The relationship between microstructure and electrochemical performance was investigated in sputter-deposited V(2)O(5) thin-film cathodes. As-deposited and heat-treated films in unlithiated and lithiated states were studied by transmission electron microscopy, X-ray diffraction, and secondary ion mass spectroscopy. Film properties including orientation, grain size, and morphology were found to be strongly dependent on the heating rate during annealing. Large enhancements in the capacity-rate performance of coarser grained over nanocrystalline grained films were observed, contrary to expectations. Potential transient methods were used to investigate the mass-transport differences between these two distinct microstructures. Slow transport phenomena during phase transformation and interfacial impedances linked to differences in grain orientation and/or grain boundary content are proposed to explain the observed performance. (c) 2006 The Electrochemical Society.

Abstract not Available.

Electrochemical experiments were performed to investigate the processing-property-performance relations of thin film vanadium pentoxide cathodes used in lithium batteries. Variations in microstructures were achieved via sputtering and anneal treatments, resulting in films with different morphologies, grain size distributions, and orientations. Key findings included (1) grain size distributions largely did not affect the current rate performance of the cathodes. Rather, the film orientation and the ability to undergo rapid phase transformation were more vital to improving performance; (2) interfacial resistance and ohmic polarization were also dominant at the high current rates used (> 600 jiA/cm2) in addition to solid diffusion; and (3) optimization of thin film batteries requires that film thickness be < 500 nm to avoid diminishing returns in power and energy densities. Kinetic parameters including the transfer coefficient (a = 0.90± 0.05) and standard rate constant (k° 2 x 10-6 cm/s) for vanadium pentoxide films were quantified using slow scan DC cyclic voltammetry and AC cyclic voltammetry. The reaction rate was found to be potentially limiting at moderate to high current rates (> 200 pA/cm2). An analysis of the wide variation in current-rate performance for different V20 5 architectures (including composite, nanofiber, and thin film) shows a convergence in results when the area of active material has been factored into the metric. This convergence suggests that either the reaction rate or interfacial resistance is limiting in V20 5 as opposed to diffusion. Thesis Supervisor: Donald R. Sadoway Title: John F. Elliott Professor of Materials Chemistry

Graft copolymer electrolytes (GCEs) of poly[(oxyethylene)(9) methacrylate]-g-poly(dimethyl siloxane) (POEM-g-PDMS) (70: 30) have been synthesized by simple free radical polymerization using a macromonomer route. Differential scanning calorimetry, transmission electron microscopy, and small angle neutron scattering confirmed the material to be microphase-separated with a domain periodicity of similar to25 nm. Over the temperature range 290 < T < 360 K, the electrical conductivities of the lithium triflate-doped POEM-g-PDMS, which exhibited solid-like mechanical behavior, were nearly identical to those of the liquid POEM homopolymer. Thermal and electrochemical stability studies showed the electrolyte to be stable over a wide temperature range and voltage window. Solid-state, thin-film batteries comprised of a metallic lithium anode, a similar to0.2 mum thick vanadium oxide cathode, and an electrolyte of POEM-g-PDMS doped with LiCF3SO3 proved resistant to capacity fade during extended cycling at room temperature (>200 cycles) at a discharge rate of 2/3 C and could be cycled (charged and discharged) at subambient temperature (0degreesC). (C) 2004 The Electrochemical Society.

Journal Article Local Chemistry of Complex Nanostructures and Their Interfaces in Block Copolymer-Templated Nanocomposite Electrodes for Rechargeable Lithium Batteries Get access V J Leppert, V J Leppert Department of Chemical Engineering and Materials Science, University of California, One Shields Ave., Davis, California, 95616-5294 Search for other works by this author on: Oxford Academic Google Scholar EC Nelson, EC Nelson National Center for Electron Microscopy, MS 72-150, Berkeley, CA 94720 Search for other works by this author on: Oxford Academic Google Scholar S C Mui, S C Mui National Center for Electron Microscopy, MS 72-150, Berkeley, CA 94720 Search for other works by this author on: Oxford Academic Google Scholar E A Olivetti, E A Olivetti Department of Materials Science and Engineering, Massachusetts Institute of Technology, 13-5025, 77 Massachusetts Ave., Cambridge, MA 02139 Search for other works by this author on: Oxford Academic Google Scholar A M Mayes A M Mayes Department of Materials Science and Engineering, Massachusetts Institute of Technology, 13-5025, 77 Massachusetts Ave., Cambridge, MA 02139 Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 9, Issue S02, 1 August 2003, Pages 388–389, https://doi.org/10.1017/S1431927603441949 Published: 19 July 2003

Department of Chemistry, Northeastern University, Boston, Massachusetts 02115-5000, USAA self-organizing, nanocomposite electrode~SONE! system was developed as a model lithium alloy-based anode for rechargeablelithium batteries. In situ X-ray adsorption spectroscopy, galvanostatic testing, cyclic voltammetry, X-ray diffraction, and trans-mission electron microscopy were used to analyze the electrode, which was fabricated from a polyethylene oxide-based blockcopolymer, single-walled carbon nanotubes, and gold salt. Processing involved a single mixing step without need of a reducingagent. It was found that thermodynamic self-assembly of the block copolymer could provide a template for incorporation of boththe gold salt and nanotubes. Electrochemical testing and subsequent analysis showed that owing to the small particle size and thesurrounding block copolymer matrix, the SONE system could cycle over 600 cycles with rates varying between C/1.8 and 8.8Cwith little evidence of decrepitation or coarsening.© 2002 The Electrochemical Society. @DOI: 10.1149/1.1518482# All rights reserved.Manuscript submitted February 6, 2002; revised manuscript received June 13, 2002. Available electronically October 31, 2002.