Growing mulberry-like copper on copper current collector for stable lithium metal battery anodes

Due to the uncontrollable growth of lithium dendrites and the considerable volume change of lithium during cycling, the practical application of lithium metal batteries has stalled. The current collector with a 3D structure has been demonstrated to effectively inhibit the growth of lithium dendrites and mitigate the volume change of lithium, which can effectively promote the practical application of lithium metal batteries. The conventional electrodeposition method for constructing 3D structures on the surface of a copper current collector is prone to forming dendritic structures with sharp surfaces. However, the dendritic structure is susceptible to the tip effect, resulting in inhomogeneous lithium deposition. In this study, PAA molecules are adsorbed on the surface of copper to hinder and disperse its growth during electrodeposition, optimizing its growth mode. Thus, mulberry-like copper with a biomimetic structure is prepared on the surface of copper foil (M-CF). The mulberry structure not only provides additional electrochemically active sites and robust conductive frameworks for lithium deposition, it also efficiently mitigates the electric field concentration at the 3D structure's tip, optimizes lithium-ion transport flux, suppresses the growth of lithium dendrites. As a result, the M-CF anode is capable of stable Li plating/stripping over 500 cycles with a high average CE of 98.1 %. The assembled symmetrical battery is stably cycled over 1600 h at a low voltage hysteresis of 11 mV. The full cells paired with M-CF-Li-6 (Li: 6 mAh cm^-2) anodes and LTO cathodes stably cycle more than 500 cycles, and the capacity retention rate is 95.3 %.