Research progress in high energy density anode-free lithium metal batteries

Abstract

With the development of portable electronic devices and electric vehicles， the energy density of traditional lithium-ion batteries is approaching their theoretical limit. The research on lithium metal batteries with high energy density has been re-focused. However， the high reactivity of lithium increases safety risks and reduces energy density when excess lithium is used. Anode-free lithium metal batteries （AF-LMBs） have emerged as a solution. AF-LMBs possess high energy density and the lowest redox potential. But they have poor cycle life， limited active materials， and complex interfacial reactions. Improving the cycle stability of AF-LMBs is key to realizing the application of high-energy-density storage systems.This paper reviews the development of AF-LMBs and analyzes in depth the current challenges they face from four aspects： lithium dendrites， electrolyte stability， solid electrolyte interface （SEI）， and current collectors. These factors together affect the cycle stability， safety， and energy density of AF-LMBs. Finally， it is pointed out that the future research directions should focus on optimizing electrolyte formulations， designing artificial SEI layers， and improving current collector materials and structures. Meanwhile， paying attention to the volumetric energy density of batteries to meet the demand for compact and efficient energy storage systems in practical applications， thereby promoting the commercialization of AF-LMBs.