Lithium ion battery and electrolyte solution thereof

Abstract

The invention discloses a lithium ion battery and an electrolyte solution thereof. The electrolyte solution comprises an electrolyte solution solvent, an electrolyte and an additive, wherein the electrolyte solution solvent comprises EC (ethylene carbonate), DEC (Diethyl Carbonate), DMC (Dimethyl Carbonate), EMC (ethyl methyl carbonate) and EP (ethyl propionate); the electrolyte is LiPF6; the additive comprises a LiBF4, PS (propane sultone) and FB (fluorobenzene) which are added for improving the high-temperature performance, and FEC (fluoroethylene carbonate) which is added for improving the low-temperature performance and the long-cycling performance. The lithium ion battery comprising the electrolyte solution can meet requirements that the electric discharge capacity of the lithium ion battery under 0.2C (Capacity) at a lower temperature of -40 DEG C is greater than the electric discharge capacity at a normal temperature by more than 75%; the electric discharge capacity of the lithium ion battery under 0.1C is greater than the electric discharge capacity at the normal temperature by more than 85%. Meanwhile, the capacity retention ratio of the lithium ion battery can be retained by more than 80% after the lithium ion battery is cycled for 500 circles. After the lithium ion battery with full charge is stored for 7 days at 60 DEG C, the thickness swelling rate of the lithium ion battery is less than or equal to 5.0%; the capacity recovery rate of the lithium ion battery is greater than 90%. After the lithium ion battery is stored for 90 days, the capacity recovery rate of the lithium ion battery is greater than 95%.

Description

technical field [0001] The invention relates to the field of chemical batteries, in particular to a lithium ion battery and its electrolyte. Background technique [0002] Due to its high working voltage, environmental protection and ability to provide more energy, lithium-ion batteries are currently used more and more popularly. They can not only be used in handheld mobile digital products such as mobile phones, notebook computers, tablet computers, Bluetooth and game consoles. It can also be applied to mobile communication base stations, energy storage and power vehicles. Conventional lithium-ion batteries need to have the characteristics of high and low temperature discharge, but the low-temperature discharge of existing lithium-ion batteries can basically only work at -20°C, which limits the use of lithium-ion batteries in military industries and low-temperature discharges at -40°C or below. Discharge for use on special needs products. If only the low-temperature discha...

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Problems solved by technology

[0004] In view of the above deficiencies in the prior art, the purpose of the present invention is to provide a lithium ion battery and its electrolyte, by providing a new electrolyte to meet the discharge requirements of lithium ion batteries at low temperatures below -40 ° C, improving the existing The defects of ultra-low temperature electrolyte high temperature storage gas production, low recovery rate of long-term storage capacity and insufficient long cycle life

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