Chemical vapor transport derived SnSe₂ nanowires within multi-walled carbon nanotubes as high-performance conversion-alloying anode for lithium-ion batteries

Conversion-alloying anodes such as SnSe₂ offer high theoretical capacity, but its usage is limited by slow kinetics, large volume expansion and unstable solid electrolyte interphase formation. An internal-confinement strategy is reported here: SnSe₂ nanowires grown inside multi-walled carbon nanotube channels via temperature gradient and mineralizer-assisted vapor-phase transport method. Unlike conventional vapor or liquid phase methods that achieve surface decoration, this approach could eliminate active SnSe₂ loss and alleviate volume expansion. The SnSe₂@MWCNTs anode delivers superior cycling stability with 730 mAh g −1 retained after 400 cycles at 0.5 A g −1 and a sound energy density of 224.0 Wh/kg with a power density of 580.5 W/kg in full cells (vs. LiFePO₄). The performance advantage originates from three effects: shortened Li + diffusion paths, elastic buffering with preserved electronic contact by the nanotube walls, and a stable SEI film on the stable carbon walls. These effects are consistent with galvanostatic intermittent titration technique, in-situ electrochemical impedance spectroscopy, DFT calculations, and ex-situ TEM. This scalable internal-confinement principle overcomes core limitations of layered dichalcogenide and conversion-alloying anodes, providing a general route to high-energy-density and long-cycle-life lithium-ion batteries.