Stable Li-Organic Batteries with Nafion-Based Sandwich-Type Separators

Similar to Li-S batteries, Li-organic batteries have also been plagued by the dissolution of active materials and the resulting shuttle effect for many years. An effective strategy to eliminate the shuttle effect is adopting solid electrolytes or Li-ion permselective separators to prohibit the dissolved electroactive species from migrating to the Li anode. A polypropylene/Nafion/polypropylene (PNP) sandwich-type separator is reported with many advantages in comparison with previously reported LISICON, polymer electrolyte, and other Nafion utilization forms. The physical and chemical properties of PNP separators are studied in detail by cross-section scanning electron microscopy (SEM), infrared spectroscopy (IR), and electrochemical impedance spectroscopy. 1,1′-Iminodianthraquinone (IDAQ), a novel organic cathode, is taken as an example to quantitatively investigate the function of PNP separators. In the presence of PNP5 with the most appropriate Nafion loading of 0.5 mg cm^-2, IDAQ is able to achieve dramatically improved cycling stability with capacity retention of 76% after 400 cycles and Coulombic efficiency above 99.6%, which reaches the highest level for reported soluble organic electrode materials. Besides Li-organic batteries, such kind of Nafion-based sandwich-type separators are also promising for Li-S batteries and other new battery designs involving dissolved electroactive species.