Bottom‐Up Synthesis of MoS₂/CNTs Hollow Polyhedron with 1T/2H Hybrid Phase for Superior Potassium‐Ion Storage

Abstract

Enslaved to the large‐size K‐ions, the construction of suitable anode materials with superior and stable potassium‐ion storage properties is a major challenge. 1T phase MoS2 possesses higher conductivity, bigger interlayer distance, and more electrochemically active sites than the 2H phase, which offers intriguing benefits for energy‐related applications. In this work, the 1T/2H‐phase hybrid MoS2 nanosheets are successfully anchored in the N‐doped carbon nanotube hollow polyhedron (1T/2H‐MoS2/NCNHP) by a bottom‐up solvothermal method. For the synthesized 1T/2H‐MoS2/NCNHP, the fewer‐layer 1T/2H‐MoS2 nanosheets are embedded in an N‐doped carbon nanotube hollow polyhedron, with an enlarged interlayer spacing of 0.96 nm. When evaluated as anode material for potassium‐ion batteries, the 1T/2H‐MoS2/NCNHP hybrid presents outstanding potassium storage performance. It delivers a high‐specific capacity of 519.2 mAh g−1 at 50 mA g−1 and maintains 281.2 mAh g−1 at 1 A g−1 over 500 cycles. The good potassium‐ion electrochemical performance is attributed to the rational structural design and the synergistic effect of the components. Moreover, the 1T‐MoS2 nanosheet has excellent electrical conductivity and its enlarged interlayer spacing reduces the barrier for the embedding and stripping of K ions. Finally, the practical application of the 1T/2H‐MoS2/NCNHP electrode material is also evaluated by assembled K‐ion full cells.

Dynamic 1T‐2H Mixed‐Phase MoS2 Enables High‐Performance Li‐Organosulfide Battery

“…[13] When charged from state C1 to C5, the (002) peak gradually but not fully recovers to the initial position. Combined with the characteristic peak at 13-14° attributed to 2H MoS 2 , [14] it appears at 2.1 V and disappears at 1.8 V, indicating that 1T MoS 2 partially transforms to 2H MoS 2 and becomes 2H-1T phase during the discharge process. Similarly, in the charge process, the characteristic peak of 2H MoS 2 begins to appear at 2.3 V and reaches the maximum at 2.7 V, indicating that the 2H-1T hybrid phase also exists in the charge process.…”

Encapsulation of 2D MoS2 nanosheets into 1D carbon nanobelts as anodes with enhanced lithium/sodium storage properties

“…5b, which implies that the electrochemical behavior of MoS 2 @C-23 NBs is determined by capacitive processes. The contribution ratios from the diffusion-controlled and capacitive processes to the total capacity can be calculated from the following equations: 63–65 i ( V ) = k 1 v + k 2 v 1/2 i ( V )/ v 1/2 = k 1 v 1/2 + k 2 where k 1 and k 2 can be determined from eqn (4). The current response can be separated into k 1 ν (capacitive contribution) and k 2 ν 1/2 (diffusion-controlled contribution).…”

Recent Advances in 2D Heterostructures as Advanced Electrode Materials for Potassium‐Ion Batteries

“…For instance, Wu et al designed the fewer-layer 1T/2H-MoS 2 nanosheets to be anchored on N-doped carbon nanotube hollow polyhedron (denoted as NCNHP), as shown in Figure 9a. [121] The heterostructures with the hollow structure created enough voids to alleviate the volume change, resulting in an ultrastable performance of 281.2 mAh g À1 after 500 cycles with a good capacity retention 66.7% (Figure 9b). Moreover, they also assembled full-cell PIBs with 1T/2H-MoS 2 /NCNHP as anode and K 2 Fe[Fe(CN) 6 ] as cathode, which presented a lifetime over 100 cycles (136.1 mAh g À1 ) at 100 mA g À1 (Figure 9c).…”

“…Moreover, they also assembled full-cell PIBs with 1T/2H-MoS 2 /NCNHP as anode and K 2 Fe[Fe(CN) 6 ] as cathode, which presented a lifetime over 100 cycles (136.1 mAh g À1 ) at 100 mA g À1 (Figure 9c). [121] Zhou et al utilized 1T-MoS 2 / MoO x @NC (N-doped carbon) for K þ storage. [122] After 400 cycles, it still had the capacity of 120 mAh g À1 at the current density of 500 mA g À1 .…”