Innovative design of nickel-manganese tellurium on heteroatom-doped graphene hollow spheres as active materials for supercapacitors

Abstract

In this work, a novel bimetallic nickel‑manganese telluride (NiMnTe) decorated heteroatom-doped graphene hollow balls (HGHB) (NiMnTe/HGHB) was synthesized using a hydrothermal process followed by tellurization. The hollow structure of HGHB mitigates structural collapse during prolonged charge/discharge cycles, while the incorporation of heteroatoms into graphene modulates its electronic properties and enhances ion adsorption. NiMnTe, with its multiple valence states and strong dipole moments, facilitates abundant redox reactions and promotes efficient charge transfer. Monometallic Ni- and Mn-based compounds were synthesized, and the metal ratio in the bimetallic compound was optimized to design NiMnTe with an ideal composition. The NiMnTe/HGHB electrode demonstrated a high specific capacitance (C_F) of 1450 F/g at a current density of 1 A/g. A hybrid device composed of NiMnTe/HGHB and activated carbon (AC) achieved a high C_F of 147.3 F/g and a maximum energy density of 47.8 Wh/kg at a power density of 772.0 W/kg. Additionally, the hybrid device exhibited excellent cycling stability, retaining 82.0% of its C_F after 10,000 cycles at 5 A/g. These findings underscore the potential of telluride bimetallic structures combined with carbon materials for advanced supercapacitor applications.