石墨烯基电极材料在柔性全固态超级电容器中的研究进展

随着电子产品向着智能化、微型化和便携化的方向发展,亟需发展与之匹配的高效柔性储能器件。 超级电容器由于功率密度高、循环寿命长、安全无污染、易于实现其柔性化等特点,近年来引起人们的广泛关注。 石墨烯材料具有极高的比表面积、优异的电化学性能和良好的机械稳定性,被广泛作为柔性全固态超级电容器的电极材料。 本文简要介绍了石墨烯电极材料的制备方法,并总结了其在柔性全固态超级电容器中的最新研究进展,探讨了其发展前景和面临的挑战。     

Improving the performance of all-solid-state supercapacitors by modifying ionic liquid gel electrolytes with graphene nanosheets prepared by arc-discharge

Ionic liquid gel polymers have widely been used as the electrolytes in all-solid-state supercapacitors, but they suffer from low ionic conductivity and poor electrochemical performance. Arc discharge is a fast, low-cost and scalable method to prepare multi-layered graphene nanosheets, and as-made graphene nanosheets （denoted as ad-GNSs） with few defects, high electrical conductivity and high thermal stability should be favorable conductive additive materials. Here, a novel ionic liquid gel polymer electrolyte based on an ionic liquid （EM1MNTF2） and an copolymer （P（VDF-HFP）） was modified by the addition of ad-GNSs as an ionic conducting promoter. This modified gel electrolyte shows excellent thermal stability up to 400 ℃ and a wide electrochemical window of 3 V. An all-solid-state supercapacitor based on commercial activated carbon was fabricated using this modified ionic liquid gel polymer electrolyte, which shows obviously improved electrochemical behaviors compared with those of the corresponding all-solid-state supercapacitor using pure ionic liquid gel polymer electrolyte. Specially, smaller internal resistance, higher specific capacitance, better rate performance and cycling stability are achieved. These results indicate that the ionic liquid gel polymers modified by ad-GNSs would be promising and suitable gel electrolytes for high performance all-solid-state electrochemical devices.     

Paper-based supercapacitors for self-powered nanosystems

Energy storage on paper: paper-based, all-solid-state, and flexible supercapacitors were fabricated, which can be charged by a piezoelectric generator or solar cells and then discharged to power a strain sensor or a blue-light-emitting diode, demonstrating its efficient energy management in self-powered nanosystems.     

聚合物水凝胶基超级电容器的研究进展

可伸展性和可压缩性是超级电容器作为现代柔性可穿戴电子设备的关键性能。聚合物水凝胶因其优异的力学性能、独特的网络状结构等优点,成为新一代高性能超级电容器的理想材料。它不仅可作为高效储能的柔性电极材料,而且可作为准固态电解质材料,在克服传统液体电解质系列缺陷的同时,获得更加轻薄、安全、稳定的柔性全固态储能器件。本文以聚合物水凝胶的化学组成为线索,分别介绍了聚合物水凝胶在超级电容器电极和电解质两方面的应用研究进展,并进一步对聚合物水凝胶在该领域的发展趋势进行了展望。     

Paper-based all-solid-state flexible asymmetric micro-supercapacitors fabricated by a simple pencil drawing methodology

A simple and novel methodology was developed for manufacturing interdigitated asymmetric all-solid-state flexible micro-supercapacitors (MSCs) by a facile pencil drawing process followed by electrodepositing MnO₂ on one of the as-drawn graphite electrode as anode and the other as cathode.     

Surface modulated hierarchical graphene film via sulfur and phosphorus dual-doping for high performance flexible supercapacitors

The steam-assistant heteroatoms of sulfur and phosphorus dual-doped graphene film fabricated via an ice-template and thermal-activation approach demonstrates an excellent pseudocapacitive behavior in flexible electrochemical capacitors.     

Flexible asymmetric supercapacitor with high energy density based on optimized MnO2 cathode and Fe2O3 anode

A flexible asymmetric supercapacitor is assembled using MnO₂ nanosheets/carbon fabric and Fe₂O₃/carbon fabric electrodes. By optimizing the reaction condition of the two electrodes, the device shows high energy densities and excellent flexibility.     

Self-propagating fabrication of 3D porous MXene-rGO film electrode for high-performance supercapacitors

2D MXene nanosheets with metallic conductivity and high pseudo-capacitance are promising electrode materials for supercapacitors.Especially,MXene films can be directly used as electrodes for flexible supercapacitors.However,they suffer from sluggish ion transport due to self-restacking,causing limited electrochemical performance.Herein,a flexible 3D porous MXene film is fabricated by incorporating graphene oxide(GO) into MXene film followed by self-propagating reduction.The self-propagating process is facile and effective,which can be accomplished in 1.25 s and result in 3D porous framework by releasing substantial gas instantaneously.As the 3D porous structure provides massive ion-accessible active sites and promotes fast ion transport,the MXene-rGO films exhibit superior capacitance and rate performance.With the rGO content of 20%,the MXene-rGO-20 film delivers a high capacitance of 329.9 F g^-1 at 5 mV s^-1 in 3 M H2 SO4 electrolyte and remains 260.1 F g^-1 at 1,000 mV s^-1 as well as good flexibility.Furthermore,the initial capacitance is retained above 90% after 40,000 cycles at 100 A g^-1,revealing good cycle stability.This work not only provides a high-performance flexible electrode for supercapacitors,but also proposes an efficient and time-saving strategy for constructing 3D structure from 2D materials.     

Recent progress in 2D materials for flexible supercapacitors

High performance supercapacitors coupled with mechanical flexibility are needed to drive flexible and wearable electronics that have anesthetic appeal and multi-functionality. Two dimensional (2D) materials have attracted attention owing to their unique physicochemical and electrochemical properties, in addition to their ability to form hetero-structures with other nanomaterials further improving mechanical and electrochemical properties. After a brief introduction of supercapacitors and 2D materials, recent progress on flexible supercapacitors using 2D materials is reviewed. Here we provide insights into the structure–property relationships of flexible electrodes, in particular free-standing films. We also present our perspectives on the development of flexible supercapacitors.     

Highly Stretchable and Conductive Hybrid Fibers for High-performance Fibrous Electrodes and All-solid-state Supercapacitors

The development of lightweight, flexible, and stretchable energy storage systems is essential for state-of-the-art electronic devices.We propose a new and broad strategy to fabricate a stretchable and conductive GO/CNTs-TPU fiber electrode by direct wet spinning, from which a flexible fibrous supercapacitor is fabricated. The fibrous electrode exhibits a high strength of 11.68 MPa, high conductivity of 342 S/cm, and high specific capacitances(21.8 mF/cm, 36.45 F/cm~3, and 95 F/g). The specific capacitance of the assembled all-solid-state hybrid fiber-shaped supercapacitor reaches 14.3 F/cm~3. After 5000 charge-discharge cycles, 97% of the capacitance of the hybrid supercapacitor is maintained. These high-strength electrochemical electrode materials could be potential candidates for applications in practical and large-scale energy storage systems and textile clothes.     

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.     

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.     

Strong and Robust Polyaniline‐Based Supramolecular Hydrogels for Flexible Supercapacitors

We report a supramolecular strategy to prepare conductive hydrogels with outstanding mechanical and electrochemical properties, which are utilized for flexible solid‐state supercapacitors (SCs) with high performance. The supramolecular assembly of polyaniline and polyvinyl alcohol through dynamic boronate bond yields the polyaniline–polyvinyl alcohol hydrogel (PPH), which shows remarkable tensile strength (5.3 MPa) and electrochemical capacitance (928 F g^?1). The flexible solid‐state supercapacitor based on PPH provides a large capacitance (306 mF cm^?2 and 153 F g^?1) and a high energy density of 13.6 Wh kg^?1, superior to other flexible supercapacitors. The robustness of the PPH‐based supercapacitor is demonstrated by the 100 % capacitance retention after 1000 mechanical folding cycles, and the 90 % capacitance retention after 1000 galvanostatic charge–discharge cycles. The high activity and robustness enable the PPH‐based supercapacitor as a promising power device for flexible electronics.     

电沉积法制备聚(3,4-乙烯二氧噻吩)微米管及其在柔性全固态超级电容器的应用

通过一步电沉积方法制备了不同的酸介质和表面活性剂掺杂的聚(3,4-乙烯二氧噻吩)(PEDOT)微米管电极材料,并用其来制备柔性的全固态对称超级电容器。同时探究了沉积时间对相同的酸介质和表面活性剂掺杂的PEDOT微米管电容性能的影响。最终产物的结构通过各种表征技术进行表征,包括扫描电子显微镜(SEM)和FT-IR光谱。电化学结果表明,用硫酸(H2SO4)和十二烷基硫酸钠(SDS)掺杂的PEDOT微米管的电容性能明显提升。用沉积时间为600 s的PEDOT微米管所制备的超级电容器的面积比电容在10 mV·s-1的扫速下达到113.5 mF·cm~(-2)。在不同的弯曲角度下,该固态的对称超级电容器的面积比电容仍保持初始电容值的93%,表明其具有较高的柔性。此外,在电流密度为0.6 mA·cm~(-2)的条件下经过2 000次循环后,其电容值几乎保持初始电容值的95.5%,显示出优异的循环稳定性。制备出来的柔性全固态超级电容器可点亮LED灯,表明其能够满足微电源的实际应用。     

3D braided yarns to create electrochemical cells

The demands for new configurations of electrochemical cells continue to grow and novel approaches are being enabled by the advent of new electromaterials and novel fabrication strategies. Wearable energy storage devices that can be seamlessly integrated into garments are a critical component of the wearable electronics genre. Recently, flexible yarn supercapacitors have attracted significant attention due to their ability to be integrated into fabrics, or stitched into existing textiles. Large-scale production of yarn supercapacitors using conventional manufacturing processes, however, is still a challenge. Here, we introduce the use of braiding technology to achieve a predetermined arrangement of fibre electrodes, the basis of a mass fabrication protocol to produce specific electrochemical cells: wearable supercapacitors. The resultant supercapacitors show a high capacitance of 1.71 mF cm^− 1. The structure is highly flexible with a 25% capacitance loss recorded after 1000 bending cycles.     

可用至3.5 V的碳纳米管阵列超级电容器

应用化学气相沉积在钽片和不锈钢片表面直接生长碳纳米管阵列(CNTA)制备超级电容器电极,并分别作正、负极组装有机体系扣式电容器.扫描电子显微镜、循环伏安、恒电流充放电和交流阻抗表征、测试材料的微观形貌和电化学性能.结果表明,该电容器可获得高达3.5 V的工作电压,较长的循环寿命,较好的倍率性能.基于CNTA质量的比功率和比能量性能分别为928 kW.kg-1和19 Wh.kg-1.     

Hierarchical Mn3O4 Anchored on 3D Graphene Aerogels via C−O−Mn Linkage with Superior Electrochemical Performance for Flexible Asymmetric Supercapacitor

Flexible asymmetric supercapacitors are more appealing in flexible electronics because of high power density, wide cell voltage, and higher energy density than symmetric supercapacitors in aqueous electrolyte. In virtues of excellent conductivity, rich porous structure and interconnected honeycomb structure, three dimensional graphene aerogels show great potential as electrode in asymmetric supercapacitors. However, graphene aerogels are rarely used in flexible asymmetric supercapacitors because of easily re-stacking of graphene sheets, resulting in low electrochemical activity. Herein, flower-like hierarchical Mn₃O₄ and carbon nanohorns are incorporated into three dimensional graphene aerogels to restrain the stack of graphene sheets, and are applied as the positive and negative electrode for asymmetric supercapacitors devices, respectively. Besides, a strong chemical coupling between Mn₃O₄ and graphene via the C-O-Mn linkage is constructed and can provide a good electron-transport pathway during cycles. Consequently, the asymmetric supercapacitor device shows high rate cycle stability (87.8 % after 5000 cycles) and achieves a high energy density of 17.4 μWh cm⁻² with power density of 14.1 mW cm⁻² (156.7 mW cm⁻³) at 1.4 V.     

聚吡咯纳米线凝胶的模板制备及储能与电化学传感性能

以配位聚合物凝胶为模板,构筑均一的聚吡咯纳米线网络,聚合后经简单处理除去模板,得到性能优异的聚吡咯凝胶.结果表明,模板法合成的聚吡咯凝胶为由均一纳米线组成的三维网络结构,具有良好的力学性能、较大的比表面积及优异的电化学特性,在0.28 A/g电流密度下,比电容可达450 F/g,在2.8 A/g电流密度下充放电1000次,比电容仍可保持88.6%.聚吡咯纳米线网络凝胶经葡萄糖氧化酶负载后得到柔性传感电极,对低浓度(0.2 mmol/L)的葡萄糖具有快速响应性能,有望用于超级电容器及生物电化学传感器等领域.     

Application of novel room temperature ionic liquids in flexible supercapacitors

This paper studied application of different types of room temperature ionic liquids (RTILs) into flexible supercapacitors. Typical RTILs including 1-buthyl-3-methyl-imidazolium [BMIM][Cl], trioctylmethylammonium bis(trifluoromethylsulfonyl)imide [OMA][TFSI] and triethylsulfonium bis(trifluoromethylsulfonyl)imide ([SET₃][TFSI]) were studied. [SET₃][TFSI] shows the best result as electrolyte in electrochemical double-layer (EDLC) supercapacitors with very high specific capacitance of 244 F/g at room temperature, overceiling the performance of conventional carbonate electrolyte such as dimethyl carbonate (DMC) with more stable performance and much larger electrochemical window.     

Efficient electrochemical incineration of phenol on activated carbon fiber as a new type of particulates

The feasibility of activated carbon fibers (ACFs) used as a new type of particle electrodes in 3-dimensional (3D) electrode for the electrochemical degradation of phenol wastewater was investigated for the first time. The surface morphology, textual properties and electrochemical behaviors of ACF were studied by scanning electron microscopy (SEM), N₂-BET sorption and cyclic voltammograms (CVs), respectively. Compared with the commercialized granular activated carbon (GAC), ACF particle electrodes exhibited higher electrochemical oxidation performance on the mineralization of target pollutant. The identification of intermediates indicated most of oxidation products were adsorbed onto the ACFs. The detection of hydrogen peroxide and hydroxyl radicals in the reaction system suggested that the reaction mechanism was direct anodic oxidation of pollutant on ACFs if the cathode did not contact the ACFs. The operative parameters including initial concentration of substrate, applied current density and the initial aqueous pH have been scientifically studied in search of the optimum condition. Based upon the obtained results, the ACFs longevity was tested in solution at pH 2.0, revealing relatively high electrooxidation capacity and long catalyst lifetime of ACFs in acid solution.