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New Room-Temperature Liquid-Metal Battery Paves the Way for Future Battery Architectures

September 18, 2020 by Nicholas St. John

At the Cockrell School of Engineering at UT Austin, researchers have built a battery combining the benefits of both their solid-state and liquid-state counterparts without their shortcomings.

There are two main types of batteries: solid-state batteries or liquid-state batteries. The solid versus liquid materials refer specifically to the electrodes of the battery. Of course, these choices affect the characteristics of the battery, and have a variety of pros and cons, causing design engineers to make trade-offs based on what specifications are required.


Image courtesy of UT Austin. 

 

For solid-state batteries, such as lithium-ion, they have significant capacity, but are susceptible to degradation over time, making them less efficient. On the other hand, liquid state batteries tend to be more efficient and do not decay like their solid-state counterparts. However, their storage is limited and they require high temperatures to keep the electrodes molten. 

According to UT Austin’s press release, their electrodes are composed of liquid metal that stays liquid at a temperature of 20 degrees Celsius, room temperature, which is the lowest operating temperature ever recorded for a liquid-metal battery. Meanwhile, the closest competitors in this category are all above the 240 degrees Celsius range.

The electrodes consist of a sodium-potassium alloy to make the anode, and a gallium-based cathode, all of which are non-toxic as compared to the lead and mercury liquid-metal anodes on the market today according to the paper’s abstract. 

The group also states that even lower operating temperatures can be achieved with further material changes for the electrodes. These changes allow these room-temperature liquid-metal batteries to provide more power than today’s lithium-ion batteries, and charge and deliver energy several times faster. Along with this, the liquid composition allows easy scaling of the battery, making it a great choice for applications ranging from smartphones to smart grids.



Image courtesy of UT Austin.
 

While these are all novel finds, the group is not done yet. The researchers aim to look for materials that are easily accessible and abundant, therefore making them cheap. The only bottleneck in their design is the fact that gallium is still quite expensive, thus other cathode configurations are being studied. On top of that, the group is looking at the materials of the electrolyte and any changes that can be made there, as that is the component that allows electric charge flow through the battery.

The team states that their design improved safety lowers maintenance costs, has a negligible self-discharge and has a very stable cycling performance. As the world looks to go green and more electric, batteries need to be ready for the demand that will be put on them. These researchers at UT Austin are not only working towards that challenge but are well ahead of the curve.