Dendrite-Free Lithium Anodes Enabled by a Commonly Used Copper Antirusting Agent

Li metal is considered the most promising anode for high energy density secondary batteries due to its high theoretical capacity and low redox potential. However, lithium is prone to form dendrites which will not only cause internal short-circuits but also bring accumulation of "dead Li" and result in fast capacity decay, thus its large-scale application is challenging. In this work, we demonstrate that the commonly used metal corrosion inhibitor, benzotriazole (BTA), can be used to modify the Cu foil surface and guide homogeneous Li+ plating/stripping due to the lithiophilic nature of the N atom in the BTA molecule. As a result, the lithium plated on the BTA modified Cu (BTA-Cu) substrate is free of dendrites, and a Coulombic efficiency (CE) as high as 99.0% was achieved for Li+ plating/stripping on the BTA-Cu substrate at a current density of 1 mA/cm2. Furthermore, the BTA-Cu foil can be used as an anode to assemble an anode-free cell (BTA-Cu∥LFP), and ∼73.3% of the initial capacity can be obtained after 50 cycles. Last but not the least, a BTA-Cu@Li electrode prepared by plating of Li+ on the BTA-Cu substrate can serve as a stable Li anode in a BTA-Cu@Li∥LFP cell and display an average cycled CE of 98.5% at a depth of discharge (DOD) of 33%. This simple method of Li+ plating/stripping behavior regulation could inspire researchers on the development of highly stable lithium metal anodes for high energy density batteries.