Heterogeneous graphene/polypyrrole multilayered microtube with enhanced capacitance

Laser Patterned In-Plane Asymmetric MXene//LIG@MnO Microsupercapacitor for Self-Powered Pressure Detection Systems

Wearable and portable microelectronic devices are attracting growing attention in the scientific and technological fields. The preparation of high-performance micro energy storage devices in self-sustaining flexible electronic systems still needs further studies. In this work, we have developed a preparation method for asymmetric microsupercapacitors (AMSCs). The MnO cathodes are fabricated by laser irradiation, which converts manganese acetate into manganese oxide on the hydrophilic laser-induced graphene interdigitated electrodes. By controlling the number of drop-coating cycles of the manganese acetate solution, precise control over MnO loading is achieved. We investigated the impacts of laser power and scanning direction on the phase and performance of the MnO cathodes, establishing the optimal laser processing parameters. The MXene//MnOAMSC after capacity matching demonstrates excellent rate performance (maintaining 82% even at 10 times the current density of 0.1 mA cm-2), outstanding mechanical flexibility, and long-term cycling stability (90% capacitance retention after 10,000 cycles). Furthermore, by serially connecting a solar cell, an AMSC, and pressure-sensitive elements, a self-powered pressure detection system is constructed. This integrated system exhibits a clear current response to finger bending, elbow bending, and finger touch.

Carbon Threads Supercapacitors for Washable e-Textile Applications: Configurations and Electrochemical Performance

Technological solutions for emerging e-textiles are being sought to enable e-wear technology to be self-sustaining and lightweight. A rippling 1D carbon fiber capacitor design was made with commercial carbon threads as electrodes using simulated sweat solution as the electrolyte. This is particularly relevant for potential sports textile applications in which sweat could serve as an electrochemical energy source. An electrospun cellulose acetate fiber membrane and a commercially available felt were used as separators capable of soaking the electrolyte. These were tested in braided and woven electrode configurations, respectively. Functionalizing the carbon wires with polypyrrole (PPy) enhanced the surface area and significantly increased the specific capacity by approximately an order of magnitude (0.62 F/g). Cyclic voltammetry and charge-discharge tests confirmed the washability and durability of the devices for at least 1000 cycles.

Preparation of flexible and free-standing polypyrrole/graphene film electrodes for supercapacitors

A free-standing polypyrrole/graphene film (PGF) electrode with an excellent electrochemical performance was obtained using spin coating and hydrothermal methods.

Smart fibers for energy conversion and storage

Fibers have played a critical role in the long history of human development. They are the basic building blocks of textiles. Synthetic fibers not only make clothes stronger and more durable, but are also customizable and cheaper. The growth of miniature and wearable electronics has promoted the development of smart and multifunctional fibers. Particularly, the incorporation of functional semiconductors and electroactive materials in fibers has opened up the field of fiber electronics. The energy supply system is the key branch for fiber electronics. Herein, after a brief introduction on the history of smart and functional fibers, we review the current state of advanced functional fibers for their application in energy conversion and storage, focusing on nanogenerators, solar cells, supercapacitors and batteries. Subsequently, the importance of the integration of fiber-shaped energy conversion and storage devices via smart structure design is discussed. Finally, the challenges and future direction in this field are highlighted. Through this review, we hope to inspire scientists with different research backgrounds to enter this multi-disciplinary field to promote its prosperity and development and usher in a truly new era of smart fibers.

Synthesis of Polypyrrole/Reduced Graphene Oxide Hybrids via Hydrothermal Treatment for Energy Storage Applications

Herein, we propose hydrothermal treatment as a facile and environmentally friendly approach for the synthesis of polypyrrole/reduced graphene oxide hybrids. A series of self-assembled hybrid materials with different component mass ratios of conductive polymer to graphene oxide was prepared. The morphology, porous structure, chemical composition and electrochemical performance of the synthesized hybrids as electrode materials for supercapacitors were investigated. Nitrogen sorption analysis at 77 K revealed significant changes in the textural development of the synthesized materials, presenting specific surface areas ranging from 25 to 199 m² g^-1. The combination of the pseudocapacitive polypyrrole and robust graphene material resulted in hybrids with excellent electrochemical properties, which achieved specific capacitances as high as 198 F g^-1 at a current density of 20 A g^-1 and retained up to 92% of their initial capacitance after 3000 charge-discharge cycles. We found that a suitable morphology and chemical composition are key factors that determine the electrochemical properties of polypyrrole/reduced graphene oxide hybrid materials.

A Route Toward Smart System Integration: From Fiber Design to Device Construction

Fiber is a symbol of human civilization, being ubiquitous but obscure in society over most of history. Fiber has been revived upon the advent of fiber-based electronic devices in the past two decades. This is due to its desirable lightweight, flexible, and conformable characteristics, which enable it to play a fundamental role in the electronic and information era. Numerous fiber-based electronic devices have sprung up in energy conversion, energy storage, sensing, actuation, etc. A possibility is thereby conceived that they can be integrated into smart systems compatible with the human body, consisting of biotic fiber-based organs and tissues, which possess similar but more advanced functions. However, the design of mono-/multifibers, the construction of fiber-based devices, and the integration of these smart systems represent great challenges in fundamental understanding and practical implementation. A systematic review of the current state of the art with respect to the design and fabrication of electronic fiber materials, construction of fiber-based devices, and integration of smart systems is presented. In addition, limitations of current fiber-based devices and perspectives are explored toward potential and promising smart integration.

Design and fabrication of polypyrrole/expanded graphite 3D interlayer nanohybrids towards high capacitive performance

Polypyrrole/expanded graphite (PPy/EG) nanohybrids, with a hierarchical structure of a three dimensional EG framework with a thick PPy coating layer, have been synthesized via a vacuum-assisted intercalation in situ oxidation polymerization method. In the synthesis, pyrrole monomers were intercalated into the irregular pores of EG with the assistance of a vacuum pump. Subsequently, the intercalated pyrrole monomers assembled on both sides of the EG nanosheets and formed PPy by an in situ polymerization method. As electrode materials, the typical PPy/EG10 sample with an EG content of 10% had a high specific capacitance of 454.3 F g⁻¹ and 442.7 F g⁻¹ (1.0 A g⁻¹), and specific capacitance retention rate of 75.9% and 73.3% (15.0 A g⁻¹) in 1 M H₂SO₄ and 1 M KCl electrolytes, respectively. The two-electrode symmetric supercapacitor showed a high energy density of 47.5 W h kg⁻¹ at a power density of 1 kW kg⁻¹, and could retain superb stability after 2000 cycles. The unique self-supporting structure feature and homogeneous PPy nanosphere coating combined the contributions of electrochemical double layer capacitance and pseudo-capacitance, which made the nanohybrids an excellent electrode material for high performance energy storage devices.

Polypyrrole/expanded graphite nanohybrids with a hierarchical structure were synthesized as electrode materials, and showed outstanding energy storage performance.