Two-pronged approach to achieving high-capacity and long stable-life aqueous Zn-ion batteries

Abstract

Rechargeable Zn-ion batteries (ZIBs) have attracted much attention due to their high energy density, high safety, and low cost. Nevertheless, the practical implementation of ZIBs has been dreadfully hindered by the lack of stable high-capacity cathode candidate and serious dendritic growth in Zn anode. Superior device-level performance can only be achieved by simultaneously addressing the fatal shortcomings of both electrodes. Herein, we explore a two-pronged approach to achieving high-capacity, long-life stable ZIBs via synergistic design in both anodes and cathodes. Specifically, hierarchical accordion-like ZnV2O4@C (A-ZVO@C) framework derived from multi-layered V2CTx is fabricated and endowed with high electronic/ionic conductivities and structural/chemical stability, exhibiting striking high-rate capacities/stability when utilized as a cathode. Meanwhile, a dendrite-free Zn with an artificial protective layer of zincophilic ZnO/C hollow spheres affords outstanding Zn plating-stripping stability with a prolonged lifespan, which reduces local current density, homogenizes Zn2+ ion diffusion/deposition, and suppresses volume changes during long-term plating/stripping. As a result, the assembled full ZIBs deliver a high-rate capacity of 232.2 mAh g−1 at 8 A g−1, and superb stability with capacity degradation of 7.8 % over 3000 consecutive cycles at 15.0 A g−1. More meaningfully, the contribution here provides an essential guidance for rationally designing next-generation ZIBs.