Speaker
Description
Hard carbon is a promising alternative anode material for lithium-ion batteries due to its low cost, structural stability, and ability to store Li$^+$ ions. However, its electrochemical performance is strongly affected by carbonisation temperature, precursor type, surface chemistry, and the presence of heteroatom dopants. This work compares literature-reported hard carbon materials prepared from various organic precursors, including nanocellulose, lignin, cotton, bacterial cellulose, chitosan, and cotton stalks, with a focus on the relationship between pyrolysis temperature, specific surface area, and specific capacity. The results show that non-doped hard carbons generally exhibit decreasing capacity with increasing carbonisation temperature, mainly due to progressive structural ordering, graphitisation, and loss of active sites. In contrast, heteroatom-doped carbons, especially nitrogen- and sulphur-containing materials, retain higher capacities over a broader temperature range due to increased defect density, modified electronic structure, and improved surface chemistry. The most favourable performance is observed at moderate pyrolysis temperatures of approximately 700-1000 °C, where a balance between structural disorder, heteroatom retention, active sites, and electrical conductivity is achieved. The comparison also indicates that specific surface area alone does not determine electrochemical performance; chemical activation, dopant type, defect structure, and carbon microstructure play equally important roles. These findings highlight the importance of controlled pyrolysis and heteroatom doping in the design of sustainable hard carbon anodes for lithium-ion batteries.
Acknowledgments
This work was supported by the Slovak Research and Development Agency under the contract no. VV-MVP-24-0264 and by the research grant for young researchers at the Technical University of Košice, no. 03/TUKE/2025.
