Peter Finamore

Aging Mechanisms of LiFePO4 Batteries Deduced by Electrochemical and Structural Analyses

The performance loss of lithium-ion batteries with lithium iron phosphate positive chemistry was analyzed using electrochemical characterization techniques such as galvanostatic charge-discharge at different rates, ac impedance, and hybrid pulse power characterization measurements. Differentiation analysis of the discharge profiles as well as in situ reference electrode measurement revealed loss of lithium as well as degradation of the carbon negative; the cell capacity, however, was limited by the amount of active lithium. Destructive physical analyses and ex situ electrochemical analyses were performed at test completion on selected cells. While no change in positive morphology and performance was detected, significant cracking and delamination of the carbon negative was observed. In addition, X-ray diffraction analysis confirmed the changes in the crystal structure of the graphite during cycling. The degradation of the carbon negative is consistent with the observations from the electrochemical analysis. Ex situ electrochemical analysis confirmed that active lithium controlled cell capacity and its loss with cycling directly correlated with cell degradation. The relationship between carbon negative degradation and loss of active lithium is discussed in the context of a consistent overall mechanism.

Comparative life cycle assessment of complex heavy-duty off-road equipment

This paper presents a method for comparative life cycle assessment (LCA) of two distinctively different systems based on industrial heavy-duty off-road equipment. The study demonstrates how to compare the environmental impact performance of two different machines when they perform the same types of operations, but have different levels of operational productivity. Considering the entire life cycle of a machine from material extraction to end-of-life treatment, the two machines are analyzed and compared in terms of their life cycle impact score. To make a fair comparison between the two machines, the impact generated by the same amount of production is used as the basis for comparison. The results of the study can quantify the relative life cycle impact across different machine architectures for design and market support purposes.Copyright

Life Cycle Assessment of Complex Heavy Duty Equipment

This paper presents a comprehensive life cycle assessment (LCA) study of heavy duty off-road equipment. The machine studied here is a typical piece of diesel construction machinery equipped with the iT4 (interim Tier 4) certified diesel engine. Two life cycle impact assessment methods, Eco-Indicator 99 and IPCC 2007, are used to calculate the environmental impact and global warming potential associated with the machine’s life cycle, from material extraction to end-of-life recycling and disposal. Due to fuel consumption and emissions, machine utilization during the usage phase is expected to account for most of the total environmental impact. However, the impact from usage can vary greatly, depending on how customers use the machine. To take into account various machine usage patterns, this LCA study performs two sensitivity analyses, varying the load factor and varying the fuel consumption rate, respectively.© 2012 ASME