Ultra-long KFeS 2 nanowires grown on Fe foam as a high-performance anode for aqueous solid-state energy storage

The development of low-cost and high-activity Fe-based anodic materials is very promising for the present solid-state energy storage. In this work, we successfully synthesize ultra-long KFeS 2 nanowires on an Fe foam substrate via a simple hydrothermal strategy. Physical characterization shows that the as-synthesized KFeS 2 nanowires possess merits of good morphological uniformity, considerable mass loading (∼76 mg cm −2 ) and strong affinity for the substrate. As an anode for solid-state energy storage, the areal capacity of the KFeS 2 electrode can reach 21.1 mA h cm −2 (at 50 mA cm −2 ), which is greatly enhanced as compared to the previous best result (