Ming Xiaoqing, Xiang Yang, Yao Le, He Wenqing, Zhu He, Zhang Qi, Zhu Shiping
School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Shenzhen, Guangdong518172, P.R. China.
ACS Appl Mater Interfaces. 2022 Oct 19;14(41):47167-47175. doi: 10.1021/acsami.2c15446. Epub 2022 Oct 6.
Ionic switches with a positive temperature coefficient (PTC) effect are highly desirable in the fabrication of smart electrolytes for the safety protection of electrochemical energy devices. However, most of them encounter liquid leaking or volume shrinking problems, limiting their long-term and stable operations. Herein, a PTC-type ionic switch is introduced based on a poly(acrylic acid) (PAA) hydrogel soaked by calcium acetate (CaAc), with a resistance change of six times in maximum between the homogeneous and phase separated state. The PTC effect is owing to the strong phase separation upon heating where the ion transport is restricted. Such a hydrogel-based PTC-type ionic switch is in the solid state and isochoric during phase separation without leaking or shrinking issues. The influence of different CaAc soaking concentrations is investigated. A simplified model consisting of interconnected ion channels is proposed based on microstructure analysis. A smart supercapacitor is successfully demonstrated by this PTC ionic switch with a safety protection ability. The research here would provide a new pathway for the design and development of PTC-type ionic switches in the safety protection of electrochemical energy storage devices.
具有正温度系数（PTC）效应的离子开关在制造用于电化学能量装置安全保护的智能电解质方面非常受欢迎。然而，它们中的大多数都遇到液体泄漏或体积收缩问题，限制了它们的长期稳定运行。在此，基于用醋酸钙（CaAc）浸泡的聚（丙烯酸）（PAA）水凝胶引入了一种PTC型离子开关，在均匀和相分离状态之间电阻变化最大可达六倍。PTC效应归因于加热时强烈的相分离，此时离子传输受到限制。这种基于水凝胶的PTC型离子开关是固态的，在相分离过程中是等容的，没有泄漏或收缩问题。研究了不同CaAc浸泡浓度的影响。基于微观结构分析提出了一个由相互连接的离子通道组成的简化模型。通过这种具有安全保护能力的PTC离子开关成功展示了一种智能超级电容器。这里的研究将为电化学储能装置安全保护中PTC型离子开关的设计和开发提供一条新途径。
