Highly Efficient Solid‐State Supercapacitor with Porous Electrode Material

Herein, a flexible solid‐state supercapacitor (FSC) with a high level of efficiency with porous electrode material derived from mahogany fruit shell waste (MS) is reported. The mahogany‐fruit‐shell‐derived activated carbon (MSAC) is produced using chemical activation, followed by carbonization at various carbonization temperatures (500, 600, 700, and 800 °C) and activation ratios (MS:KOH = 1:1, 1:2, and 1:3). The high‐performance MSAC has an intricate porous structure with a surface area of 1072 m 2 g −1 . It exhibits a specific capacitance of 267 F g −1 and outstanding capacitance retention of 97% even after 10 000 charge–discharge cycles. The MSAC‐based FSCs are constructed utilizing a gel polymer electrolyte (poly(vinyl alcohol)|sodium sulfate), and their performance is compared with that of conventional supercapacitor systems. The MSAC‐based FSC shows a very high specific capacitance of 121 F g −1 , which is remarkably superior to previously reported FSCs. Additionally, as‐prepared FSC exhibits wide electrochemical window, flexibility, ease of handling, safety, along with a high capacitance retention of 78% after 2000 charging–discharging cycles. These exceptional capacitive properties, such as its extended cycle life and excellent rate capability, suggest that it is a potential alternative for a range of next‐generation energy storage applications.