About a decade ago, Professor Thomas Nann realized the key to achieving a zero carbon economy was not renewably generating electricity, which was already well on its way to undercutting fossil fuels, but rather energy storage – figuring out how to make these clean electrons dispatchable, able to be summoned on demand.
Professor Nann is today the Head of the School of Mathematical and Physical Sciences at the University of Newcastle but became a chemist in his homeland, Germany.
In April, he launched startup Allegro Energy with two of his former students, Fraser Hughson and Rohan Borah. The startup seeks to commercialize its microemulsion battery electrolyte which, although mostly water by mass, has overcome the voltage limitations that typically hinder water-based solutions.
Battery electrolyte
Electrolyte sits between batteries’ anodes and cathodes, allowing ions to pass between the two conductors. In batteries, electrolytes are usually either water-based or use an organic solvent. Both these forms present their own issues. Organic solvent-based solutions, for instance, tend to have good electrochemical stability but are expensive and potentially toxic. With water-based or aqueous electrolytes, the issue is the solution only remains stable up to 1.23 volts, at which point the water splits into its separate hydrogen and oxygen molecules.
So when Professor Nann began training his attention on battery storage, he came up against precisely these issues which have puzzled researchers for decades. “At some point, I just thought ‘why not do both?’” Professor Nann told pv magazine Australia. That is, why not make an electrolyte with both water and solvent components in the form of a microemulsion. “We were completely blown away at how well it worked.”
Microemulsions
Of course, microemulsions aren’t quite as simple as adding dishwashing liquid and oil to water – rather, it’s the combination of water molecules with hydrophobic liquid, coupled with a surfactant which allows the two normally repellent solvents to bond. Basically the combination happens on such a ‘micro’ level it is not able to be split. “It’s thermodynamically stable,” Professor Nann said. “That makes them special and that’s why we can use them in a battery.”
When I asked why the concept had never been applied to battery storage, Professor Nann laughed – “that’s a really good question!”
“Actually when we submitted the patent in the first place, the patent officers came back to us and said ‘well, that’s too trivial’ and we made exactly that argument – why did no one else do that then?” he aid. “I think just no one has thought of that.”
The nub of Professor Nann and his co-founders’ discovery is that if you use a microemulsion as a battery electrolyte, you can overcome water’s pesky 1.2 volt barrier. “That’s kind of the secret sauce,” Professor Nann said.
“It’s very unusual – normally when you do research, you fail 99% of the time but that worked straight away,” he added. “It opened up a whole new world of research.”
