Porous carbon prepared by thermal dissolution of coal and biomass for high-performance supercapacitors

[Display omitted] •Established the relationship between molecular properties and electrode performance.•Biomass is used to realize the value of energy storage.•The carbon source unsaturation is obtained from the double bond equivalent diagram. Porous carbon materials have been considered a kind of promising materials for supercapacitors due to high specific surface area and excellent electronic conductivity. Soluble portions (SPs) acquired from thermal dissolution of carbon-based raw materials have been used as the carbon source for hierarchical porous carbons (HPC). In this work, mixtures of rice straw and coal at different mass ratios were selected as the raw materials for co-thermal dissolution to obtain SPX. The variation of soluble proportions and subsequent impacts on the electrochemical properties of HPCX were investigated. During thermal dissolution, the addition of rice straw increased the content of nitrogen-containing compounds in SPX. Therefore, the specific capacitance of HPC1/4 is 355 F/g. The specific capacitance of activated carbon material without rice straw is only 299 F/g. The relationship between the molecular characteristics of carbon source and the performance of supercapacitors has been determined. In addition to oxygen-containing compounds, the presence of nitrogen-containing compounds can also lead to a higher electrochemical property for porous carbon materials.