Enabling Aspects of Metal Halide Nanocomposites for Reversible Energy Storage
- PDF / 488,264 Bytes
- 12 Pages / 612 x 792 pts (letter) Page_size
- 80 Downloads / 243 Views
0972-AA07-01-BB08-01
Enabling Aspects of Metal Halide Nanocomposites for Reversible Energy Storage Fadwa Badway1, Azzam Mansour2, Irene Plitz1, Nathalie Pereira1, Larry Weinstein1, William Yourey1, and Glenn G Amatucci1 1 Rutgers, The State University of New Jersey, North Brunswick, NJ, 08902 2 Naval Surface Warfare Center, West Bethesda, MD, 20817 ABSTRACT The concept of reversible and non reversible conversion in high bandgap metal fluorides is expanded through the introduction of mixed conducting matrices to form dense nanocomposite structures capable of good transport to nanodomains of metal fluorides. Specific examples for BiF3 and especially CuF2 using matrices of nominal composition of MoO3 are discussed. The reversible conversion mechanism of the metal halides is expanded to enable a new concept of electrochemically self assembled microbatteries (ESAMs) based on alkali halides. Such technology enables the fabrication of a solid state microbattery between two current collectors of various configurations on the microscale. First examples demonstrated based on LiI have demonstrated cell formation, appreciable energy density, and preliminary reversibility. INTRODUCTION Based on electrodes utilizing intercalation processes, the present day state of the art Li-ion battery technology exhibits an energy density in excess of 200 Wh/kg and 420 Wh/l. The energy density of lithium battery technology is far less than half of the theoretical energy densities that could be achieved. The technology is currently limited by the energy density of the positive electrode. This is due to intercalation reactions limiting the amount of Li+ inserted thereby limiting electron transfer to typically less than 1e- per compound such as LiMeO2 where Me is a transition metal. An alternative to intercalation materials is to utilize the concept of conversion and reversible conversion compounds where multiple electrons can be transferred to the active electrode to reduce fully to the metal state plus lithium salt and then subsequently reoxidize back to the original compounds. In theory these reactions can lead to specific capacities in excess of 700mAh/g. In the past few years these reactions have been shown to exist for dichalcogenides (1) and nitrides (2) in the reaction range of 0.5-2V. To increase the potential of such reactions and make attractive for use as positive electrodes, a move to highly ionic halides was necessary. Primary metal fluorides have been known for well over 30 years as attractive electrode materials, however the higher voltage materials exhibit a high bandgap resulting in insulator properties and very poor electrochemical activity. Recently, for the first time, reversible conversion reactions in metal fluorides have been shown to occur in the metal fluorides in parallel but separate works by Li et al. (3) with lower voltage metal fluorides and our group (4) (Badway et al.) with higher voltage metal fluorides enabled by nanocomposites. Our work for the past three years has been focused on the enablement of a variety o
Data Loading...
