Construction of triple-shelled hollow nanostructure by confining amorphous Ni-Co-S/crystalline MnS on/in hollow carbon nanospheres for all-solid-state hybrid supercapacitors

Designing novel electrode materials with controlled structure and composition remains a great challenge for high-performance supercapacitors. Here, a triple-shelled hollow nanostructure has been successfully designed and constructed by confining amorphous Ni-Co-S/crystalline MnS on the inner walls and the outer surfaces of hollow carbon nanospheres. The triple-shelled hollow nanostructure can improve the electrochemically active surface areas, accelerate the transport of electrons/ions, and accommodate the volume change during cycling. Additionally, the interlayer (the porous hollow carbon nanospheres) can support each other for enhanced mechanical stability and improve the electrical conductivity of the electrode. More importantly, amorphous Ni-Co-S facilitates diffusion and redox reaction of OH^–, while the crystalline MnS offers fast electrons transport and mechanical stability. Meanwhile, the amorphous/crystalline interface can improve charge storage. Benefiting from the structural and compositional advantages, the prepared electrode delivers a high specific capacity (1093C g⁻¹ at 1 A g⁻¹) and outstanding cyclic stability (capacity retention ratio of 90.4% at 10 A g⁻¹ after 5000 cycles). The corresponding all-solid-state hybrid supercapacitor achieves long cycle life and high energy density.