  A key factor preventing the market penetration of renewable, intermittent
energy sources, such as solar, wind and wave, is the lack of cost-effective
energy storage options to counteract intermittency. Here, we propose and
demonstrate a novel flow battery architecture that replaces traditional
ion-exchange membranes with less expensive heterogeneous flow-through porous
media. We present an experimentally-validated model which demonstrates that our
architecture promises reduced crossover of reactive species compared to typical
membraneless systems employing co-laminar flows in open channels. In addition,
our prototype battery exhibits significantly improved power density (0.925
W/cm2) and maximum current density (3 A/cm2) compared to previous membraneless
systems.
