Partially exfoliated graphite oxide and lignin composites for battery electrode materials

Lignin has garnered significant research attention as a sustainable alternative for various materials and applications. However, its effectiveness as an exfoliating agent and its electrochemical properties have yet to be fully explored and validated. To address this gap, our current study focuses on the synthesis of hybrid materials based on a partial exfoliation of graphite and its oxidized analog, employing a novel method in which the ultrasound (US) forces applied are enhanced by the incorporation of lignin, further promoting the exfoliation. During the synthesis process, graphite layers are separated, and lignin particles are intercalated between these layers, promoting exfoliation. In this study, we incorporated two types of lignin, namely Kraft lignin (KL) and organosolv lignin (OL), and characterized the resulting materials using physicochemical (FTIR, Raman, EA, XRD, and XPS), morphological (AFM, and SEM), and electrochemical (CV and EIS) techniques. The physicochemical and morphological analyses provided substantial evidence supporting the exfoliating capacity of lignins and their deposition on the partially exfoliated surface. Interestingly, the effectiveness of lignins was found to be more pronounced in the case of oxidized graphite (GO) as compared to non-oxidized graphite. This observation was further corroborated by improved electrochemical performances, evidencing the deposition of lignin particles and the exfoliation as positive contributions to enhanced capacity values.