specifically, amino and tertiary amino groups, as strong electron-donating groups, can directly participate in the quenching process of singlet oxygen through the lone pair electrons on the nitrogen atom, forming relatively stable oxidation products while reducing the occurrence of free radical chain reactions; hydroxyl groups, utilizing their strong hydrogen bonding ability and hydrophilicity, promote effective contact with singlet oxygen and achieve effective removal of singlet oxygen by forming peroxides or other low-toxicity intermediates.

[0055] Specifically, when the above-mentioned singlet oxygen quencher contains phenyl groups, the singlet oxygen quencher containing phenyl groups may contain multiple phenyl groups, such as one, two or three phenyl groups. The singlet oxygen quencher containing phenyl groups may also contain tertiary amino groups.

[0056] In some embodiments, a singlet oxygen quencher containing phenyl groups may include triphenylamine compounds (which contain three phenyl groups), such as triphenylamine.

[0057] In some embodiments, when the singlet oxygen quencher contains furanyl groups, the singlet oxygen quencher containing furanyl groups may also contain hydroxyl groups (OH). The singlet oxygen quencher containing furanyl groups may contain multiple furanyl groups, such as one, two, or three furanyl groups, and may specifically include furfuryl alcohol compounds, such as furfuryl alcohol.

[0058] In some embodiments, when the singlet oxygen quencher contains an imidazole group, the singlet oxygen quencher containing an imidazole group may also contain a hydroxyl group or an amino group. The singlet oxygen quencher containing an imidazole group may contain multiple imidazole groups, such as one, two, or three imidazole groups. Specifically, it may include imidazole compounds, such as histidine.

[0059] Furthermore, any one hydrogen atom in phenyl, furanyl, or imidazolyl can be replaced by one or more groups in amino, tertiary amino, or hydroxyl groups.

[0060] In some embodiments, the singlet oxygen quencher includes at least one of triphenylamine, furfuryl alcohol, and histidine.

[0061] Specifically, triphenylamine has the following structure:

[0062] ;

[0063] furfuryl alcohol has the following structure:

[0064] ;

[0065] Histidine has the following structure:

[0066] .

[0067] Based on the inventors' long-term research, triphenylamine, possessing phenyl and tertiary amino groups, is an electron-rich organic compound with excellent electrochemical stability and chemical reversibility. This invention uses triphenylamine as a singlet oxygen quencher, enabling it to react with electrophilic singlet oxygen to form a singlet complex, which is then rapidly converted into a triplet complex via non-radiative intersystem crossing. This effectively accelerates the conversion of singlet oxygen to ground-state triplet oxygen, eliminating its derivative side reactions and promoting triphenylamine regeneration. Furthermore, triphenylamine does not form a film on the cathode surface; therefore, excessive addition will not lead to impedance growth, reducing usage risks.

[0068] In one specific embodiment, the present invention uses furfuryl alcohol as a singlet oxygen quencher. The hydroxyl groups in furfuryl alcohol can react with singlet oxygen to form peroxides or other stable compounds, thus effectively blocking the reaction between singlet oxygen and other battery components. Furthermore, excessive addition of furfuryl alcohol will not form a film on the positive electrode surface and will not affect the normal performance of the battery's positive electrode.

[0069] In some embodiments, the present invention also uses histidine as a singlet oxygen quencher. The imidazole ring (imidazolium group) in the histidine molecule can undergo an addition reaction with singlet oxygen through energy transfer or direct reaction to generate a more stable compound, thereby reducing the damage of singlet oxygen to the internal components of the battery. Histidine will not polymerize to form a film in the battery operating environment, and therefore will not affect the battery performance.

[0070] By using the above-mentioned substance as a singlet oxygen quencher, this invention helps to further reduce the expansion rate of the battery at both room temperature and high temperature, without causing a decrease in battery capacity.

[0071] In the aforementioned electrolyte, the singlet oxygen quencher comprises 1-10% by mass. For example, the mass percentage of the singlet oxygen quencher in the electrolyte may be 1%, 3%, 5%, 7%, 10%, or any combination thereof. By limiting the mass percentage of the singlet oxygen quencher in the electrolyte, this invention helps to further maintain the viscosity and conductivity of the electrolyte, thereby improving the gas generation problem in the battery.

[0072] In some embodiments, when the mass percentage of the singlet oxygen quencher in the electrolyte is 3-8%, the gas generation problem of the battery can be further improved.

[0073] In addition, the electrolyte also includes a solvent, a film-forming additive, and a lithium salt. Specifically, the present invention uses a solvent to dissolve the lithium salt and serve as a medium for conducting lithium ions. By adding the film-forming additive to the electrolyte, a stable solid electrolyte interface film can be formed on the electrode surface. This film prevents direct contact between the electrolyte and the electrode material, which helps reduce side reactions, protects the electrode structure, and extends battery life. The lithium salt is the primary ion source in the electrolyte of the present invention, providing mobile lithium ions that enable the battery to perform charge and discharge processes.

[0074] Specifically, the electrolyte of this invention can be a non-aqueous electrolyte, and the solvent in the electrolyte includes organic solvents. Specifically, the organic solvents may include at least one of ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), dimethoxyethane (DME), trimethyl phosphate (TMP), and methyl formate (MFA). The above solvents have good solubility and possess appropriate viscosity, boiling point, and flash point, which can ensure the stability and safety of the battery at different temperatures.

[0075] In one specific embodiment, the film-forming additive in the electrolyte of the present invention includes at least one selected from vinylene carbonate (VC), fluoroethylene carbonate (FEC), propylene carbonate (PC), acrylate (Ac), and dimethyl vinyl sulfate (DMDS). By using the above-mentioned film-forming additive, the present invention can further regulate lithium-ion transport and improve the cycle stability and safety of the battery.

[0076] In one specific embodiment, the lithium salt in the electrolyte of the present invention includes at least one selected from lithium hexafluorophosphate, lithium tetrafluoroborate, lithium nitrate, and lithium chloride. These lithium salts have good solubility in solvents, providing an effective ion source for the battery and thus improving its conductivity.

[0077] A second aspect of the present invention provides a battery comprising the electrolyte as described above. By using the electrolyte, the singlet oxygen generated during operation of the battery provided by the present invention can be neutralized by the singlet oxygen quencher contained in the electrolyte. Therefore, the battery provided by the present invention has high cycle stability, safety and long battery life.

[0078] In some embodiments, the battery described above may be a lithium-ion battery.

[0079] Generally, a battery includes an electrolyte, a battery cell, and a casing that encapsulates the battery cell. The electrolyte is injected into the battery cell inside the casing. The battery cell includes a positive electrode, a negative electrode, and a separator located between the positive and negative electrode. The battery cell can be a stacked cell, meaning it is composed of alternating layers of positive electrode, separator, and negative electrode; or it can be a wound cell, meaning it is composed of stacked positive electrode, separator, and negative electrode, which are then wound together.

[0080] Specifically, the positive electrode sheet includes a positive current collector and a positive active layer located on at least one side surface of the positive current collector. Specifically, the positive active layer can be provided on one side surface of the positive current collector in the thickness direction, or positive active layers can be provided on both opposite sides of the positive current collector in the thickness direction.

[0081] 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 can be 70% to 99%, for example, 70%, 75%, 80%, 85%, 90%, 93%, 95%, 97%, 99%, or any two of these ranges. The mass fraction of the conductive agent 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 these ranges. 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 these ranges.

[0082] In some embodiments, the positive electrode active material may include LiCoO2, LiNiO2, or 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 M z 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 are 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 of the transition metal elements such as Ti, Fe, Ni, Cu, Mo, etc., 1≤x≤2.5), TiO2, Cr3O8, V2O5, MnO2, etc. The above-mentioned positive electrode active materials have high energy density. Using these materials as positive electrode active materials in this invention is beneficial for improving the energy storage capacity of the battery.

[0083] In this embodiment of the 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 may include one or more of conductive carbon black, conductive graphite, carbon nanotubes (CNTs), carbon fibers, graphene, acetylene black, and Ketjen black. The above-mentioned conductive agents provide the battery of the present invention with good conductivity and mechanical strength, which is beneficial to improving the overall performance of the battery.

[0084] In this embodiment of the invention, the binder in the positive electrode active layer can be a conventional bonding 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, polyvinylpyrrolidone, polyurethane, etc. By using a binder, this invention can achieve a bonding effect between materials such as the positive electrode active material and the conductive agent, ensuring the mechanical stability and ion conduction performance of the electrode material during charge-discharge cycles. For example, the positive electrode active material layer may include the positive electrode active material, the conductive agent, the binder, and the lithium supplement agent. The binder can achieve a bonding effect between the positive electrode active material and the conductive agent, ensuring the mechanical stability and ion conduction performance of the electrode material during charge-discharge cycles.

[0085] The embodiments of the present invention may employ conventional positive current collectors in the art, for example, positive current collectors may include aluminum foil.

[0086] In this embodiment of the invention, the positive electrode sheet can be prepared by conventional methods in the art, such as by coating. Specifically, the positive electrode active material, conductive agent, binder, and other components used to form the positive electrode active layer can be dispersed in a solvent, such as N-methylpyrrolidone (NMP), to prepare a positive electrode slurry. This slurry is then coated onto the surface of the positive electrode current collector, and after drying, rolling, and other processes, the positive electrode sheet is obtained. The coating, drying, and rolling processes involved are conventional operations for preparing positive electrode sheets using the coating method, and are not particularly limited thereto.

[0087] In this embodiment of the invention, the electrolyte of the battery includes the electrolyte as described above, and the electrolyte includes a singlet oxygen quencher.

[0088] In this embodiment of the invention, the separator is used to separate the positive electrode and the negative electrode to prevent the positive electrode and the negative electrode from short-circuiting due to contact. Conventional separators in the art can be used in this embodiment of the invention, and there are no special limitations on this.

[0089] In this embodiment of the invention, the battery cell can be packaged using conventional housing materials in the art, such as flexible packaging materials like aluminum-plastic film, but is not limited thereto.

[0090] The embodiments of the present invention can assemble components such as positive electrode, separator and negative electrode into a battery using conventional methods in the art. For example, positive electrode, separator and negative electrode can be stacked in an alternating manner to obtain a stacked cell (or wound into a wound cell); then the cell is placed in a casing (outer packaging) and after conventional processes such as electrolyte injection (i.e., injection of electrolyte) and encapsulation, the battery is obtained.

[0091] In this embodiment of the invention, the battery includes a positive electrode sheet, which includes a positive active layer and a lithium replenishing agent. Specifically, the positive electrode sheet may further include a lithium replenishing agent, specifically, the positive active layer of the positive electrode sheet may include a lithium replenishing agent. When the positive active layer of the battery includes a lithium replenishing agent, the battery is a lithium-replenishing battery. This invention does not specifically limit the type of lithium replenishing agent, as long as it can provide a source of lithium ions during battery operation. For example, the lithium replenishing agent can be at least one of Li5FeO4, Li2O, Li2O2, and Li2CO3. This invention, by adding a lithium replenishing agent to the lithium-replenishing battery, helps to improve the initial coulombic efficiency and long-term cycle stability of the battery. In the above-mentioned lithium-replenishing battery, the lithium replenishing agent releases active oxygen during decomposition. Active oxygen easily reacts with electrolyte components, causing increased gas production. This invention, by adding the above-mentioned singlet oxygen quencher to the electrolyte of the above-mentioned lithium-replenishing battery, helps to block the reaction between singlet oxygen and electrolyte components, thereby achieving the effect of suppressing gas production in the lithium-replenishing battery.

[0092] In some embodiments, the mass ratio of positive electrode active material to lithium replenisher in the positive electrode of the battery is (19~1000):1. For example, the mass ratio of positive electrode active material to lithium replenisher in the positive electrode of the battery is, for example, 19:1, 50:1, 100:1, 500:1, 1000:1 or any combination thereof. The mass ratio of positive electrode active material to lithium replenisher in the positive electrode of the battery is beneficial to obtaining a battery with better cycle stability and higher energy density.

[0093] In this embodiment of the invention, a negative electrode active layer can be provided on one side of the negative electrode current collector in the thickness direction, or a negative electrode active layer can be provided on both opposite sides of the negative electrode current collector in the thickness direction.

[0094] In this embodiment of the invention, the adhesive in the negative electrode active layer and the adhesive in the bonding layer can be any adhesive suitable for negative electrodes known in the art. For example, the adhesive in the negative electrode active layer and the adhesive in the bonding layer can each independently include at least one of polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), sodium carboxymethyl cellulose (CMC), tetrafluoroethylene and its copolymers, polyvinylidene fluoride and its copolymers, polyolefins and their copolymers (e.g., polyethylene-polyethylene glycol block copolymers), polyethers and their copolymers (e.g., polyethylene oxide), polyphenylene ethers and their copolymers, polysiloxanes and their copolymers (e.g., polydimethylsiloxane, poly(dimethylsiloxane-co-alkylmethylsiloxane)), polyesters and their copolymers (e.g., polyethylene ester, polyvinyl acetate, polyacrylate), carboxymethyl cellulose, styrene-butadiene latex, nitrile rubber, and polyacrylic acid (PAA). Specifically, polyolefins include one or more of polyethylene, polypropylene, ethylene / propylene copolymer, ethylene / vinylidene fluoride copolymer, and propylene / vinylidene fluoride copolymer; polytetrafluoroethylene and its copolymers may be at least one of tetrafluoroethylene / ethylene copolymer, tetrafluoroethylene / propylene copolymer, tetrafluoroethylene / vinylidene fluoride copolymer, tetrafluoroethylene / ether copolymer, tetrafluoroethylene / branched polyether copolymer, tetrafluoroethylene / vinyl ether copolymer, tetrafluoroethylene / branched polyether / vinyl ether copolymer, and tetrafluoroethylene / siloxane copolymer.

[0095] In this embodiment of the invention, the conductive agent in the negative electrode active layer and the conductive agent in the adhesive layer can be conventional conductive materials in the art. For example, the conductive agent in the negative electrode active layer and the conductive agent in the adhesive layer can each independently include one or more of conductive carbon black, conductive graphite, carbon nanotubes (CNTs), carbon fibers, graphene, acetylene black, and Ketjen black.

[0096] The embodiments of the present invention may employ conventional negative electrode current collectors in the art, for example, negative electrode current collectors include copper foil.

[0097] For example, in a specific implementation, a negative electrode current collector with a base coating (such as copper foil) can be used, that is, the surface of the negative electrode current collector has a base coating. Then, the negative electrode film used to form the negative electrode active layer is pressed onto the negative electrode current collector. That is, the negative electrode film is bonded to the negative electrode current collector through the base coating to obtain the negative electrode sheet (the base coating forms the bonding layer of the negative electrode sheet).

[0098] In embodiments of the present invention, the negative electrode sheet can be prepared by a dry process (i.e., rolling the material used to form the negative electrode active layer into a film and then combining it with the negative electrode current collector to obtain the negative electrode sheet), or by a wet process (coating method) (i.e., coating the negative electrode slurry used to form the negative electrode active layer onto the surface of the negative electrode current collector, and then drying, rolling and other processes to form the negative electrode active layer on the surface of the negative electrode sheet to obtain the negative electrode sheet).

[0099] In the embodiments of the present invention, unless otherwise specified, the coating, drying, rolling and other processes involved are all conventional operations in the art, and the equipment used can be conventional equipment in the art, and there are no special restrictions on them.

[0100] Besides supplementing lithium batteries, the present invention can also apply the above-mentioned electrolyte to lithium batteries with a ternary system. This ternary system refers to lithium batteries where the positive electrode active material includes three elements, such as a nickel-cobalt-manganese system or a nickel-cobalt-aluminum system. During the charging and discharging process of the above-mentioned ternary system lithium battery, the excess metal elements may undergo excessive oxidation to generate singlet oxygen. Therefore, by using the above-mentioned electrolyte, the singlet oxygen generated in the battery can be effectively neutralized, solving the problem of excessive volume expansion caused by gas production in the battery.

[0101] The present invention does not impose any special limitation on the composition of the ternary lithium battery described above. For example, the positive electrode of the ternary lithium battery includes a positive electrode active layer, which includes ternary materials such as nickel cobalt manganese oxide or nickel cobalt aluminum oxide. The positive electrode also includes a conductive agent and a binder. The specific selection of the conductive agent and the binder is as described above and will not be repeated here.

[0102] The negative electrode of a ternary lithium-ion battery includes a negative electrode active layer, which comprises at least one of graphite, silicon, tin, and lithium titanate. Generally, the mass percentage of the negative electrode active material in the negative electrode active layer can be 80% to 100%, for example (but not limited to) 80%, 82%, 85%, 88%, 90%, 92%, 95%, 98%, 100%, or any combination thereof. The negative electrode of the aforementioned ternary lithium-ion battery also includes a conductive agent and a binder, the specific selection of which is as described above.

[0103] In one specific embodiment, the negative electrode of the battery contains a negative electrode active material, a conductive agent, and a binder, wherein the negative electrode active material, the conductive agent, and the binder are in a mass ratio of 100:1:1.3:1.6.

[0104] It should be clarified that the present invention is not limited to the use of the above electrolyte in lithium-ion batteries and ternary batteries. Any battery system that generates singlet oxygen can use the electrolyte provided by the present invention for battery assembly.

[0105] In the battery of this embodiment, the areal density of the positive electrode sheet is 330~340 g / m³. 2 The compaction density of the positive electrode is 2.2~2.6 g / cm³. 3 .

[0106] In one specific embodiment, the areal density of the negative electrode sheet of the battery is 160~168 g / m². 2The compaction density of the negative electrode sheet is 1.1~1.5 g / cm³. 3 .

[0107] This invention, by rationally controlling the areal density and compaction density of the electrode sheets, allows for the packing of more active materials within a limited space, thereby increasing the volumetric energy density of the battery. Specifically, the areal density and compaction density mentioned above are tested using the following method: Take a negative electrode sample (specifically, a sheet cutter can be used to cut the negative electrode sample to obtain a sample of suitable size), test the total mass m1 of the negative electrode sample, the total thickness T1 of the negative electrode sample (T1 = total thickness of the negative electrode active layer + thickness of the negative electrode current collector; when both the positive and negative surfaces of the negative electrode current collector are provided with negative electrode active layers, the total thickness of the negative electrode active layer = thickness of the negative electrode active layer on one side of the negative electrode current collector + thickness of the negative electrode active layer on the other side of the negative electrode current collector), and the surface area S of one side of the negative electrode sample in the thickness direction; then scrape off the negative electrode active layer on the negative electrode sample, and test the mass m2 of the obtained negative electrode current collector and the thickness T2 of the negative electrode current collector. Then, the total thickness of the negative electrode active layer = T1 - T2, the areal density of the negative electrode active layer = (m1 - m2) / S, and the compaction density of the negative electrode active layer = areal density of the negative electrode active layer / total thickness of the negative electrode active layer = (m1 - m2) / S. m2) / (S×(T1-T2)).

[0108] A third aspect of the present invention provides a method for preparing the above-mentioned battery, comprising the following steps:

[0109] After the battery cell is wetted with the first electrolyte, it is then subjected to formation treatment and aging treatment in sequence to obtain the battery cell precursor.

[0110] A battery is obtained by impregnating the cell precursor with a second electrolyte; wherein the second electrolyte includes the electrolyte described above.

[0111] The battery preparation method of this invention also includes the preparation of positive and negative electrode sheets. This invention does not impose special limitations on the preparation of positive and negative electrode sheets; selection can be made according to actual needs. For example, the battery of this invention can be a lithium-ion battery. The preparation of the positive electrode sheet for a lithium-ion battery involves mixing positive electrode active layer material, conductive agent, binder, and lithium supplement agent to form a positive electrode slurry, coating the positive electrode slurry onto the surface of aluminum foil, and then sequentially drying, pressing, and cutting to obtain the positive electrode sheet. Similarly, the preparation of the negative electrode active material, conductive agent, and binder involves mixing negative electrode active material, conductive agent, and binder to form a negative electrode slurry, coating the negative electrode slurry onto the surface of copper foil, and then sequentially drying, pressing, and cutting to obtain the negative electrode sheet.

[0112] It should be clarified that the above-mentioned battery preparation method can also be applied to ternary lithium batteries. Specifically, the preparation of the positive electrode sheet of a ternary lithium battery involves mixing the positive electrode active layer material, conductive agent, and binder to make a positive electrode slurry, coating the positive electrode slurry onto the surface of an aluminum foil, and then drying, pressing, and cutting it to obtain the positive electrode sheet. Similarly, the preparation of the negative electrode active material, conductive agent, and binder involves mixing the negative electrode active material, conductive agent, and binder to make a negative electrode slurry, coating the negative electrode slurry onto the surface of a copper foil, and then drying, pressing, and cutting it to obtain the negative electrode sheet.

[0113] In practice, the positive electrode, separator, and negative electrode can be assembled into a cell using conventional methods in the art. For example, the positive electrode, separator, and negative electrode can be stacked to obtain a stacked cell. The cell is then placed in a housing, with the electrolyte inlet remaining. The first electrolyte is injected into the cell through the electrolyte inlet (i.e., the first electrolyte injection treatment), and then the electrolyte inlet is sealed to obtain the battery precursor. The battery precursor is then subjected to formation treatment, aging treatment, lithium replenishment decomposition treatment, and second electrolyte injection treatment in sequence. After subsequent capacity testing and other processes, the battery is obtained.

[0114] In the embodiments of the present invention, the processes involved, such as liquid injection, sealing, formation, aging treatment, and capacity testing, are all conventional battery assembly processes in the field, and are not particularly limited thereto.

[0115] The formation process creates a stable solid electrolyte interphase (SEI) film during the first charge. The SEI film can protect the negative electrode material, reduce the occurrence of side reactions, and regulate the transport of lithium ions.

[0116] In some embodiments, the formation treatment temperature can be 20°C to 50°C, for example, a range of 20°C, 23°C, 25°C, 28°C, 30°C, or any combination thereof. In specific implementations, formation can be carried out at room temperature.

[0117] In some embodiments, the formation process may include: charging the battery precursor at a constant current rate of 0.05C for 3 hours at the formation temperature (e.g., room temperature), resting for 10 minutes, and then charging it at a constant current and constant voltage rate of 0.2C, with a cutoff voltage of 4V and a cutoff current of 0.01C (at this time, the battery precursor is fully charged).

[0118] Aging treatment refers to keeping the battery static for a period of time after formation, allowing the electrolyte to fully wet the cell and stabilizing the chemical reaction between the electrode materials and the electrolyte. This helps eliminate stress in the electrode materials and further stabilizes the SEI film and other interfacial properties.

[0119] In some embodiments, the aging temperature can be 40°C to 50°C, for example, a range of 40°C, 43°C, 45°C, 48°C, 50°C or any combination thereof.

[0120] In some embodiments, the aging time can be 20h to 30h, for example, a range of 20h, 23h, 25h, 28h, 30h or any combination thereof.

[0121] In some embodiments, the battery precursor further includes an aging treatment between the aging treatment and the lithium replenishment decomposition treatment. The aging treatment temperature can be 40°C to 50°C, for example, a range of 40°C, 43°C, 45°C, 48°C, 50°C or any combination thereof.

[0122] In some embodiments, the aging treatment time can be 20h to 30h, for example, a range of 20h, 23h, 25h, 28h, 30h or any combination thereof.

[0123] It should be clarified that, in the embodiments of the present invention, the first electrolyte does not include the above-mentioned singlet oxygen quencher, and the second electrolyte includes the above-mentioned singlet oxygen quencher.

[0124] The purpose of this invention in using an electrolyte that does not contain a singlet oxygen quencher for the first electrolyte injection treatment is primarily to introduce the electrolyte into the battery cell, ensuring sufficient wetting between the electrode materials and the separator, allowing lithium ions to move freely during charging and discharging. To avoid interference from the singlet oxygen quencher on subsequent battery aging and formation processes, this invention does not add a singlet oxygen quencher during the first electrolyte injection treatment.

[0125] Furthermore, during the formation process, some electrolyte may be consumed to form the SEI film or other side reactions. Therefore, a second electrolyte injection process is needed to replenish these losses and ensure sufficient electrolyte within the cell. After the formation, aging, and lithium replenishment decomposition processes are completed, the internal environment of the cell is relatively stable. At this point, adding a singlet oxygen quencher can effectively capture and neutralize any remaining singlet oxygen, preventing it from adversely affecting the battery.

[0126] The step-by-step liquid injection process described in this invention not only helps to form a high-quality SEI film, stabilize the electrode structure and restore capacity, but also effectively inhibits the generation of reactive oxygen species, thereby improving the overall performance and reliability of the battery.

[0127] In detail, in this embodiment of the invention, the process of wetting the battery cell with the first electrolyte includes wetting the battery cell with the first electrolyte at a first injection coefficient of 3.0~4.5g / Ah;

[0128] In some embodiments, the process of wetting the cell precursor with a second electrolyte includes wetting the battery with a second electrolyte at a second injection coefficient of 2.0 to 3.5 g / Ah.

[0129] Specifically, the electrolyte injection coefficient is defined as the ratio of the actual amount of electrolyte injected (g) to the battery capacity (Ah). By controlling the electrolyte injection coefficients of the first and second electrolyte injection treatments, this invention not only ensures that there is sufficient electrolyte inside the battery to support efficient ion conduction, but also avoids the safety hazards and energy density loss caused by excessive electrolyte.

[0130] In the battery embodiments of this invention, the cell includes a positive electrode sheet, which includes a lithium replenishing agent. The lithium replenishing agent can be directly mixed in powder form with the positive electrode active material (such as LiCoO2, LiFePO4, etc.), conductive additives (such as carbon black, graphene, etc.), and binder. Using a positive electrode sheet with added lithium replenishing agent to prepare a battery can result in a battery with higher energy density.

[0131] In some embodiments, the present invention replenishes lithium lost from the electrode material during battery charging and discharging by decomposing the lithium replenishing agent, thereby improving the initial coulombic efficiency and capacity of the battery. Through the decomposition of the lithium replenishing agent, lithium in compound form in the agent is converted into lithium ions and released into the battery system, achieving the effect of lithium replenishment.

[0132] Specifically, in this embodiment of the invention, after aging, the process further includes sequentially subjecting the aged cell precursor to a first lithium replenishing agent decomposition treatment, a second lithium replenishing agent decomposition treatment, and a third lithium replenishing agent decomposition treatment to obtain a lithium replenishing agent decomposition-treated battery precursor; and using a second electrolyte to wet the lithium replenishing agent decomposition-treated battery precursor to obtain a battery.

[0133] In this embodiment, the charging rate of the first lithium replenisher decomposition treatment is greater than that of the second lithium replenisher decomposition treatment; the charging rate of the second lithium replenisher decomposition treatment is greater than that of the third lithium replenisher decomposition treatment. By limiting the charging rate of the above decomposition treatments, this embodiment of the invention facilitates the full release of lithium ions from the lithium replenisher into the battery system.

[0134] In some embodiments, the first lithium replenishment decomposition process includes constant current charging of the cell precursor to 3.9-4.2V at a rate of 0.1-0.3C; during the constant current charging of the cell precursor to 3.9-4.2V at a rate of 0.1-0.3C, the current can be 0.25-125A.

[0135] In some embodiments, the second lithium replenishment decomposition process includes constant current charging of the cell precursor to 3.9-4.2V at a rate of 0.1-0.2C; during the constant current charging of the cell precursor to 3.9-4.2V at a rate of 0.1-0.2C, the current can be 0.13-65A.

[0136] In some embodiments, the third lithium replenishing agent decomposition treatment includes constant current charging of the cell precursor at a rate of 0.01~0.05C to 3.9~4.2V to obtain the battery precursor after lithium replenishing agent decomposition treatment; during the constant current charging of the cell precursor at a rate of 0.01~0.05C to 3.9~4.2V, the current can be 0.028~14A.

[0137] Furthermore, in this embodiment of the invention, after the first lithium replenishing agent decomposition treatment, the cell precursor is allowed to stand for 2-10 minutes. That is, after the first lithium replenishing agent decomposition treatment, the cell precursor is allowed to stand for 2-10 minutes before the second lithium replenishing agent decomposition treatment is performed.

[0138] In some embodiments, the second lithium replenishing agent decomposition treatment further includes allowing the cell precursor to stand for 2-10 minutes. That is, after performing the second lithium replenishing agent decomposition treatment, the cell precursor is allowed to stand for 2-10 minutes before the third lithium replenishing agent decomposition treatment is performed.

[0139] During the aforementioned resting process, the battery undergoes self-discharge, resulting in a decrease in voltage within the battery. This embodiment of the invention, through the aforementioned three-stage lithium replenishment decomposition treatment, enables the lithium replenishment agent within the battery to be fully activated, thereby releasing lithium ions more completely into the battery system.

[0140] This invention, by performing a lithium replenishment agent decomposition treatment on the cell precursor after the above-mentioned aging treatment, can facilitate the full release of lithium ions in the lithium replenishment agent into the battery system, thereby further improving the energy density of the battery.

[0141] In the above-mentioned battery manufacturing process, after stacking the positive and negative electrode sheets, the process also includes welding tabs to the ends of the electrode sheets and encapsulating the battery with a suitable shell. For example, when manufacturing a soft-pack battery, an aluminum-plastic composite film can be used to encapsulate the battery. After the first and second liquid injection treatments, the process also includes final encapsulation of the battery to ensure its sealing and safety.

[0142] A fourth aspect of this invention provides an electronic device comprising the battery described above or a battery prepared by the method described above. This invention does not particularly limit the type of electronic device, but includes, for example, power equipment (such as electric vehicles, electric cars), electronic devices (such as mobile phones, tablets, laptops, digital cameras, etc.), wearable devices (such as watches, bracelets, VR glasses, etc.), energy storage power stations, etc. By using the battery described above in the electronic device, a continuous and stable output of electrical energy can be provided to supply the electronic device, resulting in a longer service life. Simultaneously, it reduces the maintenance of the battery in the electronic device, thus saving costs.

[0143] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0144] Example 1

[0145] The battery preparation in this embodiment includes the following steps:

[0146] 1) Prepare an electrolyte containing a singlet oxygen quencher (i.e., the second electrolyte) by mixing the solvent with film-forming additives, singlet oxygen quenchers and lithium salts, and prepare an electrolyte excluding singlet oxygen quenchers (i.e., the first electrolyte) by mixing the solvent with film-forming additives and lithium salts.

[0147] The solvents include ethylene carbonate, ethyl methyl carbonate, diethyl carbonate, and dimethyl carbonate.

[0148] The film-forming additive is vinylene carbonate;

[0149] The singlet oxygen quencher is triphenylamine;

[0150] The lithium salt is LiPF6;

[0151] In the second electrolyte mentioned above, ethylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, vinylene carbonate, triphenylamine, and LiPF6 are in a mass ratio of 28:30:11:11:3:5:12.

[0152] In the first electrolyte, ethylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, vinylene carbonate, and LiPF6 are present in a mass ratio of 29:32:12:12:3:12.

[0153] 2) The positive electrode is made using positive electrode active materials, lithium supplementing agents, conductive agents, and binders;

[0154] The positive electrode active material is LiFePO4;

[0155] The lithium supplement is Li5FeO4;

[0156] The conductive agent is carbon black;

[0157] The adhesive is polyvinylidene fluoride;

[0158] The mass ratio of LiFePO4, Li5FeO4, carbon black, and polyvinylidene fluoride is 95:5:1:2.3.

[0159] 3) The negative electrode is made using negative electrode active materials, conductive agents, and binders;

[0160] The negative electrode active material is graphite;

[0161] The conductive agent is carbon black.

[0162] The binders are sodium carboxymethyl cellulose and styrene-butadiene rubber;

[0163] The mass ratio of graphite, conductive agent, sodium carboxymethyl cellulose, and styrene-butadiene rubber is 100:1:1.3:1.6.

[0164] 4) Assemble the above positive and negative electrodes into a pouch cell, and perform a first electrolyte injection treatment using an electrolyte that does not contain singlet oxygen quencher to obtain the battery precursor;

[0165] The first injection coefficient for the first injection treatment is 4 g / Ah.

[0166] 5) After the battery precursor undergoes formation treatment, aging treatment, and lithium replenishment agent decomposition treatment (including first lithium replenishment agent decomposition treatment, second lithium replenishment agent decomposition treatment, and third lithium replenishment agent decomposition treatment), a second electrolyte injection treatment is performed using an electrolyte containing a singlet oxygen quencher.

[0167] The formation process involves charging the battery at 0.05C for 6 hours to complete the formation process.

[0168] The aging process involves standing at 45℃ for 24 hours.

[0169] The first lithium replenishing agent decomposition treatment involves charging at a constant current rate of 0.25C to 4V and then letting it stand for five minutes; the second lithium replenishing agent decomposition treatment involves charging at a constant current rate of 0.13C to 4V and then letting it stand for five minutes; the third lithium replenishing agent decomposition treatment involves charging at a constant current rate of 0.028C to 4V to decompose the lithium replenishing agent and obtain the battery precursor after lithium replenishing agent decomposition treatment.

[0170] The second injection coefficient for the second injection treatment is 2.5 g / Ah.

[0171] In the battery prepared in this embodiment, the areal density of the positive electrode sheet is 330 g / m². 2 The electrode compaction density is 2.3 g / cm³. 3 ;

[0172] The areal density of the negative electrode sheet of the battery is 160 g / m³. 2 The electrode compaction density is 1.2 g / cm³. 3 .

[0173] The process parameters in this embodiment are shown in Table 1.

[0174] Example 2

[0175] This embodiment is basically the same as Embodiment 1, except that the singlet oxygen quencher in step 1) of this embodiment is furfuryl alcohol. The remaining parameters are shown in Table 1.

[0176] Example 3

[0177] This embodiment is basically the same as Embodiment 1, except that the singlet oxygen quencher in step 1) of this embodiment is histidine. The remaining parameters are shown in Table 1.

[0178] Example 4

[0179] This embodiment is basically the same as Embodiment 1, except that in step 1) of this embodiment, the electrolyte containing the singlet oxygen quencher has a mass ratio of ethylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, vinylene carbonate, triphenylamine, and LiPF6 of 28:30:12:12:3:3:12. Other parameters are shown in Table 1.

[0180] Example 5

[0181] This embodiment is basically the same as Embodiment 1, except that in step 1) of this embodiment, the electrolyte containing the singlet oxygen quencher has a mass ratio of ethylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, vinylene carbonate, triphenylamine, and LiPF6 of 27:30:11:11:3:7:11. Other parameters are shown in Table 1.

[0182] Example 6

[0183] This embodiment is basically the same as Embodiment 1, except that in step 1) of this embodiment, the electrolyte containing the singlet oxygen quencher contains ethylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, vinylene carbonate, triphenylamine, and LiPF6 in a mass ratio of 28:32:12:12:3:1:12. Other parameters are shown in Table 1.

[0184] Example 7

[0185] This embodiment is basically the same as Embodiment 1, except that in step 1) of this embodiment, the electrolyte containing the singlet oxygen quencher has a mass ratio of ethylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, vinylene carbonate, triphenylamine, and LiPF6 of 28:31:12:12:3:2:12. Other parameters are shown in Table 1.

[0186] Example 8

[0187] This embodiment is basically the same as Embodiment 1, except that in step 1) of this embodiment, the electrolyte containing the singlet oxygen quencher has a mass ratio of ethylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, vinylene carbonate, triphenylamine, and LiPF6 of 26:28:11:11:3:10:11. Other parameters are shown in Table 1.

[0188] Example 9

[0189] This embodiment is basically the same as Embodiment 1, except that in step 1) of this embodiment, the electrolyte containing the singlet oxygen quencher has a mass ratio of ethylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, vinylene carbonate, triphenylamine, and LiPF6 of 24:25:9:9:3:20:10. Other parameters are shown in Table 1.

[0190] Example 10

[0191] This embodiment is basically the same as Embodiment 1, except that in step 2) of this embodiment, the mass ratio of LiFePO4, Li5FeO4, conductive carbon black, and PVDF is 97:3:1:2.3. The remaining parameters are shown in Table 1.

[0192] Comparative Example 1

[0193] This comparative example is basically the same as Example 1, except that the electrolyte in this comparative example does not contain a singlet oxygen quencher. That is, both the first and second injection treatments use an electrolyte that does not contain a singlet oxygen quencher for injection treatment.

[0194] Test case

[0195] The volume change rate of the batteries prepared in the above embodiments and comparative examples was calculated after charge-discharge cycles at 25 / 45 / 60°C. Specifically, the batteries were placed in ovens at 25°C, 45°C, and 60°C, respectively. The charge-discharge regime was 0.5C constant current constant voltage charging to 3.65V, constant current discharging to 2V, and 300 cycles were performed. The battery volume was recorded before and after the cycles using the water displacement method, and the volume change rate was calculated. The volume change rate was used... Figure 1 The device shown was tested, and the results are shown in Table 2.

[0196] The formula for calculating the rate of volume change is:

[0197] Volume change rate = (Battery volume after cycle / Battery volume before cycle) * 100%.

[0198] The volume change rate of the batteries prepared in the above embodiments and comparative examples was calculated after storage at 25 / 45 / 60℃ for 1 month. Specifically, the batteries were placed in ovens at 25℃, 45℃, and 60℃ and stored fully charged for 1 month. The battery volume was tested before and after storage and the volume change rate was calculated.

[0199] Volume change rate is used Figure 1The apparatus shown is used for testing. The apparatus includes a support 202 with two long sides and two short sides. One long side rests on the surface of the pan of a balance 201 and is parallel to the largest surface of the pan. The balance 201 is placed above a table 203. A battery 205 is suspended by a thin thread from one of the long sides of the support 202 and placed in a bucket 204 containing 6L of water. The balance is used to calculate the weight difference of the battery 205 before and after charging, and then to calculate the buoyant force F exerted on the battery in the bucket 204, F = (m 充电前 -m 充电后 g;

[0200] The volume V of the battery is calculated using V=F / ρg;

[0201] The formula for calculating the rate of volume change is:

[0202] Volume change rate = (V 充电后 -V 充电前 ) / V 充电前 .

[0203] The results are shown in Table 2.

[0204] The batteries prepared in the above embodiments and comparative examples were subjected to a specific capacity test at 25°C and 0.5C. The specific test method was as follows: the batteries, after capacity gradation, were charged at 0.5C constant current and constant voltage to 3.65V, and then discharged at 0.5C constant current to 2V, for three cycles. The specific capacity was obtained by dividing the discharge capacity of the third cycle by the mass of lithium iron phosphate. The ratio of this value to the specific discharge capacity of lithium iron phosphate (142mAh / g) represents its specific capacity utilization.

[0205] The results are shown in Table 2.

[0206]

[0207]

[0208] As shown in the table, after charge-discharge cycles at 25°C, 45°C, and 60°C, and subsequent storage, the batteries prepared in Examples 1-10 exhibit a smaller volume change rate compared to the battery prepared in Comparative Example 1. The electrolyte provided by this invention effectively solves the problem of gas generation inside the battery, allowing the battery to maintain a relatively constant volume during operation, which is beneficial for improving battery life and efficiency. Furthermore, compared to Example 9, Examples 1-8 further improve the gas generation problem inside the battery by controlling the mass percentage of the singlet oxygen quencher in the electrolyte to 1-10%, thus giving the singlet oxygen quencher a good gas-suppressing effect.

[0209] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions 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, The electrolyte includes a singlet oxygen quencher, which contains an aromatic group, including one or more of phenyl, furanyl, and imidazolyl groups.

2. The electrolyte according to claim 1, characterized in that, The singlet oxygen quencher also includes at least one of amino, tertiary amino, and hydroxyl groups.

3. The electrolyte according to claim 1, characterized in that, The singlet oxygen quencher includes at least one of triphenylamine, furfuryl alcohol, and histidine.

4. The electrolyte according to claim 1 or 2, characterized in that, The singlet oxygen quencher has a mass percentage content of 1-10% in the electrolyte.

5. The electrolyte according to claim 1 or 2, characterized in that, The singlet oxygen quencher has a mass percentage of 3-10% in the electrolyte.

6. The electrolyte according to claim 1 or 2, characterized in that, The electrolyte also includes solvents, film-forming additives, and lithium salts.

7. The electrolyte according to claim 6, characterized in that, The solvent includes at least one selected from ethylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, dimethoxyethane, trimethyl phosphate, and methyl formate; and / or, The film-forming additive includes at least one selected from vinylene carbonate, fluoroethylene carbonate, propylene carbonate, vinyl sulfate, acrylate, and dimethyl vinyl sulfate; and / or, The lithium salt includes at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium nitrate, and lithium chloride.

8. A battery, characterized in that, Includes the electrolyte according to any one of claims 1-7.

9. The battery according to claim 8, characterized in that, The battery includes a positive electrode sheet, the positive electrode sheet includes a positive electrode active layer, and the positive electrode active layer includes a lithium replenishing agent.

10. The battery according to claim 9, characterized in that, The positive electrode active layer of the battery also includes a positive electrode active material, and the mass ratio of the positive electrode active material to the lithium replenishing agent is (19~1000):

1.

11. The battery according to claim 8, characterized in that, The areal density of the positive electrode sheet of the battery is 330~340 g / m³. 2 The compaction density of the positive electrode is 2.2~2.6 g / cm³. 3 ; And / or, the areal density of the negative electrode sheet of the battery is 160~164 g / m³. 2 The compaction density of the negative electrode sheet is 1.1~1.5 g / cm³. 3 .

12. A method for preparing a battery as described in any one of claims 8-11, characterized in that, Includes the following steps: After the battery cell is wetted with the first electrolyte, the battery cell is then subjected to formation treatment and aging treatment in sequence to obtain the battery cell precursor; The battery is obtained by wetting the cell precursor with a second electrolyte; wherein the second electrolyte comprises the electrolyte according to any one of claims 1-6.

13. The method for preparing a battery according to claim 12, characterized in that, The process of wetting the battery cell with the first electrolyte includes wetting the battery cell with the first electrolyte at a first injection coefficient of 3.0~4.5g / Ah. And / or, the process of wetting the cell precursor with a second electrolyte includes wetting the battery with a second electrolyte at a second injection coefficient of 2.0~3.5 g / Ah.

14. The method for preparing a battery according to claim 12 or 13, characterized in that, The battery cell includes a positive electrode, and the positive electrode includes a lithium replenishing agent.

15. The method for preparing a battery according to claim 14, characterized in that, The aging process further includes sequentially subjecting the aged cell precursor to a first lithium replenishing agent decomposition treatment, a second lithium replenishing agent decomposition treatment, and a third lithium replenishing agent decomposition treatment to obtain a lithium replenishing agent decomposition treated battery precursor. The battery is obtained by wetting the battery precursor after lithium replenishment agent decomposition treatment with the second electrolyte; The charging rate of the first lithium replenishment agent decomposition treatment is greater than that of the second lithium replenishment agent decomposition treatment; The charging rate of the second lithium replenishing agent decomposition treatment is greater than that of the third lithium replenishing agent decomposition treatment.

16. The method for preparing a battery according to claim 15, characterized in that, The first lithium replenishment agent decomposition treatment includes constant current charging of the cell precursor to 3.9-4.2V at a rate of 0.1-0.3C; And / or, the second lithium replenishment decomposition treatment includes constant current charging of the cell precursor to 3.9-4.2V at a rate of 0.1-0.2C; And / or, the third lithium replenishment decomposition treatment includes constant current charging of the cell precursor to 3.9-4.2V at a rate of 0.01-0.05C; And / or, after the first lithium replenishment agent decomposition treatment, the cell precursor is further subjected to a standing period of 2 to 10 minutes; And / or, after the second lithium replenishment agent decomposition treatment, the cell precursor is further subjected to a standing period of 2 to 10 minutes.

17. An electrical appliance, characterized in that, The battery includes the battery according to any one of claims 8-11 or the battery according to any one of claims 12-16.

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