Change in Li depth profiles of Au/LCO/mixed LATP-LAGP/Pt battery under discharging studied by ion beam analysis techniques with 9 MeV O4+ ions

• Published in: Solid state ionics 2020-01, Vol.344, p.115135, Article 115135
• Main Authors: Morita, K., Tsuchiya, B., Tsuchida, H., Majima, T.
• Format: Article
• Language: English
• Subjects: Analytical techniques; Backscattering; Batteries; Charging; Composition; Diffusion; Discharge; Electrolytes; Enrichment; Gold; Ion beams; Ions; Lithium; Platinum; Recoil; Scientific imaging
• ISSN: 0167-2738; 1872-7689
• DOI: 10.1016/j.ssi.2019.115135

Li depth profiles in Au/LCO/mixed LATP-LAGP/Pt battery (mixed LATP-LAGP (LATP/LAGP) = Li1+X+YAlYTi2−YGeXP3−XO12, LCO = LiCoO2) under discharging by biasing Pt to Au at earth potential, have been measured from both Au and Pt surfaces by means of reflection elastic recoil detection (ERD) and Rutherford backscattering spectrometry (RBS) techniques with 9 MeV O4+ ions. Ge and Ti compositions of a mixed LATP-LAGP electrolyte and thickness of LCO were determined from RBS spectrum for the as-prepared specimen, where Y and X in LATP were estimated to be 0.84 and 1.27, respectively. On charging at 2.4 V for 25 min, Li composition in LCO measured from the Au surface by ERD was reduced down to ~0.3 and hereafter on discharging at 0.5 V for 25 min the composition was not enriched, but contrary was further reduced to 0.2. However, by successive discharging at 1.0, 1.5 and 2.2 V for 50 min the composition was enriched. On the other hand, it was found from the Pt surface that Li charged in the electrolyte near Pt by biasing at 2.4 V for 20 min was reduced by discharging at 1.0 V for 20 min. By further discharging for 20 min Li was not reduced, but contrary was enriched. Both anomalous transports of Li under discharging are discussed in terms of diffusion of Li atoms in the counter direction to the biasing which is caused by the transport fraction of Li ions in the electrolyte less than unity. •Li depth profiles in LCO layer of Au/LCO/mixed LATP-LAGP/Pt battery were uniformly changed over its whole depth on charging/discharging.•Too long loading at charging brought about an anomaly in the battery at which Li was inversely transported from LCO to Pt.•The change in the Li depth profiles on charging/discharging of the battery was reversible and the battery is rechargeable.