University of Texas researchers developed a novel manganese and sodium-ion based material offering a potentially lower-cost, more eco-friendly option to fuel next-generation devices and electric cars.
Battery cost is a substantial issue, said Dr. Kyeongjae Cho, professor of materials science and engineering in the Erik Jonsson School of Engineering and Computer Science.
As manufacturers and consumers push for more electric vehicles (EVs), lithium production may have a hard time keeping up with increasing demand, Cho said. In terms of cost savings in EV battery, using sodium would be less expensive because sodium is more abundant, but it has some drawbacks.
Lithium is a more expensive, limited resource that must mine from just a few areas on the globe. There are no mining issues with sodium, it can be extracted from seawater. Unfortunately, sodium-ion batteries might be less expensive than those using lithium, sodium provides 20 percent lower energy density than lithium.
The energy density, or energy storage capacity, of a battery determines the run time of a device. “We used our previous experience and thought about these issues how can we combine these ideas to come up with something new to solve the problem?” Cho said.
In a standard lithium-ion battery, the cathode made of lithium, cobalt, nickel and oxygen, while anode made of graphite. When the battery charges, the Li ions move through the electrolyte to the anode and attach to the carbon. During discharge, the lithium ions move back to the cathode and provide electric energy to run devices.
There was great hope several years ago using manganese oxide in lithium-ion battery cathodes to increase capacity. But, unfortunately that combination becomes unstable.
In the design, sodium replaces most of the lithium in the cathode, and manganese used instead of the more expensive and rarer elements cobalt and nickel.
The sodium-ion material is more stable, but it still maintains the high energy capacity of lithium. Based on their knowledge of other experimental materials, the researchers attacked the problem with rational material design. They first ran computer simulations to determine the configuration of atoms that showed the most promise before making and testing the material.
Cho said, the research is not just about coming up with a better battery. How the research done is just as important and as interesting.
More information: [Wiley online library]