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 in situ sampling of the structural changes occurring in the electrodic materials of a Li-ion cell during charge–discharge cycling. The real-time evolution of their crystal lattice was obtained as a function of the degree of Li intercalation. As a result, new information on two electrodic materials, Li–Ti ‘‘zero strain’’ and Li–Ni–Co oxide, both of extreme interest for generation of rechargeable batteries, was gained. The actual change of the Li–Ti oxide lattice parameter upon cycling was observed in greater detail than before, 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 of cycling that remained stable in the subsequent cycles was revealed.