Sustainable Low-Cost Green Electrodes with High Volumetric Capacitance for Aqueous Symmetric Supercapacitors with High Energy Density
2016
Xie, Qinxing | Bao, Rongrong | Zheng, Anran | Zhang, Yufeng | Wu, Shihua | Xie, Chao | Zhao, Peng
Low-cost and high performance electrode materials are critical for rapid development and wide applications of supercapacitors. Herein, we report a cost-effective approach to prepare nitrogen-doped active carbon/graphene (N-AC/Gr) composites using renewable corn straw and soy protein as precursors, respectively. The as-prepared composites have moderate specific surface areas in a range of 1233.6–1412.9 m² g–¹ and abundant porosity. Furthermore, the composites demonstrate high single electrode gravimetric and volumetric specific capacitances of 378.9 F g–¹ and 257.7 F cm–³ at 0.05 A g–¹ and of 321.1 F g–¹ and 213.2 F cm–³ at 20 A g–¹, accounting for an excellent rate capability with a retention of 66.4% in 6 M KOH electrolyte. The assembled N-AC/Gr-based aqueous symmetric supercapacitor exhibits superior cycling durability with 93% retention after 10,000 cycles at 2 A g–¹ and delivers a high energy density of 13.1 Wh kg–¹ (11.1 Wh L–¹) with a power density of 12.5 W kg–¹ (10.6 W L–¹).
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