A review of the synthesis of carbon materials for energy storage from biomass and coal/heavy oil waste

Recent progress in the synthesis of carbon materials from biomass and coal/heavy oil waste and their use as the electrode materials of supercapacitors and Li-ion batteries is reviewed. The carbon precursors include seafood and agricultural waste, and coal and heavy oil by-products. The carbon materials include 0D carbon quantum dots, 1D carbon nanofibers, 2D carbon nanosheets, and 3D carbon frameworks. Techniques to tailor the carbon porosity/surface include KOH activation with and without self-templating, self-activation and/or in-situ templating, and heteroatom doping with N, O, P and their co-doping. The effects of porosity and heteroatom doping on the electrochemical performance are summarized. The challenges for the synthesis, microstructural tailoring of these materials and their potential use in supercapacitors and Li-ion batteries are analyzed.