Title

Comparative analysis of ex-situ and operando X-ray diffraction experiments for lithium insertion materials

RIS ID

103881

Publication Details

Brant, W. R., Li, D., Gu, Q. & Schmid, S. (2016). Comparative analysis of ex-situ and operando X-ray diffraction experiments for lithium insertion materials. Journal of Power Sources, 302 126-134.

Abstract

A comparative study of ex-situ and operando X-ray diffraction techniques using the fast lithium ion conductor Li0.18Sr0.66Ti0.5Nb0.5O3 is presented. Ex-situ analysis of synchrotron X-ray diffraction data suggests that a single phase material exists for all discharges to as low as 0.422 V. For samples discharged to 1 V or lower, i.e. with higher lithium content, it is possible to determine the lithium position from the X-ray data. However, operando X-ray diffraction from a coin cell reveals that a kinetically driven two phase region occurs during battery cycling below 1 V. Through monitoring the change in unit cell dimension during electrochemical cycling the dynamics of lithium insertion are explored. A reduction in the rate of unit cell expansion of 22(2)% part way through the first discharge and 13(1)% during the second discharge is observed. This reduction may be caused by a drop in lithium diffusion into the bulk material for higher lithium contents. A more significant change is a jump in the unit cell expansion by 60(2)% once the lithium content exceeds one lithium ion per vacant site. It is suggested that this jump is caused by damping of octahedral rotations, thus establishing a link between lithium content and octahedral rotations.

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Link to publisher version (DOI)

http://dx.doi.org/10.1016/j.jpowsour.2015.10.015