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

Abstract

FeCO 3 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 FeCO 3 /carbon nanofibers (CNFs) as a binder-free anode for high-performance LIBs has been synthesized by using a facile hydrothermal method. Porous FeCO 3 nanosheets grow in a stable manner on the surface of CNFs, and the flexible FeCO 3 /CNF film gives a specific surface area as high as 302.6 m 2 g À1 . The FeCO 3 /CNF film, with its porous architecture, provides open and continuous channels for fast diffusion of Li + to the active material of FeCO 3 , whereas the CNFs effectively play the leading role as the conductive core to efficiently transfer electrons for rapid lithiation/delithiation of FeCO 3 , and offer a buffering network to reduce the volume change during cycling. The hybrid FeCO 3 /CNF film, as a binderfree anode, delivers 592.2 mAh g À1 at the 3rd cycle and 546.2 mAh g À1 at the 200th cycle. As a comparison, bare FeCO 3 drops to 101 mAh g À1 at the 200th cycle. At a current density of 2 Ag À1 , FeCO 3 /CNF delivers 308.2 mAh g À1 , which is far higher than the 11 mAh g À1 of bare FeCO 3 and 52 mAh g À1 of bare CNFs. The FeCO 3 /CNF film presents an applicable hybrid structure as a binder-free anode material for ultrathin and ultralight energy-storage devices.

Hierarchical Ni(HCO3)2 Nanosheets Anchored on Carbon Nanofibers as Binder‐Free Anodes for Lithium‐Ion Batteries

“…The diffraction peaks completely match with the standard peaks of Ni(HCO 3 ) 2 (JCPDS 15‐0782) . The broad characteristic peak from 20° to 25° in the Ni(HCO 3 ) 2 /CNF composite corresponds to the amorphous structure of carbon, which is consistent with a previously reported work . As illustrated in XPS spectra shown in Figure a, the Ni 2p peaks centered at 857.2 and 875.0 eV are assigned to Ni 2+ , and two peaks at 862.6 and 880.9 eV correspond to the satellite peaks from Ni 2+ .…”

“…Zhao et. al prepared a sheath‐core hybrid of FeCO 3 /CNFs as a binder‐free anode that delivered a capacity of 546.2 mAh g −1 at the 200th cycle . Graphene‐decorated NiO nanowalls grown on porous Ni foam can maintain discharge/charge capacities of 732/722 mAh g −1 after 150 cycles at 125 mA g −1…”

Recent Progress and Challenges of Micro‐/Nanostructured Transition Metal Carbonate Anodes for Lithium Ion Batteries

“…Considering the excellent electronic conductivity and mechanical resilience, graphene was also utilized to integrate with FeCO 3 to enhance the electrochemical performance , , . For instance, Zhang et al adopted one‐pot hydrothermal route to prepare FeCO 3 nanoflakes embedded in graphene matrix .…”

“…(g) sheath/core hybrid FeCO 3 /CNF composites, and their comparison performances (c, f, h and i) with the corresponding bare FeCO 3 nanostructures. Reprinted from ref …”

“…Besides, other carbon‐based materials such as carbon nanofibers (CNF) have been explored to modify FeCO 3 anodes in LIBs. Zhao et al synthesized FeCO 3 sheet on CNF to construct sheath/core hybrid FeCO 3 /CNF composites . Relative investigation (Figure g) indicated that FeCO 3 nanosheets stably grew on the surface of carbon nanofibers.…”