High-performance hybrid supercapacitors enabled by CoTe@CoFeTe double-shelled nanocubes

Metal tellurides, known for their superior electrical conductivity and excellent electrochemical properties, are promising candidates for supercapacitor applications. This study introduces a novel method involving a metal-organic framework-hybrid to synthesize CoTe@CoFeTe double-shelled nanocubes. Initially, zeolitic imidazolate framework-67 (ZIF67) and CoFe Prussian blue analog (PBA) nanocubes are synthesized through an anion-exchange reaction with [Fe(CN)6]3− ions. Subsequent annealing treatment converts these structures into Co3O4@CoFe2O4 double-shelled nanocubes. These are then subjected to a tellurization process to form the CoTe@CoFeTe, which exhibits outstanding supercapacitive performance. Notably, the CoTe@CoFeTe based-electrode demonstrates superior supercapacitive properties compared to their oxide counterparts, mainly due to the introduction of tellurium ions. These nanocubes show an impressive specific capacity of 1312 C g−1 at a current density of 1 A g−1 and maintain 92.35% of their capacity after 10000 charging cycles, highlighting their durability and the synergistic effect of the mixed metals and their hollow structure. Furthermore, when used as the positive electrode material in a hybrid supercapacitor with activated carbon (AC), the device achieves an energy density of 64.66 Wh kg−1 and retain 88.25% of their capacity after 10000 cycles. These results confirm the potential of the developed material for advanced supercapacitor applications.