Granular Nanosheets Made of Interconnected NiTe₂-CoTe₂Nanoparticles on Carbon Fibers for High-Performance Hybrid Supercapacitors

Recently, metal tellurides have been widely used as functional materials in energy storage, environment, or catalysis. However, designing synergistic bimetallic tellurides with excellent electrochemical performance remains a huge challenge, especially in high-performance supercapacitors. Herein, high-capacity nickel-cobalt telluride nanosheets were synthesized on carbon fibers (CF@CoTe₂-NiTe₂). First, using Co-MOF nanosheet arrays as template, nickel-cobalt layered double hydroxide nanosheets were prepared by a simple Ni ion etching. Then, the CF@CoTe₂-NiTe₂was fabricated based on the as-obtained NiCo-LDH nanoarrays in tellurium vapor. Significantly, the CoTe₂-NiTe₂nanosheets are made up of many interconnected CoTe₂and NiTe₂nanoparticles, enhancing the effective contact with the electrolyte solution during the oxidation reaction. The as-prepared CF@CoTe₂-NiTe₂exhibits a high electrochemical capacitance of 261.4 mAh g^-1at 1.0 A g^-1and an outstanding capacitance retention of 70% when the current density reached 20 A g^-1. Remarkably, the hybrid supercapacitor assembled by CF@CoTe₂-NiTe₂and CF@Fe₂O₃presents 41 Wh kg^-1at 750 W kg^-1, with a high capacitance retention (87.6% after 5000 cycles). Therefore, bimetallic tellurides may be used as more functional materials for applying to energy storage.