Electrolyte additive, electrolyte comprising additive and lithium ion battery

Abstract

The invention discloses an electrolyte additive, an electrolyte comprising the additive and a lithium ion battery. The lithium ion battery comprises the electrolyte, a positive electrode and a negative electrode, wherein the positive electrode is made of a manganese oxide material; the electrolyte comprises lithium salt, an organic solvent and the additive; the dosage of the additive is equivalent to 0.1 to 0.5 percent of the total mass of the lithium salt and the organic solvent; and the additive comprises 3-cyano-6-tirfluoromethylpyridine (C7H3F3N2). According to addition of the additive, the positive electrode / electrolyte interface is optimized, the surface activity of the positive electrode is reduced, and the oxidative decomposition of the electrolyte is suppressed; and due to the introduction of fluorine and nitrogen elements, the high-temperature safety of the electrolyte is obviously improved, and therefore the high-temperature storage performance and cycle performance of a high-voltage (5V) lithium battery can be improved.

Description

technical field [0001] The invention relates to an electrolyte additive, an electrolyte containing the additive and a lithium ion battery. Background technique [0002] At present, the positive electrode materials of commercial lithium-ion batteries mainly include lithium manganese oxide, lithium cobalt oxide, ternary materials, and lithium iron phosphate. The charging cut-off voltage generally does not exceed 4.2V. It is increasingly important and urgent to increase the energy density of lithium batteries. In addition to the improvement of existing materials and battery manufacturing processes, high-voltage (5V) cathode materials are one of the more popular research directions. It achieves high energy density of batteries by increasing the charging depth of cathode active materials. [0003] Structurally speaking, the currently discovered 5V cathode materials include: (1) manganese oxides with spinel structure, such as LiMn 2-x Li x o 4 , LiMn 2-x m x o 4 etc.; (2) V...

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Problems solved by technology

[0004] However, while increasing the voltage of the positive electrode material, the electrical performance of the battery charge-discharge cycle is declining. On the one hand, the reason is that the newly developed positive electrode material is not stable enough. On the other hand, it is the matching problem of the electrolyte. At a high potential of 5V, it will be oxidized and decomposed on the surface of the positive electrode of the battery. The oxidative decomposition reaction of the electrolyte itself will also promote the deterioration of the positive electrode material.

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