Improving hierarchical porous structure of carbon aerogels for more efficient ion transport for supercapacitors with commercial level mass loading

Abstract

Designing porous structure and surface properties of carbon electrodes is the key premise for efficient electron/ion transfer, which is crucial for improving electrochemical performance of supercapacitors in practical applications. Herein, N-doped activated carbon aerogel (NACA) with hierarchical porous structure and N, O-rich functionalities has been prepared from polyimide gel by activation and carbonization process. The NACA exhibits a high surface area of 1410 m2 g−1 with hierarchical porous structures, with both high micropore volume (0.481 cc g−1) and mesopore volume (0.566 cc g−1) as well as high heteroatom content, which is favorable for charge storage, ion transfer and electrolyte penetration. As a result, the NACA2-11 can deliver a high capacitance of 386 F g−1 at 1 A g−1 in a three-electrode system and outstanding rate performance with the capacitance retaining 150 F g−1 at 100 A g−1 in aqueous electrolyte. Furthermore, the practical two-electrode device exhibits a high areal specific capacitance of 1584 mF cm−2 under the commercial level mass loading of 10 mg cm−2, and it stays a good cycling stability of 93% capacitance retention after 10000 cycles at 5 A g−1. This study paves the way for improving electrochemical performance of carbon-based supercapacitor under high mass loadings.