A general separator modification tactic enables long-term stable cycling of small organic molecule electrodes in aqueous alkaline batteries

Rechargeable aqueous alkaline batteries based on small organic molecule anodes are a promising solution for large-scale energy storage due to their environmental friendliness and high energy efficiency. However, its development is limited by the poor cycling stability caused by the shuttling of soluble organic molecules between electrodes. Here, we propose a cell separator modified by metal organic framework (MOF) grown on the surface of graphene oxide (GO) to inhibit the shuttling of small organic molecules. It is demonstrated that the MOF@GO modified separator acts as an ion sieve in aqueous alkaline cells to effectively hold up small organic molecules without affecting the movement of metal ions. With the protection of the MOF@GO separator, soluble small molecules such as indanthrone (IDT) exhibit an amazing stability in alkaline electrolytes (a high reversible capacity of 137.0 mA h g⁻¹ and a good capacity retention of 95.8% after 1000 cycles at 1 A g⁻¹). It is the first report that employs carbonyl-containing small molecules as the electrodes for stable rechargeable aqueous alkaline batteries. Additionally, this strategy is also proved available to enhance the capacity and cycling stability of other active conjugated small molecules, such as PTCDI and 6CN-DQPZ, which will pave the way for the use of small organic molecules in aqueous alkaline batteries.