Catalytic Graphitization of Candle Soot for High-Voltage Dual-Carbon Battery Electrodes

This work demonstrates the use of catalytically graphitized candle soot as a sustainable electrode material for high-voltage dual-carbon batteries (DCBs). Conventional graphite suffers from high cost, intensive mining, and environmental concerns. In contrast, candle soot is a waste-derived carbon source, with its interesting properties like low cost, high conductivity because of its interconnected nature, which acts as a sustainable electrode material for high-energy applications. However, pristine soot is highly amorphous, limiting its application. To address this, Fe-assisted catalytic graphitization was conducted at 900, 1200, and 1500 °C, significantly reducing graphitization temperature and energy consumption. Structural and electrochemical analyses revealed that the 1200 °C-treated sample achieved an optimal balance between graphitic ordering and structural disorder. This tunable graphitization enhances electronic conductivity and ion transport kinetics, outperforming the performance of commercial graphite. Furthermore, Li-ion batteries suffer from safety concerns, and their higher voltage performance is constrained due to dependency on transitional metals for cathodes. In contrast, DCB acts as a promising alternative owing to inherent safety, high power, and a wide voltage window. A symmetric DCB assembled with the optimized electrode exhibited excellent rate capability, long-term cycling stability, and high specific capacity, operating up to 5.7 V, demonstrating strong potential for next-generation sustainable energy storage systems.