Lithiophilic and Conductive CuO-Cu₂O-Cu Microspheres with Controlled Void Structure via Spray Pyrolysis for Improved Lithium Metal Anode Performance

Lithium metal anodes (LMAs) have attracted significant attention owing to their high theoretical capacity and lowest redox potential. However, dendritic growth of lithium limits its practical application. Controlling lithium deposition through structuring host materials for LMAs has been widely studied. In this study, a unique structured CuO-Cu2O-Cu composite microsphere is synthesized through facile one-step spray pyrolysis process as a new lithium host material for LMAs. During lithium deposition, lithium ions preferred to be adsorbed on composite microspheres due to the electric field generated from the metallic Cu-based conductive matrix. The adsorbed ions reacted with lithiophilic copper oxides to form copper and Li2O, promoting the generation of a uniform electric field and ion transfer. Moreover, hollow structure can guide lithium to be encapsulated inside the structures, enabling effective suppression of dendritic lithium growth. As a result, this composite microsphere is capable to store lithium with high areal capacity of 5.0 mAh cm-2 without dendritic growth of lithium. Consequently, the composite microspheres exhibit a coulombic efficiency above 99% for more than 200 cycles at a current density of 1.0 mA cm-2 as an asymmetric cell and show low voltage hysteresis of 19 mV for more than 1,000 h as a symmetric cell. This study demonstrates that the designed microstructures with an appropriate ratio of conductive and lithiophilic matrices with sufficient pore structures provide promising cycle performance as host materials for lithium metal anode.