Stable lithium metal anode achieved by shortening diffusion path on solid electrolyte interface derived from Cu₂O lithiophilic layer

The stable operation of lithium metal batteries is crucial for high energy density requirements, but it is plagued by Li dendrite growth and unstable solid electrolyte interphase (SEI). Lithiophilic transition metal oxides (TMOs) have been studied extensively on Cu current collectors to stabilize lithium metal anodes by decreasing the Li nucleation overpotential, yet less is known about the SEI derived from the lithiation reaction of TMOs. Here we report a novel approach to regulate the SEI interface precisely, especially to construct a nanoscale inorganic-dominated SEI with shortened diffusion path by controlling the oxidization state of Cu₂O film on Cu current collector. The highly stable cyclic performance is achieved by generating the thin SEI that contains dense inorganic inner layer and organic layer. Consequently, the lithium metal anode based on Cu₂O/Cu current collector exhibits low and stable polarization voltage for an ultralong life-span (∼22.5 mV at 1 mA cm⁻² for 3000 h). This work elucidates the relationship between lithiation reaction of oxides modified layer and derived SEI, guiding for constructing stable lithium metal batteries.