Date of Award

12-2012

Degree Name

Master of Science in Engineering

Department

Mechanical and Aerospace Engineering

First Advisor

Dr. S.O. Bade Shrestha

Second Advisor

Dr. Xiaosong Kang

Third Advisor

Dr. Christopher Cho

Keywords

Lithium-ion, characterization, hybrid, automotive, EIS

Access Setting

Masters Thesis-Open Access

Abstract

A lithium-ion battery is one of the key research topics in energy storage technologies. Major characterization tests such as static capacity, open circuit voltage (OCV), hybrid pulse power characterization (HPPC) have been conducted on two different chemistries, LiMnNi and LiFePO4, high capacity lithium-ion batteries over a wide range of temperatures from 50ºC to -30ºC. Detail analysis of temperature effects on battery capacity and simple models of direct current resistance (DCR) increment and power decrement over temperatures have been proposed using the test results. Electrochemical impedance spectroscopy (EIS) tests have been performed to find out the dominant internal resistances in lithium-ion cells especially at subzero temperatures. Using equivalent circuit and simulation, for both chemistries, it has been found that the anode interfacial resistance is almost twice of the cathode at subzero temperatures. Anode and cathode interfacial resistances as a function of temperature models have also been proposed which will be useful to visualize performance degradation over temperature for similar chemistry batteries without going for time consuming and costly experiments.

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