Improving compactness and reaction kinetics of MoS2@C anodes by introducing Fe9S10 core for superior volumetric sodium/potassium storage

Abstract Molybdenum disulfides (MoS2) are presently attracting immense research interest as high gravimetric capacity anode materials in next-generation electrochemical batteries. However, achieving outstanding rate capability with high volumetric capacity in a single electrode remains highly challenging. Here, MoS2-based heterostructure materials including a conductive Fe9S10 core and carbon coating (Fe9S10@MoS2@C) are developed with a dense spatial geometry architecture and demonstrated as an advanced anode for simultaneously achieving high volumetric capacity and enhanced the reaction kinetics in both sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs). The introduced Fe9S10 core plays crucial roles in significantly improving the electronic conductivity, facilitating the densifying of MoS2 particles, and constructing abundant heterogeneous interfaces with a strong electric field. Experimental studies and density functional theory calculation reveal that the formed heterointerfaces help to improve fast charging capability and cycle stability by decreasing the ion diffusion energy barrier and reinforcing geometry architecture. As a result, the Fe9S10@MoS2@C anode delivers a high volumetric capacity of 662 mAh cm−3, stable cycling performance (a capacity retention of 93.4% for 1000 cycles) and outstanding rate capability (high gravimetric capacities of 197 and 132 mA h g−1 at a large current densities of 30 and 50 A g−1, respectively) for SIBs, meanwhile, a high volumetric capacity of 408 mAh cm−3 with 95.4% capacity retention is achieved after 50 cycles for PIBs. The present work could guide the future designing protocol of heterostructure architectures by integrating suitable components for potential applications as high-performance alkali ion batteries electrode.