High Discharge Capacity and Ultra-Fast-Charging Sodium Dual-Ion Battery Based on Insoluble Organic Polymer Anode and Concentrated Electrolyte

Sodium-based dual-ion batteries have shown great promise for large-scale energy storage applications due to their wide operating voltages, environmental friendliness, abundant sodium resources, and low cost, which are widely investigated by researchers. However, the development of high-performance anode materials is a key requirement for the realization of such electrochemical energy storage systems at the practical application level. Carbonaceous anode materials based on intercalation/deintercalation mechanisms typically exhibit low discharge capacities, while metal-based materials based on conversion or alloying reactions show unsatisfactory stability in performance. On the contrary, organic materials display high theoretical capacities due to their flexible molecular structure designability and stable cyclic performance with fast reaction kinetics based on the unique enolization reaction. Herein, we report an organic polymer anode material of polyimide (PNTO), combined with a high-concentration electrolyte; the sodium-based dual-ion battery system constructed exhibits outstanding electrochemical performance. The full battery shows an ultra-high specific discharge capacity of 293.2 mAh g–1 and can be cycled stably for 3200/5600/4100 cycles at ultra-high rates of 60/120/150 C without degradation. Furthermore, the dual-ion battery system demonstrates an extremely low self-discharge rate of 0.03% h–1 and superior fast-charging–slow-discharging performance. It is one of the best performances reported up to now for a dual-ion full battery based on an organic polymer anode. This novel battery system design strategy will facilitate the advancement of high-performance organic-based dual-ion batteries and is expected to be a promising candidate for large-scale energy storage applications.