Carbon nanofiber linked FeS2 mesoporous nano-alloys as high capacity anodes for lithium-ion batteries and supercapacitors

Iron sulfide, commonly known as fool's gold, is rapidly emerging as an attractive material for both energy conversion (in photovoltaics) and energy storage, especially as an electrode in lithium-ion batteries. In this manuscript, we report on a simple one-pot two-step technique for synthesis of carbon nanofiber (CNF) cross-linked FeS2 networks, by microwave pyrolysis of ferrocene to iron decorated CNF and its subsequent sulfidation by a sustainable source, namely, L-cysteine. When used as the negative electrode in lithium-ion batteries, our 3D mesoporous FeS2-CNF hybrids exhibit high capacity of 994 mAhg(-1) even after 300 cycles, which exceeds the theoretical capacity of FeS2 (894 mAhg(-1)). Additionally, when applied as super-capacitor electrodes, our microwave-synthesized FeS2-CNF electrodes exhibit high capacitance of 612 and 342 Fg(-1) at 5 and 100 mVs(-1), respectively, and long-term cyclability, with 97% capacitance retention after 2000 cycles. (C) 2017 Elsevier B.V. All rights reserved.