Department of Chemistry, 419 Latimer Hall, University of California, Berkeley, Berkeley, CA, 94720, USA.
Joint Center for Energy Storage Research, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA.
Angew Chem Int Ed Engl. 2017 Feb 1;56(6):1595-1599. doi: 10.1002/anie.201610582. Epub 2017 Jan 10.
Intermittent energy sources, including solar and wind, require scalable, low-cost, multi-hour energy storage solutions in order to be effectively incorporated into the grid. All-Organic non-aqueous redox-flow batteries offer a solution, but suffer from rapid capacity fade and low Coulombic efficiency due to the high permeability of redox-active species across the battery's membrane. Here we show that active-species crossover is arrested by scaling the membrane's pore size to molecular dimensions and in turn increasing the size of the active material above the membrane's pore-size exclusion limit. When oligomeric redox-active organics (RAOs) were paired with microporous polymer membranes, the rate of active-material crossover was reduced more than 9000-fold compared to traditional separators at minimal cost to ionic conductivity. This corresponds to an absolute rate of RAO crossover of less than 3 μmol cm day (for a 1.0 m concentration gradient), which exceeds performance targets recently set forth by the battery industry. This strategy was generalizable to both high and low-potential RAOs in a variety of non-aqueous electrolytes, highlighting the versatility of macromolecular design in implementing next-generation redox-flow batteries.
间歇性能源，包括太阳能和风能，需要可扩展、低成本、可长时间储能的解决方案，才能有效地纳入电网。全有机非水氧化还原液流电池提供了一种解决方案，但由于氧化还原活性物质在电池膜中的高渗透性，它们会迅速出现容量衰减和低库仑效率的问题。在这里，我们展示了通过将膜的孔径缩小到分子尺寸，可以阻止活性物质的跨膜扩散，从而使活性物质的尺寸超过膜的孔径排斥极限。当齐聚氧化还原活性有机化合物（RAO）与微孔聚合物膜配对时，与传统隔板相比，活性物质的跨膜扩散速率降低了 9000 多倍，而对离子电导率的影响最小。这相当于 RAO 跨膜扩散的绝对速率小于 3 μmol·cm-2·day-1（对于 1.0 m 浓度梯度），超过了电池行业最近设定的性能目标。该策略在各种非水电解液中对高电位和低电位 RAO 均具有通用性，突出了大分子设计在实现下一代氧化还原液流电池中的多功能性。
