Synthesis and investigation of charge storage characteristics in Ni-MOF/PANI composite as an active electrode material for supercapacitor.

• Composite of Ni-MOF/PANI has been synthesized. • Composite material shows extreme specific capacity of 122 C/g at 5 mVs−1. • The material shows excellent capacitive retention of 99.25 % even after 5000 cycles. This study aimed to develop a more stable and efficient energy storage device, synthesis of nickel-based pristine metal organic framework (MOF) and combined it with the emeraldine base phase of polyaniline (PANI) which is confirmed with XRD, SEM and TEM. Both Ni-MOF and PANI exhibit faradaic (battery-like) behaviour. However, when these two materials are combined, the stability of the resulting material is enhanced. The initial materials, MOF and PANI, exhibit specific capacities of 42 C/g and 72 C/g, respectively. However, when these two materials are combined, their composite exhibits an enhanced specific capacity of 122 C/g. The cyclic voltammetry (CV) analysis shows oxidation and reduction peaks, indicating faradaic behaviour. This behaviour is further confirmed by electrochemical impedance spectroscopy (EIS). Upon comparing it with prior results, the specific capacity appears to be slightly lower. However, it is anticipated to exhibit stronger stability, which is contradictory. The composite material (Ni-MOF/PANI) exhibits remarkable capacitive retention of 99.25 % even after undergoing 5000 cycles, as anticipated. In order to validate the aforementioned findings and determine the extent of the current contribution from capacitive and diffusive control, Dunn's model was employed. The data demonstrates the prevalence of diffusive-controlled (faradaic) current over capacitive current. The highest proportion of current resulting from diffusion is 96 %, achieved at a scan rate of 5 mV/s. The highest proportion of current resulting from capacitance is 24 %, achieved at a scan rate of 300 mV/s. At lower scan rates, the material exhibits a greater faradaic behaviour, whereas at higher scan rates, there is a progressive increase in non-faradaic processes. The insufficient time for diffusive process at higher scan rates is the cause. The Dunn's model with quadratic correction is also performed and comparative results were shown. Overall, the material exhibits more stability and dominance in the faradaic process, which paves the path for improved performance. [Display omitted] [ABSTRACT FROM AUTHOR]