On the processing and properties of binary compound insertion electrodes

This dissertation explores the processing/structure/property relationship for binary compounds used as negative electrode material.; A solution route method for synthesis of binary compound electrodes, InSb, Cu₂Sb, and Cu₆Sn₅ will be introduced. The material characterization using XRD and TEM techniques suggests the formation of an amorphous phase in the reaction products. The amorphous phase was decomposed under an annealing process and under direct exposure to the electron beam. The precipitation of different phases in the form of small particles was observed.; The electrochemical analysis of InSb from the solution route will be compared with ball milled and single crystal InSb electrodes. The structure simulation of the ternary phase Li_3xIn_1−xSb, which exists in the Li-In-Sb phase diagram at 400°C proposed by W. Sitte and W. Weppner [1], was used to confirm the occurrence of ternary compounds after an initial lithium insertion into the InSb zinc-blende structure. The charge-discharge voltage profile of Li/InSb under OCV conditions shows chemical potential changing with time in the two-phase region, indicating a series of ternary phase formation according to the phase diagram. This is an experimental result confirming the existence of ternary phases, which is consistent with the simulation models.; The electrochemical analysis of Cu₂Sb and Cu₆Sn ₅ solution route electrodes will be discussed. The Cu extrusion from Cu₂Sb and Cu₆Sn₅ structures was reported to occur during the lithiation process [2, 3]. The post mortem analysis of a Cu₂Sb electrode then was conducted to examine the Cu extrusion.; The electrochemical behavior of InSb from solution route and Cu ₆Sn₅ from both solution route and ball milling exhibits a local minimum voltage in the first discharge. It was suggested that the occurrence of a local voltage minimum was due to the slow nucleation of a stable phase [4]. The growth analysis of Johnson-Mehl-Avrami [5] combined with Butler-Volmer [6] electrode kinetics was used to simulate the experimentally observed voltage minimum in the Cu₆Sn₅ and InSb systems.