Sandwich-like MoS2 @SnO2 @C with High Capacity and Stability for Sodium/Potassium Ion Batteries.

Sandwich-like MoS2 @SnO2 @C nanosheets are prepared by facile hydrothermal reactions. SnO2 nanosheets can attach to exfoliated MoS2 nanosheets to prevent restacking of adjacent MoS2 nanosheets, and carbon transformed from polyvinylpyrrolidone is coated on MoS2 @SnO2 , forming a sandwich structure to maintain cycling stability. As an anode for sodium-ion batteries, the electrode greatly deliverers a high initial discharge specific capacity of 530 mA h g-1 and maintains at 396 mA h g-1 after 150 cycles at 0.1 A g-1 . Even at a large current density of 1 A g-1 , it can hold 230 mA h g-1 after 450 cycles. Besides, as an anode for K+ storage, the electrode also shows a discharge capacity of 312 mA h g-1 after 25 cycles at 0.05 A g-1 . This work may provide a new strategy to prepare other composites which can be applied to new kind of rechargeable batteries.