Easy synthesis of a high surface area, hierarchical porous carbon for high-performance supercapacitors

Abstract

High surface area, hierarchical porous carbons are easily prepared from poly(vinylidene fluoride) (PVDF) by NaOH activation. In contrast to the conventional two-step carbonization–activation method, we directly heated the mixture of powdery PVDF and NaOH at 600 °C to accomplish carbonization and activation in one step. In this process, NaOH acts as an interceptor of HF which comes from the PVDF decomposition, as well as an activation agent. SEM and TEM observation, along with nitrogen sorption measurements reveal that the carbons have a highly developed hierarchical porous structure containing interconnected micro-, meso-, and macropores. The specific surface area and pore volume of the carbon prepared at NaOH/PVDF = 3.5 reach values as high as 2711 m² g⁻¹ and 2.280 cm³ g⁻¹, respectively. The unique hierarchical porous structure endows the carbon with a high capacitance and excellent rate capability in both aqueous and non-aqueous electrolytes. Its capacitance at a current load of 0.05 A g⁻¹ reaches values as high as 339 F g⁻¹ in 6 mol L⁻¹ KOH and 162 F g⁻¹ in 1 mol L⁻¹ Et₄NBF₄/AN. The values still remain at 230 F g⁻¹ and 98 F g⁻¹, respectively, when the current load increases up to 20 A g⁻¹. Combined with the simple preparation procedure, the present carbon may be a promising electrode material for supercapacitors.