A kind of ternary lithium ion battery electrolyte and lithium ion battery containing the electrolyte

Abstract

The invention belongs to the technical field of lithium ion batteries, and discloses a ternary lithium ion battery electrolyte and a lithium ion battery containing the same. The ternary lithium ion battery electrolyte comprises a non-aqueous organic solvent, a lithium salt and additives, wherein the additives comprise a first type of boron-containing lithium salt additive and a second type of sulfur-containing organic matter additive, wherein the first type of boron-containing lithium salt additive is one or more of formulas of M: a formula which is as shown in the specification or an N: a formula which is as shown in the specification; and at least one of the first type of additive and the second type of additive contains an unsaturated functional group. According to the electrolyte, thefirst type of additive can form a compact SEI in the reduction reaction of a graphite negative electrode, and can also participate in the formation of a positive electrode CEI film; and the second type of sulfur-containing organic matter additive and the first type of boron-containing lithium salt additive are used in cooperation, so that the cycling stability of the high-nickel or high-voltage lithium ion battery can be realized, and the requirement for high-low temperature performance of a high-energy-density power battery can be met.

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 lithium ion battery containing the electrolyte. Background technique [0002] High-energy-density ternary lithium-ion batteries are currently the main development and application direction for power batteries and energy storage products. With the ternary material LiNi 1-x-y-z co x mn y al z o 2 (0≤x≤1, 0≤y≤1, 0≤z≤1 and 0≤x+y+z≤1) the nickel content increases or the limit voltage increases continuously, the gram capacity of the battery material increases gradually, but The high and low temperature performance of the battery is difficult to balance, and there are disadvantages such as easy gas production during high temperature storage, and rapid capacity decay during cycling. Therefore, the commercial application of ternary materials puts forward higher requirements for the electrolyte. [0003] In order to meet t...

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Problems solved by technology

Studies have found that boron-containing lithium salt additives have different effects on the first-time efficiency and high-low temperature performance of high-nickel ternary systems and high-voltage ternary systems. Negative electrode film-forming additives can prolong the cycle stability of ternary batteries. Lithium difluorooxalate borate is also very effective in improving low-temperature performance and normal temperature cycle performance. However, studies have found that this type of boron-containing oxalate additives have long-term storage performance The effect is not good, and the oxalate additives are easy to release carbon dioxide under the high temperature environment and the catalysis of metal ions, which will cause problems such as pouch battery swelling; compounds containing unsaturated bond functional groups have been proved to have better performance on high-nickel ternary high-temperature performance. Good effect, but at the same time there are adverse effects of insufficient low temperature performance and large DC internal resistance

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