Functional additive for electrolyte, long-circulation electrolyte of lithium ion battery and lithium ion battery

Abstract

The invention discloses a functional additive for an electrolyte, a long-circulation electrolyte of a lithium ion battery and the lithium ion battery. The functional additive comprises the following constituents by weight part: 0.5-2.5 parts of vinylene carbonate, 0.5-2 parts of lithium bisoxalatoborate, 0.1-2 parts of lithium bisimide, 0.5-2 parts of ethylene sulfate and 0.5-2 parts of butane sultone. The functional additive for the electrolyte, disclosed by the invention, is formed by combining the vinylene carbonate, the lithium bisoxalatoborate, the lithium bisimide (LiFSI), the ethylene sulfate and butane sultone. When the functional additive is added to the electrolyte for use, the stability of an SEI membrane on a surface of a negative electrode is improved, the internal resistance of the SEI membrane is reduced, the SEI membrane is prevented from being damaged during the circulation process to further cause reaction of the electrolyte and the negative electrode, and thus, the cycle lifetime of the battery is prolonged.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, specifically relates to a functional additive for electrolyte, and also relates to a long-cycle lithium ion battery electrolyte and lithium ion battery using the functional additive. Background technique [0002] Lithium-ion battery, as a new type of green high-energy battery, has attracted much attention in the fields of energy chemistry and material chemistry; it has gradually become the mainstream choice for vehicle power batteries due to its high energy and power density, no memory effect, and low self-discharge. one. The electrolyte is an important part of the lithium-ion battery. It not only transports and conducts current between the positive and negative electrodes, but also determines the working mechanism of the battery to a large extent, affecting the specific energy, safety performance, rate charge and discharge performance, and cycle of the battery. Lifespan and produc...

AI Technical Summary

Problems solved by technology

As the number of battery cycles increases, the SEI film on the surface of the negative electrode is destroyed, the electrolyte is continuously decomposed, and the graphite negative electrode is continuously damaged, resulting in a continuous decline in battery cycle performance.

In order to improve the cycle life of lithium-ion batteries, it is usually considered to add special film-forming additives to the electrolyte to improve the stability of the SEI film on the surface of the negative electrode, in order to improve the cycle life of lithium-ion batteries; but usually a single film-forming additive has limited effects , and will greatly increase the film-forming resistance on the surface of the negative electrode, which will limit the improvement of the cycle life of the lithium battery

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