STTR Phase I: Nanofiber Based Lithium Ion Battery Separator with Reversible Thermal Shutdown Capability

This Small Business Technology Transfer (STTR) Phase I project seeks to establish the feasibility of an entirely new class of liquid electrolyte separator for Li ion batteries that has a built-in reversible thermal shutdown mechanism. With increasing use of Li ion batteries, safety is of particular concern as reports of occasional injuries appear in the news due to a short circuit, cell overcharge, or other overheating related catastrophic events. A separator medium having a reversible thermal shutdown mechanism means that Li ion batteries can automatically be shutdown before a thermal runaway incident occurs and can automatically be restarted once a safe thermal environment is restored. A Li ion battery separator with the targeted built-in reversible thermal shutdown capability not only addresses safety, but is also expected to extend the active life of a battery. The technical objectives of this project are to identify a suitable polymer material, optimize its material characteristics, and investigate the factors related to the reversible thermal shutdown, mechanical stability and durability. The polymer nanofiber web will be subjected to thermal cycling and the reversible thermal shutdown characteristics will be evaluated using impedance measurements. In this project, the composition and structure of a durable electrospun polymer nanofiber web with a reversible thermal shutdown characteristic will be identified. The broader/commercial impact of this project, if successful, will be an improvement in safety for Li ion batteries. This innovation has a direct impact on the safety of users. Moreover, the tendency to overheat also impacts Li Ion battery operations. The associated costs to address both issues have continued to be a barrier for wider adoption of Li Ion batteries, and thus, the successful outcome of this project also has the potential of lowering the cost of the battery technology. Development of a separator with reversible thermal shutdown capability will help lessen the hurdles that are deterring the Li Ion battery technology from achieving its potential in a forecasted $7 billion end user market. This collaboration between the small business and an academic partner involves a post-doctoral scientist at the academic institution, who will gain commercially relevant research experience.