Zhang Denghua, Xu Zeyu, Zhang Xihao, Zhao Lina, Zhao Yingying, Wang Shaoliang, Liu Weihua, Che Xuefu, Yang Jingshuai, Liu Jianguo, Yan Chuanwei
Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China.
School of Materials Science and Engineering, University of Science and Technology of China, Shenyang 110016, China.
ACS Appl Mater Interfaces. 2021 Jan 27;13(3):4051-4061. doi: 10.1021/acsami.0c20847. Epub 2021 Jan 12.
In this work, we propose a sulfonated poly (ether ether ketone) (SPEEK) composite proton-conductive membrane based on a 3-(1-hydro-imidazolium-3-yl)-propane-1-sulfonate (Him-pS) additive to break through the trade-off between conductivity and selectivity of a vanadium redox flow battery (VRFB). Specifically, Him-pS enables an oriented distribution of the SPEEK matrix to construct highly conductive proton nanochannels throughout the membrane arising from the noncovalent interaction. Moreover, the "acid-base pair" effect from an imidazolium group and a sulfonic group further facilitates the proton transport through the nanochannels. Meanwhile, the structure of the acid-base pair is further confirmed based on density functional theory calculations. Material and electrochemical characterizations indicate that the nanochannels with a size of 16.5 nm are vertically distributed across the membrane, which not only accelerate proton conductivity (31.54 mS cm) but also enhance the vanadium-ion selectivity (39.9 × 10 S min cm). Benefiting from such oriented proton-conductive nanochannels in the membrane, the cell delivers an excellent Coulombic efficiency (CE, ≈ 98.8%) and energy efficiency (EE, ≈ 78.5%) at 300 mA cm. More significantly, the cell maintains a stable energy efficiency over 600 charge-discharge cycles with only a 5.18% decay. Accordingly, this work provides a promising fabrication strategy for a high-performance membrane of VRFB.
在这项工作中，我们提出了一种基于3-(1-氢咪唑鎓-3-基)丙烷-1-磺酸盐（Him-pS）添加剂的磺化聚醚醚酮（SPEEK）复合质子传导膜，以突破钒氧化还原液流电池（VRFB）电导率和选择性之间的权衡。具体而言，Him-pS能够使SPEEK基质定向分布，通过非共价相互作用在整个膜中构建高导电质子纳米通道。此外，咪唑鎓基团和磺酸基团的“酸碱对”效应进一步促进质子通过纳米通道传输。同时，基于密度泛函理论计算进一步证实了酸碱对的结构。材料和电化学表征表明，尺寸为16.5 nm的纳米通道垂直分布在整个膜中，这不仅加速了质子传导率（31.54 mS cm），还提高了钒离子选择性（39.9×10 S min cm）。受益于膜中这种定向质子传导纳米通道，该电池在300 mA cm下具有出色的库仑效率（CE，≈98.8%）和能量效率（EE，≈78.5%）。更重要的是，该电池在600次充放电循环中保持稳定的能量效率，衰减仅为5.18%。因此，这项工作为高性能VRFB膜提供了一种有前景的制备策略。
