Powering next gen battery research

Energy storage technology interests led mechanical engineer Elizabeth Healy ’21 to the Sheldon Lab. A DiMase Family Internship allowed her to develop those interests in an academic research setting, pushing the boundaries on next generation lithium-ion batteries.

In previous years, the DiMase Family Internship was a summer award that allowed a rising senior the opportunity to stay on campus through June and July doing hands-on research. But in the COVID-19 pandemic summer of 2020, Brown laboratories were closed to undergraduates as lab plans were re-written to adhere to strict guidelines which slowly introduced graduate researchers back into the building. Elizabeth Healy ’21 was able to flex her project and prize money into the fall semester so that she could utilize the instruments that would allow her to experiment with a variety of material characterization techniques. 

Healy’s project involved a controlled study to address electro-chemo-mechanical phenomena in silicon-based electrodes. She is specifically interested in better understanding how to increase the lithium capacity without an increase in mechanical degradation of materials. “Currently in lithium-ion batteries, graphite is commercially used as the anode, but there’s a push for the next-generation of these batteries because graphite doesn’t have high enough capacity to be able to store enough energy,” Healy explained. 

“One investigation into this is to use silicon in the place of graphite because it has a much higher lithium capacity, so we’d have higher energy density batteries,” she said. A key difficulty there is that silicon undergoes volume expansion of greater than 300 percent during charging and discharging, leading to a multitude of problems in cycling stability and mechanical deterioration. 

“There are multiple ways of trying to fix this, but one thing I’m working on is coating a carbon layer on the outside of the silicon nanoparticles,” she said. “This acts as a buffer layer, constraining the volume expansion to reduce the stress and helps with electric conductivity of the electrode as well. I’ve been focusing not only on the procedure to coat carbon on the nanoparticles, but also running tests to see how this affects the electrochemical measurements and the stress measurements.” 

Healy’s work is well integrated with other ongoing efforts in Professor Brian Sheldon’s group, including related work currently supported by General Motors. 

“I took a first year seminar called Renewable Energy from the Chemical Perspective, through the Chemistry Department, and we talked about batteries and lithium-ion batteries specifically. That really prompted my interest in this. Because even if we can transition to renewable energy, we’ll have to store this energy somehow, and that is what led me to battery research.” 

Healy snagged a summer internship in 2018 with Cadenza Innovation, working on lithium-ion batteries. Cadenza Innovation, located in Connecticut, is a world leader in battery architecture, performance and safety. “I thought it was super interesting and I realized there was so much more to it than I really knew,” she said. “And although I enjoyed my internship in industry, I knew I wanted to try to do research in an academic setting. 

“So I went to [email protected] (Brown’s single site listing of people, departments, and activities that collectively make up research and scholarship in all disciplines on campus) and found that Professor Sheldon was doing work on lithium-ion batteries, so I reached out and was able to start working in his lab. 

“I feel like I’ve always been interested in climate change and sustainability,” Healy said. “And working in renewable energy is relevant to engineering.” Other sustainability ventures she has taken on while on campus include Scientists for a Sustainable World, Brown’s chapter of Engineers for a Sustainable World, where she is now an executive board member. This year’s project is designing and building a solar powered phone charging station. “I don’t know if we’ll finish before I graduate,” she said. “But it’s a very exciting endeavor. 

“I am so grateful for the DiMase Award,” she said. “It has provided me with the ability to really devote my time to research. Without the support that the award provides, I would have had to divide my time between research and a job, but I am now able to fully focus on my work in the lab. Because of this, I have been able to gain invaluable research skills and have learned so much about the research process,” she said. 

“I plan on applying to mechanical engineering graduate programs, where I hope to be able to continue to work on batteries and other energy storage methods. The positive experience (of the DiMase Award) has been fundamental in my decision to apply to graduate schools.”