Making cell phone batteries store more energy and last longer will require the development of new battery materials. That’s just what SDState researcher Yue Zhou hopes to do.
Zhou, an assistant professor in the Department of Electrical Engineering and Computer Science, received a one-year, nearly $75,000 grant from the South Dakota Board of Regents to begin developing a new solid polymer material designed to improve the performance of lithium-ion batteries. Two doctoral students will also work on the project.
“We use a lot of rechargeable batteries in our daily lives,” Zhou, who began work at SDSU in January. After earning his doctorate from Pennsylvania State University in 2015, Zhou, whose expertise is in energy storage and nanocomposite manufacturing, was a postdoctoral researcher at Massachusetts Institute of Technology.
More than half of the lithium-ion batteries sold worldwide power consumer electronics, including cell phones, laptops and tablets, according to a Grand View Research Report. The global market for those batteries was valued at $22.8 billion in 2016 and is expected to increase to $93.1 billion by 2025.
In addition, Zhou emphasized the importance of renewable energy storage. More than 30 percent of the electricity in South Dakota comes from wind energy. However, the availability of wind and solar energy fluctuates depending on the weather and the time of day, he explained. “We have to store energy in order to have it available in the evening, for instance, when we need a lot of electricity.”
Increasing the capacity and energy density of lithium ion batteries will help meet these challenges.
Lithium batteries consist of a cathode and an anode separated by a separator. Ions pass through the separator between the electrodes as the battery is charged and discharged.
Using lithium metal in place of graphite as the anode material can increase the battery’s energy storage capacity, but the lithium tends to form needle-like dendrites. The dendrites will pierce the separator, causing a short circuit, he explained. “The electrolyte solvent is flammable so if it short-circuits, it will catch on fire.”
Zhou will use his new solid polymer electrolyte as a separator. “It has a higher mechanical strength so we can suppress the lithium dendrites,” he said. In addition, he will design inorganic nanotubes within the polymer to make it stronger. “We can use the nanotubes as the crosslink agent to give the polymer a higher Young’s modulus,” he explained.
In addition, the nanotubes create vertical channels to improve battery performance. “The ions will travel very fast, like cars on a highway,” Zhou said.