Electrolyte and lithium ion battery

Abstract

The invention discloses an electrolyte and a lithium ion battery, the electrolyte comprises an organic solvent, a lithium salt and a first additive, the first additive is selected from at least one of phosphorylated cyclic lactone compounds with a structure shown as a formula I, n is greater than or equal to 1 and less than or equal to 3, x is greater than or equal to 0 and less than or equal to 1, and y is greater than or equal to 0 and less than or equal to 1; in the formula (I), R1, R2, R3 and R4 are respectively and independently selected from hydrogen, halogen, substituted or unsubstituted C1-C5 alkyl, substituted or unsubstituted C2-C5 unsaturated alkyl, substituted or unsubstituted C6-C10 aryl and substituted or unsubstituted C7-C10 alkaryl. According to the electrolyte disclosed by the invention, by introducing the phosphorylated cyclic lactone compound, the electrolyte can form a passive film with relatively low impedance and high polymerization degree on the surface of a positive pole piece, so that side reaction between the electrolyte and a positive pole material interface under high voltage can be remarkably reduced; the high-voltage cycle performance and the storage performance of the lithium ion battery are obviously improved, and the gas production of the battery can be inhibited.

Description

technical field [0001] The present application generally relates to the technical field of batteries, and specifically relates to an electrolyte solution and a lithium-ion battery. Background technique [0002] Lithium-ion batteries have the advantages of high specific energy, long cycle life and no memory effect, and are widely used in consumer electronics, new energy vehicles and large energy storage devices. At present, electronic products such as smart phones and new energy vehicles have higher and higher energy density requirements for lithium-ion batteries. To increase the energy density of batteries can be achieved by increasing the energy density of existing materials, such as increasing the cut-off voltage of positive electrode materials. [0003] However, increasing the cut-off voltage of the positive electrode material also faces many problems: for example, the increase in voltage aggravates the side reactions at the interface between the electrolyte and the posit...

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Problems solved by technology

[0003] However, increasing the cut-off voltage of the positive electrode material also faces many problems: for example, the increase in voltage aggravates the side reactions at the interface between the electrolyte and the positive electrode material, and the electrolyte is easily oxidized, resulting in flatulence in the battery; in addition, transition metal ions are dissolved from the positive electrode material and passed through The electrolyte migrates to the negative electrode, which will destroy the SEI on the surface of the negative electrode and cause a sharp decline in battery capacity

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