High-voltage lithium cobalt oxide lithium ion battery electrolyte and lithium ion battery

Abstract

The invention belongs to the technical field of lithium ion batteries, and discloses a high-voltage lithium cobalt oxide lithium ion battery non-aqueous electrolyte and a lithium ion battery. The non-aqueous electrolyte of the high-voltage lithium cobalt oxide lithium ion battery comprises a non-aqueous organic solvent, an electrolyte lithium salt and an additive, wherein the additive comprises a conventional additive and a nitrile additive with a structure as shown in a formula (I). The nitrile additive in the electrolyte can form a positive electrode film and inhibit dissolution of metal ions (cobalt ions) in a positive electrode material; meanwhile, N elements in cyano groups in the additive contain lone electron pairs and can be chelated with the cobalt ions dissolved out of the positive electrode material, and the situation that the metal ions migrate to a negative electrode graphite interface to catalyze reductive decomposition of the electrolyte is avoided; therefore, the effect of improving the electrochemical performance of the lithium ion battery is achieved.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a high-voltage lithium cobaltate lithium ion battery electrolyte and a lithium ion battery. Background technique [0002] Lithium-ion batteries are widely used in 3C digital products due to their high operating voltage, high energy density, long life, wide operating temperature range, and environmental friendliness. Nowadays, light and thin and high energy density have gradually become the trend of battery development, especially for 3C digital products. In order to increase 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 lithium-ion battery voltage from 4.2V→4.35V→4.4V→4.45V→4.48V→4.5V . [0003] However, there are certain defects in positive electrode materials at high voltages. For example, high-voltage positive electrode activ...

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Problems solved by technology

[0003] However, there are certain defects in positive electrode materials at high voltages. For example, high-voltage positive electrode active materials have strong oxidative properties in the state of lithium deficiency, and the electrolyte is easily oxidized and decomposed, generating a large amount of gas and heat; The active material of the voltage positive electrode 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.

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