Researchers at the University of Cambridge have developed a working lithium-oxygen battery, or ‘super battery’, which can hold up to 10 times more charge than a lithium-ion battery.

SCIENTISTS AT THE University of Cambridge have just developed a ‘super battery’, or so their creation is being dubbed. And it could put an end to range anxiety in electric cars… there’s a catch, though. It’s unlikely we’ll see a commercially available version of the lithium-oxygen battery for at least 10 years.

Indeed, according to University of Cambridge, “Such a high energy density [10 times that of current lithium-ion batteries] would be comparable to that of petrol – and would enable an electric car with a battery that is a fifth the cost and a fifth the weight of those currently on the market to drive from London to Edinburgh on a single charge”.

According to the research paper’s lead author, Clare Gray, many of the technologies we use every day have been getting smaller, faster and cheaper each year – with the notable exception of batteries. “Apart from the possibility of a smartphone which lasts for days without needing to be charged, the challenges associated with making a better battery are holding back the widespread adoption of two major clean technologies: electric cars and grid-scale storage for solar power.”

Typically, with the lithium-ion (Li-ion) batteries we use in our laptops and smartphones, the negative electrode is made of graphite (a form of carbon), the positive electrode is made of a metal oxide, such as lithium cobalt oxide, and the electrolyte is a lithium salt dissolved in an organic solvent. While Li-ion batteries are light their capacity deteriorates with age, and their relatively low energy densities mean that they need to be recharged frequently.

On the other hand, the lithium-oxygen battery developed at the University of Cambridge, uses a very different chemistry, relying on lithium hydroxide (LiOH). With the addition of water and the use of lithium iodide as a ‘mediator’, the researchers said their battery showed “far less of the chemical reactions which can cause cells to die, making it far more stable after multiple charge and discharge cycles”.

By precisely engineering the structure of the electrode, changing it to a highly porous form of graphene, adding lithium iodide, and changing the chemical makeup of the electrolyte, the researchers were able to reduce the ‘voltage gap’ between charge and discharge to 0.2 volts. A small voltage gap equals a more efficient battery – previous versions of a lithium-air battery have only managed to get the gap down to 0.5 – 1.0 volts, whereas 0.2 volts is closer to that of a Li-ion battery, and equates to an energy efficiency of 93%.

The reason for the long gestation period? Simple, there are still plenty of bugs that need to be ironed out of this new battery technology, like finding a way to protect the metal electrode so that it doesn’t form spindly lithium metal fibres known as dendrites, which can cause batteries to explode if they grow too much and short-circuit the battery.