Unlocking the structure and anion synergistic modulation of MoSe ₂ anode for ultra‐stable and high‐rate sodium‐ion storage

Abstract

Abstract The two‐dimensional MoSe 2 possesses a large interlayer spacing (0.65 nm) and a narrow bandgap (1.1 eV), showing potential in sodium‐ion storage. However, it faces slow kinetics and volume stress during Na + (de)intercalation process, thereby affecting the cycling stability and lifespan of sodium‐ion batteries (SIBs). In this work, a novel approach involving anionic doping and structural design has been proposed, wherein a two‐step in‐situ selenization and surface thermal annealing doping process is applied to fabricate a novel configuration material of fluorine‐doped MoSe 2 @nitrogen‐doped carbon nanosheets (F‐MoSe 2 @FNC). The obtained F‐MoSe 2 @FNC, benefiting from the dual advantages of structure and F‐doping, synergistically promotes and accelerates the stable (de)intercalation of Na + . Henceforth, F‐MoSe 2 @FNC demonstrates notable characteristics in terms of reversible specific capacity, boasting a high initial coulombic efficiency of 76.97%, alongside remarkable rate capabilities and cyclic stability. The constructed F‐MoSe 2 @FNC anode‐based half cell manifests exceptional longevity, enduring up to 2550 cycles at 10 A·g −1 with a specific capacity of 322.04 mAh·g −1 . Its electrochemical performance surpasses that of MoSe 2 @NC and Pure MoSe 2 , underscoring the significance of the proposed synergistic modulation. Through comprehensive kinetic analyses, encompassing in‐situ electrochemical impedance spectroscopy (EIS), it is elucidated that the F‐MoSe 2 @FNC electrode showcases elevated pseudo‐capacitance and rapid diffusion attributes during charge and discharge processes. Furthermore, the assembled full‐cell (F‐MoSe 2 @FNC//Na 3 V 2 (PO 4 ) 3 ) attains a notable energy density of 166.94 Wh·kg −1 . This design provides insights for the optimization of MoSe 2 electrodes and their applications in SIBs.

Topics & Concepts