What does it take to make a better battery?

A better battery could make all the difference. So what’s holding up progress? 

Like many of us, when I wake up I reach for the phone on my bedside table and begin scrolling through Twitter, Instagram, email and news apps. I listen to streamed music as I get ready for work and podcasts during my commute. By the time I reach the office, my phone already needs a boost. It’s not even 9am. 

It’s a modern miracle that we have computers in our pockets more powerful than those that supported the moon landings. But, despite the fact that the transistors inside our phones and laptops have been getting smaller and faster every year, the batteries that power them have not. 

The key to making electronics portable – and powering a sea change in how we communicate and consume information – was the commercialisation of lithium-ion batteries by Sony in 1991. Lithium-ion batteries are rechargeable, so when the device is connected to a charger it restores the battery for another use. 

While lithium-ion batteries have undeniable 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. 

In 2019, Grey co-founded Nyobolt with Dr Sai Shivareddy to commercialise ultra-fast charging batteries based on its patented carbon and metal oxide anode materials and other advances. The Cambridge spin-out has proven its fast-charging batteries in an electric sportscar prototype, demonstrating a charge from 10% to 80% in under five minutes, twice the speed of the fastest-charging vehicles currently on the road.

Shivareddy, CEO of Nyobolt, explains: “Nyobolt’s low impedance cells ensure we can offer sustainability, stretching out the battery’s usable life for up to 600,000 miles in the case of our technology demonstrator.”

In addition to developing entirely new types of batteries, a major strand of Grey’s research is the detection of faults. As part of her Professorship funded by the Royal Society, Grey is trying to find ways to locate faults in batteries before they happen.

“Can we detect indicators of faults in batteries before they go wrong? If we can find them, then we could potentially prevent battery safety issues. In addition, we want to explore whether a car battery that’s reached the end of its life could have a second life on the grid, for example. If we could work out, in real time, what causes the battery to degrade, we could change the way we use the battery, ensuring it lasts longer,” she says.

“The more we know about the state of health of a battery, the more valuable that battery becomes. Both strategies – increasing battery life and finding a second use – lead to cheaper batteries.”

Grey is also heavily involved with the Faraday Institution, the UK’s independent institute for electrochemical energy storage research, early-stage commercialisation, market analysis and skills development. She is co-leader of one of 10 major research projects. The project involves eight other university and eight industry partners and is examining how environmental and internal battery stresses (such as high temperatures and charging rates) 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.”

Among other projects, Dutton’s 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,” she says, adding: “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.”

Meanwhile, in the University of Cambridge’s Department of Materials Science & Metallurgy, researchers in Professor Manish Chhowalla’s laboratory have been studying the materials used in battery cathodes. Their aim is to make lithium-sulphur (Li-S) batteries lighter for applications in the aerospace industry. 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,” explains Chhowalla. “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.”