Electrolyte adopting propylene carbonate as main solvent

Abstract

The invention relates to an electrolyte adopting propylene carbonate as a main solvent, which relates to the electrolyte of a lithium ion battery. The electrolyte contains lithium salt, organic solvent and additive; the organic solvent contains propylene carbonate and chain-type carbonic ester; the additive contains a film-forming additive A and an additive B for inhibiting the embedding of the propylene carbonate; the electrolyte contains the following components by mass percent: 10 to 18 percent of lithium salt, 25 to 60 percent of propylene carbonate, 15 to 60 percent of chain-type carbonic ester, 0.5 to 5 percent of additive A and 0.1 to 10 percent of the additive B. Sulfite is used as the additive of the lithium ion battery electrolyte; since the sulfite is high in reduction potential which is higher than the decomposition potential of the propylene carbonate, the sulfite forms a layer of stable and compact SEI film on the surface of graphite before the decomposition of the propylene carbonate, the propylene carbonate solvent can be effectively prevented from being collectively embedded into the graphite layer along with the lithium ion, the initial discharging capacity of the battery is improved, and the cycle life of the battery is prolonged.

Description

technical field [0001] The invention relates to a lithium-ion battery electrolyte, in particular to a lithium-ion battery electrolyte using propylene carbonate (PC) as the main solvent of the electrolyte, and an additive capable of inhibiting PC from being embedded in negative electrode graphite is added to the electrolyte. Background technique [0002] Lithium-ion batteries are widely used due to their excellent characteristics (high energy density, long cycle life, high open circuit voltage, safety and pollution-free, no memory effect, etc.). A common lithium-ion battery is composed of a positive electrode, a negative electrode, a separator, and an electrolyte. At present, the anode materials of lithium-ion batteries on the market basically use graphite materials such as modified natural graphite and artificial graphite. [0003] The electrolyte is mainly composed of lithium salts, solvents and additives, and plays the role of conducting ions between the positive and nega...

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Problems solved by technology

[0005] Although there are some patents that use propylene carbonate instead of ethylene carbonate, such as Chinese patents 201210569711.1 and 201010267449.6, these patents do not solve the problem of co-embedding of propylene carbonate and graphite-based negative electrodes, and the scope of application is non-graphite-based negative electrodes. Electrochemical devices cannot be applied to lithium-ion batteries currently using graphite-based materials as negative poles, while the electrolyte of the present invention can be used in lithium-ion batteries with graphite-based negative poles

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