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

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 (Nb:STO) 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-Li_xCoO₂ phase; (4) cyclic voltammetry measurements have determined rectification at interface between LCO and Nb:STO causing bias on the oxidation part of cycling, thus preventing full cycling.