Read just about any article on battery-powered all-electric cars, and the time it takes to charge the battery will get a special mention – this is usually compared to the time taken to fill a tank of gas.

What’s more, this is also often put forward as a strong reason for developing hydrogen-powered vehicles, even though hydrogen, due to its energy-intensive production is not yet the solution.

But there is another energy storage system that might just fit the bill: The redox (reduction–oxidation) flow battery.

Flow batteries differ from conventional batteries in that their active material is in the form of two redox-couple solutions that are stored in external tanks and pumped through a stack of electrochemical cells where the charge and discharge reactions take place at inert electrode surfaces.

While flow batteries have found a home in grid energy storage they have yet to prove themselves in cars. However, the ability to replenish the ionic ‘salt’ solutions in a fashion that is very similar to filling a gas tank has drawn the attention of companies such as NanoFlowcell.

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This Is How The 48-Volt Quant Produces Energy From "Salt Water"

The NanoFlowcell Battery Uses "Salt Water"
Via: enginetechnologyinternational.com

Redox flow batteries typically have a very low energy density, which is roughly one order of magnitude lower than the best Li-ion. The way Nanoflowcell aims at introducing redox flow technology in a car is by making use of non-rechargeable chemistry.

NanoFlowcell, a research and development company based in Switzerland, has patented a fuel source named "bi- ION" which apparently, has zero driving emissions, no production emissions, and doesn’t require transportation. According to NanoFlowcell, "bi-ION is a salty aqueous electrolyte solution. It is not plain salt water! The bi-ION electrolyte is made of specially nano-structured molecules, which are the energy carriers and an aqueous solution with dissolved salts to make the electrolyte pumpable."

Just as in regular grid-storage flow batteries, the positively (anolyte) and negatively charged (catholyte) bi-ION liquids are stored separately in two onboard tanks, separated by a membrane. Redox refers to the differential charge states on either side of the membrane that is used as potential.

When the liquids are pumped past the membrane, the ion exchange induces an electric current, with charge added or removed through two electrodes. Thus the energy capacity is purely a function of tank size, and the power is a function of the anode surface area.

Once the energy contained in both the anolyte and the catholyte is completely consumed, these liquids are replaced with new ones - the same way an ICE car replenishes its tank with gasoline. The rest of the flow battery remains in the car and the spent electrolytes can be collected, recycled onsite, and reused by another customer.

NanoFlowcell promises a fully electric car that can be charged within minutes, offers a good driving range, and alternative clean battery chemistry with a lifespan at least comparable with Li-ion – as grid storage, some companies already offer 20 years warranty.

Although a vanadium redox flow battery costs between $1,300 and $1,500 per KWh to fully install, the electrolytes can be extremely cheap (0.1$/kg for the aqueous ones), which means that they could be serious contenders of gasoline, even in the US.

The technology however is not perfect, facing several significant challenges including limited power. Therefore small supercapacitors and/or Li-ion batteries are still required for acceleration and regenerative braking which might be why, after 6 years NanoFlowcell has yet to go into production with any of its vehicles.

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"Salt Water" Sure Gives The NanoFlowcell Cars Impressive Performance

Nano Flowcell Quantino Covers 218,000 Miles On "Salt Water"
Via: portal-energia.com

As the name suggests, the Quant is powered by four 48 volt motors and six flow cells that deliver 560 horsepower. This is good enough to get the car to 60 MPH from standstill in 2.4 seconds going on to a top speed of 200 MPH. Moreover, the company guarantees a range of 600 miles on a full tank. Even Tesla would be impressed.

Even though the Quant never made it onto the road, the company did manage to cover 218,000 test miles in its Quantino 48-volt test car, 125,000 on the road, and 93,000 in a test lab.

First unveiled at the 2015 Geneva motor show, its 48-volt electric motor produces a modest 107 horsepower - enough to propel the 3,130 lbs, two-plus-two coupe from 0 to 60 miles per hour in around five seconds with a top speed of 124 mph.

Quant claims that with software improvements over the course of testing, it has achieved energy usage of 6.2 to 7.8 miles per kilowatt-hour or more than 200 to 250 miles per gallon equivalent.

And if the name “Quant” rings a bell – it should. In 2009 Koenigsegg showed the solar-powered NLV Quant concept at the Geneva Salon, designed by none other than the founder of NanoFlowcell, Nunzio La Vecchia.