A commonly available ingredient in plant fertilisers is revolutionising battery technology by enabling a low-cost solution for storing renewable energy. Developed by Stanford chemistry Professor Hongjie Dai and doctoral candidate Michael Angell, the battery contains electrodes made from aluminium and graphite with the electrolyte’s main ingredient, urea, already industrially produced for plant fertilisers.

Professor Dai says the battery is made using inexpensive and abundantly available materials, delivers good performance and can cycle for a very long time. Dai’s lab had previously created a rechargeable aluminium battery in 2015 that could charge in less than a minute and lasted thousands of charge-discharge cycles. However, this award-wining battery used an expensive electrolyte.

The new battery overcomes the cost drawback by using a urea-based electrolyte, making it about 100 times cheaper than the 2015 model, with higher efficiency and a charging time of 45 minutes. Dai’s team recently reported its work in Proceedings of the National Academy of Sciences.

Battery storage is an important aspect of renewable energy; for instance, solar energy can be harnessed only during the day when the sun is shining. A solar panel pumps energy into the electrical grid during daylight hours. If that energy isn’t consumed right away, it is lost as heat. A cheap and efficient battery can store this excess energy for use at night. However, currently available batteries based on lithium-ion or lead acid are costly and have limited lifespans.

Angell explains that grid storage is the most realistic goal, because of the battery’s low cost, high efficiency and long cycle life. Also, unlike lithium-ion batteries, Dai’s urea battery is not flammable and therefore less risky.

The group has licensed the battery patents to AB Systems, founded by Dai. A commercial version of the battery is currently in development.

Dai’s team is also working on extending the lifetime of the new urea-based battery, which will help meet the demands of grid storage.

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