Rational Synthesis of Fern Leaf-like FeS2@Sulfur-Doped Carbon as an Anode for Superior Lithium-Ion Batteries

Fern leaf-like FeS2@sulfur-doped carbon (SC) composites are synthesized through a sulfuration process using fern leaf-like γ-Fe2O3@C as the raw material. The design of combining fern leaf-like FeS2 with SC layers is favorable to enhancing the electronic conductivity of FeS2 and buffering the severe volume change associated with the pulverization issue that exists in most metal sulfide-based electrodes. When the fern leaf-like FeS2@SC composite serves as an anode for lithium-ion batteries, it can deliver high first discharge capacities of 1656.6 and 1364.7 mA h g–1 at a low density of 0.1 A g–1 and a high current density of 5 A g–1. Besides, benefiting from the structural advantages, the FeS2@SC composite shows superior rate capability (442.5 mA h g–1 at 5 A g–1) and cyclability (848.9 mA h g–1 at 1 A g–1 after 300 cycles, corresponding to 89.14% of the second discharge specific capacity). The enhanced electrochemical performance of FeS2@SC can be ascribed to the synergistic effect of the hierarchical fern leaf-like FeS2 microstructure and the sulfur-doped carbon coating layer.