2D Anionic Nanosheet Additive for Stable Zn Metal Anodes in Aqueous Electrolyte

Abstract 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 an anionic tin sulfide nanosheets (TS-Ns) server as electrolyte additive to mitigate the dendrite growth. The negatively charge TS-Ns can attract the positive Zn2+ through electrostatic interaction from the electrolyte and increase the local concentration of Zn2+. Moreover, TS-Ns can co-deposit with Zn2+ 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 /cm2 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||MnO2 full cells. We believe that TS-Ns additive provides a new pathway to achieve high-performance Zn metal anodes in aqueous electrolytes.