A π-Conjugated Organic Cathode with Superior K ⁺ Diffusion Kinetics for Potassium Ion Batteries

Organic cathodes hold promise for potassium-ion batteries (PIBs) but suffer from dissolution and poor conductivity. Here, we report a molecular grafting strategy to construct a stable β-PTCDA-D cathode by incorporating the nitrogen-rich heterocyclic linker 3,5-diamino-1,2,4-triazole (DAT) into perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA). DAT incorporation promotes charge transfer and reduces the energy barrier for K+ storage. Meanwhile, the amidation reaction generates a robust molecule with extensive π-conjugation, strong hydrogen-bonding interactions, and enlarged interlayer spacing. These structural advantages improve electronic conductivity, suppress dissolution, and stabilize K+ intercalation/deintercalation, thereby maintaining structural integrity during cycling. As a result, β-PTCDA-D delivers a high reversible capacity of 100 mAh g–1 at 100 mA g–1, outstanding rate performance (75 mAh g–1 at 500 mA g–1), and excellent long-term stability with 76% retention after 200 cycles. Furthermore, a full cell paired with nanographite further demonstrates practical applicability. This work demonstrates the effectiveness of molecular interaction engineering in stabilizing small-molecule organic cathodes and provides a viable pathway for high-performance and sustainable PIBs.