Rechargeable lithium-sulfur batteries have attracted great interest because of their high theoretical specific energy, several times higher than that of current lithium-ion batteries. However, successful applications of sulfur cathode have been impeded by rapid capacity fading caused by multiple mechanisms, including large volume expansion of sulfur during lithiation, dissolution of intermediate polysulfides, and low ionic/electronic conductivity.Our group has addressed these problems through multifaceted approaches at different length-scales, allowing unprecedented control over the electrode architecture from the nanoscale to macroscale. We demonstrated high specific capacities and excellent prolonged cycling stability over 1,000 charge/discharge cycles through rationally designed nanostructured sulfur cathodes. We engineered empty space into monodisperse sulfur nanoparticles encapsulated with restraining shells for the accommodation of volume change and the confinement of polysulfides. We also identified the LixS detachment from carbon surface during discharge, which results from low binding energy between the nonpolar carbon and polar LixS clusters, as an important decay mechanism from both experimental observation and theoretical calculation. We demonstrated that the capacity fading caused by this interfacial effect can be overcome through appropriate molecular functionalities built into a suitable nanostructure. Our work combines molecular understanding and nanomaterials design to address critical energy storage problems, and thus opens up exciting opportunities for the next generation of high-energy battery.

High-performance lithium-sulfur battery: From molecular understanding to nanomaterials design

248th National Meeting (2014)

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