In situ studies of electrodic materials in Li-ion cells upon cycling performed by very-high-energy x-ray diffraction

A very high-energy synchrotron radiation source (87 keV) was utilized for i n situ sampling of the structural changes occurring in the electrodic mater ials of a Li-ion cell during charge-discharge cycling. The real-time evolut ion of their crystal lattice was obtained as a function of the degree of Li intercalation. As a result, new information on two electrodic materials, L i-Ti "zero strain" and Li-Ni-Co oxide, both of extreme interest for generat ion of rechargeable batteries, was gained. The actual change of the Li-Ti o xide lattice parameter upon cycling was observed in greater detail than bef ore, and provided evidence of unexpected behavior in some intervals of the cycle. In the Li-Ni-Co sample, a new phase formed during the early stages o f cycling that remained stable in the subsequent cycles was revealed. (C) 2 001 American Institute of Physics.