Suppressing vanadium dissolution in 2D V2O5/MXene heterostructures via organic/aqueous hybrid electrolyte for stable zinc ion batteries

Abstract

Zinc ion batteries (ZIBs) have become a promising candidate for next-generation large-scale energy storage devices due to the intrinsic safety and low cost. However, their practical applications are seriously impeded by unsatisfying cycling life mainly due to the cathode dissolution in traditional aqueous electrolytes. Herein, we propose an organic/aqueous hybrid electrolyte (Zn(OTf)2-TEP/H2O) made of zinc triflate (Zn(OTf)2) salt in triethyl phosphate (TEP) and H2O solvents to pair with two-dimensional (2D) vanadium hydrate oxide/Ti3C2 MXene heterostructure cathodes (V2O5·1.6H2O/MXene), which functions to greatly enhance the stability of the ZIBs. Benefiting from the suitable ionic conductivity of 5.81 mS cm−1, moderate de-solvation barrier of 0.26 eV, wide voltage window of 0.1–1.9 V and superior ability of inhibiting vanadium dissolution, the optimized organic/aqueous hybrid electrolyte with 80 % TEP in volume (Zn(OTf)2-TEP/H2O-80%) endowed V2O5·1.6H2O/MXene cathodes with superior zinc storage performance, evidenced by a high capacity of 117.8 mAh g−1 after 4000 cycles and a capacity retention of 78.6 % at 0.5 A g−1. We have shown that the reversible Zn2+ intercalation/deintercalation mechanisms are responsible for the excellent zinc storage performance. It is believed that the novel organic/aqueous hybrid electrolyte reported here may pave a new way to construct durable ZIBs.