Synergetic effect of Mo-doped and oxygen vacancies endows vanadium oxide with high-rate and long-life for aqueous zinc ion battery

Abstract

Vanadium (V)-based oxides have garnered significant attention as cathode materials for aqueous zinc-ion batteries (AZIBs) due to their multiple valences and high theoretical capacity. However, their sluggish kinetics and low conductivity remain major obstacles to practical applications. In this study, Mo-doped V2O3 with oxygen vacancies (OVs, Mo-V2O3-x@NC) is prepared from a Mo-doped V-metal organic framework. Ex situ characterizations reveal that the cathode undergoes an irreversible phase transformation from Mo-V2O3-x to Mo-V2O5-x·nH2O and serves as an active material exhibiting excellent Zn2+ storage in subsequent charge-discharge cycles. Mo-doped helps to further improve cycling stability and increases with increasing content. More importantly, the synergistic effect of Mo-doped and OVs not only effectively reduces the Zn2+ migration energy barrier, but also enhances reaction kinetics, and electrochemical performance. Consequently, the cathode demonstrates ultrafast electrochemical kinetics, showing a superior rate performance (190.9 mAh g−1 at 20 A g−1) and excellent long-term cycling stability (147.9 mAh g−1 at 20 A g−1 after 10000 cycles). Furthermore, the assembled pouch cell exhibits excellent cycling stability (313.6 mAh g−1 at 1 A g−1 after 1000 cycles), indicating promising application prospects. This work presents an effective strategy for designing and fabricating metal and OVs co-doped cathodes for high-performance AZIBs.