Coal-Based Hierarchical Porous Carbon Synthesized with a Soluble Salt Self-Assembly-Assisted Method for High Performance Supercapacitors and Li-Ion Batteries

Coal-based multiscale porous carbon materials (CPCs) have been successfully fabricated through a friendly method with NaCl, Na2CO3, and Na2SiO3 as structural templates, instead of alkali activation at a relatively low temperature. The method includes freeze-drying and calcination of salts/acid-treated coal, combined with water washing to remove salts. The optimal product (CPCs-20) obtained by the above procedure displayed a high surface area of 1100 m2 g–1. As electrode materials of supercapacitors, CPCs-20 presented a specific capacitance of 304 F g–1 at 1 A g–1 and superior stability over 10,000 cycles at 4 A g–1 owing to its hierarchical porosity with higher surface area, promoted diffusion of electrolyte, and increased conductivity. It is also worth mentioning that a symmetric device based on CPCs-20 can light a light-emitting diode (LED) for 30 min. Furthermore, CPCs-20 as the anode for Li-ion batteries exhibited a high reversible capacity of 450 mA h g–1 at 0.2 A g–1, excellent rate capability, and outstanding cycling performance. Therefore, there are bright prospects of our CPCs as high performance electrode material for energy storage applications.