Expensive membranes can be eliminated from flow batteries without compromising performance.

Flow batteries, used to store power in electricity grids, rely on fuels pumped through a power-generating region bounded by electrodes. Membranes typically stop fuels from reaching areas that would cause a short circuit. Some cheaper batteries are built so fuel flows smoothly and no membrane is required, but these have low power density and are usually not rechargeable.

Cullen Buie and his colleagues at the Massachusetts Institute of Technology in Cambridge engineered a membraneless hydrogen-bromine battery that can pump fuels at very high concentrations. The design boosts power density to three times that reported for other membrane-free batteries, and the battery can be recharged.

Nature Commun. http://doi.org/njt (2013)