Porous carbon microspheres with controlled porosity and graphitization degree for high-performance supercapacitor

Abstract

• Porous carbon microspheres are synthesized via a simple template-free method. • Porous structure and graphitization degree are controlled. • Ni-based salts and ethanolamine affect porous structure and graphitization degree. • Porous carbon microspheres exhibited excellent supercapacitor performance. The fabrication of porous carbons plays an important role in improving electrochemical performance for supercapacitors. The fabrication of carbon microspheres with controlled porous structure and graphitization degree is still a challenge in synthetic methodology, since it is difficult to achieve both goals at the same time. Porous carbon microspheres with controlled porous structure and graphitization degree are realized here via a simple template-free method, using Ni-based salts and resorcinol-formaldehyde resin microspheres as raw materials. The amount and types of Ni-based salts as well as ethanolamine significantly affect the porous structure and graphitization degree for the carbon microspheres. The porous carbon microspheres prepared with 4.0 g of Ni(CH 3 COO) 2 ·4H 2 O and 0.25 mL of ethanolamine possess the surface area of 392.1 m 2 g −1 , the pore volume of 0.395 cm 3 g −1 and the I G /I D ratio of 1.18. The as-synthesized porous carbon microspheres can serve as excellent candidates for electrode materials in supercapacitors to achieve excellent electrochemical behaviors. The as-prepared porous carbon microspheres exhibit a specific capacitance of 193.8F g −1 at 1 A g −1 , good rate capability and long cycle life in a two-electrode system. The superior electrochemical performance can be attributed to both the unique hierarchical porous structure and high graphitization degree. The hierarchical porous structure can provide fine transportation pathways and a large number of adsorption sites for electrolyte ions, and high graphitization degree can ensure rapid electron transport.