Functional Alloy Collector Capable of Sustainable Lithium Compensation for Anode‐Free Batteries by a Controlled Lithium‐Prestorage Technology

Abstract With higher energy density and reduced cost, anode‐free battery has attracted great attention from both academic and industry. However, the development of anode‐free batteries is hindered by their poor cycle life due to the continuous irreversible lithium (Li) consumption at the anode side. Here, a surface‐functionalized alloy foil, which can gradually release active lithium to the cell upon cycling, used as the collector for anode‐free batteries is proposed. The alloy foil is prestored with a certain amount of active lithium via a simple wet contacting reaction between the metal foil and liquid lithium source reagent. The prestored lithium amount can be precisely controlled by reagent concentration and contact time. When the foil is used as the anode, its alloyed surface demonstrates a low nucleation barrier for lithium deposition and a more uniform deposition behavior. More importantly, the alloy collector can rationally release active lithium to sustainably compensate for the irreversible Li consumption upon the cycling of a full cell, thus greatly prolonging the cycle life of the anode‐free battery by 10 times. Besides, this technique can be extended to diverse metal collectors demonstrating its broad applicability.