In recent years, as an energy storage device with a fast charge and discharge speed, long cycle life, and good stability, flexible supercapacitors (SCs) have been extensively used in flexible electronic devices such as smart textiles, flexible display screens, and micro-robots. Combining the advantages of conductive materials and hydrogels, conductive polymer hydrogels have good flexibility, biocompatibility, and adjustable mechanical and electrochemical properties, which enable them to be used as electrolyte or electrode materials for flexible SCs, endowing flexible SCs with various excellent properties and meeting their various working requirements. This paper comprehensively reviews the flexible SCs based on conductive polymer hydrogels, from the design, synthesis and application aspects of conductive polymer hydrogels, the various superior functions (e.g., self-healing, high stretchability and compressibility, high toughness, electrochromic and shape memory) of flexible SCs based on conductive polymer hydrogels to different structures of flexible SCs, including fiber-shaped structures, all-in-one sandwich structures, and in-plane interdigital microstructures. Finally, we summarize the challenges faced by flexible SCs based on conductive polymer hydrogels, which provides new research directions and prospects for future development in this field.

Design and fabrication of conductive polymer hydrogels and their applications in flexible supercapacitors

http://manuscript.elsevier.com/S0008622322001956/pdf/S0008622322001956.pdf

An overview of recent progress in nanostructured carbon-based supercapacitor electrodes: From zero to bi-dimensional materials

Designing high-performance electrodes via 3D printing for advanced energy storage is appealing but remains challenging. In normal cases, light-weight carbonaceous materials harnessing excellent electrical conductivity have served as electrode candidates. However, they struggle with undermined areal and volumetric energy density of supercapacitor devices, thereby greatly impeding the practical applications. Herein, we demonstrate the in situ coupling of NiCoP bimetallic phosphide and Ti3C2 MXene to build up heavy NCPM electrodes affording tunable mass loading throughout 3D printing technology. The resolution of prints reaches 50 μm and the thickness of device electrodes is ca. 4 mm. Thus-printed electrode possessing robust open framework synergizes favorable capacitance of NiCoP and excellent conductivity of MXene, readily achieving a high areal and volumetric capacitance of 20 F cm−2 and 137 F cm−3 even at a high mass loading of ~ 46.3 mg cm−2. Accordingly, an asymmetric supercapacitor full cell assembled with 3D-printed NCPM as a positive electrode and 3D-printed activated carbon as a negative electrode harvests remarkable areal and volumetric energy density of 0.89 mWh cm−2 and 2.2 mWh cm−3, outperforming the most of state-of-the-art carbon-based supercapacitors. The present work is anticipated to offer a viable solution toward the customized construction of multifunctional architectures via 3D printing for high-energy-density energy storage systems.

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3D Printing of NiCoP/Ti3C2 MXene Architectures for Energy Storage Devices with High Areal and Volumetric Energy Density

Small mesopore engineering of pitch-based porous carbons toward enhanced supercapacitor performance

Screen printing fabricating patterned and customized full paper-based energy storage devices with excellent photothermal, self-healing, high energy density and good electromagnetic shielding performances

Facile construction of 3D porous carbon nanotubes/polypyrrole and reduced graphene oxide on carbon nanotube fiber for high-performance asymmetric supercapacitors

Light-diffusing materials (LDMs) are essential for diffusing indoor light-emitting diode (LED) illumination to soft light. The size and refractive index of the light-diffusing agent are the...

Preparation of refractive-index-controlled silicone microspheres and their application in polycarbonate light diffusing materials

The ambient atmosphere has the remarkable effect on the chemical reaction mechanism and the formation of characteristic chemical structures and conjugated structures for pre-oxidized polyacrylonitrile (PAN). In the present paper, fourier transform infrared spectroscopy (FT-IR) and ultraviolet visible spectroscopy (UV–vis) were used to characterize the variations of chemical reaction characteristic structures and conjugate structures of copolymerized PAN in nitrogen and air atmosphere, respectively. Combined with the multivariate reaction model proposed by the predecessors, it can be found that two main conjugated structures (conjugated polyene and conjugated aromatic heterocycle) formed during the pre-oxidation process of copolymerized PAN. In nitrogen atmosphere, the formed main structure units were the conjugated diene and conjugated double ring with 1–2 double bonds. By contrast, the formed main units in air were the conjugated diene and conjugated tricyclic with a double bond. During the whole pre-oxidation process, the maximum unit numbers of conjugated double bonds and conjugated rings were no more than four and six, respectively. Increasing the heat treatment temperature favored to form more conjugate structures than prolonging the heat treatment time. Furthermore, with the increase of heat treatment temperature or time in air, the main conjugate unit numbers had no obvious change, while the maximum unit numbers increased slightly. For the exposure in nitrogen atmosphere, the main conjugated polycyclic structure was transformed into conjugated tricyclic structure after the heat treatment at 250 °C for more than 3 h. In addition, when the heat treatment temperature and time were 280 °C for more than 4 h, the main conjugated polyene structure was transformed into conjugated triene, and the maximum conjugated unit numbers increased slightly.

Shuai Lei

Papers

Facile construction of 3D porous carbon nanotubes/polypyrrole and reduced graphene oxide on carbon nanotube fiber for high-performance asymmetric supercapacitors

Preparation of refractive-index-controlled silicone microspheres and their application in polycarbonate light diffusing materials

Effect of ambient atmosphere on the formation and evolution of conjugated structure of pre-oxidized polyacrylonitrile