High-capacity sulfide all-solid-state lithium battery with a conversion-type iron fluoride cathode†
Abstract
Transition metal fluoride-lithium batteries with low cost and high energy densities are considered hopeful candidates for next-generation rechargeable lithium batteries. However, conversion-type metal fluorides suffer from poor electronic conductivity, irreversible structural change, unfavorable dissolution of transition metal cations, high voltage hysteresis, and rapid capacity degradation upon cycling. In this study, reduced graphene oxide (rGO) sheets with uniformly anchored iron trifluoride (FeF3) composites are prepared by an in situ solvothermal approach. The rGO-FeF3 composites are combined with soft sulfide solid electrolytes to build sufficient electronic/ionic conductive pathways, which leads to substantial improvements in the electrochemical performances of FeF3 cathodes. In this work, an unprecedented reversible capacity of 742.7 mA h g−1 (569 mA h g−1) with extraordinary 119% capacity retention at 0.1C (0.4C) for 50 (120) cycles is achieved. Moreover, an outstanding reversible capacity of 409 mA h g−1 at 1C (1C = 500 mA g−1) with excellent stability of 300 cycles is also realized, which substantially surpasses the state-of-the-art performance for the FeF3 cathode in various battery systems at a similar current density. This research provides a novel strategy to overcome the limitations of transition metal fluorides and paves a new way for their practical applications in all-solid-state batteries.
- This article is part of the themed collection: Journal of Materials Chemistry A HOT Papers