Gallium Arsenide As a New Alloying Anode for Lithium Ion Batteries

Abstract

Li alloying metals have much greater specific and volumetric energy densities than current state of the art graphite used in commercial Li ion batteries. However, the extremely large volumetric changes that the metals undergo when alloying with Li lead to the structural degradation of the electrode with consequent poor cycle life. We are attempting to make stable Li alloying metal electrodes, specifically with gallium arsenide, by akalide reduction on carbon matrices. Arsenic has been largely ignored as a candidate for Li alloying anode materials despite having the third best gravimetric capacity of the alloying metals and being abundant and inexpensive, on par with the cost of bulk silicon1. Gallium, a lithium alloying metal that melts at 29.8°C, has shown promise because of its self-healing ability at increased temperatures2, although it suffers from a lower gravimetric capacity than some of its more popular lithium alloying counterparts. Here we show the synthesis of Gallium Arsenide by akalide reduction. It is characterized by powder x-ray diffraction, transmission electron microscopy, thermo-gravimetric analysis, and x-ray fluorescence spectroscopy. Electrochemical testing of lithium half-cells, cycled from 0.02 to 1.5V versus lithium at a rate of C/10, showed a reversible capacity of 630 mAh/g with good capacity retention. (1) Nitta, N.; Yushin, G. Particle & Particle Systems Characterization, 31, 317-336. (2) Deshpande, R. D.; Li, J. C.; Cheng, Y. T.; Verbrugge, M. W. Journal of the Electrochemical Society, 158, A845-A849. Figure 1