Preparation and electrochemical performance of activated carbon microspheres from recycled novolak phenol formaldehyde

摘要

In this study, an attempt is made to obtain porous activated carbon microspheres (ACMs) as supercapac-itor electrodes by recycling waste novolak phenol formaldehyde (NPF) resins. These NPF-ACMs were prepared by a three-step procedure of hydrothermal synthesis, carbonization, and activation in turn. The effects of temperature, time, and sodium dodecyl sulfonate (SDS) addition on NPF-based microspheres were studied by the orthogonal method. The optimal preparation process of NPF-based microspheres was the following: 230 °C, 4 h, and a mass ratio of SDS: NPF of 24:1 by hydrothermal synthesis. Based on the above optimal conditions, NPF-ACMs were made, the yield of the microspheres after carbonization and chemical activation are 54% and 38%, and their electrochemical properties were analyzed. The NPF-ACMs had uniform size, a high surface area of 2528 m~2 g~(-1), good dispersion, a low impedance of 0.46 Ω, highest specific capacitance of 118.6 Fg~(-1) at 0.5 A g~(-1), good rate capability with 79% retention from 0.1 to 10 A g~(-1). Moreover, it showed high capacitance retention of 99.5% after 1000 cycles at a scan rate of 5 mV s~(-1). The results showed that waste NPF can be used as promising ACMs of the electrode material to increase its utilization value.