A kind of electrolytic solution, positive pole and its preparation method and a kind of lithium ion battery

Abstract

The invention provides an electrolyte comprising a lithium salt, an electrolyte solvent and an additive, wherein the additive is a boron nitrogen alkane compound having a structure as shown in formula (1), wherein R1, R3 and R5 are -H, R2, R4 and R6 are independently selected from one or more of -F, -Cl, -Br, CH3(CH2) n-, CX3 (CH2) n1-, CX2H (CH2) n2-, CHX2 (CH2) n3-, phenyl and difluorophenyl; or R2, R4 and R6 are -H, and R1, R3 and R5 are independently selected from one or more of -F, -Cl, -Br, CH3(CH2) n-, CX3 (CH2) n1-, CX2H (CH2) n2-, CHX2 (CH2) n3-, phenyl and difluorophenyl, wherein the X is selected from one or more of F, Cl, -Br and I, n is not smaller than 0 and is not greater than 3, n1 is not smaller than 0 and is not greater than 3, n2 is not smaller than 0 and is not greater than 3, and n3 is not smaller than 0 and is not greater than 3. The invention further discloses an anode, a preparation method of the anode and a lithium ion battery. In the electrolyte provided by the invention, the boron nitrogen alkane compound having the structure is used as the specific additive, so that the anode can be protected from being damaged, and meanwhile the oxygenolysis (excessive consumption) of the electrolyte solvent is protected, therefore the service life of the battery under high voltage is prolonged.

Description

technical field [0001] The invention belongs to the field of lithium ion batteries, and in particular relates to an electrolyte, a positive electrode, a preparation method thereof and a lithium ion battery. Background technique [0002] Since the 1990s, lithium-ion secondary batteries have developed rapidly from their birth. Generally speaking, a lithium-ion battery with an electrolyte includes a casing, a cell contained in the casing, and an electrolyte. The cell includes a positive electrode, a negative electrode, and a separator between the positive electrode and the negative electrode. During charging, lithium ions migrate from the positive electrode through the electrolyte to the negative electrode, while they flow in the opposite direction during discharging. In recent years, secondary lithium-ion batteries with high energy density have become the object of people's attention. Therefore, people have also noticed some new active materials that can be used as secondary ...

AI Technical Summary

Problems solved by technology

At this stage, most lithium battery electrolyte systems can only be used stably at a voltage of 4.2v and below. When the working voltage reaches above 4.2v, the electrolyte system will oxidize and decompose, making the battery unable to work normally. The application of high-voltage cathode materials has formed a great obstacle, and the battery cycle performance is reduced

[0003] The above-mentioned electrolyte also has the technical problem that the electrolyte solvent is prone to side reactions with the positive electrode at a high potential, so that the solvent is further oxidized and decomposed, resulting in excessive consumption of the electrolyte solvent

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