"Lasagna"-Structured SnS-TaS Misfit Layered Sulfide for Capacitive and Robust Sodium-Ion Storage.

Stannous sulfide (SnS), a conversion-alloying type anode for sodium-ion batteries, is strong Na storage activity, a low voltage platform, and high theoretical capacity. However, grain pulverization induced by intolerable volume change and phase aggregation causes quick capacity degradation and unsatisfactory rate capability. Herein, a novel "lasagna" strategy is developed by embedding a SnS layer into the interlayer of an electrochemically robust and electron-active TaS to form a misfit layered (SnS)TaS superlattice. For Na storage, the rationally designed (SnS)TaS anode exhibits high specific capacity, excellent rate capability, and robust cycling stability (729 mAh cm at 15 C after 2000 cycles). Moreover, the as-assembled (SnS)TaS || NaV(PO) full cells achieve robust and fast Na storage performance with ≈100% capacity retention after 650 cycles at 15 C, which also demonstrates good low-temperature performance at -20 °C with a capacity retention of 75% and 2 C high-rate charge/discharge ability.