Engineering the pin effect through selective doping and architecture design towards high-rate sodium storage performance

Architecture design of sulfides from interior crystal structure to exterior framework has become an effective approach to improve the Na+ storage properties. Sb2S3, as one of promising Na ion anode, exhibits a high theoretical specific capacity, yet it is limited by the depressed diffusion kinetics and severe volume expansion. Herein, the sisal-like Sb2S3 (SZS-Sisal) grains have been prepared by a facile in-situ sulfidation process of bi-metal organic framework (SbZn-MOF). Notably, the designed SZS-Sisal expresses pin effect with unique morphology, which introduces the selective heteroatom doping on the internal crystal structure and improves the electrode stability on external architecture characteristics simultaneously. More importantly, the fundamental understanding of engineered pin effect is systematically investigated by in-situ/ex-situ characterizations and theory simulations. The results demonstrate that the constructed pin effect not only decreases the energy bandgap with enhanced electronic conductivity, but also further optimizes the framework structure with designed nanostructure matrix with alleviated stress relaxation and short-range ion path. It can effectively boost the electrochemical kinetics and structure stability, synergistically resulting in the prominent Na+-ion storage performance. As expected, the dual-modified SZS-Sisal delivers a superior reversible capacity of 274.5 mA h g−1 at high-rate of 5 A g−1 over 1000 cycles, fully demonstrating the feasibility of this engineered strategy.