Chemical synthesis of tin oxide-based materials for Li-ion battery anodes : Influence of process parameters on the electrochemical behavior

Sn oxide-based materials are of interest as promising new anode materials for Li ion batteries due to their high capacity. Novel chemical approaches were developed to synthesise SnO2-based powders. Overall, chemically derived Sn oxide based-materials heat-treated in air show an improved cyclability compared to commercially derived SnO2. However the cyclability of SnO2:B2O3:P2O5 = 1:0.25:0.25, is remarkably affected by the generation of gels or precipitates. Homogeneous gels reveal better cyclability and less aggregation of Sn clusters compared to precipitated oxides. Air-treated precursors of SnO2:Li2O:B2O3:SiO2 = 1:0.39:0.13:0.48, regardless of the process, exhibit a larger capacity fade than amorphous compositions of SnO2:B2O3:P2O5 = 1:0.25:0.25, due to a breakdown of the initial homogeneous state of the components in the as-prepared precursor and the segregation of crystalline SnO2, despite a higher ratio of spectator atom:Sn. In situ reduction of chemically synthesised precursors leads to a decrease in the first-cycle loss, albeit exhibiting more fade due to large grained tin. Thus, by selecting a suitable chemical process and the spectator species, it is possible to synthesise compositions that represent a homogeneous distribution of tin oxide, while controlling the aggregation of Sn clusters during cycling. This judicious control of the process and the homogeneity of the tin oxide compositions can lead to improved cyclability and minimisation of capacity fade. 11 refs.