2D anionic nanosheet additive for stable Zn metal anodes in aqueous electrolyte

Abstract

• A novel anionic nanosheet electrolyte additive was proposed in aqueous Zn batteries. • High reversibility, evidenced by a high average CE as high as 99.6%, is achieved. • Long-term cycling, reflected by Zn plating/stripping over 3700 h, is attained. Metallic Zinc (Zn) has attracted great attention as a promising anode for aqueous batteries owing to its high theoretical capacity, low cost, and high natural abundance. However, Zn anode suffers from a crucial challenge, namely the growth of Zn dendrites, which brings not only a short life span but also severe safety concerns. In this work, we report that anionic tin sulfide nanosheets (TS-Ns) server as electrolyte additive to mitigate the dendrite growth. The negatively charge TS-Ns can attract the positive Zn 2+ from the electrolyte through electrostatic interaction and increase the local concentration of Zn 2+ . Moreover, TS-Ns can co-deposit with Zn 2+ at the initial deposition stage and then form an interfacial protection layer around the Zn surface, guiding the uniform deposition of Zn on cycling. The TS-Ns additive endow the Zn anode with excellent performance, reflected by stable cycling for 3700 h in a symmetric cell with a capacity of 0.2 mAh /cm 2 and for 500 cycles in an asymmetric cell with an average coulombic efficiency of 99.6%. These merits bring high capacity and low polarization in Zn||MnO 2 full cells. We believe that TS-Ns additive provides a new pathway to achieve high-performance Zn metal anodes in aqueous electrolytes.