Rationally engineering a binary SnSSe/carbon nest-coated Si nanosphere for a high-performance lithium-ion battery anode.

Although the silicon (Si) anode has a high theoretical capacity, large volume-expansion would lead to rapid capacity decay. Here, a core-nest structured Si@SnSSe/carbon (Si@SnSSe/C) is developed using silicon as the core and SnSSe/carbon as a binary nest. Both the core-nest structure and carbon matrix enable a stable hybrid structure during charge and discharge. The binary nest Si@SnSSe/C nanospheres as a lithium-ion battery anode display good capacity, recoverable rate-performance, and enhanced electron and ion transfer properties. A capacity of 1318 mA h g and a high coulombic efficiency of 98.9% after 50 cycles at 0.1 A g are achievable, and the capacity remains 887 mA h g after 150 cycles at 0.5 A g. A high capacity at 50 °C is also retained, showing a high initial specific capacity. It is found that the reaction resistance of Si@SnSSe/C is significantly lower than that of the pure components, and the stress-strain relationship of the Li-Si system is demonstrated by density functional theory (DFT) calculations. The engineering of the binary-nest structure should be able to provide some new ideas for developing many other high-performance energy-storage hybrids.