Battery-like high performance biocarbon electrochemical capacitor using mono redox electrolyte: a proof-of-concept
摘要
In this work, we demonstrate that an asymmetric full-cell configuration can be employed to achieve a battery-like charge-discharge profile in a mono-redox electrolyte, hydroquinone (HQ). Biocarbon was synthesized using Tamarindus indica biowaste and systematically characterized using various characterization techniques. The biocarbon-based supercapacitors were assembled using both 2 and 3-electrode setups with 1.0 M H2SO4 and 1.0 M HQ electrolyte. The specific capacities of 24.1 mAh g− 1 and 53 mAh g− 1 were obtained for the positive and negative electrode, respectively in 1.0 M HQ using a 3-electrode configuration. Symmetrical supercapacitors with the cell potential of 0.8 V delivered the specific capacity of 10.7 mAh g− 1 with 1.0 M H2SO4 and 13.8 mAh g− 1 with 1.0 M HQ electrolyte at 0.1 A g− 1 with corresponding specific energies of 8.5 and 11.0 Wh kg− 1. To realize the complete prospective of mono redox electrolyte and achieve a battery-like charge-discharge profile, an asymmetric configuration was employed. The configuration with 1.0 M HQ delivered a specific capacity of 85 mAh g− 1 and a high specific energy of 72.3 Wh kg− 1 at 0.1 A g− 1 at 0.85 V. The high specific power of 4343 W kg− 1 was measured for the asymmetric capacitor. Long-term stability of 98% and 80% for the asymmetric supercapacitors with 1.0 M H2SO4 at 0.9 V and 1.0 M HQ electrolytes at 0.85 V, respectively, after 10,000 continuous charge-discharge cycling. This proof-of-concept can be extended to fully exploit the potential of supercapacitors, incorporating a wide range of mono-redox electrolytes.