The history of electrolyte, CR2032 button cell battery electrolyte production process

　　The history of electrolyte, CR2032 button cell battery electrolyte production process. As the "blood" of lithium-ion batteries - electrolyte, it bears the important task of conducting lithium ions and is the key to obtaining high energy density and low impedance for lithium batteries; this series starts with the production process of electrolyte and begins to gradually Expand and introduce to everyone the production process of the four main materials.

　　The history of electrolytes

　　The first generation: boric acid + ethylene glycol system, which has been invented for more than 50 years, has a high water content, otherwise the conductivity will be too low. The esterification of boric acid and ethylene glycol and the conversion of boric acid into metaboric acid will produce water. The presence of a small amount of water in the electrolyte helps to support the formation of oxides and is beneficial to improving the repair ability of the oxide film, but a large amount of water will It causes corrosion of the electrode foil, produces hydrogen, and the vapor pressure is high at high temperatures, which can easily cause the capacitor to burst. Therefore, capacitors of this system cannot be used at 105°C.

　　The second generation: linear carboxylate + boric acid + ethylene glycol system, the improvement goal is how to reduce and control the water content, which means that boric acid substitutes or other solvents must be used to obtain an electrolyte with stable water content and low impedance. . The improved system still used in China is boric acid + linear carboxylic acid ammonium salt (DCA) + ethylene glycol system. Although this system can reduce water content to a certain extent and has the advantages of low use cost,

　　The third generation: linear carboxylate + ethylene glycol system. The leakage current of aluminum electrolytic capacitors is significantly improved compared to the second generation electrolyte. However, the carboxylate flash fire increases due to the increase in molecular weight, but its dissolution Volume decreases.

　　The fourth generation: branched chain carboxylate + ethylene glycol system, branched chain carboxylate replaces or partially replaces the straight chain carboxylate, the branched chain carboxylate has a large solubility and better thermal stability, but the cost is generally higher.

　　CR2032 button cell battery electrolyte production process

　　1. Preparation of solvent:

　　EC, DEC, PC, DMC and other cyclic or chain esters. The earliest method for preparing EC was to use ethylene glycol and phosgene reaction. However, this process has been eliminated due to low yield, high cost and serious pollution. EC is prepared by transesterification reaction, the reaction speed is increased, and the yield is also improved.

　　2. Purification:

　　The organic raw materials used are purified separately to meet the standards for CR2032 button cell battery electrolyte use. Here, the items that need to be inspected include purity, water content, main content, etc.

　　3.LiPF6:

　　There are currently four main preparation methods, namely gas-solid phase method, hydrogen fluoride solvent method, organic solvent method and ion exchange method. The gas-solid phase method has high product purity, but the cost of raw materials is high, there are too many processes, and continuous production is difficult. The hydrogen fluoride solvent method has a fast reaction speed and high efficiency, but it produces HF and has high requirements on the corrosion resistance of the reaction vessel. The organic solvent method avoids the generation of HF and is relatively safe to operate, but PF5 still needs to be prepared and is highly corrosive. The ion exchange method avoids the shortcomings of using PF6 as a raw material, but the lithium alkoxide used will react with ammonia, and the raw materials are expensive, making it difficult to achieve industrial production.

　　4. Due to the sensitivity of the electrolyte, the packaging barrel also needs to undergo pretreatment, water washing, argon replacement and other processes to ensure that it is dry and free of impurities.

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