Date of Award

12-2013

Embargo Period

2-17-2015

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Engineering and Public Policy

Advisor(s)

Jay F. Whitacre

Second Advisor

Jeremy J. Michalek

Abstract

Battery cost is among the largest barriers to mainstream adoption of electric vehicles. This dissertation examines near future battery technology and cost by (1) validating existing physics-based battery performance models using laboratory testing and manufacturer specifications, (2) constructing battery design optimization and production cost models to identify the least-cost design and investigating how key design-decision variables affect performance and cost for a variety of vehicle power and energy requirements, and (3) conducting expert elicitation on future battery costs and the key factors that drive cost. The validation, cost, and optimization modeling work use LiNi0.33Co0.33Mn0.33O2/LixC6 (NMC-G) as the chemistry of choice. Validation results of Battery Design Studio™ (BDS) a Li-ion battery modeling software indicated that BDS predictions of total energy delivered under our constant C-rate battery discharge tests are within 6.5% of laboratory measurements for a full discharge and within 2.8% when a 60% state of charge window is considered. Once validated, BDS is used to develop a power meta-model that predicts the 10–sec power capability of a cell design as a function of its capacity (Ah) and cathode coating thickness (microns). The production cost model is a process-based model and is constructed adopting process step information from existing literature. Subsequently, an optimization model is developed which estimates the cheapest cost battery pack design for a set of five different electrified vehicles (EVs) whereby the role of design-decision variables like cathode coating thickness is investigated among others. The energy and power requirements for the EVs, used as constraints in the optimization model, are calculated using the Powertrain Systems Analysis Toolkit (PSAT). Battery pack costs calculated are in the range of costs reported in the literature. Results indicate that higher capacity cells manufactured using higher electrode coating thicknesses can decrease manufacturing costs by 5-8%. Results suggest that economies of scale can be reached at a plant size of about 200MWh. Expert elicitation indicates that a variation of NMC-G is likely to be the cheaper cell-chemistry by 2018 with no major technological breakthroughs. Some experts also expect manufacturing improvements resulting in higher electrode coating thicknesses and cell capacities expected by 2018.

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