NASA is supporting research on the integration of nano-electrofuel (NEF) flow batteries with rim-driven electric motors to produce a safe, clean and quiet propulsion system for aircraft. This non-explosive energy storage technology has been incubated by NASA’s Armstrong Flight Research Center with NASA’s Glenn Research Center as the co-principal investigator.
In the NEF battery, positively and negatively charged electrolytes are pumped through a flow cell. The fluid electrolytes contain suspensions of nanoparticles of battery active-materials and inside the cell, the water-based fluids flow on opposite sides of an ion-exchange membrane, producing an electric current in the same way a fuel cell does. Energy storage capacity is limited by tank volume, not cell size, and power is a function of the membrane area.
The NASA supported research is being conducted by the Argonne National laboratory, the Illinois Institute of Technology and its spinoff startup company Influit. Flow batteries are not new, but previous versions had significant limits on the energy storage because of the limited amount of energy-storage materials that could be dissolved in the fluid electrolytes. Influit says surface treatment allows nanoparticle concentrations up to 80% by volume in the NEF. This results in as much as 65% of a NEF battery being active energy producing materials compared with current lithium-ion batteries with just 35% of energy producing material.
The NEF technology has the potential to produce energy densities more than 2 times Li-ion batteries. NASA engineer Kurt Papathakis says that the NEF could by 2023 an energy density of 750 Wh/kg compared to 325 Wh/kg for Li-ion batteries. The key advantages of the NEF are: nonexplosive energy storage, higher energy density than lithium-ion batteries, and fluid tank refilling is faster than charging batteries.
For further info see “Liquid Battery Promises Safe Energy-Dense Power for Electric Aircraft” Aviation Week and Space Technology, August 20-September 2, 2018, page 37.
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