Li-ion battery negative electrodes based on the FexZn1-x alloy system

Thin-film Fe-Zn libraries were investigated as negative electrode materials for Li-ion batteries using combinatorial and high-throughput techniques. X-ray diffraction, Mossbauer effect spectroscopy and electron microprobe were used to characterize the library structure. A new Fe-Zn phase with an unknown structure was observed in the zeta(FeZn13) region on the phase diagram. The electrochemistry of FexZn1-x(0.01 < x < 0.45) was studied at 30 degrees C. The cycle life and coulombic efficiency improved as Fe concentration in electrodes increased to x = 0.12. However, the capacity decreased as the iron content increased and the FexZn1-x alloys became completely inactive when the Fe content was above 12 at.%. Ex-situ X-ray diffraction and MOssbauer measurements were used to explain the structural changes that occur during cycling. This is the first report of sputtered amorphous Fe-Zn alloys in the literature. (C) 2014 Elsevier B.V. All rights reserved.