Core-Shell Tandem Catalysis Coupled with Interface Engineering For High-Performance Room-Temperature Na-S Batteries.

The sluggish redox kinetics and shuttle effect seriously impede the large application of room-temperature sodium-sulfur (RT Na-S) batteries. Designing effective catalysts into cathode material is a promising approach to overcome the above issues. However, considering the multistep and multiphase transformations of sulfur redox process, it is impractical to achieve the effective catalysis of the entire S 8 →Na 2 S x →Na 2 S conversion through applying a single catalyst. Herein, this work fabricates a nitrogen-doped core-shell carbon nanosphere integrated with two different catalysts (ZnS-NC@Ni-N 4 ), where isolated Ni-N 4 sites and ZnS nanocrystals are distributed in the shell and core, respectively. ZnS nanocrystals ensure the rapid reduction of S 8 into Na 2 S x (4 < x ≤ 8), while Ni-N 4 sites realize the efficient conversion of Na 2 S x into Na 2 S, bridged by the diffusion of Na 2 S x from the core to shell. Besides, Ni-N 4 sites on the shell can also induce an inorganic-rich cathode-electrolyte interface (CEI) on ZnS-NC@Ni-N 4 to further inhibit the shuttle effect. As a result, ZnS-NC@Ni-N 4 /S cathode exhibits an excellent rate-performance (650 mAh g -1 at 5 A g -1 ) and ultralong cycling stability for 2000 cycles with a low capacity-decay rate of 0.011% per cycle. This work will guide the rational design of multicatalysts for high-performance RT Na-S batteries.