Investigating the Solid Electrolyte/Electrode Interfaces with X-Ray Absorption Spectroscopy

Wednesday, 31 May 2017: 10:40
Grand Salon D - Section 24 (Hilton New Orleans Riverside)
G. Vardar, Q. Lu, J. Wang (Massachusetts Institute of Technology), R. Seibert, Z. Lee (Illinois Institute of Technology), Y. M. Chiang (Massachusetts Institute of Technology), J. Terry (Illinois Institute of Technology), and B. Yildiz (Massachusetts Institute of Technology)
Solid-state lithium-ion batteries hold great promise for obtaining higher energy densities but the power density is currently limited by the electrode-electrolyte interfaces. [1] The high resistances at SLIB interfaces are hypothesized to be due to chemical mixing, space charge formation, or secondary phase formation. [2,3] Although several secondary phases have been proposal theoretically, there is no experimental work studying the secondary phase formation as a function of temperature and applied voltage. Extended x-ray absorption fine structure spectroscopy (EXAFS) is a unique capability that allows us to probe the fine structure around the atoms at the electrode-electrolyte interface. Previous interface studies using XRD were not able to identify the secondary phases, either because secondary phases are small in amount or not crystalline. [3] Depth-sensitive x-ray absorption spectroscopy allows us to probe the changes in structure at the interface even if the secondary phases are not crystalline. This work studies the interface between Li7La3Zr2O12 (LLZO) and LiCoO2 (LCO).

[1] Cheng, L. et al. Phys. Chem. Chem. Phys. 16, 18294–18300 (2014).

[2] Miara, L. J., et al. Chem. Mater. 27, 4040–4047 (2015).

[3] Park, K. et al. Chem. Mater. 28, 8051–8059 (2016).