MSE Ph.D. Proposal - Benjamin H. Rainwater

MSE Grad Presentation
Event Date:
Friday, July 25, 2014 - 1:00pm
Location:
Conference Room 295, Love Building

MSE Ph.D. Proposal - Benjamin H. Rainwater

Time: Friday, July 25th, 2014 at 1:00pm

Location: Conference Room 295, Love Building

Committee:

Dr. Meilin Liu (advisor), MSE

Dr. Faisal Alamgir, MSE

Dr. Ken Sandhage, MSE

Dr. Eric Vogel, MSE

Dr. Angus Wilkinson, School of Chemistry and Biochemistry

 

Title: A study of the structure-property-processing relationships in solid state lithium ion conductors for enhanced performance of solid state devices

Abstract:

The development of solid state electrolytes with high ionic conductivity is critical for high performance solid state devices including solid state lithium ion batteries, solid oxide fuel cells, solid state chemical sensors, and solid state separation membranes. To improve the ionic conductivity of a material beyond its bulk transport properties, materials systems with high heterogeneous interfacial density have been developed. The “strain effect” has been recognized as an important mechanism for increasing ionic conductivity at interfaces and can enhance transport properties by orders of magnitude. However, the architecture of materials systems that have been fabricated for testing the ionic conductivity enhancement at interfaces is not suitable for direct implementation in solid state devices. Also, new multi-component superionic conductors, such as the garnet-type Li7La3Zr2O12, li-ion conductor are difficult to fabricate as epitaxial films and therefore the strain effect has not been tested in these materials. In this work, two experiments will be conducted to understand and develop the crystal structure, transport properties, and material processing techniques related to the strain effect in two lithium ion conducting systems, the garnet-type li-ion conductors and LiF. High pressure measurements will be conducted on the garnet-type li-ion conductors Li7La3Zr2O12 and Ta-doped Li7La3Zr2O12 to simulate the strain effect. Powder XRD and electrical resistance measurements will be conducted at high pressure to correlate the structure and transport properties of the li-ion conductor. The volume change in the material due to high pressure (10 GPa) is expected to drastically effect the migration volume and the activation energy for charge carrier transport. Additionally, a laser processing technique is proposed to create vertically-aligned, fast-conducting amorphous/crystalline interfaces in LiF thin films. This work will build on the knowledge of ion transport at heterogeneous interfaces and will develop a processing technique for fabricating vertically aligned interfaces in li-ion electrolytes for high performance solid state batteries.