Evaluation of hysteresis expressions in a lumped voltage prediction model of a NiMH battery system in stationary storage applications

Lithium-ion (Li-ion) batteries may fail through thermal runaway caused by increased temperature. It is thus important to monitor battery temperature for prevention of the battery failure. Currently, thermal monitoring of the battery for electric vehicles (EVs) is being conducted by multiple thermostats. As the size of battery system increases and the cells are closely packed to exploit high power density, the number of thermostats is also increased to monitor the battery system. However, this increased number of sensors enhances the probability of the sensor malfunction, which prevents robust thermal monitoring, and causes increased maintenance cost and customer complaints. This paper thus proposes an online applicable temperature prediction model for EV battery pack while minimizing the number of sensors and keeping the monitoring capability. This was possible with three ideas: (a) devising battery thermal characterization test under various operating conditions, (b) development of the online-applicable temperature prediction model using artificial neural network (ANN), and (c) validation of the temperature prediction model. The proposed temperature prediction model was demonstrated with the EV battery pack that consists of twelve battery modules.

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A morphological and energy-dispersive x-ray spectroscopy (EDS) investigation of separator-grade cellophane

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100169882 ◽

1994 ◽

Vol 52 ◽

pp. 430-431

Author(s):

Michael E. Rock ◽

Vern Kennedy ◽

Bhaskar Deodhar ◽

Thomas G. Stoebe

Keyword(s):

Extrusion Process ◽

Morphological Characterization ◽

Energy Dispersive ◽

Regenerated Cellulose ◽

Battery System ◽

X Ray ◽

Functional Differences ◽

Transmission Electron ◽

Separator Material ◽

Underwater Target

Cellophane is a composite polymer material, made up of regenerated cellulose (usually derived from wood pulp) which has been chemically transformed into "viscose", then formed into a (1 mil thickness) transparent sheet through an extrusion process. Although primarily produced for the food industry, cellophane's use as a separator material in the silver-zinc secondary battery system has proved to be another important market. We examined 14 samples from five producers of cellophane, which are being evaluated as the separator material for a silver/zinc alkaline battery system in an autonomous underwater target vehicle. Our intent was to identify structural and/or chemical differences between samples which could be related to the functional differences seen in the lifetimes of these various battery separators. The unused cellophane samples were examined by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). Cellophane samples were cross sectioned (125-150 nm) using a diamond knife on a RMC MT-6000 ultramicrotome. Sections were examined in a Philips 430-T TEM at 200 kV. Analysis included morphological characterization, and EDS (for chemical composition). EDS was performed using an EDAX windowless detector.

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