Self-Discharge Evaluation of Ni-MH Battery Using Metal Hydride Alloy for Energy Storage Applications

Monday, November 8, 2010: 4:05 PM
Grand Ballroom G (Salt Palace Convention Center)
Wenhua H. Zhu, Ying Zhu and Bruce J. Tatarchuk, Center for Microfibrous Materials, Department of Chemical Engineering, Auburn University, Auburn, AL

Hydrogen storage alloys have been successfully applied in the nickel-metal hydride batteries for different energy storage applications such as in hybrid-electric vehicles (HEVs) and portable electronics. The advantages of this battery system are its high-rate charge/ discharge capability, good specific energy, and high reliability. Ni-MH batteries, as an alternative solution to nickel-cadmium batteries, rapidly become the most popular rechargeable batteries for consumer appliances because the nickel-metal hydride chemistry system has fewer environmental concerns and no memory effect in comparison with nickel-cadmium chemistry. Although the Ni-MH battery system is relative expensive, it is currently a realistic resource for rapid storage of mechanical energy into chemical energy because the lithium-ion battery system is still expensive, the innovations and breakthroughs for the conventional Pb-acid battery are under development efforts to serve consumers for cost considerations. This work uses ac impedance spectroscopy to collect impedance data for the nickel-metal battery at different of state-of-charge (SoC). After the battery was charged to a level of SoC, the battery system's self-discharge process was evaluated upon measurement of battery voltage drop at open circuit and analysis of its impedance data as a function of time. Using this impedance tool, the interfacial process, variation in the internal resistance, state-of-charge, and the residual capacity can be obtained using a proper equivalent circuit for simulating of the Ni-MH battery chemistry and physical processes. Energy efficiency is potentially improved upon understanding of self-discharge mechanism and electing of a proper operating range.

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See more of this Session: Composites for Energy Applications
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