Fabrication and characterization of supercapacitor comprising mango kernel derived electrode under different electrolyte system

In this work, supercapacitor or ultra-capacitor cells are composed of active carbon material (ACM) having BET specific surface area of 1133 m(2) g(-1). The ACM is prepared by carbonizing waste biomass (mango kernel) at 900 degrees C. To develop high porosity in ACM, potassium hydroxide was used as an activating agent. Porous morphology of the synthesized ACM is explored through Scan-ning Electron Microcopy. Thereafter, two supercapacitor cells have been com-posed by using the mentioned ACM (electrode material) and KOH 6 M & NaOH 1 M (electrolytes). Applicability of the electrode material for supercapa-citor has been tested electrochemically through the standard CV, EIS, and CD techniques. Observed capacitive assets from CV curve at 5 mV s-1was 151.5 F g(-1) (with KOH 6 M) and 133 F g(-1) (with NaOH 1 M). Experimentally obtained impedance data from EIS technique were compared and fitted theo-retically by utilizing Randles fitting circuit. By taking frequency into consider-ation, it is found that the KOH 6 M based cell is providing lower time constant value and supporting better diffusion process than NaOH. Analysis of CD curve at 1.1 A g(-1) have given the capacitance of 136.5 F g(-1) and corresponding energy and power density of 12.1 Wh kg(-1) and 930 W kg(-1). In addition to this, the small voltage drop and low ohmic resistance observed with KOH based system suggests its better capacitive assets than NaOH based supercapacitor system. Moreover, good capacitance retention of 85% is observed in a 2000 life cycle test.

Automated summary

In this research, active carbon material (ACM) with a specific surface area (BET) of 1133 m(2) g(-1) was prepared from mango kernel waste through carbonization at 900 degrees C and activation with potassium hydroxide. Scanning Electron Microscopy was used to study the porous morphology of the synthesized ACM. Two supercapacitor cells were fabricated using the ACM as the electrode material and KOH 6 M & NaOH 1 M as the electrolytes. Electrochemical tests including CV, EIS, and CD techniques confirmed the suitability of the ACM as an electrode material for supercapacitors. The KOH 6 M based cell showed better performance than the NaOH 1 M based cell in terms of time constant, diffusion process, capacitive assets, energy and power density, voltage drop, and ohmic resistance. The KOH based system also exhibited good capacitance retention of 85% after 2000 life cycle tests.