Heterostructured Nanocube-Shaped Binary Sulfide (SnCo)S2 Interlaced with S-Doped Graphene as a High-Performance Anode for Advanced Na+ Batteries

Heterostructuring electrodes with multiple electroactive and inactive supporting components to simultaneously satisfy electrochemical and structural requirements has recently been identified as a viable pathway to achieve high-capacity and durable sodium-ion batteries (SIBs). Here, a new design of heterostructured SIB anode is reported consisting of double metal-sulfide (SnCo)S-2 nanocubes interlaced with 2D sulfur-doped graphene (SG) nanosheets. The heterostructured (SnCo)S-2/SG nanocubes exhibit an excellent rate capability (469 mAh g(-1) at 10.0 A g(-1)) and durability (5000 cycles, 487 mAh g(-1) at 5.0 A g(-1), 92.6% capacity retention). In situ X-ray diffraction reveals that the (SnCo)S-2/SG anode undergoes a six-stage Na+ storage mechanism of combined intercalation, conversion, and alloying reactions. The first-principle density functional theory calculations suggest high concentration of p-n heterojunctions at SnS2/CoS2 interfaces responsible for the high rate performance, while in situ transmission electron microscopy unveils that the interlacing and elastic SG nanosheets play a key role in extending the cycle life.