Sublimation-assisted formation of hollow N-doped graphitic carbon/ reduced graphene oxide frameworks hosting biphasic iron selenide nanocrystals for high performance sodium-ion storage

초록

Achieving fast reaction kinetics and robust structural stability under repeated sodiation/de-sodiation cycling is essential for high-rate and long-life sodium-ion batteries (SIBs). In this work, a sublimation-driven architecture engineering strategy is introduced to construct hollow N-doped graphitic carbon/reduced graphene oxide (NGC/ rGO) frameworks hosting uniformly dispersed biphasic iron selenide nanocrystals (FeSe2/Fe3Se4), denoted as FexSey@NGC/rGO HNFs. This hierarchical structure integrates three synergistic design elements: (i) camphenetemplated hollow tunnels that provide uninterrupted ion-diffusion channels and exceptional stress-buffering capability, (ii) a conductive NGC/rGO dual-carbon network that ensures rapid electron transport and stabilizes the interphase during deep sodiation, and (iii) a complementary FeSe2/Fe3Se4 biphasic composition that enables phase-dependent reaction pathways, enhancing reversibility and accelerating conversion kinetics. Benefiting from this multi-level structural and compositional synergy, the FexSey@NGC/rGO HNF anode delivers outstanding rate capability up to 10.0 A g-1 and remarkable long-term cycling stability at 0.5-2.0 A g-1, outperforming most iron selenide-based anodes reported to date. This work demonstrates a generalizable materials-design paradigm that combines sublimation-induced hollow carbon frameworks with phase-engineered chalcogenides to advance next-generation SIBs for large-scale energy storage.

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