Materials solutions to global problems

Materials World magazine
,
1 Jul 2018

Combining the 20th Kelly Lecture and the Gordon Seminars, the Armourers and Brasiers’ Cambridge Forum covered a range of materials science topics, including batteries, multifunctional nanomaterials, and spectral conversion materials. Kathryn Allen reports.

The Armourers and Brasiers’ Cambridge Forum took place on 12 June at the University of Cambridge, UK, with the 20th Kelly Lecture, delivered by Professor Peter Bruce, Department of Materials, University of Oxford, UK, discussing materials development for batteries. 

Highlighting a need to understand and develop the fundamental science behind battery innovations, Bruce discussed three main topics – all-solid-state batteries, storing energy using oxygen-redox materials, and electrical energy storage and rechargeable batteries. 

According to Bruce, all-solid-state-batteries can provide improved safety, as there is no flammable organic liquid electrolyte, and they have a longer lifespan. But challenges remain in improving energy density and combining high-ionic conductivity with suitable mechanical properties. The solution to the latter could be attained using 3D printing, the professor explained. A polymer template can be printed, its pores filled with a powdered ceramic electrolyte, after which the template is sintered off, and the gaps are filled with an epoxy polymer. The resulting hybrid electrolyte was found to have a reduced current polarisation compared to a ceramic disk electrolyte. 

Claiming that ‘the time for lithium-ion will come to an end [...] Lithium-ion cells will not deliver the energy storage that we will need in the longer term’, Bruce also discussed the lithium-oxygen battery, which has the highest theoretical specific energy of any battery. Stating that a ‘need to understand the underpinning science’ is necessary to innovation, Bruce discussed how this understanding has led to Li02 cells with smaller polarisation, high capacity, and an overall ‘much more attractive performance’. However, further development is needed to improve the battery’s stability. 

Materials for sustainability 

The Gordon Seminars preceded the Kelly Lecture, and, while various topics were covered, a theme of materials for sustainability stood out. 

Dr Camille Petit, Senior Lecturer in the Department of Chemical Engineering at Imperial College London, UK, provided an overview of her research into creating multifunctional materials for use in carbon management and air and water treatment. Addressing separation challenges – including oil spills and air pollution remediation – that currently require a lot of energy, Petit’s team are developing adsorbents, with a focus on metal-organic frameworks and nitride-based materials, that can achieve separation without such high energy consumption. 

The team have used boron nitride in powder form to separate oil and water. As Petit explained, ‘the important thing is that boron nitride is highly thermostable, which means you can take [the mixture], burn the oil and reuse the material.’ However, Petit acknowledged that boron nitride in powder form is not convenient for industrial use as it’s difficult to handle. The team therefore looked at altering the materials form, creating pellets of boron nitride. They are currently working to scale up the processes. Petit also explained the group’s work on designing multifunctional materials for carbon management via carbon capture and conversion. 

Embracing renewables 

Dr Rachel Evans, Lecturer in the Department of Materials Science and Metallurgy at the University of Cambridge, also addressed environmental sustainability, referring to ‘one of the biggest challenges, perhaps, facing our generation – the eradication of the use of fossil fuels to generate electricity’. Claiming that, ‘we really need to move away from the use of fossil fuels now and fully embrace energy from renewable sources technologies’, Evans described her work developing photoluminescent spectral conversion materials, which allow the collection, conversion, and concentration of sunlight for use in solar cells. 

Evans’ talk focused on luminescent solar concentrators (LSCs), which convert solar energy to wavelengths that have energies closely matching the band gap energy of solar cells, making energy absorption more efficient. Looking to move away from the use of plastics in LSCs, the team explored the use of ureasils –organic-inorganic hybrid polymer materials – and other materials, allowing mechanical and optical tunability and chemical functionalisation of the devices. 

LSCs are a ‘complimentary technology, not a competing technology’, according to Evans. They aren’t as efficient as coating an entire wall in solar cells, but could be used in situations where it isn’t possible to use solar panels. For example, LSCs are already being used in the Solar Noise Barrier Project in the Netherlands, installed along a highway, acting as a noise barrier and harvesting solar energy. Evans left the audience with a reminder that ‘global warming is all of our problem’.

Dr Michael Ramage, from the Centre for Natural Material Innovation, Department of Architecture, University of Cambridge, continued the theme of sustainability, discussing how natural materials, including timber and engineered bamboo, can be used as substitutes for steel and concrete when making taller buildings, reducing carbon emissions. 

Talks were also given by Professor Sandra Korte-Kerzel, RWTH Aachen University, Germany, who described her work into material deformation at the crystal level, and Michael LeGoff, CEO of Plessey, UK, who advised on the commercialisation of materials-based technology. The Armourers and Brasiers’ Materials Science Venture Prize – a £25,000 investment to support research commercialisation – was presented to Swansea University, UK, spinout company Kubal-Wraith Ltd for a new laser technology for steelworkers.