An efficient and versatile biopolishing strategy to construct high performance zinc anode

Conventional strategies for highly reversible Zn anodes usually involve complex and time-consuming production processes of current collectors, expensive and toxic electrolyte additives, or the introduction of inactive materials in protective layer. Here, we develop a fast, facile, and environmentally friendly biopolishing method to prepare dendrite-free Zn anodes, which merely involves the simple immersion of Zn foil in a biocompatible cysteine aqueous solution. The ravine structure formed by sulfhydryl etching for 30 min not only increases the electroactive area of Zn anode but also regulates the distribution of electric field and Zn ions, ensuring the homogeneous deposition and stripping of Zn ions. The biopolished Zn anode can be operated steadily for 2,000 h with a low voltage hysteresis at a current density of 1 mA·cm−2. In addition, Zn anodes with a cycle life of 500 h can be built by soaking for only 5 min, proving the high efficiency of the proposed method. This strategy is generalized to substances with sulfhydryl groups for polishing Zn electrodes with improved performance. The cysteine-polished Zn//activated carbon supercapacitor can stably run for 20,000 cycles without obvious capacity attenuation. The proposed strategy shows potential for producing advanced Zn anodes.