Nanoconfined Oxidation Synthesis of N-Doped Carbon Hollow Spheres and MnO 2 Encapsulated Sulfur Cathode for Superior Li-S Batteries.

The sulfur cathode, as a new generation of lithium-ion battery cathode material, has a high theoretical energy density of about 2500 Wh kg ^-1 . However, the low conductivity of sulfur and the "shuttle effect", widely presenting in the lithiation/de-lithiation process, seriously hinder its practical application. Here, we report a new nanoconfined oxidation route (first complete oxidation of metal sulfide and subsequently partial oxidation of the generated S from sulfide) for S cathode encapsulated with MnO ₂ nanosheets and N-doped carbon hollow spheres. This nanoconfined oxidation route can successfully confine the sulfur particles in the interior of the carbon shell, and the rationally introduced nonpolar carbon and polar MnO ₂ can both reduce the dissolution of polysulfide during the charge-discharge process. The obtained well-defined S-MnO ₂ @C cathode exhibits high specific capacity with excellent cycling performance and superior rate capability.
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