Li 4 Ti 5 O 12 ͑spinel͒ materials were prepared with Brunauer-Emmett-Teller surface areas ranging from 1.3 to 196 m 2 /g. The corresponding average particle sizes varied from ca. 1 m to ca. 9 nm. Twenty-five different materials were tested as Li insertion hosts in thin-film electrodes ͑2-4 m͒ made from a pure spinel. Trace amounts of anatase in Li 4 Ti 5 O 12 were conveniently determined by cyclic voltammetry of Li insertion. Electrodes from nanocrystalline Li 4 Ti 5 O 12 exhibited excellent activity towards Li insertion, even at charging rates as high as 250C. The charge capability at 50-250C was proportional to the logarithm of surface area for coarse particles ͑surface areas smaller than ca. 20 m 2 /g͒. With increasing charge/discharge rates, a narrowing plateau in performance was observed for materials with surface areas between ca. 20 to 100 m 2 /g. These materials can be charged/discharged nearly to the nominal capacity of Li 4 Ti 5 O 12 ͑175 mAh/g͒ within a wide range of the rates. Very small particles (surface areas Ͼ 100 m 2 /g) exhibit a growing decrease of charge capability at 50-250C. The Li-diffusion coefficients, calculated from chronoamperometry, decrease by orders of magnitude if the average particle size drops from ca. 1 m to ca. 9 nm. However, the sluggish Li ϩ transport in small particles is compensated by the increase in active electrode area. Materials having surface areas larger than ca. 100 m 2 /g also tend to show increased charge irreversibility. This could be caused by parasitic cathodic reactions, due to enhanced adsorption of reducible impurities ͑humidity͒ or the quality of the spinel crystalline lattice itself. The optimum performance of thin-film Li 4 Ti 5 O 12 electrodes is achieved, if the parent materials have surface areas between ca. 20 to 110 m 2 /g, with the maximum peak at 100 m 2 /g. Spinel oxides Li 1ϩx Ti 2Ϫx O 4 ; 0 р x р 1/3 were introduced in the early 1990s as promising zero-strain Li-insertion hosts. 1-3 The cubic lattice constant, a ͑space group Fd3m) scales with composition ͑x͒ according to Eq. 1 ͑for a in nm͒ 4The relations between composition ͑x͒ and Li-insertion thermodynamics were not studied very systematically, but the end members of the series, i.e., LiTi 2 O 4 and Li 4/3 Ti 5/3 O 4 (Li 4 Ti 5 O 12 ) exhibited the formal potential of Li insertion 1.36-1.338 V and 1.55-1.562 V, respectively. 1,5 The Li 1ϩx Ti 2Ϫx O 4 ͑spinels͒ are usually prepared by solid-state reactions of suitable Li-and Ti-containing precursors during 12-24 h at 800-1000°C. 1,2,4-11 The particle size was not systematically addressed in most cited works, but Abraham et al. 11 have reported that the solid-state reaction of TiO 2 with Li 2 CO 3 or LiOH gave at 800°C micrometer-sized product. Amatucci et al. 12,13 have recently reported on nanocrystalline Li 4 Ti 5 O 12 resulting from a hightemperature solid-state reaction of TiO 2 and Li 2 CO 3 , 12 but neither the particle size nor preparative details were specified in their works. 12,13 Alternatively, the lithium titanate spinels can also ...

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Objective 1. Design, synthesis and testing of Li-ion hosts for cathode service in inherently safe, long calendar life, long cycle life, high power, fast charge, secondary Li-ion batteries (Subcontract to Rutgers University). Objective 2. Design Synthesis and Characterization of Nanosensors For ChemicalBiological, and Radiological Agents (Subcontract to Western Michigan University).Objective 3. Development, Testing and Demonstration of a High-Rate LowTemperature Lithium-Ion Battery Platform.Objective 4. Interactions of Engineered Nanoparticles with Environmentally-and Societally-Important Bacteria (Subcontract to The University of California -Santa Barbara). We generated a series of electrolytes, tested those electrolytes and found that a 40% Acetonitrile + 60vol% 3-methoxypropionitrile solvent system that contained 1M-LiTFSI + 0.5M-LiBF 4 as dissolved salts was an excellent power cell electrolyte between 45degC and -40degC. If the CAN is removed and the solvent is pure 3-MPN an electrolyte that works well between 60degC and -40degC can be generated with a closed cup flash point of 79degC promoting improved safety. Further, the test cell was redesigned in an attempt to produce a testing matrix which did not limit the cell life or at least vastly extends the cell life so that active material life effects produced by this research were not masked by Li-ion cell life issues that had nothing to do with the active materials. This work was not completed in that cells with very high surface 4V actives (~10m^2/g) that allowed cycling for 6 months at 60degC were not generated. We believe we are close but the cell budget and time allowed for the research were not sufficient. Nice improvements were made from our starting point which was a cell that ballooned at 60degC and did not cycle well at -40degCComparison of Goals/ Objectives Met with Planned:The established goals of Objective One as stated in our proposal follow. Table I in the Addendum).Though the overall objective of this program is to find a Cathode Active, a Li-Ion host, that will extend cell life of nLTO anode Li-ion cells, which are currently cathode active life limited, and improve the charge/discharge rate performance of nLTO anode Li-ion cells (leading to an anode rate limited design), which again are rate limited by the cathode active, our initial research in this Project is focused on generating a Li-ion cell, of the Bellcore type, which is not in itself limiting on cell rate and cell life. Material substitutions and improvements in the cell structure were limited to commercially available materials.During the first 6 months of this program, a commercially available high molecular weight Homopolymer of PVDF was found and substituted into the cell. This substitution was essential to allow high temperature testing without softening or dissolving of the polymer by the electrolyte within the cell. The initial polymer product used was Kynar 301F. Its molecular weight is >500. This polymer of polyvinyliden fluoride is barely soluble in Acetone and Propylene Car...

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