Dual-carbon phase-protective cobalt sulfide nanoparticles with cable-type and mesoporous nanostructure for enhanced cycling stability in sodium and lithium ion batteries

A type of sandwich-type and mesoporous CoS-based coaxial nanocables with conductive CNT backbone core, well-confined CoS nanoparticle interlayer and conformal carbon coating shell (denoted as CNT@CoS@C) are developed through a bottom-up method and investigated as potential anode materials for sodium/lithium ion storage. The rationally constructed architecture successively achieves the integration of one-dimensional conducting networks, ultrafine active nanoparticles, well-developed mesoporosity and sophisticated surface modification via a layer-by-layer assembly strategy, thus upholding good structural/interfacial robustness and enhanced charge-transfer reaction kinetics. As a result, the CNT@CoS@C coaxial nanocables exhibit a high reversible capacity of 494 mAh g−1, stable cycling with more than 318 mAh g−1 at 500 mA g−1 over 500 cycles (corresponding to 74% capacity retention with 0.05% decay rate per cycle) and impressive rate capability (278 mAh g−1 at 5000 mA g−1) for sodium ion batteries (SIBs) and excellent electrochemical performance for lithium ion batteries (LIBs) (1010 mAh g−1 during 200 cycles with no capacity loss and 467 mAh g−1 at 5000 mA g−1). In addition, the electrochemical experimental results and simulated calculations suggest that the CoS-based active species possesses better electrochemical properties in term of reaction reversibility and structural stability than its Co3O4-based counterpart with similar morphological features.

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