Structural study of epitaxial LiCoO2 films grown by pulsed laser deposition on single crystal SrTiO3 substrates.

ABSTRACT

Epitaxial LiCoO2 (LCO) thin films of different orientations were fabricated by pulsed laser deposition (PLD) in order to model single-crystal behavior of intercalation cathodes during electrochemical reactions. This paper demonstrates that (1) epitaxial growth of LCO on a single crystal Nb-doped SrTiO3 (NbSTO) of different orientations occurs with a single orientation relationship; (2) surface morphology of the LCO films is established by the morphology of coalescing grains during island growth mode, whereas morphology of the grains can be visualized as different cuts from a cube with low-energy {104}R-LCO surfaces; (3) the films consist of predominately trigonal R-LiCoO2 phase, with a small fraction of the occasionally present cubic c-LixCoO2 phase; (4) cyclic voltammetry measurements have determined rectification at interface between LCO and NbSTO causing bias on the oxidation part of cycling, thus preventing full cycling.