Vanadium redox flow batteries (VRFBs) are a promising solution for large-scale energy storage, but a number of problems still impede the deployment of long-lifetime VRFBs. One important aspect of efficient operation of VRFBs is understanding interactions between vanadium species and the membrane. Herein, we investigate the interactions between all four vanadium cations and Nafion membrane by a combination of infrared (IR) spectroscopy and density-functional-theory (DFT)-based static and molecular dynamics simulations. It is observed that vanadium species primarily lead to changes in the IR spectrum of Nafion in the ${\text{SO}}_3^{-}$ spectral region which is attributed to the interaction between vanadium species and the ${\text{SO}}_3^{-}$ exchange sites. DFT calculations of vanadium$-$Nafion complexes in the gas phase show that it is thermodynamically favorable for all vanadium cations to bind to ${\text{SO}}_3^{-}$ via a contact pair mechanism. Car-Parrinello molecular dynamics-based metadynamics simulations of cation-Nafion systems in aqueous solution suggest that ${\text{V}}^{2+}$ and ${\text{V}}^{3+}$ species coordinate spontaneously to ${\text{SO}}_3^{-}$, which is not the case for ${\text{VO}}^{2+}$ and ${\text{VO}}_2^{+}$. The interaction behavior of the uncycled membrane determined in this study is used to explain the experimentally observed changes in the vibrational spectra, and is discussed in light of previous results on device-cycled membranes.

钒氧化还原液流电池（VRFB）是用于大规模储能的有前途的解决方案，但是许多问题仍然阻碍了长寿命VRFB的部署。VRFBs有效运行的一个重要方面是了解钒物质与膜之间的相互作用。在这里，我们通过结合红外（IR）光谱和基于密度泛函理论（DFT）的静态和分子动力学模拟研究了所有四种钒阳离子与Nafion膜之间的相互作用。可以看出，钒物种主要导致Nafion的红外光谱发生变化。${\text{所以}}_3^{-}$ 钒原子与钒原子之间相互作用产生的光谱区域。 ${\text{所以}}_3^{-}$交换网站。钒的DFT计算$-$气相中的Nafion配合物表明，对所有钒阳离子键合都具有热力学优势 ${\text{所以}}_3^{-}$通过接触对机制。基于Car-Parrinello分子动力学的水溶液中阳离子-Nafion系统的元动力学模拟表明${\text{伏特}}^{\mathrm{2个}+}$ 和 ${\text{伏特}}^{3+}$ 物种自发地与 ${\text{所以}}_3^{-}$，情况并非如此 ${\text{VO}}^{\mathrm{2个}+}$ 和 ${\text{VO}}_{\mathrm{2个}}^{+}$。在这项研究中确定的未循环膜的相互作用行为被用来解释实验观察到的振动光谱的变化，并根据先前在装置循环膜上的结果进行了讨论。