Confined Synthesis of FeS2 Nanoparticles Encapsulated in Carbon Nanotube Hybrids for Ultrastable Lithium-Ion Batteries

To address the large volume change and polysulfide dissolution of FeS2-based materials for lithium-ion batteries (LIBs), we demonstrate the synthesis of FeS2 nanoparticles encapsulated in carbon nanotubes (CNTs) by a confined reaction. There is sufficient void space between adjacent FeS2 nanoparticles for guaranteeing the highly structural integrity. The resultant FeS2/CNT hybrids, when served as anode materials for LIBs, predictably exhibit a very stable capacity retention of 800 mAh g(-1) over 200 cycles at 200 mA g(-1). Even at 2000 mA g(-1), they still deliver high-rate and long-life performance with a high specific capacity of 525 mAh g(-1) after 1000 cycles. Such a kind of encapsulated structure is helpful for enhancing rate capability and cycling stability in LIBs applications. Importantly, the present confined reaction strategy can be extensively applied to synthesize other analogous hybrids for energy storage and conversion.