Intrinsic chlorine-mediated self activation of quinacridones for high-performance alkali-ion batteries

To address the growing demand for efficient energy storage systems, alternative battery technologies beyond lithium-ion batteries (LIBs) are essential. Sodium-ion and potassium-ion batteries (SIBs/PIBs) have emerged as promising candidates, however, their further development is hindered by sluggish redox kinetics in graphite anodes. Disordered carbons, with enlarged interlayer spacing and defective domains, shows efficient alkali-ion storage capabilities. In this study, quinacridones (QAs) are explored as carbon precursors for alkali-ion batteries (AIBs). We demonstrate that despite having similar crystalline orientations, QAs with different substituents undergo distinct structural transformations during pyrolysis, influencing their carbon microstructures and electrochemical properties. Specifically, 2,9-dichloroquinacridone (2,9-DCQA) exhibits a high carbon yield (55 % at 600 °C) and develops hydrangea-like morphologies with an enlarged surface area. Pyrolysis behavior analysis reveals that the bond-breakage of Cl substituents induces continuous evolution of Cl-containing gases, promoting unique morphological development and surface area enlargement. Additionally, the enlarged interlayer spacing and disordered domains in pyrolyzed DCQA (p-DCQA) enhance alkali-ion storage capabilities via diffusion- and surface-driven processes. These findings provide key insights into the utilization of QAs for high-performance energy storage applications.