In this poster, we report the development of a quasi in-situ TEM technique to study structural changes of electrode materials for Li-ion and Na-ion batteries. Some preliminary results about structural (ir)reversibility of NiO conversion anode materials relating to the materials’ size and morphology will be discussed as an example. Using a quasi in-situ TEM setup, we were able to track the structural changes of electrode materials in marked locations on a TEM grid repeatedly before and after electrochemical lithiation/delithiation in LiPF6/EC/DEC electrolyte. This method is a further development of the TEM grid-in-a-coin cell method reported in the literature (F Lin et al, Nat. Comms.,5, 3356 (2014)) with much improved capability to locate the same materials on the TEM grid before and after charging/discharging. Our results show that upon lithiation, NiO is converted into a three-dimensional nanoporous network of metallic Ni. However, we found that the structural reversibility of NiO upon delithiation is highly dependent on the initial size and morphology of the materials. Particularly in our 10 nm-thick NiO nanoplate materials, the nanoporous structure can be removed and the solid-form palette structure can be fully recovered when the material is delithiated. This study shows that that size effect can be an important parameter in dictating the structural reversibility of transition metal oxide conversion 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 under Contract Number DE-SC0012704. 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.