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Title: Investigating the effects of mechanical events on electrochemical properties of Li-ion batteries
Author: Khah, Nasrin Shahed
ISNI:       0000 0004 7431 7182
Awarding Body: University of Warwick
Current Institution: University of Warwick
Date of Award: 2018
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This study explored the effects of mechanical loads on Li-ion pouch cells by considering their operation under laboratory conditions. The focus of the research conducted was exploratory in nature with the aim of developing advanced experimental methods and techniques to answer a specific research question motivating this work: \Do mechanical events influence the electrochemical performance of Li-ion batteries?". In order to address this research question, the following goals were targeted: 1) study the effects of high g impacts on the cell performance and investigate the extent of cell damage under such an event, 2) examine the influence of mechanical bending loads on cells and ageing effects introduced on the cell performance. In the context of studying the effects of high g pulses and mechanical bending load on the electrochemical performance of Li-ion batteries, a comprehensive analysis of the internal impedance and capacity measurements was undertaken. Throughout the entire study, none of the analyses established any signs of statistically significant relationships between the specified electrochemical parameters. This study therefore finds that high g pulses and external mechanical bending load have no adverse influences on the electrochemical characteristics of Li-ion batteries in use, within the bounds of the investigation, as no evidence of electrochemical performance degradation by the effects of such events were substantiated. The study examined the influence of charge/discharge cycles on the load relaxation characteristics of a cell retained under bending deformation, by quantifying its structural evolution prior to and post electrochemical cycling using X-ray CT. It was ascertained that a cell subjected to a constant bending deformation during electrochemical cycling experienced a healing effect, owing to its viscoelastic properties and volume expansion of the electrodes during charging and discharging. The work shows tantalising evidence that external mechanical load on a cell may provide possibilities to improve its electrochemical characteristics. It is recommended that this phenomena is investigated further.
Supervisor: Not available Sponsor: Jaguar Land Rover
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: TK Electrical engineering. Electronics Nuclear engineering