Progress on the Carbonate-based Electrolyte Designed for Lithium-ion Batteries with Wide Operating Temperature Range

Today the application of lithium-ion batteries (LIBs) is significantly limited by the operating temperature range. The operating temperature required for consumer electronic devices is usually -20-60℃, which is basically consistent with operating temperature of the available conventional lithium ion batteries. To adapt to regional and seasonal temperature differences of electric vehicles/hybrid electric vehicle, LIBs are idea-lly required to show high energy density similar to that at room temperature and maintain an excellent cycling performance from -30-70℃. To enhance the survival ability and adaptability, LIBs for certain military and space applications need much stricter requirement on wide temperature range. Especially, the low temperature limit should be lower than -50℃. Available LIBs are obviously difficult to work in such a wide temperature range for a long time, so LIBs with wide operating temperature have been attracted more attention in recent years. Wide operating properties should be simultaneously considered at both low and elevated temperature. The main problem at low temperature is the diffusion of lithium ion, which is a reversible process but does not cause significant damage to the composition and structure of original batte-ry. However, the main problems of elevated temperature are the decomposition of electrolyte and the chemical passivation loss of interfaces between electrolyte and positive / negative electrode. The irreversible process leads to the rapid decrease of discharge capacity and cycling perfor-mance. At present, electrolyte optimization is the most feasible and economical way to broaden the operating temperature range. The design and pro-perties studies of wide temperature electrolyte involve three aspects: the solvation of electrolyte, the surface chemical reaction between electrolyte and negative electrode, and the interface reaction on positive electrode. Liquid phase of electrolyte is basically required the wide range of liquid temperature, the high electrochemical stability and the ionic conductivity at low temperature. The interface composition and structure are the key factors to exchange the charges/lithium ions, and maintain the compatibility between electrolyte and electrode. Liquid phase modification is mainly realized through the use of new lithium salts and new wide temperature co-solvents, while interface modification is mainly carried out by the addition of interface film additives and high-temperature additives. In this paper, based on the studies of author and teammates, lots of research and exploration results on the electrolyte for wide temperature are reviewed. Novel lithium salts, co-solvents and functional additives reported in recent years are focused on their structures, properties and action mechanism. At the end, future prospect and research methods are given for lithium-ion battery electrolytes adapted wide operating temperature range. © 2020, Materials Review Magazine. All right reserved.