The electrolyte of lithium vehicle battery is the carrier of ion transmission in the battery. It plays the role of conducting ions between the positive and negative poles of lithium vehicle battery. It is like the "love bond" between the positive and negative poles, which guarantees the advantages of high voltage and high specific energy of lithium ion battery. So what are the main components of lithium vehicle battery electrolyte?
(1)The use of lithium vehicle battery electrolyte
The electrolyte of lithium ion battery is prepared by mixing high purity organic solvent, electrolyte lithium salt and necessary additives in a certain proportion. Lithium salts mainly include lithium perchlorate, lithium hexafluorarsenic, lithium tetrafluoroborate, lithium hexafluorphosphoric acid, etc. The basic requirements of electrolyte for lithium salt are: soluble in organic solvents and high conductivity of the solution, good chemical stability, good electrochemical stability, environmentally friendly, and relatively low cost. Based on the above performance, lithium hexafluorophosphate has the best comprehensive performance. Therefore, most lithium salts used in lithium ion battery at this stage are lithium hexafluorophosphate.
(2)Lithium vehicle battery electrolyte classification
The electrolyte is generally prepared by high purity organic solvent, electrolyte lithium salt, necessary additives and other raw materials under certain conditions in a certain proportion. Its main ingredients are the following:
1. Vinyl carbonate: molecular formula: C3H4O3, transparent colorless liquid (> 35℃), room temperature is a crystalline solid, and it is a good solvent of polyacrylonitrile, polyvinyl chloride.
2. Propylene carbonate: colorless odorless, or light yellow transparent liquid, soluble in water and carbon tetrachloride, miscible with ether, acetone, benzene and so on. This product should be stored in a cool, ventilated, dry place, away from fire. And it is according to the general provisions of low-toxic chemicals storage and transportation.
3. Diethyl carbonate: it is colorless liquid with a slight odor. Steam pressure is 1.33kPa/23.8℃. Flash point is 25℃. Flammable liquid can volatilize into steam, running into the air.
4. Dimethyl carbonate: it is a non-toxic, excellent environmental performance, a wide range of chemical raw materials. At the same time, it has higher evaporation temperature and faster evaporation speed.
5. Methyl ethyl carbonate: it is colorless transparent liquid and the rise of high-tech, high value-added chemical products in recent years. It is a good solvent of lithium vehicle battery electrolyte, this product should be stored in a cool, ventilated, dry place. It is according to the provisions of flammable chemicals storage and transportation.
6. Lithium hexafluorophosphate: it is white crystal or powder, deliquescence strong. When it exposed to air or heated, lithium hexafluorophosphate breaks down rapidly in air due to water vapor, releasing PF5 and producing white smoke.