Facile synthesis of porous CoO nanoflakes as an interlayer for high performance lithium-sulfur batteries.

The "shuttle effect" of long-chain polysulfides and the low conductivity of elemental sulfur lead to the inferior cycling stability of lithium-sulfur batteries and imped their practical applications. Herein, CoO nanoflakes with uniform macro pores distribution were synthesized via facile oil bath and calcination methods. Coupled with super P and coated on common polypropylene separators, they were expected to hinder the migration of lithium polysulfides (LiPSs) and accelerate the redox kinetics of polysulfides. Coin cells assembled with the CoO-super P interlayer exhibited a capacity of 760 mA h g at 1 C, maintained 598 mA h g after 350 cycles, and the decay rate of discharge capacity was only about 0.062% per cycle. Such high performance can be attributed to the synergistic effects between polar CoO and conductive super P. The facile fabrication method and high performance make the CoO-super P interlayer a feasible material to apply in lithium-sulfur batteries.