Thermodynamic investigations of copper oxides used as conversion type electrodes in lithium ion batteries

• Published in: Journal of materials science 2013-09, Vol.48 (17), p.5818
• Main Authors: Lepple, Maren, Adam, Robert, Cupid, Damian M, Franke, Peter, Bergfeldt, Thomas, Wadewitz, Daniel, Rafaja, David, Seifert, Hans J
• Format: Article
• Language: English
• Subjects: Analysis; Batteries; Cobalt; Copper oxide; Cuprite; Diffraction; Investigations; Thermodynamics; X-rays
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/sl0853-Ol3-7374-x

Copper oxides, which exhibit the conversion mechanism with lithium during electrochemical cycling, are promising electrode materials for next-generation lithium ion batteries. To better understand phase formations and equilibria in the Li-Cu-O system, the Li[Cu.sub.2][O.sub.2] phase was synthesized using the solid-state method and characterized with X-ray powder diffraction technique and Rietveld analysis as well as inductively coupled plasma--optical emission spectrometry (ICP-OES). The phase stabilities in argon atmosphere and in a mixture of argon and oxygen were determined between 200 and 900°C and between 200 and 950°C, respectively. Based on this data as well as on other literature data, a thermodynamic description of the Li-Cu-O system valid in the battery relevant temperature regime was developed using the CALPHAD method. From this thermodynamic description, titration curves for CuO and [Cu.sub.2]O cathodes, which give the equilibrium cell voltage as a function of lithium content along a selected composition path, were calculated at different temperatures.