Organic Supercapacitors as the Next Generation Energy Storage Device: Emergence,Opportunity, and Challenges

Harnessing new materials for developing high-energy storage devices set off research in the field of organic supercapacitors. Various attractive properties like high energy density, lower device weight, excellent cycling stability, and impressive pseudocapacitive nature make organic supercapacitors suitable candidates for high-end storage device applications. This review highlights the overall progress and future of organic supercapacitors. Sustainable energy production and storage depend on low cost, large supercapacitor packs with high energy density. Organic supercapacitors with high pseudocapacitance, lightweight form factor, and higher device potential are alternatives to other energy storage devices. There are many recent ongoing research works that focus on organic electrolytes along with the material aspect of organic supercapacitors. This review summarizes the current research status and the chemistry behind the storage mechanism in organic supercapacitors to overcome the challenges and achieve superior performance for future opportunities.     

The Application of Graphene and Its Derivatives to Energy Conversion,Storage, and Environmental and Biosensing Devices

Graphene (GR) and its derivatives are promising materials on the horizon of nanotechnology and material science and have attracted a tremendous amount of research interest in recent years. The unique atom‐thick 2D structure with sp² hybridization and large specific surface area, high thermal conductivity, superior electron mobility, and chemical stability have made GR and its derivatives extremely attractive components for composite materials for solar energy conversion, energy storage, environmental purification, and biosensor applications. This review gives a brief introduction of GR's unique structure, band structure engineering, physical and chemical properties, and recent energy‐related progress of GR‐based materials in the fields of energy conversion (e.g., photocatalysis, photoelectrochemical water splitting, CO₂ reduction, dye‐sensitized and organic solar cells, and photosensitizers in photovoltaic devices) and energy storage (batteries, fuel cells, and supercapacitors). The vast coverage of advancements in environmental applications of GR‐based materials for photocatalytic degradation of organic pollutants, gas sensing, and removal of heavy‐metal ions is presented. Additionally, the use of graphene composites in the biosensing field is discussed. We conclude the review with remarks on the challenges, prospects, and further development of GR‐based materials in the exciting fields of energy, environment, and bioscience.     

层状双金属氢氧化物/石墨烯复合材料及其在电化学能量存储与转换中的应用

高效的电化学能量存储与转换功能材料及其器件近年来受到了人们的广泛关注。层状双金属氢氧化物/石墨烯（LDH/G）复合物就是一类重要的能源材料。它们兼具LDH和石墨烯的优异的物理、化学性能,同时克服了LDH导电性差和石墨烯片易于团聚的问题;在超级电容器和电化学催化分解水等方面具有广泛应用。本文综述了LDH与化学修饰石墨烯（氧化石墨烯,还原氧化石墨烯及其衍生物）的有效复合的方法及其在电化学能量存储与转换领域中的应用,特别是关于基于该类材料的超级电容器及电化学析氧反应催化的研究;对LDH/G复合材料研究领域中的挑战和未来发展方向做了展望。     

Recent developments in MoS2-based flexible supercapacitors

In the modern world, miniaturization of electronic devices for various applications is becoming more common. In particular, the development of flexible energy storage devices have received much attention since they have a superior role in the development of newer technologies such as in public wearables, portable electronic devices, and electronic skin proceeds. Considering the high power density, long cycle life, and shelf life as well as outstanding mechanical strength, flexible supercapacitors are one of the integral parts of these new technologies. In the recent past, researchers have developed innumerable nanomaterials to develop supercapacitors. Among these, MoS₂ has received much attention due to its several physical and chemical properties, which are more favorable for energy storage applications. Their sheet-like structure, high surface-to-volume ratio, ease of synthesis, flexibility, high mechanical strength, and pseudocapacitive storage mechanism make them potential candidates for flexible storage applications similar to graphene. This review provides recent applications and scope of MoS₂ in flexible supercapacitors in both composite forms with other carbon nanomaterials, metal oxides, and polymers as well as MoS₂ itself. Also, we will discuss some MoS₂-based self-standing devices, which can generate and store energy in a single device.     

Realizing both High Energy and High Power Densities by Twisting Three Carbon‐Nanotube‐Based Hybrid Fibers

Energy storage devices, such as lithium‐ion batteries and supercapacitors, are required for the modern electronics. However, the intrinsic characteristics of low power densities in batteries and low energy densities in supercapacitors have limited their applications. How to simultaneously realize high energy and power densities in one device remains a challenge. Herein a fiber‐shaped hybrid energy‐storage device (FESD) formed by twisting three carbon nanotube hybrid fibers demonstrates both high energy and power densities. For the FESD, the energy density (50 mWh cm^?3 or 90 Wh kg^?1) many times higher than for other forms of supercapacitors and approximately 3 times that of thin‐film batteries; the power density (1 W cm^?3 or 5970 W kg^?1) is approximately 140 times of thin‐film lithium‐ion battery. The FESD is flexible, weaveable and wearable, which offers promising advantages in the modern electronics.     

二氧化锰与二维材料复合应用于超级电容器

现如今世界正面临着与能源相关的一系列问题与挑战,科学家们致力于研究绿色高性能的能量存储器件以适应当前乃至以后长久可持续创新发展的需要。超级电容器作为一种新型的绿色能源储存装置,具有功率密度大、理论比电容高、充放电速度快、循环寿命长、安全性高、环境友好且经济等优点,为人类解决能源危机提出了可能。电极材料是影响超级电容器性能的重要因素。近些年,由于二氧化锰基超级电容器具有理论比电容高、化学稳定性好、环境友好等特点被广泛研究。同时多种二维材料也继石墨烯后被相继用作超级电容器电极材料,具有二维结构特征材料在提高双电层电容器的能量密度、改善赝电容电容器方面发挥着重要作用。实现高比电容和高倍率性能,将二氧化锰与二维材料复合将不失为一个有前景的选择。本文系统介绍了以石墨烯为代表的各类二维材料与二氧化锰复合物在超级电容器中的应用研究,并聚焦于这些二维材料与二氧化锰复合后所展现的优异电化学性能。     

Self‐Assembling Synthesis of Free‐standing Nanoporous Graphene–Transition‐Metal Oxide Flexible Electrodes for High‐Performance Lithium‐Ion Batteries and Supercapacitors

The synthesis of nanoporous graphene by a convenient carbon nanofiber assisted self‐assembly approach is reported. Porous structures with large pore volumes, high surface areas, and well‐controlled pore sizes were achieved by employing spherical silica as hard templates with different diameters. Through a general wet‐immersion method, transition‐metal oxide (Fe₃O₄, Co₃O₄, NiO) nanocrystals can be easily loaded into nanoporous graphene papers to form three‐dimensional flexible nanoarchitectures. When directly applied as electrodes in lithium‐ion batteries and supercapacitors, the materials exhibited superior electrochemical performances, including an ultra‐high specific capacity, an extended long cycle life, and a high rate capability. In particular, nanoporous Fe₃O₄–graphene composites can deliver a reversible specific capacity of 1427.5 mAh g^?1 at a high current density of 1000 mA g^?1 as anode materials in lithium‐ion batteries. Furthermore, nanoporous Co₃O₄–graphene composites achieved a high supercapacitance of 424.2 F g^?1. This work demonstrated that the as‐developed freestanding nanoporous graphene papers could have significant potential for energy storage and conversion applications.     

Recent Advances in Porous Carbon Materials for Electrochemical Energy Storage

Climate change and the energy crisis have promoted the rapid development of electrochemical energy‐storage devices. Owing to many intriguing physicochemical properties, such as excellent chemical stability, high electronic conductivity, and a large specific surface area, porous carbon materials have always been considering as a promising candidate for electrochemical energy storage. To date, a wide variety of porous carbon materials based upon molecular design, pore control, and compositional tailoring have been proposed for energy‐storage applications. This focus review summarizes recent advances in the synthesis of various porous carbon materials from the view of energy storage, particularly in the past three years. Their applications in representative electrochemical energy‐storage devices, such as lithium‐ion batteries, supercapacitors, and lithium‐ion hybrid capacitors, are discussed in this review, with a look forward to offer some inspiration and guidelines for the exploitation of advanced carbon‐based energy‐storage materials.     

Hybrid Fibers Made of Molybdenum Disulfide,Reduced Graphene Oxide,and Multi‐Walled Carbon Nanotubes for Solid‐State,Flexible, Asymmetric Supercapacitors

One of challenges existing in fiber‐based supercapacitors is how to achieve high energy density without compromising their rate stability. Owing to their unique physical, electronic, and electrochemical properties, two‐dimensional (2D) nanomaterials, e.g., molybdenum disulfide (MoS₂) and graphene, have attracted increasing research interest and been utilized as electrode materials in energy‐related applications. Herein, by incorporating MoS₂ and reduced graphene oxide (rGO) nanosheets into a well‐aligned multi‐walled carbon nanotube (MWCNT) sheet followed by twisting, MoS₂‐rGO/MWCNT and rGO/MWCNT fibers are fabricated, which can be used as the anode and cathode, respectively, for solid‐state, flexible, asymmetric supercapacitors. This fiber‐based asymmetric supercapacitor can operate in a wide potential window of 1.4 V with high Coulombic efficiency, good rate and cycling stability, and improved energy density.     

An overview on the recent developments in polyaniline‐based supercapacitors

With the ever‐increasing depletion of nonrenewable fossil fuel reserve, greater attention has been directed towards renewable energy storage devices. One of the most important of such devices is the supercapacitor, which exhibits high specific capacitance. Polyaniline (PAni) is a versatile conducting polymer, which has demonstrated excellent electrochemical properties along with good stability and ease of synthesis. Therefore, PAni has been extensively used in the fabrication of supercapacitors. In the last few decades, researchers have studied the effect of morphology, developed during the synthesis of PAni, on its electrochemical properties. It is known that the electrical conductivity and the electrochemical properties of PAni get influenced by the level and type of dopant used, the method of synthesis adopted, and the surface area and porosity possessed. However, it has been realized that supercapacitors based on PAni suffer from short cycle life. This led to development of PAni composites with carbon‐based materials and transition metal oxides. In this review, focus has been laid on the achieved performance levels of the recently developed PAni‐based supercapacitors. In addition, an attempt has been made to study the fundamental aspects of the conductivity and the electrochemical properties of PAni and their effect on the supercapacitor performance. Moreover, several new interesting applications of PAni‐based supercapacitors have also been included in this review.     

Hybrid Fibers Made of Molybdenum Disulfide,Reduced Graphene Oxide,and Multi‐Walled Carbon Nanotubes for Solid‐State,Flexible, Asymmetric Supercapacitors

One of challenges existing in fiber‐based supercapacitors is how to achieve high energy density without compromising their rate stability. Owing to their unique physical, electronic, and electrochemical properties, two‐dimensional (2D) nanomaterials, e.g., molybdenum disulfide (MoS₂) and graphene, have attracted increasing research interest and been utilized as electrode materials in energy‐related applications. Herein, by incorporating MoS₂ and reduced graphene oxide (rGO) nanosheets into a well‐aligned multi‐walled carbon nanotube (MWCNT) sheet followed by twisting, MoS₂‐rGO/MWCNT and rGO/MWCNT fibers are fabricated, which can be used as the anode and cathode, respectively, for solid‐state, flexible, asymmetric supercapacitors. This fiber‐based asymmetric supercapacitor can operate in a wide potential window of 1.4 V with high Coulombic efficiency, good rate and cycling stability, and improved energy density.     

Electrospun‐Technology‐Derived High‐Performance Electrochemical Energy Storage Devices

Electrospinning, as a novel nontextile filament technology, is an important method to prepare continuous nanofibers and has shown its remarkable advantages, such as a broadly applicable material system, controllable fiber size and structure, and simple process. Electrospun nanofiber membranes prepared by electrospinning have shown promising applications in many fields, such as supercapacitors, lithium‐ion batteries, and sodium‐ion batteries, owing to their large specific surface area and adjustable network pore structure. The principle of electrospinning and key points relevant to its usage in the preparation of high‐performance electrochemical energy storage materials are reviewed herein based on recent publications, particularly focusing on research progress of relative materials. Also, this review describes a distinctive conclusion and perspective on the future challenges and opportunities in electrospun nanomaterials.     

Fiber‐Based Flexible All‐Solid‐State Asymmetric Supercapacitors for Integrated Photodetecting System

Integrated nanodevices with the capability of storing energy are widely applicable and have thus been studied extensively. To meet the demand for flexible integrated devices, all‐solid‐state asymmetric supercapacitors that simultaneously realize energy storage and optoelectronic detection were fabricated by growing Co₃O₄ nanowires on nickel fibers, thus giving the positive electrode, and employing graphene as both the negative electrode and light‐sensitive material. The as‐assembled integrated systems were characterized by an improved energy storage, enhanced power density (at least by 1860 % enhanced) by improving the potential window from 0–0.6 V to 0—1.5 V, excellent photoresponse to white light, and superior flexibility of both the fiber‐based asymmetric supercapacitor and the photodetector. Such flexible integrated devices might be used in smart and self‐powered sensory, wearable, and portable electronics.     

Graphene/polymer composites for energy applications

Graphene has wide potential applications in energy-related systems, mainly because of its unique atom-thick two-dimensional structure, high electrical or thermal conductivity, optical transparency, great mechanical strength, inherent flexibility, and huge specific surface area. For this purpose, graphene materials are frequently blended with polymers to form composites, especially when fabricating flexible devices. Graphene/polymer composites have been explored as electrodes of supercapacitors or lithium ion batteries, counter electrodes of dye-sensitized solar cells, transparent conducting electrodes and active layers of organic solar cells, catalytic electrodes, and polymer electrolyte membranes of fuel cells. In this review, we summarize the recent advances on the synthesis and applications of graphene/polymer composites for energy applications. The challenges and prospects in this field have also been discussed. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013     

新型超级电容器的研发进展

传统超级电容器受低能量密度的限制,在当今器件研发中需更加关注电极材料结构-组成-性能研究。 本文总结了新型赝电容器的发展历程及其研发过程中存在的挑战与解决措施,着重从胶体离子超级电容器电极材料等新型的电极材料和氧化还原电解质两个方面进行综述。 原位合成的胶体离子超级电容器电极材料比非原位合成的电极材料具有更高的反应活性,并且以近似离子的状态存在,有效增加了电极材料的比容量。 氧化还原电解质的使用在不改变电极材料的前提下,进一步提高了超级电容器的能量密度。 初步介绍了新型锂离子电容器。 锂离子电容器同时使用电池型材料和电容型材料,可提高其能量密度。 依据当前超级电容器的研发现状,未来有望将电池材料和电容器材料结合使用,进而形成电池电容器或电容电池,使其同时具有高的能量密度和功率密度。     

石墨烯基纤维储能器件的研究进展与展望

随着小型化、可穿戴等特征的智能电子以及物联网传感设备的发展,新型纤维状柔性化、小型化电化学储能器件已成为重要的研究方向。同时,对纤维材料和柔性储能器件的性能提出了更高的要求,如可任意弯折、可拉伸、可折叠、高储能密度等。石墨烯纤维具有独特的结构、优异的导电性、良好机械性能和电化学性质,已证明了是一种极具前景、高性能的新型纤维状柔性储能材料。目前,研究者已开发了多种石墨烯基纤维微观结构的调控策略来进一步改进其性能。本文首先系统总结了石墨烯基纤维的制备方法和其性能提升的策略,然后详细讨论其在柔性化纤维状超级电容器、金属离子电池、热电发电机、太阳能电池和相变材料等储能领域中的最新应用进展。最后,对石墨烯基纤维在能源存储和转换领域中存在的挑战和机会进行了展望。     

《能源电化学材料》专辑序言

以电化学能量储存和转化为特点的电池、电容器等储能技术,正在信息通讯、新能源汽车、微电网、分布式发电、大型电力储能、智能电网等领域得到广泛应用,将有力推动能源互联网的快速发展. 作为储能核心技术之一的锂电池、钠电池与超级电容器,更加受到重视. 这些电化学储能装置的性能依赖于所使用的电极材料与结构等. 发展高能量密度、高功率密度和长循环寿命的低成本储能体系成为能源电化学材料研究的核心. 本专辑围绕锂离子电池、钠离子电池、锂硫电池、超级电容器等,收录了在该领域具有丰富研究经验的团队所撰写的8篇相关综述和研究论文. 其中,围绕下一代锂离子电池负极硅材料,邀请了3篇综述和研究论文;鉴于丰富的钠资源,在钠离子电池研究方面也邀请了3篇综述论文;同时在高能量密度的锂硫电池和高功率密度的超级电容器方面各邀请1篇论文. 从这些论文中,可以部分看出锂离子电池、钠离子电池、锂硫电池、超级电容器等能源电化学材料的研究进展. 希望借助此专辑的出版,能使广大读者更好地了解上述几类电池、电容器的研究现状,研究趋势和存在问题及挑战,为更深入地开展该领域研究提供参考,以推动我国能源电化学材料研究的进一步发展. 在此,对专辑的所有作者、审稿人及编辑部工作人员的辛勤劳动,表示最衷心的感谢！     

A review of transition metal chalcogenide/graphene nanocomposites for energy storage and conversion

Recent advances in the applications of transition metal chalcogenides/graphene (TMC/graphene) nanocomposites in future energy storage and conversion are reviewed. The synthesis processes and structures of TMC/graphene, workingpriciple of evergy energy device, and the electrochemical performances are summarized.     

Graphene-based electrochemical energy conversion and storage: fuel cells, supercapacitors and lithium ion batteries

Graphene has attracted extensive research interest due to its strictly 2-dimensional (2D) structure, which results in its unique electronic, thermal, mechanical, and chemical properties and potential technical applications. These remarkable characteristics of graphene, along with the inherent benefits of a carbon material, make it a promising candidate for application in electrochemical energy devices. This article reviews the methods of graphene preparation, introduces the unique electrochemical behavior of graphene, and summarizes the recent research and development on graphene-based fuel cells, supercapacitors and lithium ion batteries. In addition, promising areas are identified for the future development of graphene-based materials in electrochemical energy conversion and storage systems.     

氧化石墨烯诱导的Ni-Co氢氧化物整体电极的制备及电储能特性

超级电容器作为一种新型储能装置,由于其能量密度、功率密度高和良好的循环稳定性,而在实际工业应用中(新能源汽车、航天航空业、电子通信系统、可穿戴设备等)显示出巨大的潜力.但目前面临的最大挑战是构造柔性、轻薄可变形的储能设备.在本项研究工作中,利用溶剂热法和真空抽滤法开发了一种碳基/层状金属氢氧化物的复合材料.设计将氧化石...