Biomass-to-Battery: Sustainable Hard Carbon for the Next Generation of Sodium-Ion Batteries

To make the shift to renewable energy sources like solar and wind, which are intermittent, large-scale energy storage is essential. Lithium-ion batteries dominate the market, but face sustainability challenges due to reliance on scarce and toxic elements which are subject to fragile supply chains. Sodium-ion batteries offer a promising alternative. Sodium is abundant, low-cost, and chemically similar to lithium, enabling use in comparable battery designs. However, sodium ions are larger, making some Li-ion electrode materials unsuitable. For example, graphite, the standard Li-ion anode, cannot effectively intercalate sodium. Instead, hard carbon has emerged as the leading Na-ion anode material. Its porous, disordered structure can host sodium ions reversibly, and it can be produced sustainably from biomass precursors such as bamboo, coconut shells, or lignin. However, despite commercial availability, HC shows variable performance, often with low initial Coulombic efficiency, limited cycle life, and poor rate capability. These inconsistencies stem from differences in pore structure, defects, and surface chemistry, which are highly dependent on the precursor material and synthesis conditions. This project, which is a collaboration between Clean Fuels, Eco Carbons, Arkimedes and TU Delft, will systematically investigate how carbonization parameters, such as processing temperature, mineral content, and pyrolysis conditions, affect HC’s structure and electrochemical properties. By focusing on economically and practically viable biomass sources, the study aims to provide concrete experimental guidelines for optimizing the HC performance, thereby advancing sodium-ion battery technology for scalable, sustainable energy storage.