FeS/C composite as high-performance anode material for alkaline nickel-iron rechargeable batteries

FeS and its composite, FeS/C, are synthesized via a simple calcination method followed by a co-precipitation process. The electrochemical properties of the bare FeS and FeS/C composite as anode materials for alkaline nickel-iron batteries are investigated. The results show that the FeS/C-3wt%Bi2O3-mixed electrode delivers a high specific capacity of 325 mAh g−1 at a current density of 300 mA g−1 with a faradaic efficiency of 90.3% and retains 99.2% of the initial capacity after 200 cycles. For the first time, it is demonstrated that even at a discharge rate as high as 1500 mA g−1 (5C) the FeS/C-3wt%Bi2O3-mixed electrode delivers a specific capacity of nearly 230 mAh g−1. SEM results confirm that after 200 discharge-charge cycles, the size of FeS/C particles reduces from 5 to 15 μm to less than 300 nm in diameter and the particles are highly dispersed on the surface of carbon black, which is likely caused by the dissolution-deposition process of Fe(OH)2 and Fe via intermediate iron species. As a result, the FeS/C composite exhibits considerably high charge efficiency, high discharge capacities, excellent rate capability and superior cycling stability. We believe that this composite is a potential candidate of high-performance anode materials for alkaline iron-based rechargeable batteries.