10-16 June 2018
Dalhousie University
America/Halifax timezone
Welcome to the 2018 CAP Congress Program website! / Bienvenue au siteweb du programme du Congrès de l'ACP 2018!

POS-17 Analysis of “Rollover Failure” of Lithium-ion Cells

12 Jun 2018, 18:00
1h 30m
SUB McInnes Hall (Dalhousie University)

SUB McInnes Hall

Dalhousie University

Poster (Non-Student) / Affiche (Non-étudiant(e)) Condensed Matter and Materials Physics / Physique de la matière condensée et matériaux (DCMMP-DPMCM) DCMMP Poster Session & Finals: Poster Competition and Mingle Session with Industry Partners (28) / Employers | Session d'affiches DPMCM et finales: Concours d'affiches et rencontres avec partenaires industriels et employeurs (28)

Speakers

Dr Xiaowei Ma (Dalhousie University) Prof. Jeff Dahn (Dalhousie University)

Description

Sometimes lithium-ion cells show a very insidious type of failure where they display close to 100% of their capacity for about 1000 charge-discharge cycles and then lose most of their capacity in only 100 cycles or so with very little warning to the user. This is called “rollover failure”. Experimental observations show that the likelihood of rollover failure increases with upper cutoff potential of lithium-ion cells. Since increasing the upper cutoff potential is essential to increase the energy density of lithium-ion cells, a full understanding of the causes of rollover failure is essential, but this is proving very difficult to attain.

In this presentation, the phenomenon of rollover failure during long-term cycling will be discussed based on a comparison among Li(Ni0.5Mn0.3Co0.2)O2/graphite pouch cells with different electrolyte and electrode designs undergoing different testing protocols. A few facts can be gleaned from the data:
1. For cells charged to the same upper cutoff potential, those showing the highest rates of electrolyte oxidation at the positive electrode (due to electrolyte or cell chemistry changes) are most prone to rollover failure.
2. Any cell is more prone to rollover failure if charged to higher potential. This increases the rate of electrolyte oxidation at the positive electrode.
3. When cells are disassembled after rollover failure, they invariably show unexpected and unwanted lithium metal plating on the surface of the graphite negative electrode.
Based on these and other observations some simple handwaving models of rollover failure can be postulated but serious experimental studies using a variety of methods are required for full understanding. It is hoped that this lecture can spur other researchers to help tackle this critical problem!

Primary author

Dr Xiaowei Ma (Dalhousie University)

Co-authors

Ms Jessie Hallow (Dalhousie University) Ms Lauren Thompson (Dalhousie University) Michael Bauer (Dalhousie University) Alison Keefe Dr Jing Li (Dept. of Physics and Atmosphere Science, Dalhousie University, Halifax, NS, Canada, B3H 3J5) Stephen Glazier (Dalhousie University) Mr Lin Ma (2. Dept. of Chemistry, Dalhousie University, Halifax, NS. B3H 4R2, Canada) David Hall (Dalhousie University) Connor Aiken Matthew Genovese (Dalhousie University) Marc Cormier (Dalhousie University) Prof. Jeff Dahn (Dalhousie University)

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