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_0.6Co_0.2Mn_0.2O₂ (17.2 mg cm⁻²) cathode and Li/Li₉Al₄ 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/Li₉Al₄ anode also demonstrates impressive long-term cycling stability. A 5.6 Ah LiNi_0.8Co_0.1Mn_0.1O₂||Li/Li₉Al₄ 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).