Freestanding Co3N thin film for high performance supercapacitors

Suitable electrode materials play a decisive role in the performance of supercapacitors. In recent years, transition metal nitrides come into view because of their advantages of superior electrical conductivity exceeding the corresponding metal oxides and higher specific capacitance compared with carbon-based materials. Herein, we have successfully synthesized the binder-free Co₃N thin films for high-efficiency supercapacitor by reactive magnetron sputtering. Remarkedly, the Co₃N thin film electrodes can reach a high specific capacity of 47.5 mC cm^?2 at a current density of 1.0 mA cm^?2 along with reasonable cycling stability (78.1% remaining after 10,000 cycles). These findings have proved that the Co₃N thin films have great potential applications for supercapacitors or other electrochemical energy storage devices.     

Mechanically strong high performance layered polypyrrole nano fibre/graphene film for flexible solid state supercapacitor

Paper like flexible electrode becomes one of the most important research objects recently in request of the fast expanding market of portable electronics. Flexible solid state supercapacitors are shortlisted as one of the most promising energy devices to power electronics with medium to high power density requirements. In this work, we developed a simple but effective way to produce a mechanically strong and electrochemically active RGO/polypyrrole (PPy) fibre paper. A well-bedded microstructure was created with interlaced polypyrrole fibres evenly distributed between the graphene layers. Such microstructure can create enormous amount of pores and therefore provides larger interfaces for charge carrier storage/release. The effects of polypyrrole fibres on the film’s morphologies, mechanical properties and electrochemical performance were discussed. A solid state supercapacitor was demonstrated using such paper electrodes and a gel type electrolyte – phosphate acid (H₃PO₄) infused polyvinyl alcohol (PVA). It showed a high capacitance (345 F g⁻¹) and an excellent cycling stability (9.4% drop after 1000 cycles).     

Fabrication and functionalization of carbon nanotube films for high-performance flexible supercapacitors

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Carbon nanotube (CNT) films have shown many promising advantages in the development of high-performance flexible supercapacitors in terms of electrode specific area, mechanical reliability under bending and stretching, electron and ionic mobility tailored for high-rate performance etc. In this review, the recent progress in the design, preparation and functionalization of CNT film based electrodes for the fabrication of high-performance flexible supercapacitors are introduced in details, including the synthesis of conductive CNT films for the electrodes of supercapacitors, and the functionalizations of CNT film with other high-capacitance materials by both mixing and in situ growth strategies for high-performance composite electrodes. Furthermore, we also discussed the assembly strategies, prototypes and electrochemical performance of flexible supercapacitors based on CNT film composite electrodes. At last, the challenges and trends of the CNT film based flexible supercapacitors are prospected as well.     

Conducting Polymer Nanostructures and their Derivatives for Flexible Supercapacitors

This review provides a brief summary of the recent research developments in the fabrication and application of conducting polymer nanostructures and their derivatives as electrodes for flexible supercapacitors (SCs). By controlling the nucleation and growth process of polymerization, conducting polymers (CPs) with different nanostructures can be prepared by employing chemical polymerization, electrochemical polymerization and photo-induced polymerization. These CPs (such as polyaniline and polypyrrole) with special nanostructures possess high capacitance, superior rate capability ascribed to large electrochemical surface, and optimal ion diffusion path in the ordered nanostructures. The composites of nano-structured conducting polymer and some conductive flexible substrates (such as carbon nanotube film and graphene film) are proved to be ideal electrode materials for high performance flexible SCs. Furthermore, high N-containing CPs are very prospective for preparing N-doped carbon materials used as flexible electrodes for flexible SCs. With respect to the extra pseudo-capacitance induced by N atoms and superior stability derived from the conjugated graphitic structure of carbon materials, the obtained flexible SCs based on N-doped carbon materials could achieve high capacitance, high rate performance, and superior cycling stability.     

基于镍材料的柔性固态超级电容器研究进展

柔性固态超级电容器在可穿戴电子设备的储能领域发挥着重要作用，电极作为关键部件，决定了储能器件的性能。镍基材料具有优越的电化学性能，作为电极材料具有广阔的应用前景。根据化学成分将镍基材料分为若干类，重点介绍了镍基/金属以及镍基/非金属材料柔性固态超级电容器的最新进展。简要总结了镍基材料面临的挑战，并对未来的发展进行了展望。     

Transparent and flexible electrodes and supercapacitors using polyaniline/single-walled carbon nanotube composite thin films

Large-scale transparent and flexible electronic devices have been pursued for potential applications such as those in touch sensors and display technologies. These applications require that the power source of these devices must also comply with transparent and flexible features. Here we present transparent and flexible supercapacitors assembled from polyaniline (PANI)/single-walled carbon nanotube (SWNT) composite thin film electrodes. The ultrathin, optically homogeneous and transparent, electrically conducting films of the PANI/SWNT composite show a large specific capacitance due to combined double-layer capacitance and pseudo-capacitance mechanisms. A supercapacitor assembled using electrodes with a SWNT density of 10.0 μg cm(-2) and 59 wt% PANI gives a specific capacitance of 55.0 F g(-1) at a current density of 2.6 A g(-1), showing its possibility for transparent and flexible energy storage.     

A green and high energy density asymmetric supercapacitor based on ultrathin MnO2 nanostructures and functional mesoporous carbon nanotube electrodes

A green asymmetric supercapacitor with high energy density has been developed using birnessite-type ultrathin porous MnO(2) nanoflowers (UBMNFs) as positive electrode and functional mesoporous carbon nanotubes (FMCNTs) as negative electrode in 1 M Na(2)SO(4) electrolyte. Both of the electrode materials possess excellent electrochemical performances, with high surface areas and narrow pore size distributions. More significantly, the assembled asymmetric supercapacitor with optimal mass ratio can be cycled reversibly in the high-potential range of 0-2.0 V and exhibits an excellent energy density as high as 47.4 W h kg(-1), which is much higher than those of symmetric supercapacitors based on UBMNFs//UBMNFs and FMCNTs//FMCNTs supercapacitors. Furthermore, our asymmetric supercapacitor (ASC) device also exhibits a superior cycling stability with 90% retention of the initial specific capacitance after 1000 cycles and stable Coulombic efficiency of ~98%. These intriguing results exhibit great potential in developing high energy density "green supercapacitors" for practical applications.     

High performance fiber-shaped flexible asymmetric supercapacitor based on MnO2 nanostructure composited with CuO nanowires and carbon nanotubes

The demand for wearable electronics has greatly promoted the development of flexible supercapacitors. Herein, we develop a series of approaches to fabricate a fiber-shaped supercapacitor with flexibility. In the device, CuO@MnO₂, carbon nanotube (CNT)@MnO₂ and PVA-KOH are respectively used as inner electrode, outer electrode and gel electrolyte. The approaches including in-situ growth of CNTs, in-situ etching removal of SiO₂ template and in-situ filling of gel electrolyte via hydrothermal process are explored to protect the device from structure damage caused by external forces and to maximize effective contact areas between active electrode materials and gel electrolyte. The optimized supercapacitor of copper wire@CuO@MnO₂//PVA-KOH//CNT@MnO₂ demonstrates a good capacitive performance (5.97 F cm^?3) and exhibits a high energy density (0.38 mWh cm^?3) at a power density of 25.5 mW cm^?3. In addition, it has perfect cycling stability (77% after 2000 cycles) with excellent flexibility. Therefore, this work will provide desirable processes to construct fiber-shaped supercapacitors as flexible and wearable energy storage devices.     

3D heterostructured architectures of Co(3)O(4) nanoparticles deposited on porous graphene surfaces for high performance of lithium ion batteries

Control of structure and morphology in electrode design is crucial for creating efficient transport pathways of ions and electrons in high-performance energy storage devices. Here we report the fabrication of high-performance anode materials for lithium-ion batteries based on a 3D heterostructured architecture consisting of Co(3)O(4) nanoparticles deposited onto porous graphene surfaces. A combination of replication and filtration processes - a simple and general method - allows a direct assembly of 2D graphene sheets into 3D porous films with large surface area, porosity, and mechanical stability. The polystyrene spheres are employed as sacrificial templates for an embossing technique that yields porous structures with tunable pore sizes ranging from 100 nm to 2 μm. Co(3)O(4) nanoparticles with high-energy storage capacity can be easily incorporated into the pore surfaces by a simple deposition strategy, thereby creating a 3D heterogeneous Co(3)O(4)/graphene film. In particular, we exploit the 3D Co(3)O(4)/graphene composite films as anode materials for lithium ion batteries in order to resolve the current issues of rate capability and cycling life. This unique heterogeneous 3D structure is capable of delivering excellent Li(+) ion storage/release and displays the following characteristics: a high rate capability of 71% retention even at a high current rate of 1000 mA g(-1) and a good cycling performance with 90.6% retention during 50 cycles. The versatile and simple nature of preparing 3D heterogeneous graphene films with various functional nanoparticles can be extended to overcome the major challenges that exist for many electrochemical devices.     

固态柔性超级电容器构筑及其材料的研究进展

传统的超级电容器因柔性差、安全性低等问题无法满足可穿戴电子产品的需求。基于此，固态柔性超级电容器应运而生，以其独特的柔性、延展性和高安全性等特点引起了众多学者的关注。本文首先简要介绍了固态柔性超级电容器的研究意义，总结了其主要的组成结构，并指出二维叉指超级电容器适用于微型电子器件，一维线型超级电容器具有更好的柔性和适应性。然后重点概述了固态柔性超级电容器用电极材料和电解质材料的研究进展，并对其现存问题进行探讨，指出该领域进一步发展的关键技术是如何提高电极的容量性能和循环稳定性以及电解质材料的力学性能、导电性和电化学稳定窗口。     

Anchoring 2D NiMoO4 nano-plates on flexible carbon cloth as a binder-free electrode for efficient energy storage devices

The energy security and mounting environmental issues compel the scientific community to allocate greatly efficient and economical energy renovation and storage systems. Among the energy storage devices, supercapacitors have become the forefront in energy storing systems in recent decades. The efficiency of supercapacitors mainly depend on the electrode's material and they usually suffer from a quick reduction in specific capacitance at higher current densities. Herein, we combined the nano-plates like bimetallic oxides (NiMiO₄) with mixed valence states on the surface of a conductive substrate (carbon cloth) without any binder and additives (denoted NMO@CC). The as-prepared electrode NMO@CC showed marvelous electrochemical properties in the aqueous basic electrolyte by achieving a high capacity of 1500 C g⁻¹ at current density of 5 A g⁻¹ with high degree of rate capability. More interestingly, the NMO@CC electrode demonstrated excellent cycling stability of 94.63% after 5000 cycles during charge-discharge process. Further, the charge storage mechanism of NMO@CC electrode is investigated by analyzing the surface capacitive and diffusion controlled processes and it shows high surface capacitive storage (71%). These admirable results are based on the highly open channels for efficient diffusion of electrolyte ions and electronic transmission through the NMO and backbone carbon cloth, respectively. Therefore, accurate morphology and surface manufacturing engineering are highly appreciated to enhance the active surface area and inherent conductivity of electrode materials.     

电泳沉积法制备高能量密度的非对称平面微型超级电容器

首先采用光刻、蒸镀金的方法制备叉指电极,随后把合成的具有赝电容特性的二维MnO2和Ti3C2纳米片分别电泳沉积到叉指电极上,构建了非对称平面超级电容器.其中MnO2为正极,Ti3C2为负极,滴涂凝胶为电解质,并利用透明的聚二甲基硅氧烷薄膜封装成器件.通过能量色散X射线光谱(EDS)、傅里叶变换红外光谱(FT-IR)、扫...     

细菌纤维素/碳纳米管/MnO2复合超级电容器电极

基于细菌纤维素(BC)的三维多孔及柔性支架结构和碳纳米管(MWCNT)的优良导电性,构筑起BC/MWCNT自支撑导电基底。其中,二者通过氢键紧密结合,协同赋予复合基底优良的电导率和机械性能。然后将二氧化锰(MnO₂)电沉积在该基底上,构建了一种新型的BC/MWCNT/MnO₂薄膜电极。BC/MWCNT复合膜的多孔结构、电解质吸收特性及蜂窝状活性MnO₂纳米片的桥连结构,赋予其出色的电化学性能(在1 mA cm_-2^{的电流密度下},其面积比电容和质量比电容分别达到1.17 F cm_-2^和200 F g_-1⁾和显著的循环稳定性(在20 mA cm_-2^{的电流密度下进行}10000次循环后,其比电容保留率稳定在96%)。这种无粘合剂的薄膜电极制备简便且成本低廉,在开发柔性储能器件方面具有巨大潜力。关键词：细菌纤维素(BC)；碳纳米管(MWCNT)；二氧化锰(MnO₂)；膜电极；电化学性能中图分类号：TQ630 文献标识码： A 文章编号：1003-5214 (2020) 01-0000-00     

纤维状柔性超级电容器的研究进展

随着智能可穿戴设备的快速发展,对柔性能量储存设备提出了更高的要求.纤维状超级电容器具有柔性、轻质、功率密度高、循环寿命长、快速充放电的优势,在可穿戴领域展现出广泛的应用潜力.碳纳米管纤维、石墨烯纤维和碳纤维具有较高的电导率,可以满足超级电容器电导率的要求,被认为是理想的纤维状超级电容器的电极材料.主要综述了碳纳米管纤维、石墨烯纤维和碳纤维基超级电容器的制备方法、电化学性能和纤维状超级电容器的应用,重点介绍了一些国内外代表性的研究工作.最后分析了纤维状超级电容器研究中存在的问题,并对未来的研究方向和发展趋势进行了预测和展望.     

Graphene‐based electrodes for flexible electronics

As ‘flexibility’ has emerged as an important issue in next‐generation electronics, many efforts to find new classes of materials have been devoted to realizing stretchable, bendable and foldable electronic devices. For these devices to be realized, graphene has been considered as one of the most promising candidates for flexible electrodes due to its extraordinary electrical, optical and mechanical properties. Particularly, recent developments in the fabrication and modification of graphene point to a bright future for graphene electrodes in flexible electronics. This mini‐review summarizes the recent progress in graphene films as flexible electrodes for various applications such as solar cells, organic light‐emitting diodes, touchscreens, transistors and supercapacitors. © 2015 Society of Chemical Industry     

Manganese oxide on fluorine-doped SnO2 inverse opal frame as pseudocapacitor electrodes

We present F-doped SnO₂ (FTO) inverse opal (IO) core-MnO shell-structured electrodes for supercapacitors. The FTO IO core structure was prepared using a polymer-templating method, and the pseudocapacitive MnO material was electrodeposited on the surface to induce faradaic charge storage reactions. The synthesized material and its microstructure were characterized by X-ray diffraction, electron microscopy, and X-ray photoelectron spectroscopy. Cyclic voltammetry was used to investigate the electrochemical reaction kinetics of the MnO-FTO IO electrode. MnO-FTO planar electrodes were adopted as control samples. The electrode exhibited superior reaction kinetics which could be ascribed to its microstructure. The conductive FTO IO core provided electronic pathways, and its three-dimensional ordered mesoporous structure helped achieve fast electrolyte penetration. Additionally, the MnO shell material's high surface areas permitted rapid pseudocapacitive faradaic reactions. Up to 40,000 cycles of galvanostatic charge-discharge cycling were performed. The capacitance was well maintained over the extremely long cycles due to the mechanical stability of the MnO shell material.     

Hierarchical porous carbon derived from one-step self-activation of zinc gluconate for symmetric supercapacitors with high energy density

Porous carbons with high specific area surfaces are promising electrode materials for supercapacitors. However, their production usually involves complex, time-consuming, and corrosive processes. Hence, a straightforward and effective strategy is presented for producing highly porous carbons via a self-activation procedure utilizing zinc gluconate as the precursor. The volatile nature of zinc at high temperatures gives the carbons a large specific surface area and an abundance of mesopores, which avoids the use of additional activators and templates. Consequently, the obtained porous carbon electrode delivers a satisfactory specific capacitance and outstanding cycling durability of 90.9% after 50000 cycles at 10 A∙g^–1. The symmetric supercapacitors assembled by the optimal electrodes exhibit an acceptable rate capability and a distinguished cycling stability in both aqueous and ionic liquid electrolytes. Accordingly, capacitance retention rates of 77.8% and 85.7% are achieved after 50000 cycles in aqueous alkaline electrolyte and 10000 cycles in ionic liquid electrolyte. Moreover, the symmetric supercapacitors deliver high energy/power densities of 49.8 W∙h∙kg^–1/2477.8 W∙kg^–1 in the Et₄NBF₄ electrolyte, outperforming the majority of previously reported porous carbon-based symmetric supercapacitors in ionic liquid electrolytes.     

生物质基柔性超级电容器研究进展

随着可穿戴设备的发展及公众环保意识的提升,开发高性能兼绿色经济型的柔性电化学储能器件已成为研究热点。以生物质为前驱体制备性能优异的储能材料,可以显著降低生产成本,实现碳资源的可持续利用,具有极大的发展潜力和实际应用价值。该文介绍了柔性超级电容器的电极材料、柔性隔膜和各种组装方式,分析了木基、纤维素凝胶基、纸基以及生物质废料电极材料的特点和优势,阐述了生物质基柔性隔膜研究现状,包括纤维素纸隔膜和生物隔膜;此外,介绍了叠层型（三明治型）、叉指型（微型叉指化）、纤维型（线型）柔性超级电容器,并对比了不同组装方式的柔性超级电容器在性能上的差异;最后分析了生物质材料用于柔性超级电容器面临的挑战,对柔性器件未来发展方向进行了展望。     

Graphene and nanostructured MnO2 composite electrodes for supercapacitors

Graphene-based materials are promising electrodes for supercapacitors, owing to their unique two-dimensional structure, high surface area, remarkable chemical stability, and electrical conductivity. In this paper, graphene is explored as a platform for energy storage devices by decorating graphenes with flower-like MnO₂ nanostructures fabricated by electrodeposition. The as-prepared graphene and MnO₂, which were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), have been assembled into an asymmetric supercapacitor. The specific capacitance of the graphene electrode reached 245 F/g at a charging current of 1 mA after an electro-activation process. This value is more than 60% larger than the one before electro-activation. The MnO₂ nano-flowers which consisted of tiny rods with a thickness of less than 10 nm were coated onto the graphene electrodes by electrodeposition. The specific capacitance after the MnO₂ deposition is 328 F/g at the charging current of 1 mA with an energy density of 11.4 Wh/kg and 25.8 kW/kg of power density. This work suggests that our graphene-based electrodes are a promising candidate for the high-performance energy storage devices.