Sub-Nanometer Porous Carbon Materials for High-Performance Supercapacitors Using Carbon Dots as Self-templated Pore-Makers

Abstract

Customizable porous carbon structures are critical for high-performance electrode materials, and the modulation of the pore parameters at different levels remains a great challenge. For supercapacitors, the preferred carbon materials should own high specific capacitance, nice rate performance, large density, low self-discharge, and high mass-loading, which could be accomplished by sub-nanometer pores (0.5–1.0 nm). Herein, a new method of using carbon dots (CDs) as self-templates is reported to produce porous carbon with uniform pore diameters of 0.64–0.80 nm. As a result, the optimal sample with a high packing density (0.81 g cm⁻³) displays outstanding capacitances (gravimetric 515.5 F g⁻¹, areal 5.16 F cm⁻², and volumetric 417.6 F cm⁻³ respectively at 1 A g⁻¹) at the commercial-level mass-loading of 10 mg cm⁻². The assembled high-loading symmetric supercapacitor shows a high energy density of 22.3 Wh kg⁻¹ at 3500 W kg⁻¹, as well as a long cycle stability (99.9% of retention rate after 10 000 cycles at 2 A g⁻¹) in an ultrawide voltage range of 1.4 V with aqueous electrolytes. This work suggests a micropore-forming strategy for the preferred porous carbon, which can be applied in supercapacitors, batteries, filters, adsorbents, and catalysts.