Vertical-Aligned Li S-Graphene Encapsulated within a Carbon Shell as a Free-Standing Cathode for Lithium-Sulfur Batteries.

Construction of a novel matrix with both high conductivity and an excellent confinement effect for polysulfides is of great importance for developing high-performance lithium-sulfur (Li-S) batteries. In this work, we have developed a double-modification strategy to integrate lithium sulfide (Li S) into a conductive composite network consisting of vertical graphene (VG) arrays and an amorphous carbon shell, forming an integrated cathode (VG/Li S-C). Facile liquid-solution/evaporation methods in combination with chemical vapor deposition were successfully adopted for preparation of the above cathode. Due to the enhanced electrical conductivity and noticeable blocking effect for the shuttle of polysulfides, the binder-free flexible VG/Li S-C cathode exhibits high rate performance and reinforced cycles (656.2 mAh g after 100 cycles). The pronounced electrochemical performance is ascribed to the unique architecture with a coherent conductive network of VG and the carbon shell, which not only provides a conductive network for fast reaction kinetics, but also forms a durable protective shield to suppress the shuttle of polysulfides. Our research further demonstrates the synergistic effectiveness by means of inner and outer carbon matrixes for electrochemical enhancement of Li-S batteries.