Supriya R Late, Shidaling Matteppanavar, S.K. Rajappa
Engineering the electronic structure and defect chemistry of transition-metal tellurides through controlled elemental incorporation is an effective strategy for improving electrochemical energy-storage performance. In this work, nickel-incorporated copper telluride (Cu 2-x Ni x Te; x = 0.01, 0.03, and 0.05) nanorods were synthesized via a facile hydrothermal method to systematically investigate the influence of low-level Ni incorporation on the structural evolution and charge-storage behaviour of Cu 2 Te. X-ray diffraction combined with Rietveld refinement confirmed the preservation of the hexagonal Cu 2 Te phase after Ni incorporation, accompanied by systematic variations in lattice parameters, unit-cell volume, and bond geometry. Raman spectroscopy, X-ray photoelectron spectroscopy, Field Emission Scanning Electron Microscopy with Energy-Dispersive X-ray Spectroscopy, and Brunauer-Emmett-Teller analyses further verified the successful incorporation of Ni and revealed modifications in the local structure, electronic states, morphology, and surface characteristics. Among the investigated compositions, Cu 1.99 Ni 0.01 Te exhibited the optimum electrochemical performance, delivering a high specific capacitance of 717 F g −1 at 10 mV s −1 in 1 M KOH, an energy density of 143 Wh kg −1 , and good long-term cycling stability with approximately 70% capacitance retention after 10,000 cycles. Comprehensive electrochemical analyses, including electrochemical impedance spectroscopy, b-value determination, and Dunn's method, demonstrate that the enhanced performance originates from the synergistic effects of optimized defect chemistry, additional redox-active Ni sites, improved charge-transfer kinetics, and efficient ion diffusion resulting from controlled low-level Ni incorporation. These findings establish that precise Ni incorporation effectively tailors the structure-property-performance relationship of Cu 2 Te and provide a practical strategy for designing high-performance telluride-based electrode materials for advanced supercapacitors.