Journal Article Domain Size of Phase-Separated NaxCoO2 as Investigated by X-Ray Microdiffraction

Niwa, Hideharu  ,  Shibata, Takayuki  ,  Imai, Yasuhiko  ,  Kimura, Shigeru  ,  Moritomo, Yutaka

3 ( 1 )  , p.5 , 2017-03 , MDPI
O3-NaCoO2 is a promising cathode material for sodium ion secondary batteries (SIBs).NaxCoO2 shows phase separation (PS) into the O3 and O03 phases in the Na concentration range of 0.89 6 x 6 0.99. In order to estimate the domain size (r) in the two-phase region, we performed X-ray microdiffraction (XRMD) of thin films of NaxCoO2 at x = 0.97 and 1. We found that r (400 nm)of the O03 domain is comparable to the particle size d (=331 87 nm) in the as-grown O3-NaCoO2 film. This observation suggests that individual particles of NaxCoO2 are single phase to minimize the strain at the O3–O03 phase boundary.

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