Date of Award

6-26-2026

Date Published

August 2026

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Mechanical and Aerospace Engineering

Advisor(s)

Quinn Qiao

Keywords

Cathode Materials;Lithium Batteries;Microwave Processing;Surfactant

Subject Categories

Engineering | Mechanical Engineering

Abstract

Lithium-Manganese-Rich-Oxide (LMRO) is a type of layered oxide cathode active material with high energy densities of up to 900 - 1,000 Wh kg-1, competitive in capacity-demanding rechargeable lithium batteries. The increased energy density is beneficial for the range and recharging interval of electric vehicles. Based on layered Ni/Mn/Co oxide cathode materials, a high Mn content is chosen for this project as being abundant, while increased Ni concentration trades off thermal stability with specific capacity, while Co is carcinogenic and sourced less sustainably. Lithium content is increased along with Manganese content stoichiometrically as a second phase is introduced. Traditional synthesis routes of such type of materials include a hydrothermal co-precipitation step, precipitating the water-soluble Mn, Ni, and Co salts together into non-soluble precipitants, which usually takes 12 hours or more. A unique microwave-assisted process is employed to significantly reduce the precipitation step time to 1 hour, and this time can be further reduced by adding surfactant(s) in the precipitation process. An optimized concentration of surfactant allows this time to be reduced to 15 minutes. In this thesis, precursor of the high-capacity LMRO cathode active material is synthesized through the microwave assisted co-precipitation process with the use of surfactant, effectively reducing the time factor in the corresponding step, with the final product exhibiting comparable electrochemical performances with the ones prepared without surfactant. Preliminary study on expanding this accelerated process on Sodium layered oxides was also carried out. Since sodium is relatively abundant in the earth crust, it is a strong candidate for substituting Lithium as a battery active cation for the less energy density demanding purposes.

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Open Access

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