Electrolyte for high-voltage lithium battery and high-energy lithium battery including electrolyte

Abstract

The invention belongs to the technical field of lithium ion batteries, and in particular relates to an electrolyte for a high-voltage lithium ion battery using silicon or a silicon-carbon composite material as a cathode. The electrolyte comprises a non-aqueous organic solvent, lithium salt and an additive and further comprises fluoro-ester and dinitrile organic compounds, wherein the dinitrile organic matter accounts for 0.01-10% of the total mass of the electrolyte. Compared with the prior art, the electrolyte has the advantages that LiDFOB and the dinitrile organic compound are added in the electrolyte, so that an SEI membrane can be formed on the surface of a high-voltage anode effectively, and the fluoro-solvent can effectively form an SEI membrane on the surface of a silicon or silicon-carbon cathode; meanwhile, the SEI membrane has relatively low resistance at low temperature, so that the cross-over resistance of lithium ions is reduced, and the high-voltage and low-temperature circulating performance of the battery including the electrolyte is significantly improved. Moreover, the invention also discloses a high-energy lithium ion battery including the electrolyte.

Description

technical field [0001] The invention relates to a high-voltage lithium battery electrolyte and a high-energy lithium battery using the high-voltage electrolyte, belonging to the technical field of lithium batteries and battery electrolytes. Background technique [0002] With the rapid growth of my country's economy, science and technology have also developed rapidly, which has driven the rapid development of the electronics industry and the automobile industry, and various electrical appliances and automobiles powered by batteries have also flourished. Before the birth of lithium-ion batteries, lead-acid batteries, nickel-cadmium batteries and zinc-manganese batteries occupied most of the market, and also caused irreversible damage to our living environment. The disorderly management and random disposal of batteries, It pollutes the land and groundwater we depend on for survival. According to research, a nickel-cadmium AA battery can pollute several square kilometers of lan...

AI Technical Summary

Problems solved by technology

[0004] At present, lithium cobalt oxide, ternary materials, and lithium iron phosphate materials are divided into three parts among the positive electrode materials of lithium-ion batteries on the market. The maximum charging cut-off voltage generally does not exceed 4.25V, and lithium iron phosphate is 3.7V. In lithium-ion batteries exceeding 4.3V, the oxidation ability of the positive electrode material is also enhanced, which can easily lead to the oxidation reaction of the electrolyte on the surface and interface of the positive electrode material, and then a large amount of gas will be generated, causing the internal pressure of the battery to increase and the battery to bulge. There are also flammable gases, such as H 2 , olefin gas, etc., which affect the safety of the battery and also reduce the service life of the battery

And batteries with a charging voltage exceeding 4.5V (based on LiNi 0.5 mn 1.5 o 4 and LiCoPO 4 The discharge voltage of the high-voltage cathode material represented by such materials can be as high as 4.6V-4.75V, and the charging upper limit voltage can reach 4.95V), and there are various problems such as electrolyte decomposition, severe battery swelling, and short battery cycle life, which limit the Application and Development of High Energy Density Batteries

[0005] Since there is still no good scientific explanation and mathematical model for the reaction mechanism between the lithium-ion battery electrolyte and the surface interface of the electrode material in the world, the development of high-voltage electrolytes has also been hindered to some extent, but various in-situ testing methods With the continuous emergence of lithium-ion batteries, human beings have more in-depth mechanism responses to lithium-ion batteries. It has become one of the research trends to develop electrolytes that can withstand high voltage and have good compatibility with electrode materials.

Images