Robust iron nanoparticles with graphitic shells for high-performance Ni-Fe battery

Aqueous Ni-Fe battery with high safety and low cost is a promising candidate for large-scale electrical energy storage; their performance, however, has been limited by the poor performance of the Fe electrodes. We reported herein a facile synthesis of Fe particles coated with graphitic shell for high-performance Fe anodes. The anodes exhibit a high capacity of 224 mAh g⁻¹ at a high current density of 32 A g⁻¹, and a high capacity retention of 90% after 1000 cycles. When coupled with a cathode made from the composites of Ni(OH)₂ and nitrogen-doped graphene, the battery delivers a high energy density of 136.7 Wh kg⁻¹ at power density of 0.7 kW kg⁻¹ or 71.4 Wh kg⁻¹ at 11.7 kW kg⁻¹ (based on the total mass of active materials). This work provides highly promising materials towards better Ni-Fe batteries.