Advanced liquid electrolyte design for high-voltage and high-safety lithium metal batteries

Abstract

High-voltage lithium metal batteries (LMBs) represent a promising technology for next-generation energy storage, yet their commercialization is impeded by rapid performance degradation and safety concerns. Key challenges include lithium dendrite growth, unstable solid electrolyte interphase (SEI) and cathode electrolyte interphase (CEI), aluminum current collector corrosion, electrolyte oxidative decomposition, and inherent electrolyte flammability. This review systematically discusses strategies to overcome these issues by designing advanced liquid electrolytes, including: 1) regulating Li+ solvation structures via highly concentrated electrolytes (HCEs) or localized HCEs to stabilize Li deposition and suppress dendrites; 2) designing weakly solvating electrolytes with tailored solvent molecules to enhance SEI/CEI robustness; 3) leveraging ionic liquids as nonflammable solvents with high electrochemical stability to mitigate electrolyte oxidation and Al corrosion; and 4) incorporating flame-retardant phosphorus- or chlorine-based solvents to improve electrolyte safety. Perspectives on future research directions emphasize developing advanced in situ and full-cell-based characterization techniques, optimizing interfacial engineering, and scaling up cost-effective electrolyte formulations, to accelerate the practical development of high-voltage, high-safety LMBs for the next-generation energy storage.