A great deal of the research on lithium batteries goes into figuring out how to keep them together for the greatest number of charge-discharge cycles. Unfortunately, the active compounds in these batteries that give the greatest energy storage capacity or power output, also tend to be those compounds that come unglued under stress. Taking high-resolution 3D movies with X-ray tomography (somewhat like the CAT scans used on human subjects), researchers at the Swiss Light Source, a mecca for seeing the unseeable, have witnessed the expansion and contraction of the internal structure of lithium-ion batteries, while the batteries are operating. Stanford University’s Dr. Cui has explained that the expansion and contraction of batteries leads to their eventual failure, but until now, there has been no real-time observation of these internal reactions. Martin Ebner, a Ph.D. candidate at the Laboratory for Nanoelectronics in the Department of Information Technology and Electrical Engineering (D-ITET) at ETH (Eidgenössische Technische Hochschule) and Professor Vanessa Wood, head of the …
Lithium Gets a Good Wrap
Shadi Dayeh, professor in the Department of Electrical and Computer Engineering at the UC San Diego Jacobs School of Engineering, has been designing new electrode architectures that could solve one of lithium batteries’ biggest problems. When lithium diffuses across the surface of a lithium-ion battery electrode, it causes the electrode to expand and contract depending on its charging or discharging. This eventually leads to cracking and ultimate disintegration of the anode or cathode – weakening and finally disabling the battery. Dayeh, working with colleagues at the University and Sandia and Los Alamos National Laboratories, came up with nanowires that, “Block diffusion of lithium (Li) across their silicon surface and promote layer-by-layer axial lithiation of the nanowire’s germanium core.” Seeing possibilities beyond his current research, Dayeh says the work could lead to, “An effective way to tailor volume expansion of lithium ion battery electrodes which could potentially minimize their cracking, improve their durability, and perhaps influence how one could think about …