Epitaxial thin films as model battery electrodes - The reaction front and ionic diffusion
EMSL Project ID
49282
Abstract
Energy conversion and storage is of great importance to a sustainable environment and meeting our energy needs. However, fundamental scientific understanding of rechargeable batteries is far behind industrial standards today. Two important open questions in basic science that impact battery stability, lifetime and performance are: (1) How do the electroactive ions move through the active material? This is particular interesting for ions of different size and charge, such as Li1+ and Mg2+. (2) How is this affected by grain boundaries and defects? Quantitative answers to these questions impact battery design and predictive performance. In order to resolve these issues we are proposing a fundamental study involving four DOE user facilities, taking advantage of important expertise and capabilities at each. These studies build upon the use of defined epitaxial thin film electrodes created in EMSL as our simple and well-defined model system. We have chosen layered compounds, such as V2O5 and MoO3 that are known to intercalate Li1+ as well as Mg2+ as the active material. Our overall research objective is to track the ions' diffusion and transport in the lateral and surface-normal direction via a wide range of complementary experimental techniques such as X-ray photon correlation spectroscopy, spatially- and depth-resolved in operando X-ray diffraction and reflectivity, as well as Raman spectroscopy. These techniques will cover fundamental length and relevant time scales, ranging from local, atomic distortions over long-range strains fields to diffusion over millimeters, corresponding to ~ 10 - 100 femtosecond, millisecond and seconds-minutes diffusion times. Our results will be discussed in relation to theoretical efforts in collaboration with Prof. Gerbrand Ceder (UC Berkeley/LBNL). Accordingly, we propose to use EMSL's pulsed laser deposition (PLD) system for the growth of epitaxial thin films on SrTiO3. Via variation of the deposition parameters, we will prepare films of different thickness, morphology, grain size as well as step edge and defect density. From this variation of film quality, we will gain insight into the effect of grain boundaries and defects in ion transport and diffusion.
We expect that our results will significantly improve the atomic level understanding of the movement of electroactive ions through the active materials, thus gathering a fundamental understanding of dynamic processes in energy storage, an important missing piece our knowledge today.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2016-10-01
End Date
2018-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Cao C ,Steinrueck HG ,Shyam B ,Stone K H,Toney M F 2016. "In Situ Study of Silicon Electrode Lithiation with X?ray Reflectivity" Nano Letters 16(12):7394–7401. 10.1021/acs.nanolett.6b02926