Supercapacitors are a highly promising class of energy storage devices due to their high power density and long life cycle. Conducting polymers (CPs) and organic molecules are potential candidates for improving supercapacitor electrodes due to their low cost, large specific pseudocapacitance and facile synthesis methods. Graphene, with its unique two-dimensional structure, shows high electrical conductivity, large specific surface area and outstanding mechanical properties, which makes it an excellent material for lithium ion batteries, fuel cells and supercapacitors. The combination of CPs and graphene as electrode material is expected to boost the properties of supercapacitors. In this review, we summarize recent reports on three different CP/graphene composites as electrode materials for supercapacitors, discussing synthesis and electrochemical performance. Novel flexible and wearable devices based on CP/graphene composites are introduced and discussed, with an eye to recent developments and challenges for future research directions.

Metal organic frameworks (MOFs) are considered as very promising candidates to build electrodes for electrochemical energy storage devices such as lithium ion batteries, fuel cells and supercapacitors, due to their diverse structure, adjustable aperture, large specific surface area and abundant active sites. Supercapacitor has been widely investigated in the past decades. Of critical importance in these devices is the electrode active materials, and this application has been intensively studied with the development of novel nanomaterials. In this review we summarize recent reports on MOFs as electrode materials for supercapacitors. Specifically, the synthesis of MOF materials for supercapacitor electrodes and their performance in electrochemical energy storage are discussed. We aim to include supercapacitor electrode materials related to MOFs, such as carbon, metal and composite materials. It is proposed that MOFs play an important role in the development of a new generation of supercapacitor electrode materials. Finally, we discuss the current challenges in the field of supercapacitors, with a view towards how to address these challenges with the future development of MOFs and their derivatives. 金属有机骨架材料具有结构多样、孔径可调、比表面积大及化学反应活性位点丰富等优点, 因此有望成为广泛应用于电化学储能 器件的电极材料, 如锂离子电池、燃料电池及超级电容器等. 近十年来金属有机骨架材料及其衍生物材料引起了广泛的研究与应用. 同 时, 金属有机骨架材料及其衍生的纳米材料作为电化学储能器件中的关键电极也受到了广泛的研究. 本文主要综述了近期金属有机骨架 材料及其衍生物在超级电容器中的研究进展, 讨论了金属有机骨架材料制备超级电容器电极材料的方法及其在电化学储能领域体现出的 优异性能及特殊性质, 同时也总结了近期金属有机骨架材料的衍生物如碳材料、金属材料及复合物在超级电容器中的研究进展, 结果说 明金属有机骨架材料在发展新一代超级电容器电极材料领域具有重要的作用. 最后讨论了金属有机骨架材料及其衍生物目前在超级电容 器领域存在的问题以及未来可能的发展方向.

As a new class of two-dimensional transition-metal carbides and carbonitrides, MXenes have been widely used in energy storage, sensing, catalysis, electromagnetic interference shielding and other fields. It is a challenge to simultaneously realize a sensor with extremely high sensitivity, wide detection limits, low power consumption and good mechanical stability. In this work, taking advantage of the high conductivity of MXenes and the porous structure of polyvinyl butyral, a highly sensitive piezoresistive sensor was fabricated. The fabricated MXene/PVB-based sensor exhibits high sensitivity and reliability with a factor of ∼11.9 kPa⁻¹, ∼1.15 kPa⁻¹ and ∼0.20 kPa⁻¹ in the ranges of 31.2 Pa–312 Pa, 312 Pa–62.4 kPa and 62.4 kPa–1248.4 kPa, respectively. The sensor has a wide detection range (∼31.2 Pa to ∼2.205 MPa), low detection limit (6.8 Pa), low detection voltage (0.1 mV), low power consumption (∼3.6 × 10⁻¹⁰ W), fast response time (∼110 ms) and good mechanical stability (over 10 000 maximum-pressure cycles). Moreover, it is demonstrated that the sensor can detect subtle bending and release activities of humans, including arterial pulses and voice signals, which makes it potentially suitable to be used as a wide detection range, highly sensitive and low power consumption piezoresistive sensor. This work provides a new avenue to expand the application of MXene-based flexible pressure sensors with a wide sensing range and ultra-low power consumption.