N-Rich carbon as Zn2+ modulation layers for dendrite-free, highly reversible zinc anodes

Abstract

Metal zinc is considered one of the most potential anodes due to its energy density, safety, and cost-effectiveness. However, severe side reactions and unwanted dendrite growth during cycling make the stability of Zn metal anodes far from satisfactory. Herein, we rationally design a highly conductive carbon with abundant nitrogen and constructs it as a homogeneous layer on the Zn anode (denoted as CN-Zn) via the Langmuir-Blodgett method. CN-Zn not only features chemically stable in aqueous electrolytes with the corrosion-inhibition layer but also provides the nucleation sites for Zn2+ to induce the uniform deposition of Zn2+. With such a synergy effect, the CN-Zn||CN-Zn symmetrical cell can deliver a high capacity (5 mAh cm−2) and exhibit a prolonged reversible plating/stripping lifespan for more than 1300 h with an ultralow overpotential (24 mV) at 1 mAh cm−2. Furthermore, the CN-Zn||MnO2 pouch cell also achieves outstanding electrochemical performance with a discharge capacity of 116 mAh/g at 5 mA, which provides high dependability of aqueous Zn batteries for commercial application.