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A pineapple crown activated carbon (PCAC) was prepared from pineapple crown waste using one step carbonisation and physical activation method for electrode super capacitor cells. The pineapple crown waste was also activated by using KOH activation in a ratio of 1 : 1 to the total mass. The precarbonised PCAC has a thermal resistance temperature of 300°C while the carbonised one has high Brunauer-Emmett-Teller (BET) with a surface area of 700 m 2 g -1 , a pore volume of 0.362 m 3 g -1 and an average pore diameter of 22 nm. The surface morphology of pineapple crown electrode shows a good fibre structure with a diameter of 42-73 nm. The electrochemical properties of supercapacitor cells have an excellent specific capacitance which is as high as 150 F g -1 while its energy and power densities are 5.2 Wh Kg -1 and 42 W Kg -1 , respectively

The activated carbon electrode made from acacia leaves (Acacia mangium wild) has been developed successfully. The preparation of the electrodes used a combination of chemical and physical activation with temperature variations at 800 °C, 850 °C, 900 °C, and 950 °C. Highest specific capacitance of activated carbon was 113 F g −1 in the two electrode system and showed excellent electrochemical performances. Additionally, activated carbon exhibits 95.73% purity with a specific surface area of 714.492 m 2 g −1 . These excellent results show great potential in developing energy storage devices with high specific capacitance for supercapacitor applications.

BACKGROUND Agro‐industrial co‐products rich in lignocellulose, for example cassava petiole (CP) waste, have high potential as sources of porous carbon materials, alongside other impressive advantages, including ease of acquisition, abundance and availability, renewability and low cost. This work shows the successful treatment of mesoporous carbon with rod‐like structure derived from agro‐industrial CP waste carbonized and physically activated by direct one‐stage integrated pyrolysis using a zinc chloride (ZnCl2) activator agent, in the production of a supercapacitor electrode for energy storage. The ZnCl2 was tested at varying concentrations, including 0.5, 0.7 and 0.9 mol L–1. The surface morphology, chemical content, surface area and porous size distribution were evaluated to determine the physical properties of activated carbon, and a cyclic voltammetry method was used to assess the electrochemical characteristics using a two‐electrode system in 1 mol L–1 H2SO4 as an electrolyte. RESULTS The porous carbon obtained displayed a rod‐like morphology structure, featuring numerous hierarchical tuneable and well‐confirmed micropores and mesopores. This monolithic material contained predominantly C (87.85%), demonstrating a maximum surface area of 759.816 m2 g−1 at 0.9 mol L–1 concentration. Furthermore, the highest specific capacitance reached was 193 F g−1 at 0.7 mol L–1, with maximum energy and power densities of 26.90 Wh kg−1 and 96.94 W kg−1, respectively. CONCLUSION The novel rod‐like mesoporous carbon derived from CP waste produced using a facile, cost‐effective and sustainable method, without metal–organic framework or templates, shows great potential as an electrode material for enhanced supercapacitor performance. © 2020 Society of Chemical Industry (SCI)