Two-dimensional layered transitional metal oxides (TMOs) could be promising electrode materials for sodium-ion batteries (SIBs). However, they tend to suffer from insufficient interlayer spacing and poor electrical and ionic conductivity, which causes slow diffusion kinetics and poor cycle stability when they are used as an electrode material. Adjusting the structure of the TMOs could alleviate these problems. However, achieving well-defined structures in TMOs can be a challenge.

Hai Wang, Guangxi Normal University, Guilin, China, Zihua Li, Tianjin Normal University, China, and colleagues have developed ultralong Mo₄O₁₁ nanoribbons (Mo₄O₁₁-NR) for use as an electrode material. The team used α-MoO₃ as model material and used a simple aniline-assisted sonochemical strategy to realize a controllable structural transformation from MoO₃ to Mo₄O₁₁. Residual aniline could be efficiently converted into amorphous carbon at 350 °C in an Ar atmosphere.

In the synthesis process, ultrasound facilitates the dissociation of the MoO₃ structure, and aniline promotes the rearrangement of the dissociated MoO₆ octahedra and MoO₄ tetrahedra. The structure of the resulting nanoribbons helps to promote the efficient storage and transfer of ions and electrons. In addition, the low oxidation state of Mo in Mo₄O₁₁ contributes to improving the material’s conductive properties.

The researchers investigated the application potential of Mo₄O₁₁-NR for SIBs. They found that a Mo₄O₁₁-NR anode provided a high rate capability and a long cycle life. Full sodium-ion cells based on a Mo₄O₁₁-NR anode and a commercial Na₄Fe₃(PO₄)₂(P₂O₇) cathode exhibited excellent battery performance. According to the researchers, this shows the potential of Mo₄O₁₁-NR as an advanced anode material.

• The ultralong Mo₄O₁₁ nanoribbons: Ultrasonic synthesis and topotactic transformation toward high-performance sodium-ion batteries,
  Yu Zhou, Zihua Li, Yong Liu, Hai Wang,
  Appl. Surf. Sci. 2024, 642, 158638.
  https://doi.org/10.1016/j.apsusc.2023.158638