Document Type

Dissertation

Degree

Doctor of Philosophy

Major

Physics

Date of Defense

4-15-2016

Graduate Advisor

Julia E. Medvedeva

Committee

Lynn Beckwith

Sonya Bahar

Phillip B. Fraundorf

Stephen M. Holmes

Abstract

Hydrogen is a non-polluting and efficient energy carrier. One barrier to utilizing hydrogen is a reliable storage method. NaAlH4 is the prototypical example of a complex metal hydride with high hydrogen storage capacities (~ 5.5 wt.%) and acceptable reaction temperatures of around 100 ℃ when using catalyst. On decomposition of these complex hydrides, such as NaAlH4, one is left with monohydride NaH. The kinetics of diffusion in the monohydrides is important because reversibility hinges on mass transport and the formation of [AlH4] - anions that must structurally coordinate with the alkali metal cation on hydrogen absorption. The NaH/NaOH system of a variety of molar ratios was investigated using in situ X-ray diffraction and differential scanning calorimetry. Nano porous carbons (NPC) materials have mesoporous structure, large surface area (> 600 m2/g), and high pore volume (> 0.5 cc/g). Several NPC materials for both hydrogen storage and battery applications were prepared and discussed. Nano-sized TiO2 is a superior material for lithium-ion batteries due to its high stability, low volume change on lithiation (~ 3%), and high energy density. High purity (~ 100%) anatase TiO2 nano particles with controllable particle size from 9 to 38 nm and excellent electrochemical properties (> 220 mAh/g) were synthesized using an efficient and reliable method. The synthesis, characterization and electrochemical measurements of prepared anatase TiO2 nano particles for lithium-ion battery applications were discussed. The lithium diffusion behaviors in TiO2 and SnO2 nano particles were analyzed and compared using an extension of the galvanostatic intermittent titration technique (GITT) that utilizes the open cell potential of the relaxation portion of the GITT measurement.

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Physics Commons

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