Construction of Co9S8/SnS heterostructures encapsulated in multi-channel carbon nanofibers as long-term stable anodes for sodium-ion batteries

This study presents the design and fabrication of multi-channel self-supported anode materials Co9S8/SnS@MCNFs, through the electrospinning technique. The high compatibility of Co9S8 and SnS at the interface enables the synthesis of a more complete heterostructure within the material, enhancing the electrochemical reaction process through rational heterostructure design. Additionally, the incorporation of high theoretical capacity SnS improves sodium storage performance. The design of multi-channel carbon nanofibers (MCNFs) effectively addresses challenges such as material volume expansion and metal particle aggregation during cycling by providing large specific surface areas and enabling carbon encapsulation. The resulting pore structure and heterostructure formation, coupled with introduction of more defects, enhance the availability of Na+ active sites for electrochemically reversible processes. As expected, Co9S8/SnS@MCNFs exhibit remarkable initial coulombic efficiency (ICE = 92.6 %) and demonstrate stable long-term cycling performance (222.5 mA h g−1 at 2 A g−1 after 400 cycles) for sodium storage, with only a 0.18 % decay rate per cycle. These findings suggest promising application for the electrode material in sustained high-current discharges and long-endurance performance. •Self-supported Co9S8/SnS@MCNFs electrode is prepared through electrospinning method.•Rational heterostructure design of Co9S8/SnS accelerates the charge transfer of Na+.•MCNFs improve the conductivity and structural integrity of electrode during cycling.•The resulting electrode exhibits excellent rate performance and cycling stability.