Practical Lithium Air Batteries

Lead Research Organisation: University of Liverpool
Department Name: Chemistry

Abstract

This project is centred around the development of a practical lithium air battery single cell with improved performance. The
project consortium includes Queens University Belfast and Liverpool University as academic partners and Johnson
Matthey, Axeon, JLR and Air Products as the industrial partners.
The instability of existing electrolytes to superoxides is a major barrier to achieving good cycle life in current laboratory
scale Li-air cells, due to capacity fade as a result of the formation of irreversible species from solvent decomposition that
occurs if current Lithium ion battery organic electrolytes are used. Therefore, significant effort will focus on synthesising
novel electrolytes capable of surviving operation in Li-air batteries, where a large operational voltage window and immunity
to degradation from superoxide attack are key features, combined with practical levels of oxygen solubility and ionic
conductivity. Novel ionic liquid electrolytes and blends will be synthesised using the expertise at QUB and also drawing on
empirical and modelling results already available in the literature, relating to solvent stability in the presence of superoxide.
Novel anode and cathode materials and catalysts will be prepared and tested (JM) in combination with improved
electrolytes synthesised in the project (JM). Emphasis will also be placed on optimising cathode structures for the novel
electrolytes to achieve improved capacity, current density and cycle life (JM, Axeon). Understanding the cathode reactions
oxygen reduction during discharge and oxygen evolution during charge with new electrolytes via iR and Raman
spectroelectrochemistry techniques will be undertaken (Liverpool University) and the behaviour at the anode interface in
the novel electrolytes will also be explored. The wide variety of analytical techniques available via the different project
partners including XPS, ATR, electron microscopy and electrochemical measurements will be applied within the project.
Cell testing studies will investigating the effects of various parameters, pressure, temperature , charge rate, the effect of
carbon dioxide and water impurities in inlet air and possible inlet air clean up strategies also be considered (JM, Axeon, Air
Products, JLR).
The key outputs from the project will be an optimised single cell configuration with the best electrolyte, electrode material
and electrode structure combination, accompanied by understanding of the electrochemistry and the effect of cathode
structure and test parameters on battery performance and cyclability. These data contribute toward establishing the
feasibility of lithium air battery technology and will lay a firm foundation for future development of larger scale
demonstration systems .

Planned Impact

The successful development of a novel electrolyte for Lithium air batteries and associated understanding gained within this
project will be a significant enabler for future industrial research, product development and ultimately the viability of lithium
air battery systems for larger scale use. This will benefit the project partners, their associates and stakeholders in the wider
battery supply chain growing within the UK.
This project is targeted at developing energy materials for advanced battery systems with energy densities > 400Wh/kg
exceeding Li-ion technology and aimed at automotive applications. Predictions (by LMC Automotive) imply the number of
vehicles that contain an element of electrification within their drive train is estimated to increase from 1.5% of the market to 8% by the end of the decade. Further expansion is prohibited by the cost and the performance of the battery packs. Lithium
air batteries have a substantially higher theoretical energy density than Lithium ion, such that a 3-5 times battery capacity
benefit in practical systems is still predicted for Lithium air, even when factors such as additional weight of cell components
and single cell to pack efficiency losses are taken into account. Thus such batteries might provide greater range/lower cost
in automotive systems. However, electrolyte instability and associated poor cyclability of these batteries remains a
significant barrier to success. Improvements to electrode materials/structure and a full understanding of the requirements
for a Lithium air battery system (air purification and on paper system feasibility investigation) will also be generated, leading
to associated scale up work within the UK in the future, for materials, electrodes, battery packs and ultimately systems.
Information on the novel materials, cell testing and system feasibility generated will be disseminated via conferences,
publications as appropriate. The project also provides training via PhD projects and application of existing expertise in new
areas via the academic and industrial project work. Research is increasing worldwide on metal air and advanced battery
materials topics, especially in Asia and the USA and this project will accelerate the progress of research on these topics in
the UK.
Results from the project also overlap into other technology areas for example, the use of high stability electrolytes in Li-ion
batteries and supercapacitors and overlap of air cathode, air purification and system aspects with other metal air battery technologies such as Zn-air.
 
Description We have evaluated a number of ionic liquid based electrolytes for lithium-air batteries using Raman spectroscopy and have noted trends relating to the properties of the ionic liquids in comparison to more conventional electrolytes.. The data is presently being written up in a PhD thesis and we will be able to add further detail shortly.
Exploitation Route The project was in collaboration with the UK company Johnson Matthey, the findings from the project are being taken forward and we look to continue work funded through Innovate UK.
Sectors Chemicals,Energy,Transport