Bai Zhiyuan, Li Ran, Li Kerui, Hou Chengyi, Zhang Qinghong, Li Yaogang, Wang Hongzhi
State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620, People's Republic of China.
Department of Chemical and Biomolecular Engineering, National University of Singapore, 117585 Singapore.
ACS Appl Mater Interfaces. 2020 Sep 23;12(38):42955-42961. doi: 10.1021/acsami.0c11876. Epub 2020 Sep 12.
Metal-organic framework (MOF)-based electrolytes under gel/solid states have been widely used for electrochemical devices recently due to their designable metal centers/ligands and diffusion channels in the porous structures. Therefore, it is always desired to apply the MOF-based electrolytes in electrochromic (EC) fields. Yet, challenges exist in realizing their high optical transparency to satisfy the unique optical requirements of EC devices. Herein, a transparent MOF-based gel electrolyte (MGE) is demonstrated through the incorporation of 2-methylimidazole among MOF nanocrystals to prevent the strong light scattering of MOF nanocrystals. As a result, the gel electrolyte showed an improved average transmittance of ca. 82.2% compared with the MOF electrolytes without 2-methylimidazole (ca. 59.2%). In addition, because of the designed large channels in the porous MOF structure, the gel electrolyte exhibited a high ionic conductivity of 2.66 × 10 S cm. At last, we used the transparent MGEs to assemble two types (rigid and flexible) of quasi-solid-state EC devices based on inorganic WO and organic poly(3,4-ethylenedioxythiophene) (PEDOT), respectively. Both devices showed great EC performances, and the flexible devices exhibited high mechanical stability under the bending state or even after being cut and punched, advancing the general applications of our transparent MGEs in EC fields.
近年来，凝胶/固态金属有机框架（MOF）基电解质因其在多孔结构中可设计的金属中心/配体和扩散通道而被广泛应用于电化学器件。因此，人们一直希望将MOF基电解质应用于电致变色（EC）领域。然而，在实现其高光学透明度以满足EC器件独特的光学要求方面仍存在挑战。在此，通过在MOF纳米晶体中引入2-甲基咪唑来防止MOF纳米晶体的强光散射，制备了一种透明的MOF基凝胶电解质（MGE）。结果，与不含2-甲基咪唑的MOF电解质（约59.2%）相比，该凝胶电解质的平均透过率提高到了约82.2%。此外，由于多孔MOF结构中设计的大通道，该凝胶电解质表现出2.66×10 S cm的高离子电导率。最后，我们分别使用透明MGE组装了基于无机WO和有机聚（3,4-亚乙基二氧噻吩）（PEDOT）的两种类型（刚性和柔性）的准固态EC器件。两种器件均表现出优异的EC性能，柔性器件在弯曲状态下甚至在切割和打孔后仍表现出高机械稳定性，推动了我们透明MGE在EC领域的广泛应用。
