Soluble Organic Cathodes Enable Long Cycle Life, High Rate, and Wide‐Temperature Lithium‐Ion Batteries. Issue 5 (14th December 2021) - Li, Mengjie
Abstract: Organic electrode materials free of rare transition metal elements are promising for sustainable, cost‐effective, and environmentally benign battery chemistries. However, severe shuttling effect caused by the dissolution of active materials in liquid electrolytes results in fast capacity decay, limiting their practical applications. Here, using a gel polymer electrolyte (GPE) that is in situ formed on Nafion‐coated separators, the shuttle reaction of organic electrodes is eliminated while maintaining the electrochemical performance. The synergy of physical confinement by GPE with tunable polymer structure and charge repulsion of the Nafion‐coated separator substantially prevents the soluble organic electrode materials with different molecular sizes from shuttling. A soluble small‐molecule organic electrode material of 1, 3, 5‐tri(9, 10‐anthraquinonyl)benzene demonstrates exceptional electrochemical performance with an ultra‐long cycle life of 10 000 cycles, excellent rate capability of 203 mAh g −1 at 100 C, and a wide working temperature range from −70 to 100 °C based on the solid–liquid conversion chemistry, which outperforms all previously reported organic cathode materials. The shielding capability of GPE can be designed and tailored toward organic electrodes with different molecular sizes, thus providing a universal resolution to the shuttling effect that all soluble electrode materials suffer. Abstract : Soluble organic cathodes are demonstrated with an ultra‐long cycle life, excellent rate capability, and a wide operation temperature range from −70 to 100 °C based on bi‐functional gel polymer electrolytes, which can eliminate the shuttling of the soluble organic electrode materials through molecular sieving and charge repulsion while maintaining a fast reaction kinetics.