The search for sustainable energy storage has led researchers Susana Chauque, Pejman Salimi, Amine Lataf, William Gomes de Morais, Mohammadhossein Safari, An Hardy, Dries Vandamme, and Remo Proietti Zaccaria to investigate hardwood waste as a potential anode material for both lithium-ion and sodium-ion batteries. In a study available as a preprint through SSRN, the team explored whether the standard industrial practice of steam activation truly enhances the performance of biomass-derived carbon. Their results challenge common assumptions by showing that the energy-intensive process of activation may not be the most effective way to prepare wood waste for advanced battery technologies. By comparing unprocessed wood biochar with steam-activated versions, the study provides a clear path toward more economical and eco-friendly battery production.

The findings indicate that steam activation has a minimal impact on the performance of these materials when used in lithium-ion batteries. While the activation process significantly increases the surface area of the carbon from 92.7 to 1133.5 square meters per gram, this physical change does not translate to a substantial improvement in lithium storage. In lithium systems, both the non-activated and activated materials maintained high stability over 850 cycles with very little loss in capacity. The activated wood biochar exhibited a slightly higher initial discharge capacity, but the difference was not significant enough to justify the increased energy, gas, and chemical inputs required for its production.

The most surprising results appeared in the tests involving sodium-ion batteries, where the non-activated wood biochar significantly outperformed its more processed counterpart. The unprocessed material achieved an average discharge capacity that was nearly double that of the activated biochar, specifically reaching 72 compared to 33 milliampere-hours per gram. This superior performance is largely attributed to the larger internal spacing between the graphitic layers in the raw biochar. These wider gaps allow the larger sodium ions to move more effectively through the material during charging and discharging cycles. Additionally, the non-activated biochar retained more surface atoms like oxygen and nitrogen, which helped facilitate the diffusion of ions and improved the overall interaction with the battery’s electrolyte.

Beyond just capacity, the study highlighted the importance of initial coulombic efficiency, which measures how much energy is retained after the first charge cycle. The non-activated wood biochar showed higher efficiency in both battery types compared to the activated version. This suggests that the simpler material forms a more stable solid electrolyte interphase, which is a protective layer that grows on the surface of the electrode during its first use. A more stable protective layer generally leads to better long-term durability and more efficient energy use over the lifespan of the battery. The activated material’s extremely high surface area actually seemed to encourage more side reactions, which lowered its initial efficiency and made it less ideal for sodium systems.

The broader implications of this research are significant for the manufacturing of sustainable energy storage devices. Producing activated biochar is an energy-intensive and costly process that often offsets the environmental benefits of using biomassBiomass is a complex biological organic or non-organic solid product derived from living or recently living organism and available naturally. Various types of wastes such as animal manure, waste paper, sludge and many industrial wastes are also treated as biomass because like natural biomass these More. By demonstrating that unprocessed biochar can compete with or even beat activated materials and commercial benchmarks like hard carbon, this study identifies a way to lower the resource consumption and financial costs of battery production. The researchers advocate for a targeted material design strategy that focuses on optimizing specific properties like layer spacing and elemental composition rather than relying on indiscriminate activation.

Source: Chauque, S., Salimi, P., Lataf, A., de Morais, W. G., Safari, M., Hardy, A., Vandamme, D., & Zaccaria, R. P. (2025). Biochar or activated biochar for batteries? Unveiling the electrochemical potential of hardwood waste in lithium and sodium-ion systems. SSRN.