From wood to supercapacitor electrode material via fast pyrolysis

Adding high-value products, such as carbon-based electrode materials for electrochemical energy storage, to the value chain of biorefinery may increase the profits of the whole concept. In this work, carbon-based super -capacitor electrode materials were produced by chemical activation (using KOH) of two fractions of bio-oil (aerosol and condensed) as well as bio-char precursors, all of them originally made from fast pyrolysis of stem wood from pine and spruce. The produced materials show a hierarchical porous structure, a high surface area (1300-1500 m2 g-1) and, almost double the specific capacitance (149-152 F g-1 @ 50 mA g-1) compared to commercially available activated carbon (79 F g-1 @ 50 mA g-1). The benefit of using bio-oils compared to biochar is having an electrode material almost free from metal impurities alongside marginally higher energy storage performance. Together with the material yield in the production chain (fast pyrolysis and activation), a normalized energy storage value was presented for each material that may be used in the future to select the best techno-economic route for the whole concept.

Automated summary

Introducing carbon-based electrode materials into the value chain of biorefinery can potentially increase profits. In this study, carbon-based supercapacitor electrode materials were synthesized by chemically activating bio-oil and bio-char precursors, resulting in hierarchical porous structures with high surface areas. These materials exhibited nearly double the specific capacitance compared to commercially available activated carbon. Using bio-oil as the precursor offered the advantage of lower metal impurities and slightly better energy storage performance than bio-char. Additionally, a normalized energy storage value was presented for each material to aid in selecting the best economic route for the concept.