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Abstract The development of alternative energy sources is crucial for reducing reliance on fossil fuels, particularly for mobile applications such as personal electronics and transportation. This necessitates the advancement of battery materials based on abundant and inexpensive constituent elements. To achieve this requires investigating materials in a broader compositional and structural design space. Early transition metal oxides, including the intercalation electrode $\alpha -$V₂O₅, however, the performance of V₂O₅is hindered by phase transformations during battery cycling that lead to capacity fade and short device lifetimes. This study investigates the modification of V₂O₅through Mo substitution in a series of the form V ${}_{2-x}$Mo_xO₅forx= 0.05, 0.1, 0.2, 0.4, 0.6, and 0.8. X-ray diffraction data reveal progressive structural changes with increasing Mo content, which in turn change the progression of phase transformations during the first discharge. The different product also results in different cycling profile shapes that indicate differences in the charge storage mechanism as a function of Mo content. As a result, samples with higher Mo-substitution, especially V_1.2Mo_0.8O₅, have narrower hysteresis, higher capacity, and improved capacity retention. While there is a limited solubility of Mo in the V₂O₅structure, with secondary phases and defects at many compositions, we show that Mo substitution alters the cycling behavior of V₂O₅to deep discharge, which can inform the design of intercalation materials for energy storage applications. 

Abstract Lithium–sulfur batteries are promising candidates for next‐generation energy storage devices due to their outstanding theoretical energy density. However, they suffer from low sulfur utilization and poor cyclability, greatly limiting their practical implementation. Herein, we adopted a phosphate‐functionalized zirconium metal–organic framework (Zr‐MOF) as a sulfur host. With their porous structure, remarkable electrochemical stability, and synthetic versatility, Zr‐MOFs present great potential in preventing soluble polysulfides from leaching. Phosphate groups were introduced to the framework post‐synthetically since they have shown a strong affinity towards lithium polysulfides and an ability to facilitate Li ion transport. The successful incorporation of phosphate in MOF‐808 was demonstrated by a series of techniques including infrared spectroscopy, solid‐state nuclear magnetic resonance spectroscopy, and X‐ray pair distribution function analysis. When employed in batteries, phosphate‐functionalized Zr‐MOF (MOF‐808‐PO4) exhibits significantly enhanced sulfur utilization and ion diffusion compared to the parent framework, leading to higher capacity and rate capability. The improved capacity retention and inhibited self‐discharge rate also demonstrate effective polysulfide encapsulation utilizing MOF‐808‐PO4. Furthermore, we explored their potential towards high‐density batteries by examining the cycling performance at various sulfur loadings. Our approach to correlate structure with function using hybrid inorganic–organic materials offers new chemical design strategies for advancing battery materials.