Zn and S in situ-doped vanadium-based metal–organic framework derivatives for aqueous zinc ion batteries

Abstract

Cathode materials with excellent performance are a key to exploiting aqueous zinc ion batteries. In this study, we developed a cathode material for aqueous zinc ion batteries using an in situ anion–cation pre-intercalation strategy with a metal–organic framework. In situ doping of S and Zn in a vanadium-based metal–organic framework structure forms a Zn–S pre-intercalated vanadium oxide ((Zn, S)VO) composite. The combination of the additional Zn²⁺ storage sites with pseudocapacitive behavior on the amorphous surface of the enriched oxygen defects and the enhancement of the structural toughness by strong ionic bonding together the unique nanostructure of the nanochains by the process of “oriented attachment” led to the preparation of the high-performance (Zn, S)VO composite. The results show that the (Zn, S)VO electrode has a capacity of 602.40 mAh·g⁻¹ at 0.1 A·g⁻¹, an initial discharge capacity of 300.60 mAh·g⁻¹ at 10.0 A·g⁻¹, and a capacity retention rate of 99.93% after 3,500 cycles. Using the gel electrolyte, the capacity of (Zn, S)VO electrode is 233.15 and 650.93 mAh·g⁻¹ at 0.2 A·g⁻¹ in − 20 and 60 °C environments, respectively. Meanwhile, the (Zn, S)VO flexible batteries perform well in harsh environments.