In-Situ Growth and DFT Analysis of Nickel Halide Nanostructures for Enhanced Electrochemical Supercapacitors

Abstract

Electrochemical supercapacitors with battery-like performance are pivotal for addressing the automobile industry’s increasing energy demands, offering rapid charge/discharge capabilities, high power density, and excellent cycling stability. Nickel-based electrodes emerge as a promising solution due to their high capacity and cost-effectiveness compared to noble metals. Herein, nickel halide nanostructures (NiF₂, NiBr₂, NiI₂) were synthesized via a hydrothermal method, with nickel foam serving as both the substrate and Ni⁺ source, enabling binder-free, self-growing electrodes. The synthesis process, supported by density functional theory (DFT) calculations, utilized different halide sources (NH₄F, NH₄Br, NH₄I) to tailor performance. Among these, NiBr₂ electrodes, characterized by interlinked nanowire structures, exhibited the highest specific capacity of 421.11 mAh g⁻¹ (equivalent to 2526.7 F g⁻¹) at 5 A g⁻¹, with 93.3% capacity retention after 1500 cycles. This study highlights the superior performance of NiBr₂ electrodes, underscoring their potential for advanced supercapacitor applications.