Compact energy storage: Opportunities and challenges of graphene for supercapacitors

碳纳米储能材料发展迅速,质量容量性能不断刷新。但通常碳纳米材料的密度较低,导致其体积比容量有限,在很多时候很难将材料水平上的优异性能反映到最终的器件上。发展高体积能量密度储能材料,在器件水平上实现致密储能,对推动储能材料和器件的实用化至关重要。作为其它sp2碳质材料的基本结构单元和一种柔性二维材料,石墨烯通过组装可以实现纳米结构致密化,在致密储能方面具有先天优势。本文以石墨烯在超级电容器中的应用为主,分别从材料、电极、器件3个层次讨论了实用化储能器件的设计原则,梳理了高体积能量密度碳基储能材料的研究进展,重点介绍了高体积容量碳电极材料的致密化设计理念,强调了从器件角度考虑储能材料设计的重要性,并对致密储能面临的机遇和挑战作了分析。     

Electrode and electrolyte materials for electrochemical capacitors

Among different electric energy storage technologies electrochemical capacitors are used for energy storage applications when high power delivery or uptake is needed. Their energy and power densities, durability and efficiency are influenced by electrode and electrolyte materials however due to a high cost/performance ratio; their widespread use in energy storage systems has not been attained yet.Thanks to their properties such as high surface area, controllable pore size, low electrical resistance, good polarizability and inertness; activated carbons derived from polymeric precursors are the most used electrode materials in electrochemical capacitors at present. Other electrode materials such as shaped nano-carbons or metal oxides are also investigated as electrode materials in electrochemical capacitors, but only as useful research tools.Most commercially used electrochemical capacitors employ organic electrolytes when offering concomitant high energy and high power densities. The use of aqueous based electrolytes in electrochemical capacitor applications is mainly limited to research purposes as a result of their narrow operating voltage. Recent studies on room temperature ionic liquids to be employed as electrolyte for electrochemical capacitor applications are focused on fine tuning their physical and transport properties in order to bring the energy density of the device closer to that of batteries without compromising the power densities.In this paper a performance analysis, recent progress and the direction of future developments of various types of materials used in the fabrication of electrodes for electrochemical capacitors are presented. The influence of different types of electrolytes on the performance of electrochemical capacitors such as their output voltage and energy/power densities is also discussed.     

A critical review on progress of the electrode materials of vanadium redox flow battery

Nowadays, renewable energy sources are taken great attention by the researchers and the investors around the world due to increasing energy demand of today's knowledge societies. Since these sources are non-continuous, the effective storage and re-use of the energy produced from renewable energy sources have great importance. Although classical energy storage systems such as lead acid batteries and Li-ion batteries can be used for this goal, the new generation energy storage system is needed for large-scale energy storage applications. In this point, vanadium redox flow batteries (VRFBs) are shinning like a star for this area. VRFBs consist of electrode, electrolyte, and membrane component. The battery electrodes as positive and negative electrodes play a key role on the performance and cyclic life of the system. In this work, electrode materials used as positive electrode, negative electrode, and both of electrodes in the latest literature were complained and presented. From graphene-coated and heteroatom-doped carbon-based electrodes to metal oxides decorated carbon-based electrodes, a large scale on the modification of carbon-based electrodes is available on the electrode materials of the VRFBs. By the discovering of novel electrode components for the battery system, the using of the VRFBs probably increase in a short time for many industrial and residential applications.     

全钒液流电池用电极及双极板研究进展

全钒氧化还原液流储能电池是一种新型的储能装置,电极及双极板是其关键材料。介绍了全钒液流储能电池的两种电极（金属电极、碳素电极）和三种双极板（金属双极板、碳塑双极板和石墨双极板）以及一体化电极双极板的研究进展。     

Conjugated carbonyl compounds as electrode materials for sodium-ion/potassium-ion batteries

钠（钾）离子电池资源丰富、成本低廉,是极具大规模应用潜力的新型电池体系。然而,受制于较大的钠（钾）离子半径,这两类电池电极材料的选择受到了极大的限制。以共轭羰基化合物为代表的有机电极材料具有柔性的骨架结构,对阳离子半径选择性小,且结构多样、理论比容量高、环境友好,基于有机共轭羰基化合物构建的钠（钾）离子电池是未来“绿色电池”发展的重要方向。本文介绍了共轭羰基化合物的分类、储钠/钾性能及机理,重点探讨了羰基化合物作为储钠（钾）材料存在的问题和改进方法。最后,总结了羰基化合物作为钠钾离子电池电极材料存在的基础科学问题、技术挑战以及竞争力,同时进一步展望了有机共轭羰基化合物的发展方向以及大规模储能领域的应用前景。     

Fundamental scientific aspects of lithium batteries(I)--Thermodynamic calculations of theoretical energy densities of chemical energy storage systems

本文主要讨论电池的能量密度.基于热力学数据,根据能斯特方程,可以计算不同电化学反应体系的理论能量储存密度,从而了解化学储能体系理论能量密度的上限,了解哪些体系能够实现更高的能量密度,哪些材料具有更高的电压.     

Research on key materials for potassium ion batteries

钾具有资源丰富、价格低廉以及较低的电化学电势的特点,利用其开发的钾离子电池具有低成本、长寿命、能量密度高等特点,可满足储能领域需要。然而,钾离子半径大和质量大,给电池电极材料与电解质材料开发提出新的挑战。近年来,在电动汽车与储能应用等重大需求的牵引下,人们对钾离子电池的高容量电极材料和电解液进行了大量的研究工作。其中普鲁士蓝及其类似物、过渡金属氧化物和聚阴离子材料等正极材料展现了应用前景;负极材料主要包括碳基、钛基和合金类材料;电解质材料有酯类电解质和醚类电解质,这些研究成果为钾离子电池的基础与应用研究提供了重要的指导意义。     

Investigation of germanium selenide electrodes for the integrated photo-rechargeable battery

Autonomous photo-rechargeable electronic energy storage device has become a new type of solution to the problems of renewable energy fluctuations and storage. The combination of light conversion equipment and energy storage equipment improves the packaging efficiency of the equipment, however how to explore a type of electrode materials for energy collection and storage become a real challenging issue. Here, we try to explore the GeSe nanoparticles as the potential idea electrode for the integrated photo-rechargeable battery. On the one hand, GeSe nanoparticle electrode shows good Li⁺ storage performances. At the current density of 0.2 A g⁻¹, its reversible capacity is 670 mAh g⁻¹ after 100 cycles. On the other hand, during the photo-voltaic measurement, GeSe electrodes could generate a photocurrent that increases by 8 uA/cm² under the visible light irradiation in aqueous electrolyte. When LiClO₄ in polycarbonate solvent is used as the electrolyte, the electrons move in the reverse direction from the GeSe electrode, form reverse current, reduce Li⁺ to lithium metal, and finally store light energy into chemical energy in a short time. Considering its presenting behaviors in Li⁺ storage and photon harvesting, our research proposed the possibility for the application of GeSe materials in the integrated photo-rechargeable batteries.     

Recent progress of electrode materials for room-temperature sodium-ion stationary batteries

随着风能、太阳能等可再生能源的不断发展,储能作为影响其发展的关键技术越来越受到人们的关注。在储能领域,锂离子电池以高能量密度、长循环寿命、高电压等诸多优点在电子领域已得到广泛的应用,并成为未来电动汽车动力电池的最佳选择。但因锂资源储量有限、分布不均匀,而且原材料成本比较高,所以锂离子电池在电网大规模储能方面的应用遇到了瓶颈。与锂相比,钠不但具有与锂相似的物理化学性质,更具有资源丰富、分布广泛、原料成本低廉等优势。近些年室温钠离子电池再次引起了人们的研究兴趣,特别是在电网储能方面表现出极大的应用潜力。虽然目前已报道了多种钠离子电池电极材料,但大都离实用化以及进一步产业化尚有一定的距离。本文重点介绍一些性能较为突出的室温钠离子电池电极材料,并指出要实现钠离子电池的产业化,需要开发空气中稳定、高安全、高容量、高倍率、循环稳定、低成本的新型正、负极材料。     

Research progress of electrode suspensions of lithium-ion flow batteries

锂离子液流电池将锂离子电池的工作原理与传统液流电池的结构特点相结合,是一种正处于基础技术开发阶段的新型电化学储能电池技术,具有输出功率和储能容量彼此独立、成本较低等特点,适用于未来电网储能领域。电极悬浮液作为实现锂离子液流电池充放电功能的主体材料,其导电性能和流动性能是影响锂离子液流电池倍率特性和能量密度的重要因素。论文结合实验数据对该方向面临的主要技术问题及研究重点进行了分析,认为电极悬浮液的研究需要从导电机理、质量比容量、流变性能等方面进一步深入研究,并建立标准评价体系。     

Economic analysis for room-temperature sodium-ion battery technologies

随着人们对新能源和环境的重视,锂离子电池的应用逐渐扩展到电动汽车和储能领域,这势必增加了锂资源的使用和消耗.在锂资源日益紧缺的形势下,锂离子电池原材料成本必然难以降低,使其在大规模储能中的应用受到限制.而室温钠离子电池由于其资源丰富,成本低,能量转换效率高,循环寿命长,维护费用低等诸多优势已成为目前研究的热点.本文对室温钠离子电池材料选择和原材料成本进行了分析,并与当前常用的锂离子电池体系进行对比,从电池经济性角度表明室温钠离子电池是大规模储能领域的优秀备选电池.     

Application of Calix[4]quinone in secondary batteries

随着社会对大型储能设备的环保、充放电性能以及可持续发展的要求越来越高,基于金属氧化物的传统锂/钠离子电极材料受限于比容量,已难以满足未来储能系统的要求。有机材料、锂-硫/氧、液态流体等电池的研发与应用已成为未来能源系统研究的重要内容。其中,有机正极材料中的羰基类化合物Calix[4]quinone（C4Q）是一种很有前途的正极材料。该分子的空间位阻小,8个羰基结构都能发生可逆电极反应,其理论比容量高达446 mA·h/g,远超传统无机电极材料。C4Q不仅可以作为储锂材料,也可作为钠、锌、镁等二次电池的电极材料。本文分别介绍了C4Q在锂、钠二次电池和锌水系电池中的应用成果,并对C4Q今后进一步的开发利用做了展望。     

Graphene‐based ternary composites for supercapacitors

The research on electrode materials for supercapacitor application continues to evolve as the request of high‐energy storage system has increased globally due to the demand for energy consumption. Over the past decades, various types of carbon‐based materials have been employed as electrode materials for high‐performance supercapacitor application. Among them, graphene is 1 of the most widely used carbon‐based materials due to its excellent properties including high surface area and excellent conductivity. To exploit more of its interesting properties, graphene is tailored to produce graphene oxide and reduced graphene oxide to improve the dispersibility in water and easy to be incorporated with other materials to form binary composites or even ternary composites. Nowadays, ternary composites have attracted enormous interest as 2 materials (binary composites) cannot satisfy the requirement of the high‐performance supercapacitor. Thus, many approaches have been employed to fabricate ternary composites by combining 3 different types of electroactive materials for high‐performance supercapacitor application. This review focuses on the supercapacitive performance of graphene‐based ternary composites with different types of active materials, ie, conducting polymers, metal oxide, and other carbon‐based materials.     

Self-discharge behavior and its temperature dependence of carbon electrodes in lithium-ion batteries

Self-discharging characteristics of negative electrodes with different carbon materials have been investigated by monitoring the open circuit potential (OCP), the capacity loss and the ac impedance change during the storage at different temperatures. The OCP change with the storage time reflected state-of-charge (SOC), which depended on both the carbon material and the storage temperature. Higher specific surface area of the material and higher storage temperature lead to higher self-discharging rate. The activation energy for self-discharging was estimated from the temperature dependence of the self-discharging rate. Although small difference was observed among the materials, the value of the activation energy suggests that the self-discharging reaction at each electrode is controlled by a diffusion process. Changes in the interfacial resistance with the storage time reflected the growth of so-called Solid Electrolyte Interphase (SEI) at carbon surface. The rate of SEI formation at lower temperature does not depend on the carbon material, but at higher storage temperature the rate on spherical graphite was much higher than those on the other carbon materials.     

金属有机框架及其衍生金属氧化物在锂和钠离子电池中的应用

高性能锂和钠离子电池是未来便携电子设备、电动汽车和大规模储能电站的重要组成部分,受到了各行业的广泛关注。目前商用的锂离子电池和研发中的钠离子电池都面临着一些技术瓶颈,主要表现为能量密度低、充放电慢等,导致无法满足市场的需求。具有独特结构、高比表面积的金属有机框架及其衍生金属氧化物可作为电化学储能器件新型电极材料,满足高性能锂和钠离子电池的要求。本文综述了近年来金属有机框架及其衍生金属氧化物作为锂和钠离子电池电极材料的研究进展,同时指出了金属有机框架及其衍生金属氧化物在实际应用中的不足及未来可能的一些改进措施。     

Recent progress in the application of carbon materials to supercapacitors and lead-carbon batteries

新型炭材料是电化学储能领域中非常重要的一类储能材料,目前广泛应用于各种电化学储能器件.本文综述了具有电容特性的高比表面积炭材料在超级电容器与铅炭电池中的应用.采用不同的方法合成具有高比表面积的新型炭材料作为超级电容器电极材料,能够得到较高的比容量.适量高比表面积的炭材料应用于铅酸电池负极,形成铅炭电池,极大地提高了电池的储能特性.论文最后探讨了新型炭材料在超电容以及铅炭电池中应用的发展方向.     

Self-assembly of novel cobalt iron phosphate nanoparticles for the solid-state supercapattery and high-performance hydrogen evolution reaction

In this article, we report the preparation of novel cobalt iron phosphate nanoparticles which are self-assembled for energy storage, energy conversion, and sustainability. The self-assembled nanoparticles provide an efficient pathway for the transfer of electrons from the bulk of the materials to the interface of the electrode. This hypothesis has been derived from the analysis based on the electrochemical results for the supercapacitor-based energy storage and hydrogen evolution. The electrode consisting of self-assembled nanoparticles exhibits a maximum specific capacity of 280 C g⁻¹ at a specific current of 1 A g⁻¹. The cyclic voltammetric results suggest the prominent charge storage is by the faradaic reaction which has been concluded from Dunn's approach. The supercapattery device utilizing activated carbon (AC) as the negative electrode and cobalt iron phosphate as the positive electrode exhibit a specific capacity of 210 C g⁻¹ at 2 A g⁻¹ while the specific energy of 47.6 Wh kg^-1 at 1.6 kW kg⁻¹. Furthermore, the electrode actively catalyzes the electrochemical hydrogen evolution reaction and it can be lowering the overpotential required by the hydrogen generation. It exhibits the overpotential of 197 mV while the electrode represents the long-time (24 h) consistency for hydrogen production. These results indicate that the novel cobalt iron phosphate nanoparticles could be a potential candidate for energy storage and conversion purposes.     

Research progress on biomass-derived carbon electrode materials for electrochemical energy storage and conversion technologies

Electrochemical energy technologies such as fuel cells, supercapacitors, and batteries are some of the most suitable energy storage and conversion devices to meet our needs proving the future generation’s equitable opportunity to meet their own needs. For this purpose, an earth-abundant precursor such as biomass is the best candidate for the synthesis of the next generation of low-cost and green electrode materials. This review summarizes the most recent progress in biomass-derived carbons for use in fuel cells, supercapacitors and lithium-ion batteries, the physical-chemical properties, desired features, performances, and limitations for electrochemical energy technologies. Several thermochemical treatments such as chemical activation, template methods, doping and hydrothermal treatments have been reviewed. Finally, we provide the reader with comprehensive information of the challenges, future research efforts, advantages, limitations and opportunities which will be a fundamental insight for the future design of biomass-derived carbon electrode materials for electrochemical storage and conversion systems.     

Calculation on energy densities of lithium ion batteries and metallic lithium ion batteries

锂电池是理论能量密度最高的化学储能体系,估算各类锂电池电芯和单体能达到的能量密度,对于确定锂电池的发展方向和研发目标具有重要的参考价值。本工作根据主要正负极材料的比容量、电压,同时考虑非活性物质集流体、导电添加剂、黏结剂、隔膜、电解液、封装材料占比,计算了不同材料体系组成的锂离子电池和采用金属锂负极、嵌入类化合物正极的金属锂离子电池电芯的预期能量密度,并计算了18650型小型圆柱电池单体的能量密度,为电池发展路线的选择和能量密度所能达到的数值提供参考依据。同时指出,电池能量密度只是电池应用考虑的一个重要指标,面向实际应用,需要兼顾其它技术指标的实现。     

Capacitance-dominated hierarchical porous three-dimensional carbon framework enhanced Prussian blue analogue as superior cathode for sodium-ion batteries

The 3D framework carbon is an ideal host of active materials for energy storage batteries. In this work, K_xNa_yMn[Fe(CN)₆] (KNMF) nanocubes were in-situ grown on hierarchical porous 3D framework carbon (3DFC) to construct a composite cathode (KNMF@3DFC) for sodium-ion batteries. Owing to the hierarchical porous structure and large specific surface area, the highly conductive 3DFC offers abundant active sites for sodium storage and contributes to extra capacity. The considerable content of surface capacitance-dominated sodium storage of KNMF@3DFC composite cathode reveals faster charge transfer and better reaction kinetics, conducing to its rate capability. Ex-situ XRD/Raman measurements further reveal well structural stability of KNMF@3DFC during the whole cycle. Consequently, the KNMF@3DFC composite electrode reveals excellent rate performance and superior long-term cycling stability. Combining active materials with 3D framework carbon to enable a capacitance-dominated sodium storage mechanism is a promising strategy to stimulate the development of advanced electrode materials.