Interfacial modulation of Cu2S/CuS nanodomains embedded in MOF-derived carbon matrix on hollow-structured titanoniobate for ultrastable sodium-ion batteries

초록

Two-dimensional titanoniobate (TiNbO5/Ti2Nb2O9) nanosheets, characterized by their wide interlayer spacing and high ionic conductivity, are promising anode materials for sodium-ion batteries (SIBs), offering high-rate capability and long-term cycling stability. Therefore, this study aims to develop a novel TiNbO5/Ti2Nb2O9based hybrid anode material-Cu2S/CuS/N-doped nanocarbon-coated TiNbO5/Ti2Nb2O9 hollow spheres (Cu2S/ CuS/NNC/TNO-HS)-designed for high-rate capability and long-term stability in SIB anodes. This hierarchical hollow-sphere nanoarchitecture was fabricated through a layer-by-layer self-assembly strategy using N-doped Cu-BTC metal-organic frameworks (N-Cu-BTC-MOF, also known as N-HKUST-1), followed by sulfurization and carbonization processes. TiNbO5/Ti2Nb2O9 nanosheets served as robust structural scaffolds, offering wide interlayer spacing and superior ionic conductivity. Simultaneously, the Cu2S/CuS and N-doped nanocarbon layers enhanced electrical conductivity while introducing abundant redox-active sites. The resulting composite effectively mitigated volume changes during cycling, reduced interfacial resistance, and facilitated rapid ion diffusion. The Cu2S/CuS/NNC/TNO-HS anode demonstrated outstanding long-term performance, maintaining a reversible capacity of 356.6 mA h g- 1 after 1,000 cycles at 100 mA g- 1 and 137.4 mA h g- 1 after 3,000 cycles at 5.0 A g- 1 with 89 % capacity retention. The composite also exhibited superior rate capability and stable pseudocapacitive behavior, highlighting its potential as a high-performance anode material for large-scale SIB energy storage systems.

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