Date of Award
2016
Document Type
Thesis
Degree Name
Master of Science in Engineering (MSE)
Department
Mechanical and Aerospace Engineering
Committee Chair
George Nelson
Committee Member
Yu Lei
Committee Member
Eunseok Lee
Subject(s)
Lithium cells., Lithium ions., Lithium ion batteries., Cathodes.
Abstract
Li-ion batteries have emerged as a leading energy storage technology for several applications including portable electronics devices and electric vehicles. Rigorous efforts are made to develop these batteries with higher energy density, higher power density, and better cycling stability while reducing cost and environmental impact. To better understand how electrode morphology and process parameters contribute to the electrode performance, spinel LiMn2O4 (LMO) cathode material was prepared using sol-gel synthesis method. Simultaneously, nanostructured LMO electrodes were prepared using the template-assisted sol-gel method, which involves soaking of polycarbonate template membranes in the precursor solution followed by drying, to remove the solvent. The dried templates containing precursor materials were etched in an oxygen plasma to remove the template, and the nanostructured electrode formed was then calcined to convert these nanostructures to spinel LiMn2O4. A series of tests were performed to study the effect of processing conditions on the crystallinity, purity and morphology of the LMO spinel material. The resulting electrodes fabricated using powdered LMO material were characterized using X-ray diffraction (XRD) and scanning electron microscope (SEM) in support of efforts to understand the effects of process parameters on the electrochemical performance of the electrode. Increasing calcination time and temperature was found to create a better-defined spinel structure for the LMO that resulted in the improvement in the cyclic behavior of LMO cathode. After 100 cycles, it was found that the discharge capacity retained by higher calcined (800oC) LMO cathode was 93% of the original value, while the lower calcined (500oC) LMO cathode could retain only 77%. Whereas, the template-assisted synthesis approach yielded an electrode of well-defined nanotubules. Extending the template soaking time was found to provide better definition of individual tubule structures. These observations provide insight into process parameters relevant to electrode fabrication and characterization.
Recommended Citation
Jibhakate, Piyush D., "Fabrication and characterization of nano/micro-sized cathodes for LI-ion batteries" (2016). Theses. 190.
https://louis.uah.edu/uah-theses/190