Mar
11
Making That Lithium Ion Battery Last Longer
March 11, 2015 | Leave a Comment
Dan Buttry, professor and chair of ASU’s Department of Chemistry and Biochemistry, the research led a team using silicon based ionic liquids and a new formulation.
The research, just 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.
Buttrey explained, “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. 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.”
Dan Buttry, professor and chair of ASU’s Department of Chemistry and Biochemistry, examines a battery sample with graduate student Tylan Watkins.
Room temperature ionic liquids have attracted a great deal of interest in recent years due to their remarkable physicochemical properties, including high thermal stability, wide electrochemical window and low vapor pressure.
Buttry added: “The hope is that this new formulation will find its way into commercial use.”
Current graduate student Tylan Watkins explained, “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. 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.”
This work provides new science related to the interfacial stability of silicon-based materials while bringing positive exposure to ionic liquid electrochemistry.
By combining a high-performance silicon electrode architecture with a room temperature ionic liquid electrolyte containing the new bis-fluorosulfonylamide anion, the researchers demonstrate a highly energy-dense lithium-ion cell with an impressively long cycling life, maintaining over 75% capacity over 500 charge/discharge cycles with almost perfect current efficiency (no wasted electrons).
Buttrey said, “This study brings home the fact that energy storage technology still has a lot of room to run, with new technological changes coming at a fast pace. This is important when considering areas where storage is important, such as grid storage and electric vehicles.”
According to Watkins, there are a multitude of reasons why modern society demands more energy dense batteries, “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. This exciting collaboration could bring us one step closer to realizing more energy dense batteries with silicon anodes.”
Lithium ion battery chemistry is popular in consumer electronics, in military applications, electric vehicles aerospace applications and many more. Giving the battery technology an even longer life cycle is always a welcome and worthwhile effort.
Buttrey’s group extensive. With Watkins are former undergraduate researcher Jarred Olsen who is currently a doctoral student at the University of Washington, Daniela Molina Piper, Tyler Evans, Kevin Leung, Seul Cham Kim, Sang Sub Han, Vinay Bhat, Kyu Hwan Oh, and Se-Hee Lee.
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