Fe1-xS/reduced graphene oxide composite as anode material for aqueous rechargeable Ni/Fe batteries

Abstract

Owing to the abundant resources of Ni and Fe elements, aqueous Ni/Fe battery has emerged as an attractive electrochemical energy storage device. However, the performance of the Ni/Fe battery is largely limited by the low specific capacity and poor discharge rate capacity of the Fe electrodes. Herein, we report a new Fe1-xS/reduced graphene oxide composite (Fe1-xS@rGO composite) as anode material for high performance Ni/Fe batteries. In the composite, the highly conductive rGO sheets wrap the Fe1-xS particle sheets, creating a compact sheet-particle interface and thereby greatly improving the conductivity of the anode electrode. Moreover, the Fe1-xS particle sheets of nanosized architectures and the rGO sheets can effectively prevent the crystal unit cell changes and the aggregation/dissolution of the Fe1-xS particle sheets. Consequently, the resultant Fe1-xS@rGO electrode delivers a specific capacity of ∼320, 282, 270 and 120 mAh g−1 at a current density of 0.3, 0.6, 1, and 10 A g−1, respectively, exhibiting high specific capacity and high rate capacity. Moreover, the Fe1-xS@rGO electrode exhibits a long cycling stability, with 83.3% of initial capacity retained after 100 cycles at 1 A g−1. These results suggest that the Fe1-xS@rGO composite is a promising anode material for practical Ni/Fe battery.