Polydopamine Coating Layer Modified Current Collector for Dendrite-Free Li Metal Anode

Lithium metal is considered to be the most promising anode material due to its high theoretical capacity, low density and low electrochemical potential. However, continuous lithium dendrite growth results in low coulombic efficiency, capacity decay and safety hazard, which hinder the practical application of lithium metal anode. In this work, a functional polydopamine (PDA) layer inspired by nature is introduced to the surface of Cu foil, which is used as a current collector for lithium metal anode here. During depositing of lithium, lithium ions will firstly react with the hydroxyl groups of PDA layer, yielding uniformly distributed lithium complexing carbonyl groups which can work as nucleation sites and is favorable for uniform and stable deposition of lithium metal on the current collector, thus effectively suppress dendrite formation and growth. As a result, lithium metal batteries with PDA modified current collectors exhibit high coulombic efficiency of above 97% for 100 cycles at 0.5 mA cm^-2 and the Li/Li symmetric cells show more than 800 h stable repeated lithium plating and stripping. The LiFePO₄/Li batteries with the modified current collectors show extended cycle life (more than 150 cycles). This work provides a novel way to address the problems of lithium metal anode.