Lithium-ion batteries are all well and good until, as Samsung found out to its peril with the Note 7 disaster, they suffer a fault, swell up like a rock star’s ego, and suddenly turn into potential safety hazards.
“What we’re trying to understand is what happens physically inside a battery when it generates gas and swells up like a pillow,” energy storage and composite materials researcher Toby Bond told Digital Trends. “This swelling can happen for many reasons, but it is often the result of overheating, overcharging, or some other kind of stressful conditions. Many batteries swell up without further incident — some even keep on operating — but swelling can also be the first step on the way to an explosion or fire.”
The team used high-resolution CT scans to create an internal 3D image of a battery before and after they forced it to generate gas and swell up.
“What we found is that there are small imperfections in the way the electrodes are layered, and [these] become more pronounced when the battery swells up,” Bond continued. “This likely affects what happens to the battery after that, since this kind of non-uniform swelling changes how the pressure is distributed inside the battery.”
It’s not known if this “pillowing” was the reason for some of the recent high profile lithium-ion battery-related disasters, but Canadian Light Source’s study certainly sheds some light on potential major design faults. Considering that the same type of lithium-ion battery geometry is used in many electric vehicles — but on a much larger scale — it’s a piece of research we hope can trigger positive change.
“We’ve taken the first step in showing what happens inside a typical commercial battery during swelling, and we hope that battery manufacturers can use this information to better understand how the swelling process works on an engineering level,” Bond said. “If the effect of these small manufacturing defects is significant, then companies might be able to make safer batteries by better controlling these imperfections, or changing the internal structure of the battery to prevent them from growing during the swelling process.”
Let’s keep our fingers crossed and hope!