Niinomi Kazuma, Miyazawa Satoru, Hibino Mitsuhiro, Mizuno Noritaka, Uchida Sayaka
Department of Basic Sciences, School of Arts and Sciences, The University of Tokyo , 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan.
Department of Applied Chemistry, School of Engineering, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Inorg Chem. 2017 Dec 18;56(24):15187-15193. doi: 10.1021/acs.inorgchem.7b02524. Epub 2017 Dec 7.
Keggin-type polyoxometalate (POM)-based compounds have long been considered as one of the environmentally friendly candidates of solid electrolytes exhibiting high proton conductivity under high relative humidity (RH >95%). However, their application has been limited by the lack of structural stability and large decrease in conductivity with a slight decrease in RH. In order to overcome these disadvantages, we report a series of crystalline composites based on Preyssler-type POMs ([Na(HO)PWO], [Bi(HO)PWO]), which are known to show higher acidity in comparison to Keggin-type POMs, and polymers (polyethylene glycol (PEG), polyallylamine (PAA)). Electrostatic interactions between POMs and polymers contribute to enhance the structural stability, and it has been widely known that polymer electrolytes promote cation transport via segmental motion of the polymer chain. In the crystalline composites, K acts as a linker to connect the POMs three-dimensionally, resulting in an all-inorganic framework, and polymers and waters of crystallization reside in the framework. The composites with PEG exhibit moderate proton conductivities of 10 S cm under nonhumidified (RH <10%) and low-temperature (<368 K) conditions by the aid of segmental motion of PEG. The composite with PAA exhibits a high proton conductivity of 10 S cm under humidified (RH 75%) and low-temperature (<338 K) conditions.
长期以来，基于Keggin型多金属氧酸盐（POM）的化合物一直被认为是在高相对湿度（RH>95%）下具有高质子传导率的环保型固体电解质候选材料之一。然而，它们的应用受到结构稳定性不足以及随着相对湿度略有下降电导率大幅降低的限制。为了克服这些缺点，我们报道了一系列基于Preyssler型POMs（[Na(HO)PWO]、[Bi(HO)PWO]）的晶体复合材料，已知Preyssler型POMs与Keggin型POMs相比具有更高的酸度，以及聚合物（聚乙二醇（PEG）、聚烯丙胺（PAA））。POMs与聚合物之间的静电相互作用有助于提高结构稳定性，并且众所周知，聚合物电解质通过聚合物链的链段运动促进阳离子传输。在晶体复合材料中，K作为连接体三维连接POMs，形成全无机框架，聚合物和结晶水存在于该框架中。借助PEG的链段运动，含PEG的复合材料在非加湿（RH<10%）和低温（<368 K）条件下表现出10 S cm的适度质子传导率。含PAA的复合材料在加湿（RH 75%）和低温（<338 K）条件下表现出10 S cm的高质子传导率。
