Non-inflammable lithium secondary battery and application thereof

Abstract

The invention discloses a non-inflammable lithium secondary battery and the application thereof. The positive electrode of the battery adopts one of lithium iron phosphate, lithium cobalt oxide, lithium manganate, a ternary material and a lithium-enriched material; the negative electrode adopts a carbon material. Electrolyte is prepared from a non-inflammable organic phosphorus solvent, lithium salt and a film forming additive. The non-inflammable organic phosphorus solvent has the following general formula: R1R2R3P(O), wherein R1, R2 and R3 are independently selected from alkyl, alkoxy, halogen-containing alkyl and halogen-containing alkoxy; the lithium salt is difluorosulfonamide lithium or ditrifluoromethyl sulfonimide lithium; the film forming additive is one or several of lithium borate dioxalate, ethylene carbonate, vinylene carbonate, vinyl carbonate vinyl ester, fluoroethylene ester and vinyl chloride ester; a mole ratio of the lithium salt in the non-inflammable electrolyte toorganic phosphorus electrolyte is higher than 1 to 3. The non-inflammable lithium secondary battery solves the problems of co-intercalation and continuous reductive decomposition of an organic phosphorus compound and the lithium salt and improves the coulombic efficiency and the reversible capacity of a graphite negative electrode.

Description

technical field [0001] The invention relates to a non-combustible lithium secondary battery and its application, belonging to the technical field of electrochemical and chemical power supply products. Background technique [0002] Due to its high energy density, high voltage, environmental friendliness, and low self-discharge, lithium-ion batteries have dominated the portable electronic product market, and are gradually showing a vigorous development trend in markets such as electric vehicles and energy storage. However, with the gradual development of lithium-ion batteries in the direction of higher energy density, high power density and large-scale application, safety issues frequently occur, which has aroused widespread concern from the public. In 2016, the "Samsung Note 7 Spontaneous Combustion" incident led to the recall and discontinuation of all Note 7 products, causing huge losses to Samsung, which not only cast a shadow on the hearts of consumers, but also caused a ...

AI Technical Summary

Problems solved by technology

However, in the current research, there are mainly two types of problems in organophosphorus compounds: (1) The co-intercalation of organophosphorus compounds and lithium ions together leads to the destruction of the layered structure of graphite, such as trimethyl phosphate (TMP), Dimethyl methyl phosphate (DMMP); (2) Graphite can catalyze the reduction and decomposition of organophosphorus compounds, and it cannot form a stable SEI film on graphite, resulting in the continuous irreversible redox decomposition of organophosphorus compounds. In some cases, the sheet structure of graphite has not been destroyed, such as triethyl phosphate (TEP), diethyl ethyl phosphate (DEEP)

These two types of problems will lead to low Coulombic efficiency and low or even no reversible capacity of the graphite anode.

In order to solve these problems, some film-forming additives such as fluoroethylene carbonate (FEC) and lithium bisoxalate borate (LiBOB) can be added to help the graphite negative electrode, although it can inhibit the co-intercalation of organophosphorus compounds and the continuous Reductive decomposition improves the Coulombic efficiency and reversible capacity of the graphite negative electrode, but does not fundamentally improve the performance of the battery, and is far from meeting the application requirements of commercial lithium-ion batteries

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