One of the biggest missing links in renewable energy is affordable and high performance energy storage, but a new type of battery developed at Stanford University could be the solution.
Solar energy generation works great when the sun is shining [duh…like taking a Space Mission to the Sun .. but only at night! :-)] and wind energy is awesome when it’s windy (double duh…), but neither is very helpful for the grid after dark and when the air is still. That’s long been one of the arguments against renewable energy, even if there are plenty of arguments for developing additional solar and wind energy installations without large-scale energy storage solutions in place. However, if low-cost and high performance batteries were readily available, it could go a long way toward a more sustainable and cleaner grid, and a pair of Stanford engineers have developed what could be a viable option for grid-scale energy storage.
With three relatively abundant and low-cost materials, namely aluminum, graphite, and urea, Stanford chemistry Professor Hongjie Dai and doctoral candidate Michael Angell have created a rechargeable battery that is nonflammable, very efficient, and has a long lifecycle.
“So essentially, what you have is a battery made with some of the cheapest and most abundant materials you can find on Earth. And it actually has good performance. Who would have thought you could take graphite, aluminum, urea, and actually make a battery that can cycle for a pretty long time?” – Dai
A previous version of this rechargeable aluminum battery was found to be efficient and to have a long life, but it also employed an expensive electrolyte, whereas the latest iteration of the aluminum battery uses urea as the base for the electrolyte, which is already produced in large quantities for fertilizer and other uses (it’s also a component of urine, but while a pee-based home battery might seem like just the ticket, it’s probably not going to happen any time soon).
According to Stanford, the new development marks the first time urea has been used in a battery, and because urea isn’t flammable (as lithium-ion batteries are), this makes it a great choice for home energy storage, where safety is of utmost importance. And the fact that the new battery is also efficient and affordable makes it a serious contender when it comes to large-scale energy storage applications as well.
“I would feel safe if my backup battery in my house is made of urea with little chance of causing fire.” – Dai
According to Angell, using the new battery as grid storage “is the main goal,” thanks to the high efficiency and long life cycle, coupled with the low cost of its components. By one metric of efficiency, called Coulombic efficiency, which measures the relationship between the unit of charge put into the battery and the output charge, the new battery is rated at 99.7%, which is high.
In order to meet the needs of a grid-scale energy storage system, a battery would need to last at least a decade, and while the current urea-based aluminum ion batteries have been able to last through about 1500 charge cycles, the team is still looking into improving its lifetime in its goal of developing a commercial version.
The team has published some of its results in the Proceedings of the National Academy of Sciences, under the title “High Coulombic efficiency aluminum-ion battery using an AlCl3-urea ionic liquid analog electrolyte.”
Grid-scale energy storage to manage our electricity supply would benefit from batteries that can withstand repeated cycling of discharging and charging. Current lithium-ion batteries have lifetimes of only 1,000-3,000 cycles. Now a team of researchers from Stanford University, Taiwan, and China have made a research prototype of an inexpensive, safe aluminum-ion battery that can withstand 7,500 cycles. In the aluminum-ion battery, one electrode is made from affordable aluminum, and the other is composed of carbon in the form of graphite.