The results of using newly developed chemical-sensitive scanning transmission electron microscopic (STEM) tomography, aberration-corrected imaging, and STEM-EELS to study structural changes of electrode materials for Li-ion battery will be reported. Some initial results regarding the structural irreversibility and chemical segregation of layer-layer compounds relating to their composition will be discussed as an example. Our results show that upon charge/discharge cycles, it is possible to use STEM tomography to three-dimensionally resolve the internal pore structure and its development with sub-nanometer resolution. This structural degradation is correlated with chemical segregation of the electrode materials at two drastically different length scale—single-digit nanometer and sub-micron length scales. Using our experimental results as a direct input for our high-throughput ab initio calculations, we are able to show that the solubility of transition metals in a specific solid phase can be used as an important parameter in predicting the structural reversibility of transition metal cathode materials.

Acknowledgements

This work was supported by the U.S. Department of Energy, the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies (BMR and VTO Battery500 projects) under Contract Number DE-AC02-98CH10886 This research used resources of the Center for Functional Nanomaterials, which is a U.S. DOE Office of Science Facility, at Brookhaven National Laboratory under Contract No. DE-SC0012704