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What are the components of the lithium battery electrolyte

2019-05-23 来源:亚科官网
The electrolyte is an ionic conductor that conducts electricity between the positive and negative electrodes of a lithium battery, and is prepared by a certain ratio of raw materials such as an electrolyte lithium salt, a high-purity organic solvent, and a necessary additive. The energy density and power density of the lithium battery are Wide temperature applications, cycle life, safety performance and other aspects play a vital role. As the blood of the lithium battery, the electrolyte bears the heavy responsibility of transporting lithium ions. Its quality will directly affect the performance of the lithium ion battery, and also affect the safety of the lithium ion battery to some extent.
Lithium battery electrolyte composition
1. Solvent: cyclic carbonate (PC, EC); chain carbonate (DEC, DMC, EMC); carboxylate (MF, MA, EA, MA, MP, etc.) (for dissolving lithium salt).
2. Lithium salt: LiPF6, LiClO4, LiBF4, LiAsF6, etc.
3. Additives: film-forming additives, conductive additives, flame retardant additives, over-charge protection additives, additives to control H2O and HF content in electrolytes, additives to improve low-temperature performance, multi-functional additives.
Lithium battery electrolyte composition type
1. Vinyl carbonate: molecular formula C3H4O3
Transparent colorless liquid (>35°C), crystalline solid at room temperature. Boiling point: 248°C/760 mmHg, 243-244 °C/740 mmHg; flash point: 160°C; density: 1.3218; refractive index: 1.4158 (50 °C); : 35-38 °C; This product is a good solvent for polyacrylonitrile and polyvinyl chloride. In the battery industry, it can be used as an excellent solvent for lithium battery electrolytes.
2. Propylene carbonate: molecular formula C4H6O3
Colorless, odorless, or light yellow transparent liquid, soluble in water and carbon tetrachloride, miscible with acetone, benzene, etc. It is an excellent polar solvent. This product is mainly used in polymer processing, gas separation process and electrochemistry. It is especially used to absorb carbon dioxide from natural gas and petrochemical plants. It can also be used as plasticizer, spinning solvent, olefin and aromatic extractant.
3. Diethyl carbonate: molecular formula CH3OCOOCH3
Colorless liquid, slightly odor; vapor pressure 1.33kPa/23.8 °C; flash point 25 °C, melting point -43 °C; boiling point 125.8 °C; solubility: insoluble in water, miscible in alcohol, ketone, ester and other organic solvents. Main use: as a solvent and for organic synthesis.
The general principles for selecting the electrolyte composition of a lithium battery are as follows:
(1) Good electrochemical stability, no reaction with positive electrode material, negative electrode material, separator, current collector, binder, etc.;
(2) The ion conductance is good, the dielectric constant is high, the viscosity is low, and the resistance of ion migration is small;
(3) Maintaining a liquid state over a wide temperature range, generally in the temperature range of -40 °C to 70 °C, suitable for improving the high and low temperature characteristics of lithium batteries;
(4) can optimally promote the progress of the electrode reversible reaction, that is, have a higher cycle efficiency;
(5) Environmentally friendly, preferably non-toxic or low toxicity.
Related links: lithium battery
Edited by Suzhou Yacoo Science Co., Ltd.