FeSe₂ Graphite Intercalation Compound as Anode Materials for Sodium Ion Batteries

Based on theoretical calculations, the molecule predominantly generated by the combination of sodium with graphite is identified as NaC186. Consequently, this compound has a relatively limited capacity for sodium storage, amounting to only 36 mA h g(-1). In this study, we construct FeSe2 graphite intercalation compounds (FeSe2-GIC) by in situ inserting FeSe2 between the graphite interlayers by a hydrothermal process. The resulting FeSe2-GIC material is then subjected to ball milling to form the FeSe2-GIC-BM. The FeSe2 material was found to be tightly intercalated within the graphite layers, resulting in a limited volume expansion and improved electrical conductivity. The electrochemical test results indicate that the FeSe2-GIC-BM anode exhibits a remarkable electrochemical performance. It exhibits an initial specific discharge capacity of 676.2 mA h g(-1) at a current density of 0.1 A g(-1) and a specific discharge capacity of 425.0 mA h g(-1) at a current density of 5 A g(-1). After 1200 cycles, the observed reversible capacity remains at 182.9 mA h g(-1). The exceptional storage and cycling characteristics can be attributed to the distinctive layered structure.