Electrolyte-centric strategies for high-energy-density lithium metal batteries

Abstract

Achieving lithium metal batteries (LMBs) with energy densities beyond 500 Wh kg−1 requires electrolyte systems capable of operating under increasingly stringent conditions, including thin lithium metal anodes, lean electrolyte configurations, and high-voltage layered-oxide cathodes. In this context, electrolyte design has evolved from incremental component optimization to a system-level, electrolyte-centric strategy that couples bulk chemistry, interfacial processes, and manufacturability considerations. This review provides a comprehensive and critical overview of recent advances in electrolyte design for high-energy-density LMBs, organized across three major pathways: liquid electrolytes, polymer and quasi-solid electrolytes, and inorganic solid-state electrolytes. For liquid systems, progress in solvation-structure engineering, ionic-cluster regulation, and interfacial chemistry has enabled improved stability under high voltage and low electrolyte loading. Polymer-based systems offer enhanced safety and interfacial compatibility, though challenges remain in achieving sufficient room-temperature ionic conductivity. Inorganic solid electrolytes deliver superior thermal and electrochemical stability, yet are constrained by interfacial resistance, mechanical coupling, and air stability. Beyond individual material classes, we identify six cross-cutting challenges governing practical LMB deployment, including interfacial instability, integrated solvation-network engineering, performance–safety–cost synergy, data-driven discovery, scalable manufacturing compatibility, and solid–solid interface limitations. By consolidating mechanistic insights and system-level design principles, this review aims to provide a coherent framework to guide the development of next-generation, high-energy, and practically viable lithium metal batteries.