A novel "caterpillar with eggs" mesostructured iron sulfide as an anode for a Li-ion battery displaying stable electrochemical performance.

Emerging anodes are important for high energy-density lithium-ion batteries. Here, we present a mesostructured FeS 2 comprising nanoparticles embedded in a nanoneedle-assembled nanotube to form a novel "caterpillar with eggs" (CWE) structure. The voids alleviated the volumetric change upon charge-discharge; the nanoneedles-assembled shell provided rapid transport pathways for ions and electrons. The FeS 2 anode exhibited a high capacity of 805.1 mA h g -1 after 500 cycles at 2 A g -1 . When cycling at -10 °C and 45 °C, the anode provided capacities of 754.5 and 744.4 mA h g -1 after 100 cycles at 1 A g -1 , respectively. This good electrochemical performance will enable our special design to find broad applications for developing high-performance energy-storage systems.