Development of Thin Films as Potential Structural Cathodes to Enable Multifunctional Energy-Storage Structural Composite Batteries for the U.S. Army's Future Force

Report No. ARL-TR-5644
Authors: Eric Ngo, James Snyder, Clifford Hubbard, S. Garrett Hirsch, Conrad Xu, and Robert Carter
Date/Pages: September 2011; 18 pages
Abstract: Well formed films of pure LiMn2O4 were obtained by spin-coating stoichiometric amounts of manganese acetate Mn(CH3COOH)2.4H2O and lithium acetate Li(CH3COOH)2.4H2O dissolved in a mixture of acetic acid (CH3COOH) and 2-methoxyethanol (H3COCH2CH2OH) onto platinum coated silicon substrates. Several coats of solution were applied to reach the desired film thickness of approximately 200nm and then annealed at various temperatures ranging from 400 °C to 800 °C to crystallize the films into a spinel phase. The resulting films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and atomic force microscopy (AFM). In addition, electrochemical properties were determined by cyclic voltammograms measurements. At 700 °C-800 °C, the films exhibited distinctly improved crystallinity and the spinel grains adopted a polyhedral shape of submicron size with well-defined edges and faces, thus enhancing particle connectivity. The films were found to deliver capacities around 0.12 mAh/cm2 up to 25 cycles.
Distribution: Approved for public release
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Last Update / Reviewed: September 1, 2011