Synthesis, characterization, and electrochemical investigation of novel electrode materials for lithium ion batteries

As the demand for better energy storage devices increases, finding new materials capable of improvement on existing technology becomes essential. Within this body of work, several new electrode materials of different structure type have been synthesized, characterized, and evaluated for their lithium insertion/deinsertion behavior in lithium ion batteries.; Nanocomposites of novel alloy, and convertible oxide anode materials have been studied. Nanoparticles of Ge and Sn that are able to form lithium rich alloys have been synthesized, and their low potential lithium insertion behavior studied. In order to inhibit agglomeration of the tiny particles, a novel synthesis route was designed to attach ionically conducting polymers to their surfaces. Characterization by a combination of techniques (XRD, TEM, SEM and FTIR spectroscopy) verified the existence of nanoparticles embedded in a polymer matrix, albeit with some impurities. Electrochemical data show that even when the lithium insertion capacity within these materials is high, the process is extremely irreversible as lithium ions become trapped within the matrix, and only a very small anodic capacity is realized.; The first convertible polymer/oxide nanocomposite (poly(para-phenylene)/MoO ₃) to be evaluated as an anode material was synthesized using a novel surfactant mediated method. XRD data indicated a 5.2 Å increase in the MoO₃ layer spacing to 12.1 Å after polymer incorporation. Low potential electrochemical insertion properties show that the polymer/oxide nanocomposite behaves in a similar manner to the host MoO₃ material.; A variety of cathode materials were also synthesized and evaluated for their high potential lithium insertion properties. A comparative study on the effect that synthetic procedure may have on the electrochemical properties of the poly(aniline)/MoO₃ cathode material have been studied. Poly(aniline)/MoO ₃ nanocomposites have been synthesized from a solution insertion route and via hydrothermal methods. Similar electrochemical performance at high potential for the two nanocomposites suggests that the size range of the polymer-oxide interaction is more important than the overall makeup of the compounds.; From hydrothermal methods, the novel molybdenum oxide structure [C ₆H₅NH₃+]_0.33MoO ₃ has been formed using protonated aniline as a templating agent. The anilinium ions remain in the structure as a bilayer, yielding a d-spacing of 19.5 Å between the oxide sheets. Interesting electrochemical behavior is demonstrated from this material that is different from that of pristine MoO₃. The unique lithium insertion behavior is derived from the novel molybdate structure in which anilinium cations prop up the oxide layers during cycling. Better reversibility and cyclability makes this material an interesting candidate for high potential electrodes in a lithium ion battery.; Electrochemical lithium intercalation into a new vanadium phosphate, ϵ-VOPO ₄, with a 3D structure has been studied. X-ray diffraction shows the lithiated material to be structurally similar to high-temperature α-LiVOPO ₄. Increased stability and capacity are achieved with chemically lithiated ϵ-VOPO₄ when contact with the conductive additive is enhanced by mechanical grinding. Following the first charge cycle, reversible electrochemical lithium extraction/insertion at a cycling rate of C/10 affords a specific capacity of over 100 mAh/g that is stable for at least 100 cycles. This material demonstrates the best properties, thus far, of any polyanionic vanadium phosphate structure.