Regulating the interconnected microporous structure of porous carbon by alkali metal ions for improved surface and space utilization for organic supercapacitors

Abstract

Developing porous carbon with suitable microporous structure and large effective surface area is crucial for pursuing high volumetric performance of organic supercapacitors. Herein, we proposed a homogeneous activation method to regulate the interconnected microporous structure of porous carbon through choosing the alkali metal ion activators (Li+, K+, Cs+). We have revealed the pore evolution mechanism from the points of ion activation strength, cluster transport, and metal boiling points. Compared to others, the optimized sample activated by Cs+ shows large micropore volume, high effective surface area (2463 m2 g−1), and high compaction density (0.75 g cm−3), performing an improved volumetric capacitance (126 F cm−3 at 1 A g−1) and good rate performance (79 F cm−3 at 20 A g−1) in organic electrolyte. The symmetric supercapacitor at the commercial electrode mass loading shows a competitive energy density (23.9 Wh L−1 at 211.4 W L−1, 4 Wh L−1 at 1638 W L−1). Moreover, this pore-regulating strategy has a general availability when using other non-foaming carbon precursors, which will open up new paths for improving the surface and space utilization of porous carbon for compact capacitive energy storage.