Homogeneous Intercalation Chemistry and Ultralow Strain of 1T’’’ MoS₂ for Stable Potassium Storage

Abstract

Intercalation anodes usually exhibit better cyclability than conversion and alloying anodes for lithium or sodium storage due to the robust layered structure. However, for larger‐sized potassium accommodation, these intercalation anodes usually undergo huge layer expansion and structural distortion, triggering severe capacity fading. Herein, the novel 1T’’’ MoS2 is revealed the intercalation anode for stable K+ storage, in which metallic Mo─Mo bonds and puckered S layers accelerate the charge transfer and homogeneous K+ insertion. Moreover, the ultralow strain (3.5%) induced by the non‐detachable potassium ions pillar sustains the layered structure. Consequently, 1T’’’ MoS2 achieves a reversible capacity of 125 mA h g−1 at 0.2 C and keeps nearly 100% capacity retention at 1 C over 500 cycles. In situ characterizations and density functional theory simulations reveal the in‐depth intercalation reaction accompanied by the MoS2 phase transformation between 1T’’’ and 1T’ during cycling. Furthermore, a 1T’’’ MoS2//MCMB K‐dual ion battery displays a superior cycling lifespan with 98% capacity retention over 250 cycles. This study provides a new intercalation anode and contribute to the electrode design for stable potassium ion storage.

1D Insertion Chains Induced Small‐Polaron Collapse in MoS2 2D Layers Toward Fast‐Charging Sodium‐Ion Batteries

“…This phenomenon can be explained by the interlayer coulombic force between positive Na + and negative Mo 2 S 3 layers, which makes the Na + intercalation difficult. [ 14,60 ] In the charging process, a reversible peak shift of Mo 2 S 3 (100) to its original position can be observed at stages IV, V, and VI, respectively, demonstrating the superior electrochemical reversibility of Mo 2 S 3 . As a contrast, the in situ XRD patterns of MoS 2 present an irreversible (002) peak (Figure S19, Supporting Information), manifesting partial residual Na + in the interlayers.…”

“…[10][11][12] Nevertheless, the thermodynamically stable 2H phase MoS 2 (2H-MoS 2 ) shows poor electrical conductivity due to its semiconducting property, triggering slow electron transfer. [13,14] Moreover, the large volume variation during the cycling process inevitably causes the continuous collapse of the layered structure, resulting in sluggish ion diffusion kinetics and severe capacity fading. [15,16] Considerable efforts based on compositional or structural modification of MoS 2 have been devoted to boosting the electron/ion migration kinetics to achieve favorable sodium storage performance.…”

“…[ 10–12 ] Nevertheless, the thermodynamically stable 2H phase MoS 2 (2H‐MoS 2 ) shows poor electrical conductivity due to its semiconducting property, triggering slow electron transfer. [ 13,14 ] Moreover, the large volume variation during the cycling process inevitably causes the continuous collapse of the layered structure, resulting in sluggish ion diffusion kinetics and severe capacity fading. [ 15,16 ]…”