Fast‐Charging High‐Energy‐Density Lithium Metal Pouch Cells Achieved Through the In Situ Formation of Inter‐Bridged Micrometer‐Scale Li‐Al Alloy Architecture

Abstract Lithium metal batteries are viewed as promising energy storage systems due to their high energy density. However, their practical applications are hindered by insufficient fast‐charging capability and cycle lifespan. These challenges primarily stem from the limited electrochemical reaction active area/sites on the planar foil surface. In this work, an in situ formed inter‐bridged micrometer‐scale Li‐Al alloy architecture is introduced on thin Li foil. A rapid self‐discharge process is initiated between Li and Al upon electrolyte injection, leading to the in situ alloying reaction. Such specific architecture offers a multitude of sites for Li nucleation/growth and void for inner Li plating, alongside increased area to reduce the practical current density, enabling fast and stable Li plating behavior. An 1 Ah pouch cell, comprising LiNi 0.6 Co 0.2 Mn 0.2 O 2 (17.2 mg cm − 2 ) cathode and Li/Li 9 Al 4 anode, demonstrates exceptional fast‐charging performance. The cell exhibits 84% of the capacity after fast charging for just 20 min at 3 C (3 A, ∼9 mA cm − 2 ). The Li/Li 9 Al 4 anode also demonstrates impressive long‐term cycling stability. A 5.6 Ah LiNi 0.8 Co 0.1 Mn 0.1 O 2 ||Li/Li 9 Al 4 pouch cell delivers high energy density of 526 Wh kg − 1 , and maintains a high capacity retention of 97.4% after 80 cycles under low negative/positive capacity ratio (1.25).