GO Wrapping Yolk‐Shell S/MnO₂ Nanocomposites as High Performance Cathode for Lithium/Sulfur Cells

Abstract

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‐MnO2 (S/MnO2/GO) nanocomposite is prepared with improved rate capability and cyclic performance. The inner layer is the protective layer of MnO2 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 MnO2 shells crack. The cell with S/MnO2/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/MnO2/GO nanocomposites can be easily fabricated with our method.

High Performance of Sulfur/Carbon Cathode Synthesized via a Facile Green Microwave Approach

“…Various strategies have been proposed to overcome these issues. For instance, various sulfur hosts, novel electrolytes/electrolyte additives, functionalized separators, and protective films on a lithium anode have been proposed to suppress the shuttle effect. − Among which, much research has been devoted to developing porous sulfur hosts since they can address all three listed issues, such as carbons, − polymers, metal oxides, graphenes/graphene oxides, , and composites based on two or more items listed previously. − These hosts are expected to not only mitigate the shuttle by anchoring polysulfides via physical/chemical interactions but also hold the volume variation occurred during cycling, and moreover, the hosts may facilitate the electron/ion conduction depending on their characteristic. In this regard, numerous carbons have experienced extensive research since they possess high conductivity, large porosity, and light weight.…”

A Facile Synthesis of Stable TiO2/TiC Composite Material as Sulfur Immobilizers for Cathodes of Lithium–Sulfur Batteries with Excellent Electrochemical Performances

“…However, the low electrical conductivity of sulfur (5 × 10 −28 m −1 ), and during the electrochemical reaction, the shuttle effect of lithium polysulfide, leads to continuous sulfur loss, which seriously affects the cycle life and commercial prospects of lithium–sulfur batteries. Currently, tremendous efforts are taken to solve these problems . One of the most effective methods is to build sulfur immobilizers.…”