Strutted graphene foam loading sulfur for high-rate long-lifetime Li-S batteries

Lithium-ion (Li-ion) batteries are currently limited by the capacity and cost of conventional Li-intercalated cathodes. Lithium-sulfur (Li-S) batteries, with high theoretical capacity of sulfur cathode and low cost, have been considered as one of the most promising next-generation batteries. Nevertheless, the application of Li-S batteries is hampered by limited rate and cycle capability stemming from the low conductivity, volume expansion of the sulfur cathode, and the shuttle effect of polysulfides. In this study, a strutted graphene (SG) foam is developed with interconnected networks, rich porous structures, and stable defects, as a sulfur host directly for Li-S battery. This SG foam improves conductance of cathodes, relieves volume change, facilitates electron and ion transports, and inhabits the shuttle effect. As a result, the sulfur-loaded SG cathode demonstrates excellent performances, with a capacity of 1442 mAh g−1 at 0.2 C, a high-rate capacity of 857 mAh g−1 at 4 C, and the cyclability with a capacity of 691 mAh g−1 after 500 cycles at 2 C. It thus provides an effective host for cathodes for Li-S batteries.