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

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.

Densified Metallic MoS2/Graphene Enabling Fast Potassium‐Ion Storage with Superior Gravimetric and Volumetric Capacities

“…[ 11 ] Worse still, the volume change of MoS 2 electrode during charge/discharge process results in a rapid decay of capacity. [ 12 ] A main strategy to improve its electrochemical performance is to combine nanostructured MoS 2 with highly conductive graphene, such as preparing MoS 2 /graphene nanosheets, [ 13 ] growing MoS 2 nanoflower on reduced graphene oxide, [ 14 ] and combining MoS 2 with nitrogen‐doped graphene. [ 15 ] Unfortunately, the graphene‐supported nanomaterials are usually limited to the electrodes with rather low mass loading (≈1 mg cm −2 ) because stacked graphene with high tortuosity hinders ion transport in thicker electrodes.…”

How does Molybdenum Disulfide Store Charge: A Minireview

“…[5] Besides, it has advantages of high theoretical capacityand low cost as electrode materials.Nevertheless, pristine MoS 2 electrodes suffer from poor cycling stabilitya nd huge voltage polarization. [6] Many strategies have been proposed to improve the electrochemical performance of MoS 2 , such as compositing with ac onductive carbonaceous matrix, [7] doping with heteroatoms, [8] defectengineering, [9] enlarging the interlayer spacingo f( 002), [10] synthesizingf ew-layer MoS 2 , [11] or fabricating specialn anostructures. [12] These modified MoS 2 electrodes show excellent cycling stability and rate performance.…”

Few-layer WS2nanosheets with oxygen-incorporated defect-sulphur entrapped by a hierarchical N, S co-doped graphene network towards advanced long-term lithium storage performances

“…26,27 For instance, the designed and synthesized bundled defect-rich MoS 2 or few-layer MoS 2 /C nanosheets with rich defect has shown the superior rate capability and cycling ability as an anode material. 28,29 Nitrogen and halogen dual-doped graphene as an anode material in LIBs also reveals the outstanding reversible capacity and cycling stability. 30 Therefore, it is very important to rational design of unique 3D nanocomposite that is rich in defects to enhance the electrochemical performance of electrodes.…”