‘Ultimate’ battery demonstrated by Cambridge researchers

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Researchers at Cambridge University have developed a working laboratory demonstrator of what they call the ‘ultimate battery’. The lithium-oxygen battery is said to have high energy density, to be more than 90% efficient and which has, so far, been recharged more than 2000 times.

The energy density of the battery is said to be comparable to that of gasoline, which would allow a car to drive from London to Edinburgh on one charge.

According to the team, lithium-oxygen batteries have been viewed as the ‘ultimate’ battery due to a theoretical energy density ten times that lithium-ion battery.

The demonstrator relies on a highly porous – or ‘fluffy’ – carbon electrode made from graphene (comprising one-atom-thick sheets of carbon atoms) and additives that alter the chemical reactions in the battery, making it more stable and more efficient.

“What we’ve achieved is a significant advance for this technology and suggests whole new areas for research – we haven’t solved all the problems inherent to this chemistry, but our results do show routes forward towards a practical device,” said Professor Clare Grey of Cambridge’s Department of Chemistry.

By engineering the structure of the electrode, adding lithium iodide and changing the chemical makeup of the electrolyte, the researchers reduced the ‘voltage gap’ between charge and discharge to 0.2V, equating to an energy efficiency of 93%.

Additionally, the demonstrator can only be cycled in pure oxygen, the , nitrogen and moisture in air are generally harmful to the metal electrode.

While the results, reported in the Science, are promising, the researchers caution that a practical lithium-air battery remains at least a decade away.