Poly(1,5-diaminoanthraquinone) coated carbon cloth composites as flexible electrode with extraordinary cycling stability for symmetric solid-state supercapacitors

"Improving with using" effect and mechanism analysis of electrodeposited poly(1,5-diaminoanthraquinone)/carbon cloth electrode for high-performance flexible supercapacitors

As a robust and conductive substrate, carbon cloth (CC) has been modified with various pseudocapacitive materials to boost its electrochemical performance in flexible supercapacitors. Here, poly(1,5-diaminoanthraquinone) (PDAA) electrodeposited CC electrodes were developed and much higher areal specific capacitance was obtained in comparison with the functionalized CC (FCC). Most importantly, an unusual phenomenon of "improving with using" was found for the optimized one, FCC@PDAA-3, which exhibited the increased capacitance retention from 150.4% to 194.8% with increasing the number of cycles from 10,000 to 50,000. Such extraordinary cyclic life was mainly ascribed to the doping and electropolymerization of the encapsulated 1,5-diaminoanthraquinone (DAA) in the immobilized PDAA during the electrochemical cycles. These findings are expected to contribute to a deeper understanding of the pseudocapacitive materials evolution during long charging/discharging cycles, favoring the design of long-life supercapacitors for practical application.

Highly Efficient Solvothermal Synthesis of Poly(1,5-diaminoanthraquinone) Nanoflowers for Energy and Environmental Applications

Poly(1,5-diaminoanthraquinone) (PDAA) has attracted more interest because of its unique molecular structure. However, the lower polymerization yield limits its practical application. Here, the solvothermal chemically oxidative polymerization of 1,5-diaminoanthraquinone (DAA) was developed, and the well-defined PDAA nanoflowers were obtained with a high yield of 72.6% within 16 h. The PDAA nanoflower-based flexible film electrodes were fabricated with expandable graphene as conductive support, delivering a capacitance of 277 F g-1 and 258 mF cm-2 at 0.5 A g-1 (1 mA cm-2) and superior cycling stability with retention of 99% after 10000 cycles. The flexible symmetric solid-state supercapacitors (SSSCs) possessed a high capacitance of 52.5 F g-1 at 0.25 A g-1 and 96.6 mF cm-2 at 1 mA cm-2 and had only a 14% capacitance loss after 10000 cycles at 0.1 V s-1 as well as excellent flexibility. Besides, the PDAA nanoflowers could be used as self-separable adsorbent for methylene blue (MB) with a capacity of 93.8 mg g-1 at pH 9.

Preparation of Electrode Materials Based on Carbon Cloth via Hydrothermal Method and Their Application in Supercapacitors

Supercapacitors have the unique advantages of high power density, fast charge and discharge rates, long cycle life, high safety, and reliability, and are increasingly being used for applications including automobiles, rail transit, communication equipment, digital electronics, and aerospace equipment. The supercapacitor industry is currently in a stage of rapid development; great breakthroughs have also been made in improving the performance of supercapacitors and the expansion of their application. Electrode technology is the core of supercapacitors. Transition-metal compounds have a relatively high theoretical capacity and have received widespread attention as electrode materials for supercapacitors. In addition, there is a synergistic effect between the different components of various electrode composite materials. Due to their superior electrochemical performance, supercapacitors are receiving increasing research attention. Flexible supercapacitors have been hailed for their good plasticity, resulting in a development boom. This review article mainly outlines the development process of various electrode materials, including carbon materials, conductive polymers, metal compounds, and composite materials, as well as flexible electrode materials based on carbon cloth.

Systematic Review on the Effects, Roles and Methods of Magnetic Particle Coatings in Magnetorheological Materials

Magnetorheological (MR) material is a type of magneto-sensitive smart materials which consists of magnetizable particles dispersed in a carrier medium. Throughout the years, coating on the surface of the magnetic particles has been developed by researchers to enhance the performance of MR materials, which include the improvement of sedimentation stability, enhancement of the interaction between the particles and matrix mediums, and improving rheological properties as well as providing extra protection against oxidative environments. There are a few coating methods that have been employed to graft the coating layer on the surface of the magnetic particles, such as atomic transfer radical polymerization (ATRP), chemical oxidative polymerization, and dispersion polymerization. This paper investigates the role of particle coating in MR materials with the effects gained from grafting the magnetic particles. This paper also discusses the coating methods employed in some of the works that have been established by researchers in the particle coating of MR materials.

Two-for-one strategy: Three-dimensional porous Fe-doped Co3O4 cathode and N-doped carbon anode derived from a single bimetallic metal-organic framework for enhanced hybrid supercapacitor

"Two-for-one" strategy is an effective method to construct two kinds of materials from a single precursor owing to the simplicity of fabricating procedure and reduction of manufacturing cost. However, such a strategy has seldom been utilized to produce both battery-type and capacitive electrodes of a hybrid supercapacitor (HSC) device. Here, we adopt the "two-for-one" strategy to fabricate three-dimensional (3D) porous iron-doped (Fe-doped) Co₃O₄ and nitrogen-doped (N-doped) carbon via a single bimetallic metal-organic framework, FeCo-ZIF-67. Fe-doped amounts and carbonization temperature are used to adjust their individual electrochemical behaviors. The optimal 3D porous Fe-doped Co₃O₄ and N-doped carbon possess a high capacitance of 767.9 and 277C g^-1 at 1 A g^-1, respectively. Charge storage mechanism of Fe-doped Co₃O₄ is further investigated via analysis of capacitive and diffusion-controlled contribution. A Fe-doped Co₃O₄//N-doped carbon HSC device achieves desirable specific energy (37 Wh kg^-1) and power (750 Wkg^-1), and satisfied cycling stability (90% retention after 4000 cycles). A light-emitting diode (LED) is successfully light by the HSC device, suggesting its potential application in the field of green energy conversion and storage devices.