Achieving low-temperature fast charging with PC-based electrolytes: regulating solvation structure, diffusion coefficient, and conductivity by concentration

Propylene carbonate (PC)-based electrolytes offer significant advantages for low-temperature discharge, but their performance at extreme ion concentrations is not yet well understood. This study explores the molecular-level differences in solvation shell structures of PC and ethylene carbonate (EMC) mixed electrolytes at extreme LiPF₆ concentrations under low-temperature conditions (253.15K), and analyzes the transport properties of diffusion coefficients and electrolyte conductivity. The study finds that with increasing LiPF₆ concentration, the number of PC molecules in the solvation shell decreases, while the number of PF₆̅ ions increases, leading to a rise in conductivity. When the LiPF₆ concentration exceeds 1M, the increment of PF₆̅ involved in the solvation structure diminishes, and the rate of increase in conductivity gradually slows down. This indicates that at high concentrations, more PF₆̅ ions participate in the formation of solvation structures, which contributes to the enhancement of conductivity. This research provides a design basis for the application of PC-based electrolytes in low-temperature fast-charging batteries.