Taming Lithium Nucleation and Growth on Cu Current Collector by Electrochemical Activation of ZnF₂ Layer

Lithium-metal anodes are essential for the advancement of next-generation batteries. However, their practical use is largely hindered by the uncontrollable growth of dendrites and intricate problems associated with fabricating anodes that meet capacity requirements. Here, it is demonstrated that an ultrathin ZnF₂ layer deposited on the copper foil can produce a novel and efficient current collector to address these challenges. It is observed that ZnF₂ can be transformed into LiZn alloy and LiF salt in one step by simple electrochemical activation. The resulting LiZn alloy exhibits high lithiophilicity, which reduces overpotential and promotes uniform lithium nucleation, while the LiF salt enhances the solid electrolyte interphase, ensuring uniform lithium growth. This synergistic effect led to a dendrite-free, densely packed lithium anode with an extended lifespan, achieving over 900 h in symmetric cells at a high current density of 3 mA cm^-2 and a high cut-off capacity of 3 mAh cm^-2. Furthermore, full cells utilizing the lithium anode (Li capacity of 6 mAh cm^-2) paired with LiNi_0.8Mn_0.1Co_0.1O₂ cathodes (mass loading of 11.5 mg cm^-2) demonstrates drastically improved rate capability and excellent cycling stability. This approach holds great promise for developing safer and more efficient lithium-metal-based batteries for future energy storage solutions.