Bread-inspired foaming strategy to fabricate a wine lees-based porous carbon framework for high specific energy supercapacitors

Abstract

Herein, inspired by the fermentation process of bread, a novel wine lees-based porous carbon framework (WLCF) with a three-dimensional porous structure is prepared via a one-step simple and environmentally friendly sodium bicarbonate foaming and activation strategy. Based on the dual functions of a self-generating expansion gas and activator originating from the thermal decomposition of sodium bicarbonate, the resulting WLCF presents a fluffy carbon frame structure, high specific surface area (1494.6 m² g⁻¹) and high nitrogen doping effect (7.5 wt%), which significantly improve the electrochemical performance. The symmetrical supercapacitor assembled with WLCF electrodes and Na₂SO₄ aqueous electrolyte exhibits a wide and stable voltage window of 2 V and a high energy density of 18 W h kg⁻¹ at the power density of 225 W kg⁻¹. Furthermore, the supercapacitor fabricated based on WLCF electrodes and ionic liquid ([Emim]BF₄) electrolyte delivers an ultrahigh output voltage up to 4 V, a high energy density of 54 W h kg⁻¹ at a high power density of 401 W kg⁻¹, and a superior capacitance retention of 90% after 100 000 cycles. The green preparation of a biomass-based porous carbon framework and the successful realization of wide operating voltage provide a promising strategy toward achieving high energy density supercapacitors.