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 …
Unzipped Nanotubes Show Energetic Promise
Rice University, supported by the Air Force Office of Scientific Research (AFOSR), has demonstrated “a way to boost the efficiency of the ubiquitous lithium ion (LI) battery by employing ribbons of graphene that start as carbon nanotubes.” The AFOSR explains, “Four years ago, [Rice chemist James] Tour’s research team demonstrated that they could chemically unzip cylindrical shaped carbon nanotubes into soluble graphene nanoribbons (GNR) without compromising the electronic properties of the graphitic structure. A recent paper by the Tour team, published in IEEE Spectrum and partially funded by AFOSR, showed that GNR can significantly increase the storage capacity of lithium ion (Li-ion) by combining graphene nanoribbons with tin oxide. “By producing GNR in bulk, a necessary requirement for making this a viable process, the Tour team mixes GNR and 10 nanometer wide particles of tin oxide to create a slurry. GNRs, a single atom thick and thousands of times longer than they are wide, not only separate and support the …