Electric car battery fires are rare but widely reported by the press, even though fires in gasoline-powered vehicles are much more common. It may not be good journalism, but “If it bleeds, it leads” is still the basic principle for many news outlets. And don’t forget, fossil fuel shills seize upon every bit of negative news they can find about EVs and push it to anyone who will listen.
One of the primary causes of battery fires is dendrites — little sharp spikes of lithium that penetrate the insulating layer that separates the anode and cathode. When that happens, it creates a short circuit, which can cause a battery cell to overheat. Conventional lithium-ion batteries use a semi-liquid paste to hold the materials in place that actually store an electrical charge.
The solvents in that paste are flammable at high temperatures — the sort that happen when a short circuit occurs. Once one cell overheats, it tends to cause the cells closest to it to overheat. Suddenly, boom! It’s Roman Candle time. To see what happens next, check out this story of another Chevy Bolt that erupted in flames in Georgia this week.
And while you are visiting Autoblog, be sure to read the other story, the one about the 40 conventional cars destroyed by fire after what appears to be a lightning strike. Those who snicker up their sleeve about how dangerous EVs are should try controlling their snide remarks, because karma is a certified bitch!
Researchers at the Nanyang Technological University in Singapore say they have found a way to prevent those internal short circuits that lead to lithium-ion battery fires. Professor Xu Zhichuan and his research team have invented an additional “anti-short layer” on the separator they say prevents any dendrite from reaching the cathode and creating a short circuit.
“We know that for a Li-ion battery to work, lithium ions must be able to travel between the positive and negative sides during charge and discharge cycles,” explains Xu. “However, the transfer of the lithium ions also means the formation of dendrites is inevitable for current commercial Li-ion batteries.
“Instead of preventing the formation of dendrites, we decided to make use of their intrinsic properties by coating an additional layer of conductive material on the separator for these dendrites to connect with. Once the dendrites make the connection they will not be able to continue their growth further, thus preventing them from ever reaching the other side.”
According to TechXplore, Xu and his team have tested their new technology in the laboratory on over 50 cells with different lithium-ion battery compositions, and no short-circuits have been detected during the charging phase even when the battery cells are used beyond their life cycle. The anti-short layer is a common material used in battery manufacturing and can be easily integrated into the current separator manufacturing process, making it easy for companies to adopt and scale up. The team estimates adding the anti-dendrite layer would add about 5% to the cost of a lithium-ion battery cell.
Dr. Avishek Kumar is the CEO and co-Founder of V-Flow Tech, an energy storage technology firm. He says “this invention, which solves the most critical puzzle of thermal runaway issue in Li-ion energy storage solutions, will prove to be one of the biggest enabler for mass adoption for Li-ion energy storage technology.”
There are lots of ways to avoid dendrites and battery fires. LFP batteries like the blade battery from BYD seem to be far less prone to overheating, but have a lower energy density than the best lithium-ion batteries available today. Solid state batteries like those under development by Quantumscape eliminate the solvents and other combustible chemicals used in conventional lithium-ion battery cells, but have yet to advance much beyond the laboratory stage.
If there is a way to significantly reduce lithium-ion battery fires using the same manufacturing process commonly used to manufacture them, that would be great news for the EV revolution. What manufacturer wouldn’t pay a 5% premium to avoid the economic pain of seeing its products in flames on the front page of the world’s newspapers?
And what customer wouldn’t opt to purchase an EV that is less likely to catch fire than the one next door at that other dealer? Of course, driving down the cost of batteries is a high priority for every EV maker, but using batteries that are resistant to fires seems like a no-brainer and a win-win situation for manufacturers and customers alike. This could be the greatest invention since sliced bread.
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