Ultralong Cycle Life Organic Cathode Enabled by Ether-Based Electrolytes for Sodium-Ion Batteries

Organic cathode materials have gained substantial attention in sodium-ion batteries (SIBs) because of their low cost, structure versatility, and environmental friendliness. Nevertheless, the use of organic materials is plagued by the unsatisfactory cycling performance caused by dissolution of organic electrode materials, use of inappropriate electrolytes, and/or poor interfacial compatibility. In this work, an ultralong cycle life of SIBs through coupling an insoluble organic cathode, N, N '-bis(glycinyl) naphthalene diimide, with ether-based electrolytes, is realized. A thin and stable inorganic-rich solid electrolyte interphase is constructed through a prior reduction of salt in the organic solvents in the ether-based electrolytes, promising fast charge transfer kinetics and stable cycling performance of organic electrodes in SIBs. A superb long cycle life of 70 000 cycles at 10C is demonstrated, which is a new record for organic cathode materials in SIBs. The findings highlight the key role of electrolytes and electrolyte/electrode interfaces in furthering the practical prospects of organic electrodes.

Automated summary

By coupling an insoluble organic cathode with ether-based electrolytes, an ultralong cycle life of 70,000 cycles in SIBs was achieved. The stable inorganic-rich solid electrolyte interface ensures the stable cycling performance of organic electrodes in SIBs.