Downers Grove North High School ESRP 2013
In-Situ X-ray Absorption Spectroscopy of Ti-Cr Based Cathodes for Li-ion Batteries
Authors:
- Students:
- Nicholas Bonanno
- Tristan Burnham
- Sarah Brzenski
- Elizabeth Evans
- Madeline Forouhi
- Emma McDonnell
- Reid Melton
- Alana Osterling
- Teachers:
- Keith Dvorkin
- Mentors:
- Mahalingam Balasubramanian (Argonne National Laboratory, Advanced Photon Source, X-ray Science Division)
- Jason Croy (Argonne National Laboratory, Chemical Sciences and Engineering Division)
Advanced Photon Source Sector 20: Spectroscopy Group, Chemical Sciences and Engineering
Nearly every item on the average individual’s desk - an iPod, cellphone, computer, or tablet - is run on rechargeable Lithium-ion batteries. Plug-in hybrid electric vehicles (PHEVs) also rely heavily on this technology. The most commonly used cathode in a lithium-ion battery is LiCoO2. Although this is currently one of the best cathode materials available, it is relatively expensive to produce, leaving a desire to find a cheaper alternative of the same capacity. However, a significant problem with low-cost alternatives that have been tested thus far is their inability to maintain constant working productivity. We will be testing a Chromium-Titanium oxide-based cathode material. By monitoring the x-ray absorption spectra with respect to time during a charge and discharge cycle, we will be able to characterize the time evolution of oxidation within the cathode, as well as the time evolution of any local structure changes. Our findings will hopefully provide important information regarding the charge compensation mechanism in this system. In a similar study of manganese-chromium based cathode material, it was determined that chromium ions were oxidized and reduced while the role of the Mn was relatively passive. Since we are using Chromium with a different transition metal (Titanium) we will be able to offer new insight into Chromium’s role in this cathode material. Knowledge of local atomic and electronic structure obtained by in-situ XAS under lithiation and delithiation cycles will provide important information on the operating charge compensation mechanism in Ti-Cr based cathodes.