Lithium-ion batteries are one of the most popular rechargeable energy storage devices for portable electronics and electrical vehicles. To design safe, high-energy electrodes with long-cycle life, we need a better understanding of how electrode materials function in real-time at nanoscale. In this presentation, I will show a method we developed for performing in-situ electron microscopy and spectroscopy to track lithium transport and electrochemical reactions. Three examples will be given. One is on lithium conversion reaction in individual iron fluoride nanoparticles and the other is on lithium intercalation reaction in spinel titanate nanoplatelets. The third one is on lithium diffusion in doped hollandite nanorods which exhibit intriguing 1D tunnel structure that can be manipulated for charge transfer. The microscopy investigations were integrated with bulk x-ray and electrochemical measurements as well as theoretical calculations at atomic scale based on DFT and meso scale based on phase-field theory. The kinetics of ionic transport and the role of defects in the lithiation process will be discussed.

The author would like to thank F. Wang, L. Wu, W. Zhang, F. Xu, Q. Meng, M. Hybertsen, AC. Marschilok and ES. Takeuchi for their collaborations. The work was supported by the U.S. DOE/BES under contract DE-SC0012704.