Achieving low-temperature and high-voltage LiCoO₂ prototype batteries through balanced molecular interactions in electrolytes

Achieving excellent low-temperature performance of high-voltage LiCoO₂ batteries remains a critical challenge due to the sluggish Li⁺ transport kinetics at low temperatures and uncontrolled decomposition of electrolytes at high voltages. In this work, the ionic conductivity of LiPF₆-based multi-solvent electrolytes and their electrochemical stability have been tuned by regulating the ion-dipole interaction between Li⁺ and solvents. Specifically, ethyl propionate (EP) and propionate (PP) is demonstrated to facilitate anion-cation dissociation and enhance Li⁺ transport efficiency at low temperature due to their strong binding with Li⁺. Ethylene carbonate (EC) and propylene carbonate (PC) show good electrochemical stability under high-voltage conditions. Optimization on the solvent-ion interactions and formation of uniform organic/inorganic-rich solid electrolyte interface at the cathode side has been realized through systematic tuning on the carboxylate-based solvents and carbonate-based solvents, leading to high discharge ratio at −40 °C (73.5% vs that at RT) and sustained high electrochemical stability. The results unveil that the balance and coupling effect of molecular interactions is crucial for enhancing the overall performances of practical batteries. This work provides significant guidance for the rational design of a low-temperature electrolyte for high-voltage LiCoO₂-based batteries by optimizing the solvent composition.