Observation of lithium-ion battery by using the Bragg-edge imaging technique

甲斐 哲也; Su, Y. H.; 廣井 孝介; 篠原 武尚; 及川 健一; 林田 洋寿*; Parker, J. D.*; 鬼柳 善明*; 松本 吉弘*; 瀬川 麻里子; et al.

no journal, , 

The lattice spacing of a graphite anode of a lithium ion battery increases with the state-of-charge (SOC) due to the intercalation of lithium ions, and a spatial distribution in the lattice spacing is visualized by the neutron Bragg-edge imaging technique. At RADEN of J-PARC MLF, two dimensional neutron spectra were measured for lithium ion batteries (140 mm in thickness) to examine possible effects of casing structure on the distribution of the lattice spacing. The lithium ion batteries were constrained by containing in two types of thick aluminum casings of different structures. The measurements were performed for 20 minutes after changing SOC by charging or discharging. The Bragg-edge of graphite (002) was found to change between 0.67 nm and 0.70 nm over the full range of SOC, while the neutron transmission rates at wavelengths longer than 0.70 nm remained unchanged. Spatial distributions of transmitted neutrons between 0.67 and 0.70 nm relative to those between 0.73 and 0.82 nm for lithium ion batteries were obtained, and a localization of lithium ion intercalations in the graphite anode was successfully visualized by the Bragg-edge imaging technique.