Highly textured Li(Ni_0.5Mn_0.3Co_0.2)O ₂ thin films on stainless steel as cathode for lithium-ion battery

Epitaxial and highly textured Li(Ni_xMn_yCo _1-x-y)O₂ thin film cathodes are deposited by a one-step, high temperature pulsed laser deposition technique. Structural characterization using X-ray diffraction, transmission electron microscopy and selected area electron diffraction (SAED) reveals highly textured film along (003). The best film quality has been achieved at high temperature, with temperature as high as 750 C. Different substrates and buffer layers have been investigated and Li(Ni_0.5Mn_0.3Co_0.2)O₂ (NMC) on stainless steel with a thin Au-buffer layer gives the best film quality. The NMC thin film cathodes give a high capacity of 167 mAh g^-1 and 125 mAh g^-1 at 0.1 C and 0.5 C, respectively. In addition, the cyclic voltammetry and charge discharge curves obtained after different cycles indicate good electrochemical stability with capacity retention of 89% after 100 cycles at 0.5 C. The electrochemical characteristics are correlated to the microstructure of the film and the effects of texture, grain size and density are discussed.