Ultra‐Tough Room‐Temperature Dielectric Switching Ionic Gels with Long‐Cycle Stability

Abstract

As a favorable candidate for the next‐generation smart electronic devices, thermo‐responsive dielectric materials are faced with two crucial challenges: insufficient mechanical toughness and lack of the combination of promising dielectric switching properties, desired mechanical properties, and long‐cycle stability. Herein, a new scalable strategy is proposed for designing thermo‐responsive dielectric switching materials that simultaneously integrate the individual features, such as promising dielectric switching properties, outstanding mechanical properties, and great cycle stability, into one gel, based on a new dual dielectric switching mechanism induced by interfacial structure evolution. The ionic gel can readily achieve a superb combination of distinct reversible dielectric bistability, a high dielectric switching ratio above 150, a ≈15 °C wide thermal hysteresis loop, and tunable room‐temperature dielectric transition behavior, impressive high ductility, desirable high mechanical strength, record‐high stability of at least 1000 cycles. Such an all‐in‐one design enhances the adaptability to multiple application scenarios, durability, and a lifetime of the dielectric switching gels. Together with the facile fabrication process and recyclable thermoplastic system, thereby contributing to cost and energy saving, this research provides a feasible and sustainable strategy for constructing highly desirable thermo‐responsive dielectric switching materials.

Unparalleled Dielectric‐Switching Effects Caused by Dual Polarization Synergy

“…Our recent studies [35,36] demonstrate that significantly enhanced dielectric switching ratios can be obtained by modulating the competition between electrode polarization and interfacial polarization. For example, [35] the phase transition of polyethylene glycol has been exploited to alter the mobility of ionic liquid, greatly enhancing the electrode polarization in the molten state, resulting in the highest dielectric switching ratio reported to date (320.6), as shown in Situation 1 of Figure 1c.…”

“…For example, [35] the phase transition of polyethylene glycol has been exploited to alter the mobility of ionic liquid, greatly enhancing the electrode polarization in the molten state, resulting in the highest dielectric switching ratio reported to date (320.6), as shown in Situation 1 of Figure 1c. Alternatively, the opposite approach [36] is used to obtain a high dielectric switching ratio by inhibiting the electrode polarization using the polymer matrix and instead enhancing the interfacial polarization at low temperatures. The interfacial polarization state transition caused by the crystallization/melting phase transition can also achieve a significantly enhanced dielectric switching ratio (up to 150.89) in stable solid-phase systems.…”

“…These solid-phase systems not only provide an appreciable dielectric switching ratio, but also excellent stability and mechanical properties. This series of studies [33][34][35][36] all suggest that a change in polarization state due to a significant structural phase transition (e.g., solid/liquid phase transition) is the most promising way to obtain a high dielectric switching ratio. Although the aforementioned composite systems based on interfacial polarization and electrode polarization, respectively, have achieved important success in improving the dielectric switching ratio.…”

Functionalized carbon nanotubes/polyimide nanocomposites with high energy density for high‐temperature dielectric materials

“…Meanwhile the polymer-based dielectric capacitors have attracted much attention because of their good flexibility, light weight, and high-power density. [1][2][3][4] The best polymer dielectric material currently available is biaxially stretched polypropylene (BOPP), which has excellent high breakdown strength (700 MV/m), extremely low loss factor (0.0002), but has low dielectric constant (2.2) and limited temperature (105 C). [5][6][7][8][9] Therefore, the research of high-temperature-resistant polymer dielectrics with high dielectric constant, low loss, and high breakdown strength is the key to whether the nextgeneration film capacitors can be applied in harsh environments.…”

“…In recent years, dielectric capacitors have been widely used in the fields of automotive electronics and aerospace. Meanwhile the polymer‐based dielectric capacitors have attracted much attention because of their good flexibility, light weight, and high‐power density 1–4 . The best polymer dielectric material currently available is biaxially stretched polypropylene (BOPP), which has excellent high breakdown strength (700 MV/m), extremely low loss factor (0.0002), but has low dielectric constant (2.2) and limited temperature (105°C) 5–9 .…”