Electrolyte is one of the four key materials (positive electrode, negative electrode, separator, electrolyte) of lithium ion battery. It is called "blood" of lithium ion battery. It plays the role of conducting electrons between the positive and negative electrodes in the battery. It is a lithium ion battery. The high voltage, high specific energy and other advantages are guaranteed. The electrolyte is generally prepared from a high-purity organic solvent, an electrolyte lithium salt (lithium hexafluorophosphate, LiFL6), and a necessary additive lamp raw material under certain conditions and at a certain ratio.
The organic solvent is the main part of the electrolyte, which is closely related to the performance of the electrolyte. It is generally mixed with a high dielectric constant solvent and a low viscosity solvent. Commonly used electrolyte lithium salts are lithium perchlorate, lithium hexafluorophosphate, lithium tetrafluoroborate, etc., but Considering cost, safety and other aspects, lithium hexafluorophosphate is the main electrolyte used in commercial lithium-ion batteries; the use of additives has not been commercialized, but it has always been one of the research hotspots of organic electrolytes.
Since the successful development of lithium-ion battery electrolyte in 1991, lithium-ion batteries have quickly entered the market of electronic information products such as notebook computers and mobile phones, and gradually occupied a dominant position. At present, ion-based battery electrolyte product technology is also in the process of further development. In the research and production of electrolytes for lithium-ion batteries, the companies engaged in the research and development of special electrolytes for lithium-ion batteries are mainly concentrated in Japan, Germany, South Korea, the United States, Canada and other countries. The market share is the largest.
Different electrolytes have different conditions of use, and have different compatibility with the positive and negative electrodes of the battery, and the decomposition voltage is also different. The electrolyte composition is lmol/L?LiPF6/EC+DMC+DEC+EMC, which has better cycle life, low temperature performance and safety performance than ordinary electrolyte, which can effectively reduce gas generation and prevent battery bulging. The decomposition voltages of the EC/DEC and EC/DMC electrolyte systems were 4.25 V and 5.10 V, respectively. According to Bellcore research, LiPF6/EC+DMC has good compatibility with carbon negative electrode. For example, in LixC6/LiMnO4 battery, LiPF6/EC+DMC is used as electrolyte. It can be stabilized to 4.9V at room temperature and stable at 55°C. Up to 4.8V, its liquid phase range is -20 ° C ~ 130 ° C. The outstanding advantages are wide temperature range, good compatibility with carbon negative electrode, high safety index, good cycle life and discharge characteristics.