Electrochemical Evaluation of Polydopamine/MXene Nanocomposite Cathodes for Lithium‐ and Potassium‐Ion Batteries

ABSTRACT In this study, a series of polydopamine (PDA)/MXene nanocomposites with varying weight ratios (90:10, 70:30, and 50:50) are synthesized via in situ polymerization and evaluated as cathode materials for both lithium‐ion (LIBs) and potassium‐ion batteries (KIBs). Electrochemical evaluations revealed superior performance of these composites in LIB systems, attributed to smaller ionic radius and faster diffusion kinetics of Li ⁺ compared to K ⁺ . PDA exhibits low capacities of 98.6 and 96.1 mAh g ‐1 for LIB and KIB, respectively. The incorporation of conductive MXene into PDA resulted in significantly improved performance. The PDA90MXene10, PDA70MXene30, and PDA50MXene50 nanocomposites delivered high specific capacities of 198.5, 297.8, and 246.6 mAh g −1 for LIBs, and 165.3, 249.3, and 171.8 mAh g −1 for KIBs, respectively, at 100 mA g −1 . These materials also exhibited excellent rate capabilities, with capacities of 133.1, 171.4, and 163.4 mAh g −1 for LIBs, and 131.1, 151.5, and 125.2 mAh g −1 for KIBs at a high current density of 5 A g −1 . Among all compositions, PDA70MXene30 demonstrated the most outstanding electrochemical performance, underscoring synergistic effect between redox‐active PDA and highly conductive MXene nanosheets. This synergy facilitates improved electron transport and ion diffusion, making PDA70MXene30 a promising candidate for high‐performance cathodes in both LIBs and KIBs.