Quantitative characterization of the ionic mobility and concentration in Li-battery cathodes via low frequency electrochemical strain microscopy

abstract

Electrochemical strain microscopy (ESM) can provide useful information on the ionic processes in materials at the local scale. This is especially important for ever growing applications of Li-batteries whose performance is limited by the intrinsic and extrinsic degradation. However, the ESM method used so far has been only qualitative due to multiple contributions to the apparent ESM signal. In this work, we provide a viable approach for the local probing of ionic concentration and diffusion coefficients based on the frequency dependence of the ESM signal. A theoretical basis considering the dynamic behavior of ion migration and relaxation and change of ion concentration profiles under the action of the electric field of the ESM tip is developed. We argue that several parasitic contributions to the ESM signal discussed in the literature can be thus eliminated. The analysis of ESM images using the proposed approach allows a quantitative mapping of the ionic diffusion coefficients and concentration in ionic conductors. The results are validated on Li-battery cathodes (LiMn2O4) extracted from commercial Li-batteries and can provide novel possibilities for their development and further insight into the mechanisms of their degradation.

keywords

NANOSCALE; SPECTROSCOPY; INTERFACE; INJECTION; MECHANISM; DIFFUSION; TRANSPORT; SOLIDS; ENERGY

subject category

Chemistry; Science & Technology - Other Topics; Materials Science; Physics

authors

Alikin, DO; Romanyuk, KN; Slautin, BN; Rosato, D; Shur, VY; Kholkin, AL

our authors

acknowledgements

The work was financially supported by the Portuguese Foundation for Science and Technology (FCT) within the project PTDC/CTM-ENE/6341/2014. This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (FCT Ref. UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement. K. N. R. is grateful to FCT for the support of his postdoctoral fellowship SFRH/BPD/88362/2012.; The electrochemical strain microscopy measurements were done in Ural Federal University (UrFU). This part of research was made possible by Russian Science Foundation (Grant 17-72-10144). The equipment of the Ural Center for Shared Use "Modern nanotechnology" UrFU was used.

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