Biocarbons are difficult to graphitize even at 3000 °C. In this study, three-dimensional porous graphene-like sheets (3DPGLS) were directly synthesized from biocarbons at 900 °C. Potassium carbonate was utilized as a catalyst to release graphite microcrystals from the crosslinked sp³ carbon atoms in the hard carbon phase, and subsequently recrystallized them to form graphene layers. The as-obtained 3DPGLS showed a high purity and low defect density, and possessed high conductivity (32.14 S cm⁻¹) and specific surface area (1506.19 m² g⁻¹). Without conductive additives, the capacitance of 3DPGLS reached 91.15 F g⁻¹ at a current density of 0.2 A g⁻¹ acting as a two-electrode symmetrical supercapacitor electrode material in an organic electrolyte. 85.1% of the initial capacitance was maintained after 5000 cycles at a current density of 0.1 A g⁻¹.

L-Ti₃C₂ was prepared by exfoliating Ti₃AlC₂ in 40% HF. With sulfur-loaded L-Ti₃C₂ as cathodes, Li–S batteries deliver a high initial discharge capacity of 1291 mA h g⁻¹, an excellent capacity retention of 970 mA h g⁻¹ and coulombic efficiency of 99% after 100 cycles.

Biomass is rich, renewable, sustainable, and green resources, thereby excellent raw material for the fabrication of carbon materials. The diversity in structure and morphology of biomass are relevant in obtaining carbon materials with different structures and performances. The inherent ordered porous structure of biomass also benefits the activation process to yield porous carbons with ultrahigh specific surface area and pore volume. Besides, obtained biomass‐derived carbons (BDCs) are hard carbon with porous morphology, stable structure, superior hardness/strength, and good cycling performances when used in electrochemical capacitors (ECs). The inherent N, S, P, and O elements in biomass yield naturally self‐doped N, S, P, and O BDCs with unique intrinsic structures. In this paper, the synthesis approaches and applications of BDCs in ECs are reviewed. It shows that BDCs electrochemical performances are highly determined by their pore structures, specific surface areas, heteroatoms doping, graphitization degree, defects, and morphologies. The electrochemical performances of BDCs can further be improved by compositing with other materials, such as graphene, carbon nanofibers/nanotubes, transition metal oxides or hydroxides, and conducting polymers. The future challenges and outlooks of BDCs are also provided.

Ru nanoparticles supported on a multi-walled carbon nanotube paper as a cathode in a Li–O₂ battery can significantly reduce the charge overpotentials, and present a large discharge–charge capacity and stable cycles.