Photo-rechargeable lithium-ion batteries, which are able to both harvest and store solar energy within electrodes, are a promising technology for a more efficient use of intermittent solar radiation . However, there is a lack of understanding on how the light-induced lithium extraction reaction occurs within the electrode host lattice. In fact, this technology is based on bifunctional nanostructured electrodes, which undergo simultaneous complex modifications : structural reorganization through lithium-ion insertion and photo-excited charges creation through solar illumination.
In order to get more insight on the mechanism governing the photo-recharge of a single device based on a TiO2 thin film electrode made of mesoporous anatase, we perform ex-situ glancing-incidence XRD experiments. Using laboratory glancing incidence diffraction, and implementing proper corrections for the instrumental broadening of this diffraction geometry in the Rietveld refinement software XND, it was possible to extract quantitative information about the structure (lattice strain and atomic positions) and the microstructure (crystallite size and micro-strain), selectively probing the material on a depth of few nanometers.
We believe that electrodes composition and architecture, nanocrystals orientation and constraints play an important role in the dynamics of the light-induced processes. In this poster, we will present how the grazing-incidence XRD can be used before and after electrodes cycling under illumination to better understand the impact of these parameters on the photo-recharge kinetics in a view of making performant devices.
 O. Nguyen, E. Courtin, F. Sauvage, N. Krins, C. Sanchez, C. Laberty-Robert, Shedding light on the light-driven lithium ion deinsertion reaction: towards the design of a photorechargeable battery, J. Mater. Chem. A 5 (2017) 5927-5933