Phase Transition in Nanocomposites LixCuySnz as Anode Material in Recharcheable Lithium Batteries

Phase Transition in Nanocomposites LixCuySnz as Anode Material in Recharcheable Lithium Batteries

M. Mladenov(a), P. Zlatilova(a), D. Kovacheva(b), K. Belov(c), I. Dragieva(a)
a: Institute of Electrochemistry and Energy Systems, Bulgarian Academy of Sciences, Acad. G.Bonchev str., Block 10, 1113 Sofia, Bulgaria
b: Institute of Inorganic and General Chemistry, Bulgarian Academy of Sciences, Acad. G.Bonchev str., Block 11, 1113 Sofia, Bulgaria
c: Central Laboratory of Mechatronics and Instrumentation, Bulgarian Academy of Sciences, Acad. G.Bonchev str., Block 1, 1113 Sofia, Bulgaria

Abstract

This investigation summarizes work on preparing of CuySnz alloys in the micron-size particle range and its changes as electrochemical active material in Li-ion cells. The nanoparticles were obtained by low-temperature synthesis from corresponding metal salts using boron hydride as a reducing agent. By means of microprobe analyses the Cu:Sn atomic ratio of the obtained nanosized materials was found to vary from 1.1 to 1.57 depending on the synthesis conditions. XRD analyses were performed in order to determine the phase composition of the materials and the changes at different consecutive stages of the electrochemical lithiation process. The progressive phase transformation from hexagonal phase Cu6Sn5 (hcp type) into the cubic face-centered structure (fcc type) of the Li2CuSn and further to lithium rich amorphous phase of type Li4.4-xSn and Cu was observed. The mechanism of the lithiation process and electrochemical anode performances was discussed. In the cycling setup a novel data collection and experiment control methods are tested which utilize contextual information connected with the experiment.