Quasi-Solid-State Conversion with Fast Redox Kinetics Enabled by a Sulfonamide-Based Electrolyte in Li–Organic Batteries

The serious dissolution of organic electrode materials (e.g., perylene-3,4,9,10-tetracarboxylic dianhydride, PTCDA) in electrolytes is a major challenge, deteriorating their electrochemical performances and hindering the interpretation of the fundamental redox reaction mechanisms including the intrinsic kinetics and the solvent cointercalation. To address these issues, we propose a rationally designed sulfonamide-based electrolyte to enable a quasi-solid-state conversion (QSSC) of the PTCDA cathode by effectively suppressing its dissolution in the electrolyte. Benefiting from the QSSC, the Li||PTCDA cells can retain ∼95.8% of the original capacity after 300 cycles with both high and stable energy efficiencies >95%, even comparable to the layered transition-metal oxide cathodes, greatly outperforming an ether-based electrolyte with a high PTCDA solubility. The high energy efficiencies indicate that the QSSC of PTCDA has intrinsic fast redox kinetics. Furthermore, the solvent cointercalation mechanism was investigated by density functional theory/molecular dynamic calculations. This work develops a strategy for designing electrolytes for highly stable and efficient Li-organic batteries.