Combining Quinone Cathode and Ionic Liquid Electrolyte for Organic Sodium-Ion Batteries

Summary Quinone-based sodium-ion batteries (SIBs) are highly desirable electrochemical devices with high capacity and low cost but suffer from poor cycle life and low practical energy because of quinone dissolution in aprotic electrolyte. Herein, we report a facile strategy of using ionic liquid (IL) to tackle the dissolution of quinone electrodes. The inhibitory effect of ILs on quinone dissolution correlates with their polarity, donor number, and interaction energy, as revealed by combined density functional theory and spectroscopy studies. Particularly, in N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl)amide ([PY13][TFSI]) electrolyte with weak donor ability and large polarity, calix[4]quinone cathode exhibits high capacity (>400 mAh g−1) and superior capacity retention (∼99.7% at 130 mA g−1 for 300 cycles), significantly outperforming that in ether-based electrolyte. Moreover, the remarkable cyclability and considerable rate capability of 5,7,12,14-pentacenetetrone in [PY13][TFSI] render it a promising sodium-storage material. This work would promote the development of high-performance SIBs with quinone electrodes and IL electrolyte.