St Andrews Research Repository

St Andrews University Home
View Item 
  •   St Andrews Research Repository
  • Chemistry (School of)
  • Chemistry
  • Chemistry Theses
  • View Item
  •   St Andrews Research Repository
  • Chemistry (School of)
  • Chemistry
  • Chemistry Theses
  • View Item
  •   St Andrews Research Repository
  • Chemistry (School of)
  • Chemistry
  • Chemistry Theses
  • View Item
  • Register / Login
JavaScript is disabled for your browser. Some features of this site may not work without it.

Layered lithium manganese oxide cathodes

Thumbnail
View/Open
AllanPatersonPhDthesis2003_original_C.pdf (30.70Mb)
Date
2003
Author
Paterson, Allan J.
Supervisor
Bruce, Peter G.
Metadata
Show full item record
Abstract
The synthesis, characterisation and electrochemical performance of layered lithium manganese oxide materials have been investigated in terms of their application as an intercalation cathode in rechargeable lithium batteries. Non-stoichiometric LiₓMnᵧO₂, stoichiometric LiMnO₂ (α-NaFeO₂ type) with doped forms, LiₓMn₁₋ᵧMeᵧO₂ and LiMn₁₋ᵧMeᵧO₂ (where Me = Al, Mg, Li, Ni, Co), were prepared by solid-state and solution synthesis routes coupled with ion exchange from sodium precursors. These materials were investigated by X-ray and neutron powder diffraction, as well as chemical and compositional analysis, SEM, TEM, surface area and galvanostatic cycling measurements. The structure and performance of non-stoichiometric materials is highly dependant on the synthesis conditions and ion exchange process which determine the defect chemistry. LiₓMnᵧO₂ exhibits high capacities, 190mAhg⁻¹ at a rate of 25mAg⁻¹ (C/8) with good retention of this capacity (fade rate of ~0.1% per cycle). However, performance is hindered by a first cycle charge capacity which is less than the subsequent discharge. This is a problem for lithium ion cells which require a slight excess of Li on the first charge to form the SEI layer on the carbon anode. The performance of LiMnO₂ is less dependant on synthesis conditions, exhibiting high discharge capacities, ~200mAhg⁻¹at 25mAg⁻¹with minimal fade rate and essentially theoretical charge capacity on the first cycle. Doping of layered materials was found to result in a reduction in the initial dip and rise in capacity over the first few cycles, improved rate capability and first cycle efficiency for non-stoichiometric materials as well as higher overall capacity >200mAhg⁻¹. Structural transformation from a layered to spinel-like configuration on cycling has been investigated. Performance of the spinel-like material formed in situ is markedly superior to directly prepared spinels, being attributed to the formation of a nanostructure able to accommodate the lattice strain caused by the Jahn-Teller distortion. Ball milling and variation in carbon and Kynar concentration were investigated as well as the possibility of electrodes containing both stoichiometric and non-stoichiometric components, to permit an excess of charge capacity on the first cycle in order to accommodate the irreversible losses due to SEI surface layer formation when cycling against a carbon based anode.
Type
Thesis, PhD Doctor of Philosopy
Collections
  • Chemistry Theses
URI
http://hdl.handle.net/10023/21849

Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated.

Advanced Search

Browse

All of RepositoryCommunities & CollectionsBy Issue DateNamesTitlesSubjectsClassificationTypeFunderThis CollectionBy Issue DateNamesTitlesSubjectsClassificationTypeFunder

My Account

Login

Open Access

To find out how you can benefit from open access to research, see our library web pages and Open Access blog. For open access help contact: openaccess@st-andrews.ac.uk.

Accessibility

Read our Accessibility statement.

How to submit research papers

The full text of research papers can be submitted to the repository via Pure, the University's research information system. For help see our guide: How to deposit in Pure.

Electronic thesis deposit

Help with deposit.

Repository help

For repository help contact: Digital-Repository@st-andrews.ac.uk.

Give Feedback

Cookie policy

This site may use cookies. Please see Terms and Conditions.

Usage statistics

COUNTER-compliant statistics on downloads from the repository are available from the IRUS-UK Service. Contact us for information.

© University of St Andrews Library

University of St Andrews is a charity registered in Scotland, No SC013532.

  • Facebook
  • Twitter