Scalable Synthesis of Composite As Cathode in Li-S Batteries with Improved Performance

On the demand of large-scale energy storage, the secondary lithium-ion batteries (LIBs) are attracting more attentions on portable devices and electric vehicles. Numerous efforts are being taken into finding new electrode materials which have folds higher capacity with respect to the traditional materials over the last decade. In particular, scientists have explored silicon shows a 7-10 times higher capacity of >2000 mAh/g than the commercial graphite. However, on the cathode side, substantial capacity improvement in comparison of silicon anode is lacking, which largely restrict the commercialization of high energy density batteries. Sulfur has been identified as one of most promising cathode materials for its high theoretical capacity (1675 mAh/g, 8-10x times higher than LiCoO₂) and the theoretical specific energy (~2600 Wh/kg, 5x times higher than LiCoO₂/graphite) of Li-S battery. Nevertheless, researchers remain stagnant in pushing this high power-density battery into industrial applications. The major barrier is from the rapid capacity decay, which is due to the low electrical conductivity, volume expansion and the shuttling effect. Averting chemomechanical degradation thus poses as one of the primary challenges in exploiting sulfur cathodes in the development of next-generation batteries.

       Here we present a scalable synthesis of lithium-sulfur composite cathode with improved performance. An open network of conductive carbon black nanoparticles (Cnet) is infused with sulfur (Snet) to form sponge-like interpenetrating, doubly percolating random networks (Cnet + Snet). A >750 mAh/g discharge specific capacity of this sulfur nanosponge cathode was received after 100 cycles under a rate of 0.2 C. A >500 mAh/g discharge capacity was attained after 300 cycles, making this cathode material attractive for powering portable electronic devices.