Sheath/Core Hybrid FeCO3/Carbon Nanofibers as Anode Materials for Superior Cycling Stability and Rate Performance

Abstract

AbstractFeCO3 is a potential anode material, owing to advantages such as facile synthesis, low cost, and abundant natural resources, but its poor cyclic stability and low rate performance seriously limit practical applications in lithium‐ion batteries (LIBs). In this paper, the sheath/core hybrid of FeCO3/carbon nanofibers (CNFs) as a binder‐free anode for high‐performance LIBs has been synthesized by using a facile hydrothermal method. Porous FeCO3 nanosheets grow in a stable manner on the surface of CNFs, and the flexible FeCO3/CNF film gives a specific surface area as high as 302.6 m2 g−1. The FeCO3/CNF film, with its porous architecture, provides open and continuous channels for fast diffusion of Li+ to the active material of FeCO3, whereas the CNFs effectively play the leading role as the conductive core to efficiently transfer electrons for rapid lithiation/delithiation of FeCO3, and offer a buffering network to reduce the volume change during cycling. The hybrid FeCO3/CNF film, as a binder‐free anode, delivers 592.2 mAh g−1 at the 3rd cycle and 546.2 mAh g−1 at the 200th cycle. As a comparison, bare FeCO3 drops to 101 mAh g−1 at the 200th cycle. At a current density of 2 A g−1, FeCO3/CNF delivers 308.2 mAh g−1, which is far higher than the 11 mAh g−1 of bare FeCO3 and 52 mAh g−1 of bare CNFs. The FeCO3/CNF film presents an applicable hybrid structure as a binder‐free anode material for ultrathin and ultralight energy‐storage devices.