Challenges, Strategies, and Prospects of the Anode-Free Lithium Metal Batteries

The anode-free lithium metal batteries (AF-LMB), eliminating the use of host anode, can exploit the full potential of the lithium-containing cathode system in terms of the highest retrievable gravimetric/volumetric energy densities, simplified processing of the anode coating, as well as the reduced cost of cell production and maintenance. However, the issues of interfacial contact resistance, curtailed ion pathway, as well as the dead lithium formation coherently lead to the unsatisfactory cation utilization upon repetitive cycling, which impairs the performance endurance of the practical relevance. Hitherto, a plethora of optimization strategies for the electrolyte and deposition substrate are proposed to extend the cell lifespan. Most of the methods, however, are still based on empirical attempts and lack of systematic diagnosis tools to elucidate the interplay between the structural evolution of the cathode and Li deposition behavior. Herein, the recent research process is summarized and the current development dilemma from multiple perspectives is probed, aiming to highlight the key features of the system that dedicate the cycling endurance. In addition, prospects of the operando characterizations that can be used to accelerate the mechanism elucidation of the AF-LMB configuration are systematically commented.