L-Cysteine-Assisted Synthesis of Cubic Pyrite/Nitrogen-Doped Graphene Composite as Anode Material for Lithium-ion Batteries

• We have demonstrated a new and general strategy to synthesize FeS2/nitrogen-doped graphene composite by an L-cysteine-assisted solution-phase method.
• Cubic FeS2 particles are uniformly distributed on the surface of nitrogen-doped graphene nanosheets.
• Nitrogen-doped graphene nanosheets can not only prevent the cubic FeS2 particles from aggregating, but also accommodate the volume change of cubic FeS2 particles during cycling.
• We have demonstrated that electrochemical performance of cubic FeS2 particles significantly improve with nitrogen-doped graphene.

Transition-metal sulfides have received increasing attention as electrode materials for high-performance Lithium-ion Batteries (LIBs). However, most of them are suffering from poor cycling stability and rate capability. Herein we report a new and facile strategy for synthesizing FeS2/nitrogen-doped graphene (FeS2/N-G) composite which shows improved electrochemical performance as an anode material for LIBs. The as-prepared FeS2/N-G (1:2, molar ratio) composite exhibits reversible discharge and charge capacities of 979 and 920 mAh g−1, respectively, with good cycling performance and rate capability. SEM and TEM results show that the cubic FeS2 are uniformly distributed on the surface of the nitrogen-doped graphene nanosheets (N-GNS) in the composite. The superior electrochemical performance of FeS2/N-G composite as LIBs anode is attributed to their robust composite structure and the synergistic effects between cubic FeS2 and N-GNS. This synthesis approach could open up new opportunities in the design and fabrication of energy storage devices.

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