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Liquid battery could revolutionise electric cars

Electric cars have been slow to take off in Australia, with only a tiny fraction of us taking to them. Among the barriers to their adoption are range anxiety, price and recharging times. Even at its fastest it can take 30 minutes to recharge an electric car for long distance journeys on a rapid charger. That’s quite a wait if you’re in a hurry, especially compared to the few minutes it takes to fill a conventional car at the bowser.

If only you could just pour the electrical charge into the car at the same rate as petrol or diesel in a conventional car it would overcome one of the biggest obstacles to owning an electric car.

Flow battery

Well a group of scientists at the University of Glasgow have come up with a system that might just do that. It’s a liquid battery, or flow battery system, that stores electrical energy in a liquid form using nanoscale battery molecules. Stored energy can then be released as electrical power on demand to power an electric vehicle. Its inventors describe it as an “exotic rust” – a metal oxide that can be electrically charged when added to water with the ability to release electricity or hydrogen gas.

Because it’s a pumpable liquid, the battery of an electric car could be recharged as quickly as it takes to fill your car with petrol. Just before that happens the old battery liquid is removed for recharging, ready to be used again.

The researchers believe the system could be the genesis of a new electrical storage system for electric cars and for storing renewable energy more generally.

Professor Lee Cronin is one of the lead researchers on the project.

"For future renewables to be effective high capacity and flexible energy storage systems are needed to smooth out the peaks and troughs in supply. Our approach will provide a new route to do this electrochemically and could even have application in electric cars where batteries can still take hours to recharge and have limited capacity. Moreover, the very high energy density of our material could increase the range of electric cars, and also increase the resilience of energy storage systems to keep the lights on at times of peak demand," Professor Cronin said.

Quick recharging

It's early days for the technology which has been described in the scientific journal Nature Chemistry. It’s still in a prototype stage but it holds the promise of giving electric cars the same range as internal combustion engines with a similar refuelling time. Furthermore it can use a modified form of pre-existing infrastructure – fuel stations – to deliver the electric fuel.

Normal batteries have an electrolyte which hold the charge sandwiched between two electrodes. A chemical reaction inside the electrolyte sees a charge passing from one electrode to the other until the electrolyte is depleted. When you charge the battery you push charge in the opposite direction until recharging is complete. In a flow battery the liquid is pumped past the electrodes creating the charge. Flow batteries have been around for awhile but what makes the Glasgow scientists’ effort so revolutionary is that the liquid has 10-times the energy density of previous flow batteries.

It’s very early days for the technology which is currently moving from the laboratory to a test rig and a prototype. According to Professor Cronin big companies are already showing interest in the technology.

Solid state technology

Flow batteries are not the only potential battery revolution, however. Solid state batteries offering two-to-three times the energy capacity of lithium-ion without the flammable, volatile and corrosive problems of the latter are also being developed.

Solid Power, a Colorado start-up with origins in a battery research program at the University of Colorado, has attracted some big backers including BMW, Hyundai and Samsung. It holds the promise of batteries that are more powerful, safer, cheaper and easier to manufacture than current Lithium-Ion batteries.

Australians have so far been reluctant to embrace electric cars but with a host of new models on the way from major carmakers that might be about to change. New technology promises to reduce costs, extend the range and reduce charging times, all barriers to their uptake at present. Watch this space.

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