| AVS 66th International Symposium & Exhibition | |
| Thin Films Division | Monday Sessions |
| Session TF-MoM |
| Session: | Thin Films for Electrochemistry and Energy Storage |
| Presenter: | Angelique Jarry, University of Maryland, College Park |
| Authors: | A. Jarry, University of Maryland, College Park N. Pronin, The Ohio State University M. Walker, The Ohio State University J. Ballard, University of Maryland D. Stewart, University of Maryland, College Park L.J. Brillson, The Ohio State University G.W. Rubloff, University of Maryland, College Park |
| Correspondent: | Click to Email |
The requirements to enable all-solid-state batteries (SSBs) are extremely stringent and necessitate control of the chemistry and interfaces over a wide structural length and long-time scales. Investigations using multi-probe approaches have confirmed that surface composition, defects, structure, and morphology of the electrodes/electrolyte themselves has a strong impact on interfacial processes. Therefore, to understand how to overcome the barriers related to the implementation of SSBs, it is necessary to start with pure, well-defined models systems such as cathode thin films. V2O5 is of particular interest due to the large interlayer spacing of its metastable varieties that allows a topochemical de-intercalation of various cation (MxV2O5 withM = Li, Na, Mg). However this cation de-insertion leads to structural distortion/surface reconstruction that impedes the cathode performance. A detailed understanding of these degradation mechanisms is needed to identify the appropriate remedies.
In this work, V2O5 thin films of ~500 nm were produced by atomic layer deposition (ALD) on sputtered gold on silicon substrate. The films were subsequently electrochemically lithiated in liquid electrolytes by galvanostatic cycling i.e, LixV2O5 with x < 2. We investigated the effects of lithiation on the structural characteristics and surface morphology of LixV2O5 thin films as a function of depth through multiple methods. Change in the crystallinity and local atomic structure were probed with Raman spectroscopy (RS), X-ray photoelectron spectroscopy (XPS), optical/scanning electron microscopy and, atomic force microscopy (AFM). We demonstrated that partial lithiation of V2O5 results in reduction of the vanadium that is accompanied by a progressive surface hydroxylation and amorphization of the films. At high lithium content, significant non reversible structural rearrangements associated with the destabilization of the V-O framework are observed. The correlation between the lithium content, structural stability, electrode’s surface activity and electrochemical performance will be presented and discussed.
Acknowledgement
This work was supported by the Nanostructures for Electrical Energy Storage (NEES), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science and by the NSF grant DMR-18-00130.