Taking a lot of heat from lithium-ion batteries

Some stories are tough to get your head around. This is one of those. About four years ago, Merlinda in sales at PACT LLC got a call. Someone wanted to buy two of the company’s industrial corrugated crates. The caller didn’t care what size they were, he just wanted two crates. Merlinda was a little befuddled, so she redirected the call to Rodger Mort, company president.

Turns out, the caller didn’t want to ship anything in the crates. Instead, he wanted to paint the outside of both and turn a blow torch on them. Yes, a blow torch. He was trying to figure out just how fire suppressant the paint was. Before the call was over, Mort was off and running down an unexpected path.

In March, after four years of development and a continuing string of regulatory hurdles, PACT announced ThermoShield, a paper-based, fire-resistant shipping wrap for lithium-ion batteries. If you’re following the story so far, I’m with you. But, this is where it gets a little challenging.

Quite simply, says Mort, the paper-based wrap is so fire resistant that it entirely contains flames from a damaged lithium-ion battery. We’ve all seen stories about lithium-ion batteries self-igniting in cargo holds and elsewhere. The photo shows what a shipping carton looks like after the ThermoShield-wrapped batteries in it burned themselves out. But how can that be? A paper wrap that doesn’t burn?

As Mort explains, the wrap is treated with a non-toxic moisture vapor coating. When a battery starts to burn, the coating releases moisture on the outside of the wrap. The outside of the wrap is 80°C while the burning battery is at 780°C. The wrap protects the other contents in the shipping container while allowing the battery to burn itself out.

In the four years of development, quite a bit has transpired, says Mort. To begin, the coating used on ThermoShield is a reformulation of the original paint developed by Fireproof Products. It took two and a half years to come up with the right formulation, says Mort. Since then, he has been focused on clearing the regulatory hurdles needed to use the wrap to protect shipments of lithium-ion batteries.

An early stop was at the Western Fire Center in Oregon. The test there involved putting 100 wrapped batteries, two computer tablets and a package of Styrofoam cups in a shipping container. The batteries burned for four hours. Meanwhile, the tablets were unscathed and the cups were ready for some steaming hot Joe.

Another of Mort’s stops was the SAE (Society of Automotive Engineers). When he first visited, the engineers were skeptical. “That’s impossible” is the phrase Mort most remembers. Today, ThermoShield exceeds the proposed SAE G27 lithium battery packaging performance standard. Mort says PACT has filed for a special permit with the DOT to protect up to 16 batteries in a shipping container.