Advanced electron holography techniques for in situ observation of solid-state lithium ion conductors

Advanced techniques for overcoming problems encountered during in situ electron holography experiments in which a voltage is applied to an ionic conductor are reported. The three major problems encountered were 1) electric-field leakage from the specimen and its effect on phase images, 2) high electron conductivity of damage layers formed by the focused ion beam method, and 3) chemical reaction of the specimen with air. The first problem was overcome by comparing experimental phase distributions with simulated images in which three-dimensional leakage fields were taken into account, the second by removing the damage layers using a low-energy narrow Ar ion beam, and the third by developing an air-tight biasing specimen holder. •Phase distributions derived by comparing experimental and simulated measurements.•Simulations take into account leakage electric fields.•Electric potential distributions inside Li-ion conductors are obtained.•FIB damage layers are removed using a low-energy narrow Ar ion beam.•An air-tight biasing TEM holder for protecting air-sensitive specimens is reported.