Lithium-manganese-oxide thin-film cathodes prepared by plasma-enhanced chemical vapor deposition

Lithium-manganese-oxide thin-film electrodes have been fabricated using the plasma-enhanced chemical vapor deposition technique. Process parameters su ch as flow rates of the reactants, deposition temperature, and RF power hav e been systematically varied to optimize the charge and discharge propertie s. The thin films are amorphous as found by X-ray diffraction spectrometry and can be cycled reversibly in the range from 4.5 to 3 V or 4.5 to 2.5 V w ith maximum capacities of 30 and 39 mu Ah/cm(2) mu m, respectively. The cap acity fade of the films is ca, 0.04% per cycle over more than 700 cycles wh en tested in liquid electrolytes, Films which are optimized for cycling bet ween 4.5 and 3 V demonstrate a near-perfect balance between the charge and discharge capacities during the initial cycle and also show very small capa city fade in the subsequent cycles. Our results indicate that these lithium manganese oxide thin films are good candidates for use as cathodes in thin -film lithium-ion batteries. (C) 1999 The Electrochemical Society. S0013-46 51(98)08-070-7. All rights reserved.