Recently, MIT’s Professor Donald Sadoway and his team of students published a paper that may have brought a new breakthrough in liquid battery implementation that can vastly improve the benefits of the technology.
But first, what is a liquid battery? A liquid battery, or molten salt battery, consists of a salt heated to its melting point, which functions as the salt bridge in conventional batteries. In addition, the electrodes are also molten metals. What this means for the battery is a longer life, higher current output, and faster charging. This is a huge advantage over conventional batteries, but of course there is a major drawback: the temperatures. Salts have extremely high melting points, which is why you don’t have a liquid battery in your phone, or anywhere for that matter. Currently, liquid batteries are mainly used in military applications such as missiles.
Charging and discharging cycle of a liquid metal battery. Note that the chemistry is not entirely the same as this new process, but the concept is the same. Image courtesy of Ambri.
The research lead (and more or less founded) by Professor Sadoway can potentially lead to great improvements in power grid storage. This is because he and his team have found a way to lower the temperature required to maintain a liquid battery, yet not lose the benefits associated with them. Instead of using pure calcium which has a rather high melting point around 900 C, Professor Sadoway used an alloy of magnesium and calcium which lowered the melting point by approximately 300 C without any performance decrease. Not only does this make liquid batteries more feasible to create, there is an additional bonus: cost.
Professor Donald Sadoway in his lab. He was the original creator of such technology and now has further improved it. Image courtesy of Donald Sadoway
Magnesium and calcium are found naturally paired together when mining their ore and are separated when purified. Lower-grade calcium contains a quantity of magnesium already, which in this application reduces cost and production time. On top of that, due to the large abundance of magnesium and calcium, it would be an environmentally friendly alternative to the powerhouse that is the lithium battery. And yet there is still an additional benefit to this new chemistry, which is the physical composition of the battery. The magnesium and calcium alloy can function as the negative electrode and the salt layer in the battery, thus reducing the amount of materials needed and therefore cost.
While this battery technology will almost certainly not be inside of your laptop, phone, or car in the coming years, you may be able to power your house with a liquid battery. With the fast charging times and high power output, this could be the best thing that has ever happened to renewable energy as we may finally have a battery that can store enough energy, and not need to be maintained very often. The issue with heating to rather high temperatures is still an immediate concern, but with further advancements, or simply leaving the batteries in an industrial setting away from the individual, large strides can be made to bring the benefits of liquid batteries to your doorstep.
Want to learn straight from the man himself? Go watch Professor Sadoway's Ted Talk below.