Batteries have been used since the 1800s, although early batteries were used to power devices with only small power loads. Recently, however, battery technology has advanced to provide large loads and a significant number of devices are powered exclusively from batteries. This is a result of the use of materials (anodes and cathodes) with higher energy densities and with excellent cyclability for long-term use. However, the anode and cathode materials are still not adequate for extended use in high power, such as for fully electric vehicles (EVs). Both the battery capacity and lifetime must be increased for use in EVs, since current technology is not capable of meeting the demands for long distance travel or the long lifetimes.
Li-ion batteries are likely candidates for future EVs. For example, Tesla Motors has designed a battery cell that powers the Tesla Roadster for 200 miles per charge. However cost, performance, and cyclability are still not quite adequate and new materials are still being developed. We have begun a program to use in situ X-ray diffraction and transmission X-ray microscopy to study battery anode and cathode materials. To date (August 2011), we have developed an X-ray transparent pouch cell, which can be cycled up to a few days without failure. With this cell design, we have studied the changes in crystalline species and morphology during electrochemical cycling of various silicon anode and sulfur cathode batteries. We will continue to explore these materials with X-ray absorption and emission spectroscopy and inelastic X-ray Raman spectroscopy. We also plan to characterize a number of transition metal oxides as cathode materials. Check back here for progress.
Li-ion Battery Materials