Unique Flexible NiFe2O4@S/rGO-CNT Electrode via the Synergistic Adsorption/Electrocatalysis Effect toward High-Performance Lithium-Sulfur Batteries.

A unique flexible NiFe2O4 hollow sphere@S/rGO-CNT (NiFe2O4@S/C) cathode was rationally designed and synthesized to tackle the issues of lithium-sulfur batteries. In this strategy, the introduced rGO and CNTs offer a flexible and conductive skeleton to facilitate the transport of electrons and/or ions and a physical barrier to confine polysulfides. Furthermore, as an efficient sulfur host, NiFe2O4 hollow spheres can further absorb the soluble polysulfides by strong chemical interaction due to their intrinsic polarity and also serve as a catalyst to promote the redox kinetics of polysulfide conversion. Benefiting from the synergism of the physical confinement, polar chemical adsorption, and catalytic conversion, the as-prepared flexible NiFe2O4@S/C electrode delivers a high initial capacity of 1193 mAh g-1 at 100 mA g-1 and excellent long-term cycling stability up to 500 cycles with a low decay rate of 0.059% per cycle at 500 mA g-1.