Department of Earth and Environmental Engineering, Columbia University, New York, New York 10027, United States.
Acc Chem Res. 2020 Aug 18;53(8):1468-1477. doi: 10.1021/acs.accounts.0c00205. Epub 2020 Jul 13.
Flexible symmetric supercapacitors (FSSs) have received enormous attention in energy storage and conversion areas by virtue of their superior flexibility, high power density, and good cycling stability. FSS devices are typically composed of one solid electrolyte layer laminated by two electrode layers, which can realize energy storage, response to electrical stimulus, and even detect external stress or strain change based on various working mechanisms. The as-mentioned multifunctions of FSS devices are expected to play many critical roles in practical applications of wearable power supply and in artificial intelligence. This realization strongly associates with the rapid development of materials science and engineering, especially nanomaterials and smart structure design, and the multifunctions are results of rational designs of critical materials, optimization of device dimensions, and selectivity of active ion species.This Account showcases the latest advances in FSS devices concerning several critical aspects from fundamental material engineering to practical wearable applications. We first describe advanced functional materials utilized in flexible solid electrolytes and electrodes of FSS systems. Several highly ion-conductive hydrogel and ionogel electrolytes with excellent mechanical properties have been designed for the fast and stable ionic migration kinetics in devices. Some high-performance electrode materials with high charge storage capacity, efficient electromechanical conversion, and sensitive ionic response are presented for realizing multifunctions of FSS devices. After that, analysis of interfaces in devices on their performances is provided, and the construction strategies of robust interface are displayed as well. We then summarize flexible and wearable applications of FSS devices, including high-energy density power sources, flexible and electroactive actuators, and wearable and sensitive sensors. These multifunctions are realized by optimization of device dimensions, control of ion migration kinetics, and development of advanced materials, and the corresponding working mechanisms of the devices are presented in detail. The long-term development and future research directions of FSS devices are also envisioned.At present, the rise of nanomaterials and nanoscience is providing great opportunity to further improve performances of FSS devices and finally realize their wearable applications. These wearable FSS devices with smart multifunctions will significantly promote the development of next-generation flexible electronics for artificial intelligence. It is expected that this Account can promote tremendous efforts toward fundamental clarification of FSS devices, and the design mentality will accelerate the development of other flexible and wearable electrochemical energy devices.
柔性对称超级电容器（FSSs）因其优异的柔韧性、高功率密度和良好的循环稳定性而在储能和能量转换领域引起了极大的关注。FSS 器件通常由一层固体电解质层和两层电极层组成，通过各种工作机制实现能量存储、对电刺激的响应，甚至检测外部应力或应变变化。FSS 器件的上述多种功能有望在可穿戴电源的实际应用和人工智能中发挥重要作用。这种实现强烈关联着材料科学与工程的快速发展，特别是纳米材料和智能结构设计，而多种功能则是对关键材料的合理设计、器件尺寸的优化以及活性离子种类的选择性的结果。本综述从基础材料工程到实际可穿戴应用的几个关键方面，展示了 FSS 器件的最新进展。我们首先描述了 FSS 系统中柔性固体电解质和电极中使用的先进功能材料。设计了几种具有优异机械性能的高离子传导水凝胶和离子凝胶电解质，以实现器件中快速稳定的离子迁移动力学。展示了一些具有高电荷存储容量、高效机电转换和敏感离子响应的高性能电极材料，用于实现 FSS 器件的多种功能。然后，分析了器件界面对性能的影响，并展示了稳健界面的构建策略。然后，我们总结了 FSS 器件的柔性和可穿戴应用，包括高能量密度电源、柔性和电活性致动器以及可穿戴和敏感传感器。通过优化器件尺寸、控制离子迁移动力学和开发先进材料来实现这些多功能性，并详细介绍了器件的相应工作机制。还展望了 FSS 器件的长期发展和未来研究方向。目前，纳米材料和纳米科学的兴起为进一步提高 FSS 器件的性能并最终实现其可穿戴应用提供了巨大的机会。这些具有智能多功能性的可穿戴 FSS 器件将极大地推动下一代人工智能柔性电子产品的发展。我们希望本综述能够促进对 FSS 器件的基本原理的深入研究，并且这种设计理念将加速其他柔性和可穿戴电化学能源器件的发展。
