Green and scalable synthesis of 3D porous carbons microstructures as electrode materials for high rate capability supercapacitors

Abstract

Porous carbon nanostructures have long been studied because of their importance in many natural phenomena and their use in numerous applications. A more recent development is the ability to produce porous carbon materials with tuneable properties for electrochemical applications, which has enabled new research directions towards the production of suitable carbon materials for energy storage applications. Thus, this work explores the activation of carbon from polyaniline (PANI) using a less-corrosive potassium carbonate (K₂CO₃) salt, with different mass ratios of PANI and the activating agent (K₂CO₃ as compared to commonly used KOH). The obtained activated carbon exhibits a specific surface area (SSA) of up to ∼1700 m² g⁻¹ for a carbon derived PANI : K₂CO₃ ratio of 1 : 6. Moreover, the prepared samples were tested as electrode materials for supercapacitors with the results showing excellent electrical double layer capacitor behavior. Charge storage was still excellent for scan rates of up to 2000 mV s⁻¹, and a capacitance retention of 70% at a very high specific current of 50 A g⁻¹ was observed. Furthermore, the fabricated device can deliver an energy density of 25 W h kg⁻¹ at a specific current of 0.625 A g⁻¹ and a power density of 260 W kg⁻¹ in 1-ethyl-3-methylimidazolium bistrifluorosulfonylimide (EMIM-TFSI) ionic liquid, with excellent rate capability after cycling for 16 000 cycles at 3.0 V with ∼98% efficiency. These results are promising and demonstrate the electrode's potential for energy storage, leading to the conclusion that K₂CO₃ is a very good alternative to corrosive activation agents such as KOH in order to achieve high electrochemical performance.