High-nickel ternary lithium ion battery electrolyte and ternary lithium ion battery

Abstract

The invention belongs to the technical field of lithium ion batteries, and particularly relates to a ternary lithium ion battery non-aqueous electrolyte and a lithium ion battery. The ternary lithiumion battery electrolyte comprises a non-aqueous organic solvent, an electrolyte lithium salt and an additive, the additive comprises an oxalic acid lithium phosphate additive with a structure shown ina formula (I), and can also comprise conventional additives such as vinylene carbonate (VC), 4-vinyl-1,3-dioxolan-2-one (VEC), 1, 3-propane sultone (PS), ethylene sulfate (DTD), tris (trimethylsilane) phosphate (TMSP) and the like. Under the combined action of the uniquely combined conventional additive and the oxalic acid lithium phosphate additive with the structure shown in the formula (I), the generation of cracks in positive electrode material particles in the circulation process can be inhibited, the dissolution of transition metal elements at high temperature can be reduced, the reduction reaction decomposition of a solvent on a negative electrode interface can be inhibited, the cycle performance, the high-temperature storage performance and the low-temperature performance of the ternary lithium ion battery are effectively improved.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a ternary lithium ion battery electrolyte and a ternary lithium ion battery. Background technique [0002] Lithium-ion batteries are widely used in 3C digital products, power tools, electric vehicles, aerospace and other fields due to their high operating voltage, high energy density, long life, wide operating temperature range, and environmental friendliness. Especially in the 3C digital field, in recent years, mobile electronic devices, especially smart phones, have been developing rapidly towards lighter and thinner, which puts forward higher requirements for the energy density of lithium-ion batteries. [0003] In order to improve the energy density of lithium-ion batteries, a common measure is to increase the charge cut-off voltage of the positive electrode material, such as the commercial lithium cobalt oxide battery voltage from 4.2V→4.35V→4.4V→4.45V→4.48V→4....

AI Technical Summary

Problems solved by technology

However, there will be certain defects in the positive electrode material under high voltage. For example, the high-voltage positive electrode active material has a strong oxidation property in the state of lithium deficiency, and the electrolyte is easily oxidized and decomposed, generating a large amount of gas and heat; in addition, high voltage The positive electrode active material is also very unstable in the state of lithium deficiency, and some side reactions are prone to occur, such as the release of oxygen, the dissolution of transition metal ions, etc.

[0004] Another way to increase the energy density of lithium-ion batteries is to increase the nickel content in ternary materials, such as commercialized ternary materials from NCM111→NCM422→NCM523→NCM622→NCM811, with the increase of nickel content, the energy of the battery The density can be further improved, but there are also some negative effects, such as the material is too alkaline, and the lattice energy changes during charging and discharging, which leads to the collapse of the material structure and the dissolution of ions, etc.

[0005] As the reaction proceeds, transition metal ions leave the crystal and enter the electrolyte to catalyze the decomposition of the electrolyte and damage the passivation film of the active material. At the same time, the transition metal lithium ions will also occupy the lithium ion migration channel of the passive film on the surface of the negative electrode material, hindering lithium ion migration. The migration of ions, thus affecting the service life of the battery, and when the lithium-ion battery is used under high temperature and high pressure, this negative effect will be more obvious

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