Porous carbons derived from waste printing paper for high rate performance supercapacitors in alkaline, acidic and neutral electrolytes

Abstract

Renewable biomass as a precursor in the preparation of sustainable carbon materials for supercapacitors has gained much attention due to its huge reserves and being economical. In this paper, we used waste printing paper as the precursor to prepare highly porous carbons via a combined method of pre-carbonation and KOH activation. The prepared carbon materials exhibit huge specific surface areas and good conductivities as high as 2616.1 m² g⁻¹ and 198.8 mS cm⁻¹, respectively. They were used as the electrode materials of supercapacitors in the most common aqueous electrolytes, including 6 M KOH, 1 M H₂SO₄, and 1 M Na₂SO₄, and showed excellent capacitive performance in all the investigated electrolytes, such as very high specific capacitances (e.g. 385.0, 370.1, and 317.7 F g⁻¹ in KOH, H₂SO₄ and Na₂SO₄ electrolyte at 0.2 A g⁻¹, respectively), outstanding rate capabilities (e.g. 198 F g⁻¹ at 60 A g⁻¹ in H₂SO₄), high energy densities (e.g. 21.9 W h kg⁻¹ in Na₂SO₄), high power capability (at 28 000 W kg⁻¹, remains at 5.83 W h kg⁻¹ in Na₂SO₄), and good recyclability (about 94% retention after 10 000 cycles).