Dual‐Confined Sulfur in Hybrid Nanostructured Materials for Enhancement of Lithium‐Sulfur Battery Cathode Capacity Retention

Herein, we report a dual‐confined sulfur cathode with a nanostructure where sulfur (72.5 wt %) is first encapsulated in microporous carbon (MC) cores and embedded by graphene (G) shells. Larger and soluble polysulfide intermediates (Li 2 S x , 4≤ x ≤8) are trapped by the graphene shells and thus to refrain from dissolution into the organic electrolyte, so that a stable cycling performance can be achieved. Moreover, the graphene shell and hollow space in‐between also help to ensure the integrity of the hybrid cathode against the volume expansion upon cycling. On the other hand, MC confines smaller sulfur molecules (S 2‐4 ) within its small pores and suppresses the formation of soluble polysulfides. The resulting electrode delivers a high initial discharge capacity of 982 mAh g −1 with enhanced capacity retention of 85.4 % after 100 th cycles at 0.2 C rates. More importantly, it exhibits a high discharge capacity of 886 mAh g −1 , which is maintained at 601 mAh g −1 after 500 cycles at 0.5 C with a coulombic efficiency of nearly 100 %, which is the best performance among reported cycle stabilities.