Electrolyte and lithium ion battery

Abstract

The invention discloses an electrolyte and a lithium ion battery. The electrolyte comprises a non-aqueous solvent, a lithium salt and an additive, wherein the lithium salt comprises a compound represented by a formula I shown in the description; and the non-aqueous solvent comprises a compound represented by a formula II shown in the description and a compound represented by a formula III shown inthe description, and the mass ratio of the compound represented by the formula II to the compound represented by the formula III ranges from 1: 1 to 1: 5. The electrolyte disclosed by the invention is relatively high in conductivity and is beneficial to lithium ion conduction; and the lithium ion battery containing the electrolyte has longer high-temperature cycle life, higher high-temperature storage capacity retention rate, higher high-temperature storage capacity recovery rate and lower high-temperature storage volume expansion.

Description

technical field [0001] The invention relates to the field of lithium ion batteries, in particular to an electrolyte and a lithium ion battery. Background technique [0002] Lithium-ion battery secondary battery Lithium-ion batteries are widely used as power sources for mobile electronic devices, electric vehicles, and energy storage devices. Generally, a lithium-ion battery is composed of a positive electrode, a negative electrode, a diaphragm, and an electrolyte. The electrolyte conducts electrons between the positive and negative electrodes of the lithium-ion battery, which is one of the important factors affecting the performance of the lithium-ion battery. [0003] The inventor finds that there are at least the following problems in the prior art: [0004] The ternary lithium-ion battery has a higher energy density, and its operating voltage range is wider than that of the traditional lithium iron phosphate battery, which can reach 2.4V to 4.2V. Under the same condition...

AI Technical Summary

Problems solved by technology

[0004] The ternary lithium-ion battery has a higher energy density, and its operating voltage range is wider than that of the traditional lithium iron phosphate battery, which can reach 2.4V to 4.2V. Under the same conditions, more electricity is generated during charging and discharging. Joule heat, the heat generated makes the LiPF in the electrolyte 6 Pyrolysis into LiF and PF 5 , as the PF of the strong Lewis acid 5 It is easy to react with non-aqueous solvents, and the internal environment of the battery will undergo chemical changes, resulting in reduced battery performance and life, and poor stability

Although this method can improve the high-temperature capacity retention rate, it only improves the high-temperature capacity retention rate within 7 days, and does not solve the problem of long-term storage (one month) of lithium-ion batteries at high temperatures.

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