SBIR Phase I: Porous carbon substrate for long life lithium-sulfur batteries

This Small Business Innovation Research Phase I project will address issues related to the development of high-energy lithium-ion batteries. Today, mobile devices require faster performance and smaller sizes for greater portability. However, the faster processors in these devices impose energy density requirements that push today's lithium battery technologies to their limits. State-of-the-art lithium-ion electrode materials used in mobile devices produce a maximum energy density of 0.28-0.6 kWh/kg. Our team is developing a commercial secondary/rechargeable Li-S battery with a theoretical energy density of 2.3 kWh/kg, which could dramatically alter the electrical energy storage landscape for all portable devices. Development of this Li-S battery has been limited by poor cycle life. This project will remedy this by developing an optimal porous carbon host for sequestering sulfur in the battery cathode. The host will limit polysulfide dissolution in order to increase cycle life of our current sulfur-infused carbon nanostructure (S@C) composite cathode materials from 650 cycles to 1000 (or more) cycles. In addition, by utilizing low-cost, commercially available carbon feedstocks (carbon aerogels, graphene, and high-sulfur coal), the results of this research will likely reduce the direct costs of manufacturing carbon-sulfur composite cathodes. The broader impact/commercial potential of this project is significant. Li-ion batteries currently have a $11-13 billion market and the market size is expected to reach $44 billion by 2020. Li-ion batteries account for close to 75% of all secondary (rechargeable) batteries used in portable electronics. Secondary lithium-sulfur batteries employing sulfur as the cathode and metallic lithium as the anode offer the highest energy storage potential of any battery based on two solid elements. These devices offer more than twice the energy capacity of the currently deployed lithium-ion battery technology with half the weight. If this potential can be brought to commercialization, it has the potential to displace lithium-ion cell technology because of the higher energy density, low cost, and widespread availability of sulfur. This could have significant impacts on mobile devices, electric vehicles market, and the broader energy storage market, enabling greater efficiency and performance in all those sectors.