Advances in High-Throughput in-Situ X-Ray Diffraction Analysis of Lithium Ion Batteries

X-ray diffraction using hard radiation (>17 keV) is able to measure lattice parameter and phase changes of cathode and anode materials simultaneously during battery cycling. Advances in hard radiation optics and detectors, combined with data logging software to correlate diffractometer and potentiostat data, are being used to improve in-situ battery analysis using laboratory diffractometers. Research previously done at synchrotrons can now be conducted with the laboratory diffractometer, improving opportunities for long-term experimental design. In this study, a reversible displacive phase transition in NMC cathodes, marked by significant contraction of the unit cell, is observed during cycling at a modest 4.2V potential. The magnitude of lattice contraction is dependent on the Ni content. This phase transition appears distinct from the H1 to H2 phase transition. Quantitative Rietveld anlaysis is used to precisely track lattice parameter changes in the cathode material. Because transmission diffraction measures cathode and anode simultaneously, anode phase content is quantified between C, LiC12, and LiC6 and these quantities are correlated to behavior of the cathode.