Improved lithium storage performance of sulfur loaded by CMK-3 with a tailored hierarchical pore structure

Porous carbon materials such as CMK-3 are proved as effective hosts for loading sulfur in the design of the positive electrode for lithium-sulfur batteries. In this work, CMK-3 with a tailored hierarchical pore structure (CMK-3 M) is prepared by using SBA-15 and Sn nanoparticles as the sacrificial templates. Compared to CMK-3, CMK-3 M possesses higher surface area and larger pore size, which are conducive to the transfer of electron and Li⁺ ions. The large contact area with sulfur also enhances the interaction of CMK-3 M and sulfur. Moreover, the generated micropores of CMK-3 M can contain smaller sulfur molecules, which avoids the formation of soluble polysulfides and suppresses the shuttle effect of lithium polysulfides. Therefore, compared to sulfur-loaded CMK-3, sulfur-loaded CMK-3 M exhibits superior electrochemical performance. Besides, the performance of sulfur-loaded CMK-3 M can be further improved by coating with polyethylene glycol. This suggests that polymer protection is still an effective way to inhibit the polypyl sulfide shuttle.