Hierarchical porous carbon from mango seed husk for electro-chemical energy storage

Abstract

Bio-waste valorization of Mango Seed (MS) husk to Activated Carbon (AC) was conducted via carbonization followed by chemical activation using KOH for sustainable supercapacitor material. Various physicochemical techniques were used to characterise both MS husk and AC, while electrochemical techniques were used to assess the energy storage capability. Carbonized MS husk was activated at four different temperatures 800, 900, 1000, and 1100 °C. Optimal activation temperature was found to be 1100 °C resulting in a hierarchical porous structure, possessing the highest specific surface area 1943 m2 g−1 and average pore volume 0.397 cm3 g−1, the critical parameters for their energy storage performance. In a three-electrode configuration, the MS-AC sample synthesized at 1100 °C (MS-AC 1100) exhibited a maximum specific capacitance of 135 F g−1 at 5 mA cm−2 with the energy density of 19 Wh kg−1 at the power density of 1077 W kg−1, which is higher than the commercially available AC. The MS-AC 1100 delivered 97% of the capacitance when increasing the current densities from 2 to 10 mA cm−2. The capacitance retention is 100% at 5 mA cm−2 with 1000 cycles. Moreover, Machine Learning (ML) models are used to identify the non-linear pattern for predicting the AC capacitance using various input parameters. Out of the four ML models considered in this work, the Multi-Layer Perceptron (MLP) model outperformed the other models to better correlate the predicted data and the experimental measurements. This study demonstrates the economic perspective of repurposing MS husk bio-waste to a low-cost super-capacitor electrode material and developing high-performance carbon materials to aid the integration of renewable energy into electricity systems.