Enhancing Performances of Polydopamine as Cathode for Lithium- and Potassium-Ion Batteries by Simple Grafting of Sulfonate Groups

Abstract Polydopamine (PDA) is a bioderived organic electrode material which exhibits a low capacity of ∼100 mAh.g−1 due to the large PDA aggregates formed at the electrode during self-polymerization of DA. In this work, it found that a simple grafting of sulfonate groups via Michael addition can endow sulfonated PDA with superior electrochemical performances. Benefiting from the homogeneity of the coated active material and the improved ionic conductivity, the optimized PDA delivered high storage capacities of 206 mAh.g−1 for LIBs and 82 mAh.g−1 for KIBs at a high current density of (1000 mA.g−1) with a coulombic efficiency of nearly 100 \%.