Permselective metal-organic framework gel membrane enables long-life cycling of rechargeable organic batteries

Rechargeable organic batteries show great potential as a low-cost, sustainable and mass-producible alternatives to current transition-metal-based cells; however, serious electrode dissolution issues and solubilization of organic redox intermediates (shuttle effect) have plagued the capacity retention and cyclability of these cells. Here we report on the use of a metal-organic framework (MOF) gel membrane as a separator for organic batteries. The homogeneous micropores, intrinsic of the MOF-gel separator, act as permselective channels for targeted organic intermediates, thereby mitigating the shuttling problem without sacrificing power. A battery using a MOF-gel separator and 5,5 '-dimethyl-2,2 '-bis-p-benzoquinone (Me(2)BBQ) as the electrode displays high cycle stability with capacity retention of 82.9% after 2,000 cycles, corresponding to a capacity decay of similar to 0.008% per cycle, with a discharge capacity of similar to 171 mA h g(-1) at a current density of 300 mA g(-1). The molecular and ionic sieving capabilities of MOF-gel separators promise general applicability, as pore size can be tuned to specific organic electrode materials. The use of MOF-gel separators to prevent side reactions of soluble organic redox intermediates could lead to the development of rechargeable organic batteries with high energy density and long cycling life.