Lithiophilic hyperbranched Cu nanostructure for stable Li metal anodes

Porous copper (Cu) current collectors are regarded as a promising host for stabilizing lithium (Li) metal anodes but suffer from uncontrollable Li metal deposition due to the intrinsic lithiophobic nature of Cu. This study proposes a vertically aligned Cu host with hyperbranched Cu_xO nanostructure to provide lithiophilic nucleation sites for homogeneous Li metal deposition. Specifically, the vertically aligned Cu nanostructure dramatically reduces the local current density and brings homogeneous Li-ion flux. The lithiophilic hyperbranched Cu_xO nanostructure with a low nucleation barrier could induce homogeneous Li nucleation and growth. As a result, the Cu@Cu_xO nanostructured host exhibits a low nucleation overpotential of 44.3 mV and achieves highly electrochemical reversibility with high Coulombic efficiency of 98.33% in a half-cell. The Cu@Cu_xO nanostructured electrode is capable of working under different current densities varying from 0.5 to 5 mA/cm² in a symmetric cell. The assembled full cell coupling of the Li/Cu@Cu_xO composite anode with the LiFePO₄ cathode manifests stable long-term cycling life at 1 C. This study elaborates on the synergistic effect of electrode structure design and interfacial chemistry modification to regulate the Li deposition/dissolution behavior, thus exhibiting remarkable electrochemical performances for next-generation Li-metal batteries.