A new lithium-sulfur battery capable of operating in extreme temperatures
Scientists at the University of California, San Diego, are researching designs for batteries that can operate in extreme temperatures. Recently, they were able to demonstrate the capabilities of a new lithium battery can operate at extremely low temperatures, but also at very high temperatures. This new battery could however double stored energy compared to the batteries that currently exist. It is also more ecological.
Last year, this same team of researchers discovered a way to manipulate the movement of ions in a lithium battery. They were able to do this thanks to a reinvented electrolyte solution. This type of solution serves to transport the lithium ions between the two electrodes of the battery. Scientists had been able to obtain positive results with an electrolyte that forms weaker bonds with lithium ions. This allows for a more even distribution of these ions during charging.
In their new study, the researchers incorporated this electrolyte solution into an experimental lithium battery. The latter had an anode made with high density metal and a sulfur-based cathode. This battery could already operate in temperatures well below freezing while retaining much of its capacity.
Scientists continued to work with the reinvented electrolyte and eventually they were able to develop a version that also works at high temperatures. The new electrolyte contains, among other things, lithium salt and dibutyl ether. The latter has a boiling point of 141°C, which allows the solution to remain in a liquid state at high temperatures.
During the experiments, it was observed that the batteries were able to retain 87.5% of their capacity at -40°Cand 115.9% of their capacity at 122°C. The batteries also showed Coulomb efficiencies exceeding 98% at these extreme temperatures. This means they can withstand more recharge cycles before the end of their life.
According to the researchers, a battery that can operate at very low temperatures can be used in electric cars in very cold areas. On the other hand, a battery that can operate at very high temperatures can eliminate the need for cooling systems.
Because the electrolyte is compatible with high-density lithium anodes and sulfur-based cathodes, a battery using these elements can store twice the energy stored by current batteries. For electric cars, this means doubled range. Moreover, sulfur is a more abundant and less problematic element than cobalt which is relatively rare and expensive.
According to scientists, the new technology allows for longer battery life than current lithium-sulfur batteries. Researchers are now seeking to extend this lifespan even further and to allow use at even higher temperatures.