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

Abstract

Abstract Molybdenum disulfide (MoS 2 ), 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 MoS 2 are the low rate capability suffering from the sluggish kinetics of Na + intercalation and the poor cycling stability owning to the stack of MoS 2 sheets. In this work, a unique architecture of bundled defect‐rich MoS 2 (BD‐MoS 2 ) that consists of MoS 2 with large vacancies bundled by ultrathin MoO 3 is achieved via a facile quenching process. When employed as anode for a SIB, the BD‐MoS 2 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 MoS 2 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.