Investigation of energy storage performance in organic molecule-stabilized nickel ferrocyanide nanoparticles for supercapacitor applications†

Supercapacitors are gaining attention as an ideal energy storage solution due to their excellent specific power, fast charging rates and high durability. This study presents the development of an organic molecule stabilized nickel ferrocyanide (NFC) hybrid material, synthesized through a complexation-mediated approach, which demonstrates outstanding electrochemical performance, making it a promising candidate for high-efficiency supercapacitor applications. X-ray diffraction analysis confirms the formation of nickel ferrocyanide with a cubic crystal structure (space group: Fmm). Transmission electron microscopy analysis revealed spherical shaped nickel ferrocyanide particles within the size range of 2–4 nm. Fourier-transform infrared spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy confirmed the successful formation of nickel ferrocyanide and offered detailed insights into its bonding environment and chemical states. The electrochemical performance of the hybrid material displayed a specific capacitance of 298 F g⁻¹ at 6 A g⁻¹ and retained 88% of its original capacitance after 10 000 cycles in a three-electrode system. An asymmetric supercapacitor device, fabricated using NFC as the cathode and activated carbon as the anode electrode, delivered a specific capacitance of 94 F g⁻¹ at 1.0 A g⁻¹. The device exhibited maximum specific energy and specific power values of 44 W h kg⁻¹ and 6067 W kg⁻¹, respectively, with a moderately good cycle life (84% capacitance retention after 10 000 cycles). The results emphasize the potential of the NFC-based hybrid system as an efficient material for energy storage applications.