Tues Jan 15 – 11:30am: Networking & Pizza; Noon-1PM: Seminar
Cost: $4 to $6
Location: EAG Laboratories – 810 Kifer Road, Sunnyvale

     Hard X-ray transmission X-ray microscopy (TXM) is an ideal tool for in situ and operando studies of functional materials and materials synthesis routes. The high energy X-rays provides relatively relaxed restrictions on in situ environments enabling high resolution 2D microscopy and tomography (3D microscopy) across a large range of pressures and temperatures and in varying gas or liquid environments. The full field geometry of TXM allows imaging at the sub-second time scale, allowing relevant dynamics to be captured during, for example, battery cycling, catalysis reactions, electrochemical synthesis, and corrosion. Moreover, by tuning the incident X-ray energy to specific absorption edges, TXM can capture elemental and chemical (spectro-microscopy) changes at 30 nm resolution within a few minutes (see figure).

            
Li-ion batteries promise the high specific capacity required to replace the internal combustion engine with a number of possible earth abundant electrode materials; however, setbacks such as capacity fading hinder the full capability of these rechargeable batteries. In the search for better electrode materials, high resolution X-ray microscopy during typical battery operation is vital in understand and overcoming the failure mechanisms of these materials. I will discuss the use of X-ray microscopy including spectro-microscopy and nano-tomography to track electrochemical and morphological changes in the electrode material in real time during typical battery operation.

                  
Dr. Johanna Nelson Weker is a staff scientist in the Materials Science Division at the Stanford Synchrotron Radiation Light source at SLAC National Accelerator Laboratory. Her research centers on X-ray microscopy of materials under realistic (in situ) and/or operating conditions. Her recent work has included characterizing energy storage materials in situ with X-ray microscopy, diffraction, and absorption spectroscopy. She also uses X-ray microscopy to characterize catalytic materials and study the selective laser melting process of alloys for advanced manufacturing. Dr. Nelson Weker graduated in 2005 with a B.S. in mathematics and physics from Muhlenberg College. She received her Ph.D. in physics from Stony Brook University in 2010, where she studied coherent diffractive imaging.