GO Wrapping Yolk-Shell S/MnO ₂ Nanocomposites as High Performance Cathode for Lithium/Sulfur Cells

The lithium/sulfur cell with high theoretical capacity has drawn much attention recently because of its high energy density and low cost. However, the shuttle effect caused by polysulfide dissolution and migration, and the destruction of cathode particles due to large volume expansion during lithiation, are the key challenges. Here, the novel graphene oxide (GO) wrapping sulfur-MnO ₂ (S/MnO ₂ /GO) nanocomposite is prepared with improved rate capability and cyclic performance. The inner layer is the protective layer of MnO ₂ shell, which accommodates the volume expansion of sulfur and minimizes polysulfides dissolution. The outer layer of fabricated graphene oxide is the stable layer, which gives further protection in suppressing the polysulfides dissolution in case the MnO ₂ shells crack. The cell with S/MnO ₂ /GO electrode delivers 1378 mAh g ⁻¹ initial discharge capacity at the current density of 2 C and remains 818 mAh g ⁻¹ over 1000 cycles, which exhibits the very low fading rate of 0.04 % per cycle. Moreover, the S/MnO ₂ /GO nanocomposites can be easily fabricated with our method.