Coming Soon: A Low-Cost, Long-Term Energy Storage Battery From Imperial College

A team of engineers and chemists of Imperial College London recently developed a path breaking new battery design that could allow long-term energy storage at affordable price. It has polysulfide-air redox flow battery (PSA RFB) with two membranes as an alternative to the electrolyte vanadium, used in conventional redox flow batteries, which is typically expensive and primarily sourced from China or Russia.

To start with, the team came up with a new design that will have a liquid, polysulfide, as one electrolyte and a gas, air, as the other which contained a solution of sodium hydroxide in between both parts of the cell. The materials are cheap and widely available, and the team said there is still room for experimentation to look for even cheaper materials that would do the same job. Look for this space for another revolutionary innovation pushing the price further down besides improving the longevity of the battery.

In their experiments, the Imperial team found that their polysulfide-air redox flow battery provided up to 5.8 milliwatts per centimeter squared, while the energy cost — the price of the storage material compared to the amount of energy stored — was calculated to be roughly $2.5 per kilowatt hour. The power cost — the rate of charge and discharge compared to the price of materials — was about $1,600 per kilowatt. Though this is too high for long-term storage, the researchers said they believed they would be able to greatly improve the power cost.

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“To make this cost-effective for large-scale storage, a relatively modest improvement in performance would be required,” said Professor Nigel Brandon, who also worked on the project. This could be done “by changes to the catalyst to increase its activity or by further improvements in the membranes used.”

The Imperial team’s work meets a pressing need for new forms of energy storage as the world transitions into an era of renewable energy, following the IPCC’s latest report, which warns of dire consequences if the required steps aren’t taken to drastically reduce humanity’s global carbon footprint.

Shedding light on how the work was kick started Imperial College’s Dr. Mengzheng Ouyang said, “If the polysulfide crosses over into the air side, then you lose material from one side, which reduces the reaction taking place there and inhibits the activity of the catalyst on the other,”. Working on the project, he added, “This reduces the performance of the battery – so it was a problem we needed to solve.”

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