Fe2VO4@N−C cathode for high performance aqueous zinc and ammonium-ion batteries

Abstract

Fe₂VO₄(FVO) has a high specific capacity and abundant material resources. However, due to volume expansion, its capacity decreases rapidly at high current density. In this paper, FVO@N−C is designed by dopamine coating on the surface of FVO, it can effectively adsorb Fe²⁺ and inhibit the hydrolysis of FVO. At a current density of 0.1 A g⁻¹, the specific discharge capacity is measured at 330 mAh g⁻¹. And when the current density increases to 10 A g⁻¹, the specific discharge capacity attains 100 mAh g⁻¹ after 2000 cycles. Combined with the projection density of state and migration path, it proves that PDA coating improves the ionic conductivity and promotes the transport of zinc ions. In order to prove the applicability of FVO@N−C electrode in aqueous battery, we applied the FVO@N−C electrode to the ammonium ion battery system for electrochemical performance testing. In ammonium ion batteries, whereas the discharge specific capacity of FVO@N−C reaches 150 mAh g⁻¹ at the current density of 0.1 A g⁻¹, and the capacity retention rate is close to 100 % at the current density of 2 A g⁻¹. The superior electrochemical performance proves that it is an ideal cathode material for zinc and ammonium ion batteries.