Architecting Anode Current Collectors for Practical Anode-Free Alkali Metal Batteries.

Anode-free alkali metal batteries (AFAMBs) are emerging as a compelling strategy to surpass the cell-level energy density limits of Li-ion batteries while simplifying battery configuration. In these systems, the working anode forms in situ on a bare current collector and is continuously reshaped during cycling with a limited alkali metal inventory. As a result, the anode current collector is not merely a passive electron conductor, but a multifunctional interfacial platform that governs alkali metal nucleation, growth, stripping, and interphase evolution. This review examines the fundamental differences among anode-free lithium, sodium, and potassium systems and highlights key performance metrics for practical AFAMBs. Recent current collector engineering strategies developed for these chemistries are then summarized. Essential parameters shaping current collector design are identified, including electronic conductivity, alkali metal affinity, collector morphology, and interphase stability. Finally, practical design principles are presented to balance electrochemical performance with manufacturability under realistic operating conditions. This review aims to clarify the alkali metal-dependent design logic of current collectors and to provide guidance for the practical development of next-generation anode-free batteries.