Long‐Life Quasi‐Solid‐State Anode‐Free Batteries Enabled by Li Compensation Coupled Interface Engineering

Abstract Initially, anode‐free Li metal batteries present a promising power source that merges the high production feasibility of Li‐ion batteries with the superb energy capabilities of Li‐metal batteries. However, their application confronts formidable challenges of extremely short lifespan due to the inadequacy of zero‐Li‐excess cell configuration against irreversible Li loss. A Li compensation coupled interface engineering strategy is reported for realizing long‐life quasi‐solid‐state anode‐free batteries. The Li2S is utilized as a sacrificial Li supplement to effectively counterbalance irreversible Li loss without damage to cell chemistry. Meanwhile, it demonstrates remarkable efficacy in establishing a robust yet slender inorganic–organic hybrid solid‐state interphase for inhibiting cell degradation by dead and dendritic Li. This strategy enables quasi‐solid‐state anode‐free batteries with a long lifespan of 500 cycles. The Ah‐scale quasi‐solid‐state pouch cells, featuring a high‐loading LiFePO4 cathode and lean gel polymer electrolyte, exhibit a high specific energy of 300 Wh kgcell−1. This achievement translates into an improvement of 46% in gravimetric energy and 94% in volumetric energy compared to LiFePO4||graphite batteries while outperforming LiFePO4||Li‐metal batteries by 22–47% in volumetric energy. Such quasi‐solid‐state anode‐free cells also demonstrate good safety, showcasing remarkable resistance against nail penetration in ambient air without failure, smoke, or fire accidents.