Lithiophilic interlayer driven 'bottom-up' metal infilling in high current density Li-metal anodes

Abstract

Lithium (Li) metal holds great potential for pushing practical energy densities beyond state-of the art Li-ion batteries. However, parasitic problems including Li dendrite formation can result in separator piercing, subsequent short-circuit and ultimately thermal runaway. Here we propose an innovative interlayer strategy that is guided by continuum simulations in 1D and 3D, which shows that materials with low Li nucleation overpotentials and high surface areas can enable spatially controlled plating of Li. This insight inspires an interlayer consisting of highly lithiophilic germanium nanowires (Ge NWs) coated on one side of a carbon cloth (CC). This anode geometry effectively unlocks Li infilling by a "bottom-up" motif during stripping/plating cycles. As a result, dendrite formation is eliminated, with the GeCC interlayer acting as a controlling Li reservoir during stripping/plating cycles. Ultra-stable symmetric cell performance up to 2500 h was achieved, with low overpotentials at high current density (2 mA cm-2) and plating capacity (2 mA h cm-2). Furthermore, aggressive higher current density (4 mA cm-2) and plating capacity (4 mA h cm-2) conditions were enabled by this approach. The high performing GeCC interlayer modified Li metal anodes were tested with LiFePO4 and NMC cathodes, facilitating greatly enhanced cyclic stability compared to control cells.