Industrial VN@reduced graphene oxide cathode for aqueous zinc ion batteries with high rate capability and long cycle stability

Abstract

Aqueous zinc ion batteries (ZIBs) have the advantages of environmental friendliness, high safety and high energy density. In this work, we modify the industrial vanadium nitride (VN) with the high conductivity of realized graphene oxide (rGO), and the VN@rGO electrode has high rate capability and long cycle stability. Through the charge-discharge test, VN@rGO has 267.0 mA h g −1 specific capacity and 94.68% capacity retention rate at 1 A g −1 current density after 585 cycles, and 125.6 mA h g −1 specific capacity and 91.24% capacity retention rate at 20 A g −1 current density after 10,900 cycles. Through kinetic study, rGO can accelerate the redox reaction on the electrode surface and improve the electrode pseudocapacitive by accelerating the electron transport. Through ex situ characterization, VN will convert to V 5 O 12 ·6H 2 O in the first charge, and the electrode activation process is creating holes in the electrode surface by deposition/dissolution of Zn 4 SO 4 (OH) 6 ·5H 2 O. The VN@rGO electrode can provide 69.28–246.5 W h kg −1 energy density and 78.16–10938.95 W kg −1 power density, which can drive light emitting diode and motors, and have good practicality. • VN@rGO preparation is simple and low cost (atmospheric pressure, 80 °C). • The electrode has high stability with 91% capacity retention after 10,900 cycles. • The electrode has high energy density and power density. • The activation is confirmed by the deposition/dissolution of Zn 4 SO 4 (OH) 6 ·5H 2 O.