Cambridge researchers are working to solve one of technology’s biggest puzzles: how to build next-generation batteries that could power a green revolution. A better battery could make all the difference. So what’s holding up progress?
The key to making electronics portable was the commercialisation of lithium-ion batteries - batteries which are rechargeable, so when a device is connected to a charger it restores the battery for another use.
Lithium-ion batteries have advantages, such as relatively high energy densities and long lifetimes in comparison with other batteries and means of energy storage, they can also overheat or even explode and are relatively expensive to produce. Additionally, their energy density is nowhere near that of petrol. This limits their market penetration in two major clean technologies: electric vehicles and grid-scale storage for solar power. Cambridge researchers are working to solve the puzzle of how to build next-generation batteries that could power a green revolution.
Professor Dame Clare Grey (Department of Chemistry), one of the UK’s leading battery researchers, pioneered the optimisation of batteries using NMR (nuclear magnetic resonance) spectroscopy. The process enables the inner working of batteries to be monitored while in operating, without cutting them open. The work of the Grey Group investigates materials that could be used in next-generation batteries, fuel cells and supercapacitors. Increased stored energy or faster rate of charge
The Grey Lab Group is developing a range of different next-generation batteries, including lithium-air batteries (which use oxidation of lithium and reduction of oxygen to induce a current), sodium batteries, magnesium batteries and redox flow batteries.
A working lithium-air battery would have a theoretical energy density ten times that of a lithium-ion battery. However, although a comparable energy density to that of petrol, the practical energy density achievable is noticeably lower and significant research challenges remain to be addressed. While Grey works with industrial partners to improve the batteries going into electric cars today, she says the role of universities is to think about entirely new types of batteries, such as the ones she is developing in her lab.
“Universities need to be coming up with answers for ten to 15 years from now – we’re the ones who are best placed to innovate, think creatively and generate radical, new solutions. We want to make sure that our work has an impact well beyond today’s batteries.” Professor Clare Grey, Dept of Chemistry
Nyobolt, Cambridge spin-out founded by Clare Grey and Sai Shivareddy, aims to commercialise ultra-fast charging batteries based on its patented carbon and metal oxide anode materials and other advances. The company has demonstrating a charge from 10% to 80% in under five minutes, twice the speed of the fastest-charging vehicles currently on the road.
Professor Grey co-leads one of 10 major research projects at the Faraday Institution, the UK’s independent institute for electrochemical energy storage research, early-stage commercialisation, market analysis and skills development. Involving eight universities and eight industry partners, the project examines how environmental and internal battery stresses damage electric car batteries over time. The results will be a crucial step towards making batteries of the future have longer life.
“When you think about other electronic devices, you’re generally only thinking about one material, which is silicon,” says Professor Siân Dutton at Cambridge’s Cavendish Laboratory in the Department of Physics, and who is also working on the Faraday Institution project.
“But batteries are much more complex because you’ve got multiple materials to work with, plus all the packaging, and you’ve got to think about how all these components interact with each other and with whatever device you’re putting the battery into,” Professor Siân Dutton, Cavendish Laboratory, Dept of Physics
The Dutton Research Group is investigating the possibility of a battery electrolyte that is solid instead of liquid. One of the primary safety concerns with lithium-ion batteries is the formation of dendrites – spindly metal fibres that make a battery short-circuit, potentially causing the battery to catch fire or even explode.
“If the electrolyte is solid, however, you may still get dendrites, but the batteries are far less likely to explode. It’s important for universities to look at unconventional battery materials like the ones we’re investigating. If everyone moves in the same direction, we won’t get the real change we need,” Professor Siân Dutton, Cavendish Laboratory, Dept of Physics
Researchers in Professor Manish Chhowalla’s laboratory are studying battery cathode materials.The aim is to make lighter lithium-sulphur (Li-S) batteries aerospace industry applications. Working with nine other universities with funding from the Faraday Institution, they have developed a new cathode material that uses two-dimensional nanosheets of molybdenum disulfide instead of carbon.
“Li-S batteries possess high energy density and are lightweight, which makes them potentially deployable in short-range commercial flights. Their other advantage is the electrodes of Li-S batteries don’t contain expensive transition metals like cobalt that have social and environmental issues associated with their mining,” Professor Manish Chhowalla, Dept of Material Science and Metallurgy