Agro-waste-derived porous carbon has received more attention as electrode material for high-performance supercapacitor application due to its diversity and reproducibility. Herein, hierarchical porous carbon was successfully synthesized from most abundant biomass onion peel via double crucible method and it was explored as renewable carbon source for low-cost energy storage device. The supercapacitor electrode exhibits high specific capacitance of 127 Fg−1 at the current density of 0.75 Ag−1 with capacitance retention of 109% after 2000 cycles in three-electrode system. More importantly, its symmetric supercapacitor device exhibits energy density of 13.61 Wh kg−1 at the power density of 200.8 W kg−1 with remarkable electrochemical stability revealing capacitance retention above 100% over 14000 cycles. Our study demonstrates that onion peel-derived carbon is suitable for future low-cost energy storage device.

中文翻译：

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用于超级电容器应用的洋葱皮多孔农业废弃物衍生碳的制备

农业废弃物衍生的多孔碳由于其多样性和可重复性，作为高性能超级电容器应用的电极材料受到越来越多的关注。在此，通过双坩埚法从最丰富的生物质洋葱皮成功合成了分级多孔碳，并将其作为低成本储能装置的可再生碳源进行探索。超级电容器电极在 0.75 Ag-1 的电流密度下表现出 127 Fg-1 的高比电容，在三电极系统中 2000 次循环后电容保持率为 109%。更重要的是，其对称超级电容器装置在 200.8 W kg-1 的功率密度下表现出 13.61 Wh kg-1 的能量密度，并具有显着的电化学稳定性，表明在 14000 次循环中电容保持率超过 100%。