Preparation And Electrochemical Properties Of Lignin-Modified Phenolic Resin Carbon Microspheres

Phenolic resin is a kind of carbon precursor,which can be prepared into porous carbon material with excellent properties after carbonization and activation treatment,but its raw materials phenol and formaldehyde cost high and are not friendly to the environment.Lignin is a kind of natural organic polymer material,which contain many aldehyde groups,alcohol hydroxyl groups and phenolic hydroxyl groups,so it can replace the petroleum product phenol.This paper mainly used lignin to partially replace phenol and formaldehyde to synthesize lignin modified phenolic resin microspheres.Then by carbonization activation method,lignin modified phenolic resin carbon microspheres were prepared and used as electrode materials to study their electrochemical properties.Firstly,the preparation conditions of lignin-modified phenolic resin microspheres were studied.The effects of the molar ratio of phenolic resin,the amount of dispersant,the amount of catalyst and the amount of lignin on the particle size distribution and yield of lignin-modified phenolic resin microspheres were studied.The results showed that the introduction of lignin significantly reduced the particle size of the modified phenolic resin microspheres.When the content of lignin was 50%（mass fraction,same below）,the modified phenolic resin microspheres with particle size ranging from 5μm to 30μm could be prepared.At the same time,the infrared spectrum and thermogravimetric analysis showed that lignin was involved in the reaction and improved the thermal stability of the modified phenolic resin microspheres.Then,the modified phenolic resin microspheres with 50%lignin content were prepared into modified phenolic resin carbon microspheres,and the preparation process was studied.The effects of pre-oxidation,carbonization and activation on carbon microspheres of phenolic resin modified by lignin were studied.The results show that:The activation temperature had great influence on the specific surface area,pore size distribution and pore volume of lignin-modified phenolic resin carbon microspheres.When the carbonization and activation temperature was900℃,the specific surface area of lignin-modified phenolic resin carbon microspheres was 1859.61 m² g^-1,the pore volume was 0.89 cm³ g^-1,and the pore size distribution was mesoporous structure.The nitrogen content of lignin-modified phenolic resin carbon microspheres was significantly higher than that of phenolic resin carbon microspheres by X-ray photoelectron spectroscopy.Finally,the electrochemical properties of lignin-modified phenolic resin carbon microspheres were tested at different activation temperatures.The results showed that the specific capacitance of the lignin-modified phenolic resin carbon microspheres prepared at the activation temperature of 900℃reaches 298 F g^-1 at the current density of 1.0 A g^-1,and the rate performance and cycling stability after 5000 cycles of lignin based phenolic resin carbon microspheres was 73.57%and 98.87%.At the same activation temperature,the lignin-modified phenolic resin carbon microspheres had better electrochemical properties.