Complete encapsulation of sulfur through interfacial energy control of sulfur solutions for high-performance Li−S batteries

Complete encapsulation of high-content sulfur in porous carbon is crucial for high performance Li-S batteries. To this end, unlike conventional approaches to control the pore of carbon hosts, we demonstrate controlling the interfacial energy of the solution in the process of penetrating the sulfur-dissolved solution. We unveil, experimentally and theoretically, that the interfacial energy with the carbon surface of the sulfur solution is the key to driving complete encapsulation of sulfur. In the infiltration of sulfur solutions with N-methyl-2-pyrrolidone, we achieve complete encapsulation of sulfur, even up to 85 wt %. The sulfur fully encapsulated cathode achieves markedly high volumetric capacity and stable cycle operation in its Li-S battery applications. We achieve a volumetric capacity of 855 mAh/cm3 at 0.2C and a capacity reduction of 0.071% per cycle up to 300 cycles at 1C.