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Three‐Dimensional Porous Carbon Materials from Coix lacryma‐jobi L . Shells for High‐Performance Supercapacitor

2022; Wiley; Volume: 7; Issue: 10 Linguagem: Inglês

10.1002/slct.202104189

2365-6549

Lian Liu, Hong Zheng, Wenjie Wu, Yurun Zhang, Qin Wang, Yang Liu, Haiyan Yin, Wei Lü, Shuya Wang, Xian Yang,

Electrocatalysts for Energy Conversion

Abstract Three‐dimensional (3D) porous carbon materials are widely concerned because of their excellent electrochemical performance in supercapacitors. Herein, a new porous Coix lacryma‐jobi L . shells‐based carbon (CSC) is prepared by carbonization and activation for super‐capacitors. The obtained CSC‐3 (CSC‐x, x: KOH/CSC mass ratio) possesses abundant porous structures, some functional groups with nitrogen and oxygen atoms, and good electrochemical performance. When the mass ratio of KOH to CSC is 3 : 1, the obtained CSC‐3 has the largest specific surface area (SSA, 1191.7 m 2 g −1 ). Besides the material exhibits good electrochemical capability in the three‐electrode system with 6 m KOH aqueous electrolyte, such as desirable specific capacitance (at 0.5 A g −1 , the specific capacitance is 413.5 F g −1 ), ideal rate performance (from 0.5 A g −1 to 10 A g −1 , the specific capacitance retention rate is 70.86 %) and long cycle life (the specific capacitance only reduced by 2.47 % after 5000 cycles at 0.5 A g −1 ). Assembled symmetric supercapacitor (CSC‐3//CSC‐3) shows gratifying energy density (11.58 Wh Kg −1 at the power density of 324.93 W Kg −1 in 6 m KOH aqueous electrolyte and 14.67 Wh Kg −1 at 474.93 W Kg −1 in 1 m Na 2 SO 4 aqueous electrolyte). This work provides possibility of utilizing waste Coix lacryma‐jobi L . shells to produce low‐cost and high‐performance super‐capacitor electrode materials for sustainable electrochemical energy storage.