Electrolyte for power lithium ion battery

Abstract

The invention discloses high-wettability and high-pourability electrolyte for a power lithium ion battery. The electrolyte comprises a wetting additive, a lithium salt, a non-aqueous organic solvent and other additives, wherein the wetting additive is a nonionic surfactant, and the wetting additive accounts for 0.001 to 5 percent of the mass of the electrolyte; the non-aqueous solvent is one or a mixture of more of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, dimethyl carbonate, diethyl carbonate and gamma-butyrolactone, and the non-aqueous solvent accounts for 50 to 90 percent of the mass of the electrolyte; the lithium salt at the concentration of 0.6 to 1.5 mol / L is at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(oxalato)borate and lithium trifluoromethanesulfonate; and the other additives accounts for 0.5 to 8 percent of the mass of the electrolyte. The electrolyte has high wettability for a polyolefin diaphragm and electrode active materials, and has long cycle life.

Description

【Technical field】 [0001] The invention relates to an electrolyte for a power lithium-ion secondary battery, more specifically, the invention relates to an electrolyte for a power lithium-ion battery with good wettability, pourability, and excellent cycle life. 【Background technique】 [0002] As an energy conversion device, lithium-ion batteries have the following advantages: [0003] (1) The working voltage is high, and the working voltage of the commercial lithium cobalt oxide-carbon battery is 3.6V ~ 3.7V; [0004] (2) The energy density is high, and the specific energy of lithium-ion batteries varies with different electrode materials, but it can basically reach 150-200Wh / kg; [0005] (3) Long cycle life, the lithium-ion battery has a cycle life of more than 2000 times, and can reach tens of thousands of times at a low discharge depth; [0006] (4) No pollution. Materials such as positive and negative electrodes and electrolytes used in lithium-ion batteries are non-tox...

AI Technical Summary

Problems solved by technology

[0012] At present, the liquid lithium-ion battery electrolyte uses a mixed solvent of cyclic carbonate and chain carbonate; this kind of aprotic solvent has high viscosity and high surface tension; when injecting liquid, the pouring property is not very good

On the other hand, the affinity between PE and PP diaphragm materials and the electrolyte is small, resulting in poor wettability of the electrolyte to the diaphragm; due to the increase in battery capacity, the density of motor components increases, and the space between the components and the housing is very small. Small, making filling the electrolyte very difficult

[0013] The wettability of aprotic solvents to positive and negative electrode active materials with high specific surface area is not very good, which will cause the contact resistance between the electrode material and the electrolyte to be too high, and it is difficult to meet the requirements of low internal resistance of the power lithium-ion battery; the electrolyte Poor wettability to electrode active materials will affect the utilization rate of positive and negative electrode materials, which is not conducive to the development of battery capacity

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