Solid-solution based metal alloy phase for highly reversible lithium metal anode.

Lithium metal batteries are vital devices for high-energy-density energy storage, but Li metal anode is highly reactive with electrolyte and forms uncontrolled dendrite that can cause undesirable parasitic reactions thus poor cycling stability and raise safety concerns. Despite remarkable progress made to partly solve these issues, the Li metal still plate at the electrode/electrolyte interface where the parasitic reactions and dendrite formation invariably occur. Here we demonstrate the inward-growth plating of Li atoms into a metal foil of thickness of tens of micrometers while avoiding surface deposition, which is driven by the reversible solid-solution based alloy phase change. Lithiation of the solid solution alloy phase facilitates the freshly generated Li atoms at the surface to sink into the metal foil, while the reversible alloy phase change is companied by the dealloying reaction during delithiation, which extracts Li atoms from inside of the metal foil. The yielded dendrite free Li anode produces an enhanced Coulombic efficiency of 99.5±0.2% with a reversible capacity of 1660 mA h g-1 (3.3 mA h cm-2).