Tuesday, 30 May 2017: 10:20
Prince of Wales (Hilton New Orleans Riverside)
Majority of electrode materials used for advanced lithium based batteries have well defined chemical composition and particle morphology. The chemistry as well as the microstructure can undergo reversible or irreversible changes under continuous electrochemical charge-discharge cycles. These could have measurable impact on the battery capacity and life. Combining multi-length scale characterization with electrochemical modelling can provide vital information regarding battery electrode degradation and inomogeneity. The talk will cover our recent work related to applying a number of neutron, X-ray and laser based spectroscopy and imaging methods to a number of relvant battery chemistries such as NMC and multi-lithium transition metal based compostions. These techniques covers from meso to micron length scale truly providing the mulit-scale nature of transport in batteries. Specifcally, we demonstrate lithiation in graphitic anodes using insitu neutron imaging in a pouch cell format. The neutron absorption contrast shows a direct correlation between degree of lithiation and the discharge voltage plateau at various time steps. We further provide a semi-quantitative comparison between the observed spatial variations of neutron absorption contrast in graphite with the calculated lithium concentration profiles computed using a 3D electrochemical transport model. In conjunction with imaging, in situ neutron diffraction of a similar pouch cell under identical test protocol was carried to obtain information about the local phase changes upon lithiation. Combined in-situ radiography and diffraction opens up a powerful nondestructive method to understand the multi-scale nature of lithium transport and degradation in practical lithium-ion cells.