Abstract
ABSTRACT
Redox flow batteries are promising candidates for grid‐scale energy storage due to their intrinsic safety and low cost, but their practical applications are often limited by instability of redox‐active species and crossover between the two electrolytes. Here, we design a molecular capsule formed by dimeric 4‐tert‐butylcalix[8]arene (TBC8). Due to their similar hydrophobic properties, the redox‐active molecules (metal acetylacetonates) tend to be enriched in the cavities with tert‐butyl groups of the formed capsules, which enables a several‐fold enhanced solubility of redox‐active species, compared with the system without TBC8. By using the electrolytes containing encapsulated redox species, the constructed non‐aqueous redox flow battery shows a capacity retention of 90.41% after 1000 cycles, much better than that of the device (52.2% after 400 cycles) without using TBC8 capsules. This work demonstrates a promising strategy to design novel electrolytes containing sensitive redox‐active species toward high‐performance flow batteries with long‐term stability.