Lithium sulfur battery (Li-S) has attracted intensive interest in recent years due to its high specific capacity, low cost, and abundant resources of sulfur. Theoretically, a high specific capacity of 1675 mAh g^-1 and a specific energy of 2567 Wh kg^-1 are expected for sulfur cathode. Practically, the energy density of Li-S battery is projected to be two to three times higher than that of state-of-the-art Li-ion batteries (180 Wh kg^-1). However, the commercial applications of Li-S batteries are still hindered by several challenges.²  One is that with elevated sulfur loading above 3 mg/cm², which is essential for high energy applications, new problems occur including the cathode cracking, electrode wetting and low sulfur utilization rate. The second and more detrimental issue that limits Li-S cell performance is interfacial stability and cycling reversibility of lithium metal anode, which easily reacts with both electrolyte solvents and the formed polysulfides during battery cycling and leads to unavoidable shuttle and continuous consumption of active sulfur species. These side reactions are significantly exacerbated under conditions of coupling with high-areal loading sulfur cathode and/or cycled at elevated current densities. As a result, thick and porous interface will be quickly built up on lithium anode and leads to quick impedance increase and thus fast capacity decay of the battery.³ The third problem is the amount of electrolyte required for full dissolution of the polysulfides. The dissolved polysulfides cause endless shuttle and continuous Li anode corrosion due to the lack of effective solid electrolyte interface (SEI) on lithium. In addition, the large amount of electrolyte significantly lowers the energy density of the battery, which is undesired for high-efficient portable devices or electric vehicle energy storage applications

     To overcome the aforementioned hurdles in Li-S batteries, multiple approaches have been proposed and successfully demonstrated by our group, spanning from sulfur cathode, anode and electrolyte.  At the meeting, we will present our recent progresses on the Li-S battery system including the rational design of carbon/sulfur composite for large area and high loading sulfur cathode preparation, alternative non-Li anode materials for Li-ion sulfur batteries, and development of new electrolyte.

References

 1.          Ji X, Lee KT, Nazar LF. A highly ordered nanostructured carbon-sulphur cathode for lithium-sulphur batteries. Nat Mater 2009, 8(6): 500-506.

 2.           Lv D, Zheng J, Li Q, Xie X, Ferrara S, Nie Z, et al. High Energy Density Lithium–Sulfur Batteries: Challenges of Thick Sulfur Cathodes. Advanced Energy Materials 2015, 5,1402290.

 3.          Lv D, Shao Y, Lozano T, Bennett WD, Graff GL, Polzin B, et al. Failure Mechanism for Fast-Charged Lithium Metal Batteries with Liquid Electrolytes. Advanced Energy Materials 2015, 5,1400993.