Constructing rational pore in nanocarbons by chemical and physical co-activation of polyaniline for high performance electrical double layer capacitors

Abstract

Rationalizing pore structure of carbon electrode materials is an effective strategy to improve electrochemical performance of electrical double layer capacitors (EDLCs). Herein, chemical-physical co-activation method is developed to prepare polyaniline-derived N-doped porous nanocarbon with useable micropore and small mesopore for guaranteeing high electrostatically adsorptive area and fast ion transport, respectively. K₂CO₃ firstly pre-activates to create appropriate pores, following by CO₂ deep activation for pore development. The resulting coral-like nitrogen-doped porous carbon (NPC_KC) exhibits stable nitrogen-doping, largely efficient surface area, reasonable pore configuration (0.7–3 nm), which are highly desirable for capacitive behaviors. When conducted in aqueous electrolyte, NPC_KC electrode displays a specific capacitance up to 236 F g⁻¹ at 0.5 A g⁻¹ and conspicuous cyclic stability of 96.9 % retention after 10,000 cycles. More meaningful, the organic NPC_KC-based EDLC reaches a 132 F g⁻¹ specific capacitance at 0.2 A g⁻¹ and maintain 120 F g⁻¹ even at 10 A g⁻¹ (90.9 % capacitance retention), greatly surpassing that of commercial AC with similar specific surface area, which exclusively clarifies the significant influence of small mesopores on EDLC energy storage. Meanwhile, it possesses high density energy (40.7 W h kg⁻¹ at 149.6 W kg⁻¹) and power density (23.5 W h kg⁻¹ at 6020 W kg⁻¹), as well as excellent cyclic stability (89.4% of initial capacitance after 10,000 cycles), holding great practical potentials to application in commercial EDLCs.