High-performance silicon electrode extends lithium-ion battery life cycle

Technology News |
By eeNews Europe

The innovative solution claims to maintain more than 75 percent capacity over 500 charge/discharge cycles with almost perfect current efficiency (no wasted electrons).

The research, published in Nature Communications, brings together scientists from Arizona State University, University of Colorado at Boulder, Sandia National Laboratories, Boulder Ionics Corporation and Seoul National University, Korea.

Led by Dan Buttry, professor and chair of ASU’s Department of Chemistry and Biochemistry, the research also involves former undergraduate researcher Jarred Olsen and current graduate student Tylan Watkins. Olsen joined Buttry’s group as an undergraduate researcher to work in the ionic liquids area. The work he contributed to this study was performed while he was on an internship at Boulder Ionics working at both Boulder and ASU with Watkins. Olsen is currently a doctoral student at the University of Washington, Seattle.

Room temperature ionic liquids have attracted interest in recent years due to their physicochemical properties, including high thermal stability, wide electrochemical window and low vapor pressure.

“We used a device called a quartz crystal microbalance to measure very tiny mass changes in thin films at the surface of the battery material during charging and discharging,” said Buttry. “One of the key features of successful lithium battery materials is that they develop thin films that protect the surface of the battery electrodes, which prolongs the life of the battery. This study documents the development of just such a film in a new type of battery formulation that has many more attractive features than existing commercial lithium batteries."

“These were not trivial measurements to make because composite films (meaning a film of the active material in a polymer matrix) are often difficult to use with a quartz crystal microbalance,” said Watkins. “Most, if not all, quartz crystal microbalance studies of this sort use very thin films of the active material alone, which means specialty deposition methods must be used. What was cool here is that we were able to make the measurement on a more practical film, something you might realistically see in a commercial battery.”

The work provides science related to the interfacial stability of silicon-based materials while bringing positive exposure to ionic liquid electrochemistry.

“For some time, silicon anodes have been proposed as replacements for the carbon based anodes found in current state-of-the-art devices as they could potentially give energy densities almost 10 times that of modern anodes," Watkins said.

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