Investigation of Copper-Cobalt-Oxides as Model Systems for Composite Interactions in Conversion-Type Electrodes for Lithium-Ion Batteries

Different Cu-Co-O mixtures (CCO) with cation ratios from 5:1 to 1:5 were investigated as conversion type electrodes in half cells against lithium counter electrodes. To achieve a nearly homogeneous distribution of the elements on the nanometre scale, the self-combustion method was employed. The electrochemical redox behavior of the single oxides and CCO were characterized with cyclic voltammetry and galvanostatic cycling. These investigations showed different element specific electrochemical characteristics. Copper oxide was more stable with respect to cycling stability, while cobalt oxide had a higher specific capacity. The combination of both elements in ternary CCO leads to an improvement of the specific capacity and the cycling stability compared to the binary metal oxides of only copper and cobalt, respectively. This stabilization effect qualifies CCO as a promising model system to elucidate the underlying mechanisms in such composites with complex interactions between the different metals during conversion and in successive cycling. (C) 2013 The Electrochemical Society.