Phosphazene flame retardant and preparation method thereof, as well as lithium ion battery electrolyte

Abstract

The invention discloses a phosphazene flame retardant and a preparation method thereof. The phosphazene flame retardant is obtained through the reaction of fluorocarbon alcohol and phosphonitrilic chloride trimer, wherein, as the phosphazene flame retardant contains the elements of P and N, the flame-retardant effect is more obvious; as at least one of Rf1, Rf2, Rf3, Rf4, Rf5 and Rf6 is a fluorocarbon group which provides convenience for enhancing the flashing points of the electrolyte and reducing the viscosity of the electrolyte, the viscosity of the phosphazene flame retardant is proper, and the phosphazene flame retardant has favorable systematic consistence; moreover, the O bond and the P bond on the side chain of the phosphazene flame retardant are connected to a P group of a loop chain at the same time, so as to form a V-shaped hole, which provides convenience for absorbing metal positive ions to get far away from corresponding negative ions as well as for the migration of the positive ions, and further improves the electric conductivity of the electrolyte. The invention further provides a lithium ion battery electrolyte comprising electrolyte salt, a solvent and the phosphazene flame retardant. Experimental results show that the lithium ion battery electrolyte provided by the invention has favorable conductibility.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, more specifically, to a phosphazene flame retardant for lithium ion electrolyte, a preparation method thereof, and a lithium ion battery electrolyte using the flame retardant. Background technique [0002] Lithium-ion batteries have the characteristics of high energy density, low self-discharge rate, wide operating temperature range, long cycle life, environmental protection, no memory effect, and high current charge and discharge, etc., and are widely used in mobile phones, notebook computers, video cameras, digital cameras Among high-energy portable electronic devices, it also has broad application prospects in the fields of new energy vehicles, aerospace, and national defense equipment. However, safety is a key issue restricting the development of large-capacity and high-power lithium-ion batteries. For example, lithium-ion battery electrolytes are widely used in organic carbonat...

AI Technical Summary

Problems solved by technology

The Chinese patent literature with the application number 200710028419.8 reports the application of alkyl phosphates in the electrolyte of lithium-ion batteries. Due to the poor electrochemical compatibility of alkyl phosphates, when they are used as additives, they have a greater impact on the performance of the battery. big negative impact

Chinese patent document CN101694885A discloses an electrolyte containing an ethylene bisphthalimide derivative flame retardant. The electrolyte has good flame retardancy, but the cycle performance of the battery is not good

Chinese patent document CN101938008A reports the preparation of a 1-alkynyl phosphonate flame retardant and the electrolyte containing the flame retardant. The electrolyte has good flame retardant performance, but the battery capacity loss is serious

[0004] In recent years, researchers have found that phosphazene compounds have good flame retardant effects and can be used as flame retardants for lithium-ion batteries. However, phosphazene compounds have high viscosity and poor system compatibility, so they can be used as flame retardants. When used, the conductivity of the electrolyte is low, which affects the electrochemical performance of lithium-ion batteries

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