Stabilizing Decavanadate Cluster as Electrode Material in Sodium and Lithium-ion Batteries

Decavanadate ([V₁₀ O₂₈ ]^6- , {V₁₀ }) clusters are a potential electrode material for lithium and post-lithium batteries; however, their low stability due to the solubility in liquid organic electrolytes has been challenging. These molecular clusters are also prone to transform into solid-state oxides at a moderate temperature needed in the typical electrode fabrication process. Hence, controlling the solubility and improving the thermal stability of compounds are essential to make them more viable options for use as battery electrodes. This study shows a crystal engineering approach to stabilize the cluster with organic guanidinium (Gdm⁺ ) cation through the hydrogen-bonding interactions between the amino groups of the cation and the anion. The comparison of solubility and thermal stability of the Gdm{V₁₀ } with another cluster bearing tetrabutylammonium (Tba⁺ ) cation reveals the better stability of cation-anion assembly in the former than the latter. As a result, the Gdm{V₁₀ } delivers better rate capability and cycling stability than Tba{V₁₀ } when tested as anode material in a half-cell configuration of a sodium-ion battery. Finally, the performance of the Gdm{V₁₀ } anode is also investigated in a lithium-ion battery full cell with LiFePO₄ cathode.