Operando measurement of single crystalline Li4Ti5O12 with octahedral-like morphology by microscopic X-ray photoelectron spectroscopy

Abstract To develop innovative materials for lithium-ion batteries (LIBs), intensive research has been carried out in the research fields of materials, processing, and electrochemistry. Studies of novel analytical methods using synchrotron radiation X-rays have been a focus because understanding the charge-discharge mechanism of LIBs will lead to design strategies for innovative materials. Especially, the establishment of an operando measurement system is one of the most important topics to extract the true information of materials, like electronic structures, under the operating conditions as LIBs. We report operando microscopic photoelectron X-ray photoemission spectroscopy for octahedral single crystalline Li 4 Ti 5 O 12 as an anode material of LIB under the potential control by an all solid-state LIB. From the photoelectron mapping of a single crystal, we confirm the reversible change of Ti 3 p spectra from a facet of a single crystal at a selected nano-area by Li insertion and extraction.