Separator for Improved Safety in Large-Format Li-ion Batteries like Those in the Boeing Dreamliner

February 03, 2013 by Jeff Shepard

Thermal events, as have happened recently in batteries in the Boeing Dreamliner, occur when the internal temperature of the battery rises to between 135 and 160 degrees C. This temperature range corresponds to the melting point of traditional separators, and above this temperature the internal reactions can generate enough heat to result in thermal runaway, which can cause smoke, ignition and even explosions.

DreamWeaver International's Gold™ battery separator combines microfibers and nanofibers in a porous substrate that has very high temperature stability without significant thermal shrinkage--up to 300 degrees C. Large format batteries such as those used in electric vehicles, aircraft, grid storage or uninterrupted power supplies are more difficult to design for safety than cell phone or laptop batteries because each cell holds much more energy.

DreamWeaver Gold is stable for up to 150 degrees C higher temperatures than these traditional membranes, which is expected to enhance the safety of large format batteries, offering significant advantages over conventional separators. To achieve its extraordinary thermal stability, Dreamweaver Gold uses Teijin's Twaron® aramid fiber as a high-temperature microfiber scaffolding on which the nanofiber lattice network is built.

Twaron is stable up to 500 degrees C, is durable and chemical resistant. Twaron aramid fiber has been used for over 30 years to provide structural integrity and thermal and electrical insulation in a wide variety of applications ranging from transformers, generators, printed circuit boards, heat shields and honeycombs, in addition to traditional ballistic and composite applications.

"By providing a battery separator with far higher temperature stability, we are giving battery manufacturers a tool to enhance their design of safety mechanisms, which is expected to significantly reduce the risk of ignition in high-power, high-capacity batteries," said Dr. Brian Morin, Dreamweaver's co-founder and the inventor of the patent pending technology.

DreamWeaver Gold has the additional benefits of delivering higher power and being available at a lower cost than traditional membranes. "We have truly designed this product from the ground up for mass markets, and it furthers our long-term goal of providing the lowest-cost high technology battery separators in the world," said Jim Schaeffer, Dreamweaver's other co-founder and CEO.

DreamWeaver Gold is available for customer development in thicknesses from 25 to 40 microns, with rolls cut to customer specifications.