Bundled Defect‐Rich MoS₂ for a High‐Rate and Long‐Life Sodium‐Ion Battery: Achieving 3D Diffusion of Sodium Ion by Vacancies to Improve Kinetics

Molybdenum disulfide (MoS₂ ), a 2D-layered compound, is regarded as a promising anode for sodium-ion batteries (SIBs) due to its attractive theoretical capacity and low cost. The main challenges associated with MoS₂ are the low rate capability suffering from the sluggish kinetics of Na⁺ intercalation and the poor cycling stability owning to the stack of MoS₂ sheets. In this work, a unique architecture of bundled defect-rich MoS₂ (BD-MoS₂ ) that consists of MoS₂ with large vacancies bundled by ultrathin MoO₃ is achieved via a facile quenching process. When employed as anode for a SIB, the BD-MoS₂ electrode exhibits an ultrafast charge/discharge due to the pseudocapacitive-controlled Na⁺ storage mechanism in it. Further experimental and theoretical calculations show that Na⁺ is able to cross the MoS₂ layer by vacancies, not only limited to diffusion along the layer, thus realizing a 3D Na⁺ diffusion with faster kinetics. Meanwhile, the bundling architecture reduces the stack of sheets with a superior cycle life illustrating the highly reversible capacities of 350 and 272 mAh g⁻¹ at 2 and 5 A g⁻¹ after 1000 cycles.