Dense cuprous oxide sheath decorated three-dimensional copper foam enabling stable lithium metal anodes

Uneven lithium deposition causing the growth of lithium dendrites is a major obstacle to the practical application of high-energy lithium metal batteries. In this study, a simple hydrothermal reaction is adopted to evenly coat copper foam (CF) with cuprous oxide particles. The resulting three-dimensional composite current collector can achieve dendrite-free lithium plating. Control experiments show that FeF₃ is a better oxidant than FeCl₃ for creating a more uniform and dense cuprous oxide coating on the CF. It is also found that the reaction temperature plays a crucial role in determining the thickness of the coating layer. Furthermore, the electrochemical experimental results confirm that a dense and uniform coating layer with an appropriate thickness is essential in achieving high coulombic efficiency (CE) for CF current collectors. The CF with the optimal coating exhibits only a small nucleation overvoltage (15 mV) and high CE (98% retention after 120 cycles) at a current density of 1.0 mA cm⁻² and a Li deposition of 1.0 mA h cm⁻² in an ether electrolyte without lithium nitrate.