title: Operando observations of solid-state electrochemical reactions in Li-ion batteries by spatially resolved TEM EELS and electron holography.
abstract: All-solid-state Li-ion batteries having incombustible solid electrolytes are promising energy storage devices because they have significant advantages in terms of safety, lifetime and energy density. Electrochemical reactions, namely, Li-ion insertion/extraction reactions, commonly occur around the nanometer-scale interfaces between the electrodes and solid electrolytes. Thus, transmission electron microscopy (TEM) is an appropriate technique to directly observe such reactions, providing important information for understanding the fundamental solid-state electrochemistry and improving battery performance. In this review, we introduce two types of TEM techniques for operando observations of battery reactions, spatially resolved electron energy-loss spectroscopy in a TEM mode for direct detection of the Li concentration profiles and electron holography for observing the electric potential changes due to Li-ion insertion/extraction reactions. We visually show how Li-ion insertion/extractions affect the crystal structures, electronic structures, and local electric potential during the charge-discharge processes in these batteries.
authors.affiliation: Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Aichi456-8587, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Yamamoto
authors.affiliation: Department of Materials, Physics and Energy Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi464-8601, Japan.
authors.forename: Yasutoshi
authors.initials: Y
authors.lastname: Iriyama
authors.affiliation: Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Aichi456-8587, Japan.
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Hirayama
keywords: Li distribution; electron energy-loss spectroscopy; electron holography; lithium-ion battery; operando observation