Is battery advance on the horizon for EVs?
Scientists have developed a working laboratory demonstrator of a lithium oxygen battery which has very high energy density, is more than 90 per cent efficient, and to date, can be recharged more than 2,000 times
The headlines finally suggest a big breakthrough for electric vehicles.
Some samples: “New battery could be a game-changer for EVs.” And: “New design points a path to the ‘ultimate’ battery.”
We’ve been down this road before. Everyone involved with EVs dreams of a battery that powers a car 600 kilometres between charges, costs no more than internal combustion and lasts a long time.
With those qualities, EVs could dominate.
The latest headlines came from research at the University of Cambridge, where, says a statement: “Scientists have developed a working laboratory demonstrator of a lithium-oxygen battery which has very high energy density, is more than 90 per cent efficient, and to date, can be recharged more than 2,000 times, showing how several of the problems holding back the development of these devices could be solved.”
What a Christmas gift for the industry.
EVs now rely on lithium ion. U.K.-based market-research experts IDTechEx call it “the best battery technology we have ever seen. It has increased energy density by 5 per cent per year and decreased its cost at 8 per cent per year.”
But it’s not and never will be good enough “because of the inherent material limitations. A new generation of battery technologies will be necessary.”
Several are being tried, including silicon anode, solid state, sulphur, sodium ion and magnesium.
But lithium air is the most intriguing. When I first wrote about it in 2010, I offered this rough explanation: Lithium-based batteries generate a current when lithium ions stored on one side of the battery are attracted by something to the other side.
As they cross over, they pass through an electrolyte and generate current. Recharging the battery sends the ions back to their original side so the process can be repeated.
In lithium-ion batteries, the attraction comes from one of several metals. Different manufacturers have their favourites. With lithium air, the catalyst is oxygen from air drawn from outside. This allows for a battery that weighs less and has up to 10 times greater capacity to store and release energy.
In 2010, lithium air was pie in the sky. Just numbers on paper, said Jeff Dahn, a physicist at Dalhousie University in Halifax, who has researched batteries for 35 years. “Nobody has actually built even a single-use lithium air cell yet, let alone a rechargeable version, and there are many roadblocks.”
The Cambridge research brings the pie a little closer to Earth. The scientists developed a “working demonstrator” with chemical components that start to address a major problem with lithium-air batteries; they’re extremely unstable.
But major issues remain.
- The impressive capacity is only available at certain rates of charge and discharge, so it’s not fit for EVs with their wide variety of demands on the battery.
- Lithium-air generates spindly lithium-metal fibres known as dendrites, which, if they grow too much, can short-circuit the battery and cause it to explode.
- The demonstrator only operates in pure oxygen, while the air in which EVs run also contains carbon dioxide nitrogen and moisture.
“There’s still a lot of work to do” admitted Dr. Tao Liu, from Cambridge’s chemistry department and lead author of the research paper. “What we’ve seen here suggests that there are ways to solve these problems — maybe we’ve just got to look at things a little differently.”
This Christmas gift the researchers predict is another 10 years away.
Freelance writer Peter Gorrie is a regular contributor to Toronto Star Wheels. To reach him, email email@example.com and put his name in the subject line.