Fef3·0.33h2o@C Nanocomposites Derived from Pomegranate Structure as High-Performance Cathodes for Sodium- and Lithium-Ion Batteries

Abstract

Abstract:Iron fluoride is an excellent cathode material for alkali metal-ion batteries due to its high operating voltage and extremely high specific discharge capacity. To overcome its voltage hysteresis and compensate for capacity fading due to volume change and electrode dissolution, a FeF 3 ·0.33H 2 O@carbon nanocomposite with a pomegranate-like structure (FeF 3 ·0.33H 2 O@C) is designed and successfully synthesized via hydrothermal synthesis followed by a solid-phase process. The FeF 3 ·0.33H 2 O@C nanocomposite derived from pomegranate structure effectively can reduce electrode polarization via its unique hierarchical carbon-coated architecture. Additionally, combining other structural advantages (e.g., coordination of volume expansion, reduction of Fe dissolution, and inhibition of nanoparticle coarsening) can result in high reversibility and rate performance. The nanocomposite cathode demonstrates a discharging capacity of 225 mAh g -1 at 0.1C in a galvanostatic charging/discharging test in lithium-ion batteries, as well as an excellent long-cycle performance with a capacity retention rate of 93% after 200 cycles. When the cathode materials are used in sodium-ion batteries, the nanocomposite cathode achieves an exceptionally high energy density of 1015 W·h kg -1 , which is more than twice that of the commercial LiCoO 4 cathode (504 Wh kg -1 ).

Keywords: Lithium-ion battery cathode, Sodium-ion battery cathode, Iron fluoride, Electrode polarization, Pomegranate structure