2D Confined Alloying-Type SnS Anode Enabled by van der Waals Interaction for Fast and Long-Life Sodium Storage

Sodium ion batteries (SIBs) are facing a shortage of anode materials with high-capacity, durable, and high-rate performance. SnS is a promising alloying-type anode with high theoretical capacity, but still faces serious problems such as large volume expansion and sluggish ion transport kinetics. Herein, a van der Waals interaction strategy is proposed by atomically disperse SnS into interlayers of 2D 2D NbS₂ frameworks to form (SnS)_1.18NbS₂. In situ and ex situ analyses reveal the multistep reversible reaction processes during the charging (formation of layered structure NbS₂ confining amorphous SnS, (SnS)_AmorphousNbS₂) and discharging (precipitation of fracture-resistant Na₉Sn₄ in the ionic-conductive Na_0.67NbS₂/Na₂S matrix) processes. Consequently, the (SnS)_1.18NbS₂ anode exhibits a capacity of 943 mAh cm^-3 at 0.44 C after 150 cycles, and retains 667 mAh cm^-3 at 11 C after 2500 cycles with 100% capacity retention. The assembled (SnS)_1.18NbS₂ || Na₃V₂(PO₄)₃ full cell maintains ≈100% capacity retention over 1000 cycles at 15 C. The full cell also exhibits good low-temperature performance at -20 °C with a capacity retention of 100% after 1200 cycles at 1 C. The proposed van der Waals interaction strategy for stabilizing fast and high-capacity Na⁺ storage offers a viable pathway for practical SIBs.