High-temperature-resistant high-voltage electrolyte of high-nickel lithium ion battery

Abstract

A high-temperature-resistant high-voltage electrolyte of a high-nickel lithium ion battery is composed of a composite electrolyte lithium salt, an organic multi-component solvent and an additive, andthe composite electrolyte lithium salt is at least two of lithium hexafluorophosphate, lithium perchlorate, lithium difluorophosphate, lithium bis (fluorosulfonyl) imide, lithium bis (oxalato) borate,lithium difluoro (oxalato) borate, lithium difluoro (oxalato) phosphate and the like. The electrolyte lithium salt and the additive in the electrolyte participate in positive electrode film formationat the same time to hinder contact between the electrolyte and an electrode, so that decomposition reaction between the electrolyte in a high-potential region and an active substance is inhibited, and the storage and cycle performance of the lithium ion battery at high temperature and high voltage is improved.

Description

technical field [0001] The invention relates to an electrolyte solution of a lithium ion battery, in particular to a high temperature resistant high voltage electrolyte solution of a high nickel lithium ion battery. Background technique [0002] With the development of the new energy market, the improvement of the energy density of lithium-ion power batteries is imminent. High-nickel ternary cathode material (more than 60% nickel content), compared to the currently used LiNi 0.5 co 0.2 mn 0.3 o 2 (NCM523) material, which has higher specific capacity and lower cost, and high charge and discharge capacity at high voltage, greatly improves the energy density of lithium batteries, thus attracting widespread attention. However, under high-temperature cycling, the Ni in the high-nickel cathode material 3+ Easily reduced to Ni 2+ , Occupying the lithium layer vacancies, resulting in mixed cations, the material is prone to phase structure transformation (layered → spinel → roc...

AI Technical Summary

Problems solved by technology

However, under high-temperature cycling, the Ni in the high-nickel cathode material 3+ Easily reduced to Ni 2+ , Occupying the lithium layer vacancies, resulting in mixed cations, the material is prone to phase structure transformation (layered → spinel → rock salt) to form an electrochemically inert NiO-like phase, which affects the free deintercalation of lithium ions; and high nickel at high temperature The self-discharge phenomenon of the ternary positive electrode material is serious, which is easy to cause capacity loss and battery expansion, and shorten the storage life of the battery

In addition, under high voltage, Ni 4+ It is prone to violent side reactions with the electrolyte, resulting in the destruction of the material structure and the release of oxygen and heat, which makes the cycle performance and thermal stability of the electrode material worse, and the safety performance of lithium-ion batteries is reduced

[0003] CN110649319A discloses a high-temperature-resistant electrolyte for lithium-ion batteries that match high-nickel cathode materials, but does not address the high-temperature performance of high-nickel cathode materials under high-voltage conditions

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