Li-ion Battery Negative Electrodes Based on the FexZn1-x Alloy System (Preprint)

Abstract

Thin-film Fe-Zn libraries were investigated as negative electrode materials for Li-ion batteries using combinatorial and high-throughput techniques. X-ray diffraction, Mössbauer 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 ζ (FeZn13) region on the phase diagram. The electrochemistry of FexZn1-x (0.01< x <0.45) was studied at 30ºC. 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 atom %. Ex-situ X-ray diffraction and Mössbauer 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.