High Energy-Density and Long Life-Time Lithium-Sulfur Batteries

Conventional lithium-ion batteries demonstrate great potential for applications in electrical vehicles, but they face some major challenges such as low energy density and high cost. It is worthwhile to pursue alternative strategies to address the barriers of cost and energy density. We propose to develop advanced rechargeable lithium-sulfur (Li-S) batteries that have much higher theoretical energy density and lower cost. We will improve the practicality and cycle life of Li-S batteries to make them more commercially viable. In the Phase I project, we have improved the energy density and cycle life of Li-S batteries using button cells. First, highly conductive lithium-ion exchange (LIE) films have been used as battery separators. Second, concentrated Li electrolytes has been applied to the sulfur electrodes. These efforts have prevented cathode sulfur loss due to the polysulfide diffusion, thus significantly enhancing the cycle life of Li-S batteries. In the Phase II project, we will further develop this technology using more advanced and low-cost lithium-ion exchange (LIE) separators and ionomers to further reduce polysulfide diffusion. We will then increase the S loading, fabricate pouch cells and evaluate their energy density and cycle life under more realistic EV conditionsCommercial Applications and Other Benefits The proposed lithium-sulfur technology will address two major barriers of electrical vehicles, cost and energy density; therefore it may directly facilitate the deployment and commercialization of electrical vehicles. They may also be applicable in the consumer market to portable electronics and communication devices.