CN-116505078-B - Lithium battery electrolyte and preparation method thereof

Abstract

The invention relates to the technical field of lithium ion batteries and discloses a lithium battery electrolyte and a preparation method thereof, wherein the lithium battery electrolyte comprises, by weight, 10-20 parts of lithium salt, 3-10 parts of flame retardant, 2-8 parts of additives and 60-90 parts of organic solvents, the flame retardant is a silane modified flame retardant carrier, and the flame retardant carrier takes inorganic flame retardant as a core and PAN as a shell. According to the invention, the inorganic flame retardant is coated by PAN, and the inorganic flame retardant is isolated from the electrolyte by the coating effect, so that side reactions caused by directly adding the flame retardant are avoided.

Inventors

• HUANG FENGXIANG
• YUAN BO
• YANG JUN
• SHI FEI

Assignees

• 四川鸿鹏新材料有限公司

Dates

Publication Date

20260508

Application Date

20230609

Claims (5)

1. 1. The lithium battery electrolyte is characterized by comprising, by weight, 10-20 parts of lithium salt, 3-10 parts of flame retardant, 2-8 parts of additive and 60-90 parts of organic solvent; the flame retardant is a silane modified flame retardant carrier; The preparation method of the silane modified flame-retardant carrier comprises the steps of reacting APTES or APS with the flame-retardant carrier, wherein the mass ratio of the APTES or APS to the flame-retardant carrier is 1:3-10, the reaction temperature is 85-100 ℃, and the reaction time is 10-30 hours; the flame-retardant load carrier takes inorganic flame retardant as a core and PAN as a shell; the preparation method of the flame-retardant load carrier comprises the following steps of, The inorganic flame retardant is modified by a vinyl silane coupling agent to obtain a first modified body; Polymerizing the first modified body, acrylonitrile and an initiator to obtain a flame-retardant load carrier, specifically, ultrasonically dispersing the first modified body to obtain a pretreatment liquid, adding the acrylonitrile and an emulsifying agent into the pretreatment liquid, heating, adding an initiator potassium persulfate, and reacting for 4 hours at a reaction temperature of 60-70 ℃; The mass ratio of the inorganic flame retardant to the vinyl silane coupling agent to the acrylonitrile is 1:0.2-0.6:1-3; After the polymerization reaction, naOH is added for reaction, and the mixture is obtained through centrifugation, washing and drying; the concentration of NaOH is 1mol/L, the reaction parameters are 75 ℃ and 1h.
2. 2. The lithium battery electrolyte of claim 1, wherein the lithium salt comprises at least one of lithium hexafluorophosphate, lithium bis-fluorosulfonimide, and lithium trifluoromethane sulfonate.
3. 3. The lithium battery electrolyte of claim 1, wherein the additive comprises at least one of fluoroethylene carbonate and lithium nitrate.
4. 4. The lithium battery electrolyte according to claim 1, wherein the organic solvent comprises at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methylethyl carbonate, methylpropyl carbonate.
5. 5. A method for preparing the lithium battery electrolyte according to any one of claims 1 to 4, comprising the steps of: and (3) blending the lithium salt, the organic solvent, the additive and the flame retardant to obtain the flame retardant.

Description

Lithium battery electrolyte and preparation method thereof Technical Field The invention relates to the technical field of lithium ion batteries, in particular to lithium battery electrolyte and a preparation method thereof. Background Lithium ion batteries are currently the mainstream power sources because of their high energy density and excellent cycling stability. The lithium ion battery mainly comprises a positive electrode, a negative electrode, electrolyte and a diaphragm, wherein the electrolyte has inflammability, when the battery is in thermal runaway, the internal temperature of the battery is increased, and the battery can burn and explode due to continuous thermal process. The main factor responsible for this is the combustible electrolyte. Therefore, how to improve the safety of the electrolyte is a technical problem to be solved currently. One of the currently available methods is to add flame retardants to the electrolyte to achieve the purpose of suppressing the combustion of the electrolyte. However, the conventional flame retardant additives have low flame retardant efficiency, so that excessive flame retardant additives are required to be added, and in case of large amounts, side reactions occur in the battery, resulting in degradation of electrochemical performance of the battery. Disclosure of Invention < Technical problem to be solved by the invention > The method is used for solving the problem of electrochemical performance degradation of the battery caused by excessive flame retardant additives in the prior art. < Technical scheme adopted by the invention > The invention aims to provide lithium battery electrolyte and a preparation method thereof. The specific contents are as follows: Firstly, the invention provides a lithium battery electrolyte, which comprises, by weight, 10-20 parts of lithium salt, 3-10 parts of flame retardant, 2-8 parts of additive and 60-90 parts of organic solvent; the flame retardant is a silane modified flame retardant carrier, and the flame retardant carrier takes inorganic flame retardant as a core and PAN as a shell. Second, the present invention provides a method for preparing the aforementioned lithium battery electrolyte, comprising the steps of: and (3) blending the lithium salt, the organic solvent, the additive and the flame retardant to obtain the flame retardant. < Beneficial effects achieved by the invention > According to the invention, the inorganic flame retardant is coated by PAN, and is isolated from electrolyte by the coating effect, so that side reaction caused by directly adding the flame retardant is avoided, meanwhile, PAN is taken as a shell, and then flame retardant elements in the inorganic flame retardant are utilized, so that the loading amount of the flame retardant elements is increased, the adding amount of the flame retardant additive is reduced, when thermal runaway occurs, the PAN shell is decomposed, so that the inorganic flame retardant is released, the flame retardance of the electrolyte is reduced, and the flame retardant is subjected to silane modification treatment, so that the stability of the flame retardant before being heated is ensured, and silane can form Si-O-Si bonds on the surface of an electrode, so that the additive is prevented from being embedded into the electrode. Detailed Description In order to make the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention. < Technical solution > First, the invention provides a lithium battery electrolyte, which comprises, by weight, 10-20 parts of lithium salt, 3-10 parts of flame retardant, 2-8 parts of additive and 60-90 parts of organic solvent. Specifically, the flame retardant is a silane modified flame retardant carrier, wherein the flame retardant carrier takes inorganic flame retardant as a core and PAN as a shell. In the present invention, the lithium salt includes at least one of lithium hexafluorophosphate, lithium difluorosulfonimide and lithium trifluoromethane sulfonate. In the invention, the additive comprises at least one of fluoroethylene carbonate and lithium nitrate. In the present invention, the organic solvent includes at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, and propylmethyl carbonate. In the invention, the preparation method of the flame-retardant load carrier comprises the following steps of, The inorganic flame retardant is modified by a vinyl silane coupling agent to obtain a first modified body; And polymerizing the first modified bo