Electrochemical Behavior of Li_xMn₂O₄ and Li_xCoO₂ Thin Films Produced with Pulsed Laser Deposition

Thin films of Li_xMn₂O₄ and Li_xCoO₂ have been prepared by pulsed laser deposition on heated stainless steel substrates. These films have thicknesses from 0.2 to 1.5 μm and are crystalline without postdeposition annealing. The films' electrochemical properties were studied with cyclic voltammetry, current pulse measurements, and galvanostatic charge/discharge techniques. Film capacity densities as high as 56 and 62 μAh/cm²-μm were measured for Li_xMn₂O₄ and Li_xCoO₂, respectively. Chemical diffusivities on the order of 2.5 x 10^-11 and 1 x 10^-10 were measured for Li_xMn₂O₄ and LiCoO₂, respectively. Some of the films were cycled electrochemically for up to 300 cycles against lithium metal in 1 M LiC1O₄/propylene carbonate electrolyte, demonstrating the promise of pulsed laser deposition for the production of cathode films for rechargeable lithium microbatteries.