All Inorganic Frameworks of Tin Dioxide Shell as Cathode Material for Lithium Sulfur Batteries with Improved Cycle Performance

SnO2 shells with micromesopores are synthesized using the template sacrifice method from silica sphere templates. The pores and specific surface area are characterized with SEM, TEM, and BET absorptions. Sulfur is introduced into the SnO, shells up to 66 wt % according to TGA results. Extra sulfur can only be located at the outer surface of SnO2, resulting in a drastically reduced specific surface area. Because of the unique structure, the S/SnO2 composites with 66 wt % sulfur content exhibit a high initial capacity of 1517 mA-11.g(-1) at a current density of 0.2 C, and 1176 mA-h.g(-1) at 0.5 C, and remaining capacity of 1176 and 736.6 mA.h-g(-1) after 50 cycles, respectively. The performance is much better than that of pure sulfur or S/SnO2 at higher sulfur content. Better performance of S/SnO2 at 66 wt % is attributed to the micromesopores and the shell framework of SnO2, while the performance fading at higher sulfur content is owing to the coating of extra sulfur on the outer surface of SnO2 shells.