Lithio-amphiphilic nanobilayer for high energy density anode-less all-solid-state batteries operating under low stack pressure

Abstract

Anode-less all-solid-state batteries (ALASSBs) offer unparalleled energy density and enhanced safety. ALASSB cells usually incorporate a protective layer on the anode current collector to stabilize lithium (Li) deposition, yet are liable to short-circuiting even at low current densities. Here we report a nanobilayer comprising tungsten (W) and magnesium (Mg) with a total thickness of 230 nm for anode protection. The upper lithiophobic (Li-insoluble) W layer induces highly dense Li deposits underneath through its high interfacial energy, whereas the lower lithiophilic Mg layer nucleates Li for uniform Li deposition. Even at room temperature and low stack pressure (2 MPa), an energy density of 1100 Wh L−1 and 71.9% retention after 300 cycles are demonstrated in a pouch-type full-cell. Furthermore, the effect of lithio-amphiphilicity is validated for other Li-insoluble metals, proving the versatility of the concept. This study unveils a simple yet effective approach for short-circuit-free cycling at high current densities, a challenging achievement for ALASSBs.