共查询到20条相似文献，搜索用时 0 毫秒
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Qun‐Zheng Zhang Dian Zhang Zong‐Cheng Miao Xun‐Li Zhang Shu‐Lei Chou 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(24)
With the serious impact of fossil fuels on the environment and the rapid development of the global economy, the development of clean and usable energy storage devices has become one of the most important themes of sustainable development in the world today. Supercapacitors are a new type of green energy storage device, with high power density, long cycle life, wide temperature range, and both economic and environmental advantages. In many industries, they have enormous application prospects. Electrode materials are an important factor affecting the performance of supercapacitors. MnO2‐based materials are widely investigated for supercapacitors because of their high theoretical capacitance, good chemical stability, low cost, and environmental friendliness. To achieve high specific capacitance and high rate capability, the current best solution is to use MnO2 and carbon composite materials. Herein, MnO2–carbon composite as supercapacitor electrode materials is reviewed including the synthesis method and research status in recent years. Finally, the challenges and future development directions of an MnO2–carbon based supercapacitor are summarized. 相似文献
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Weixing Song Jianxiong Zhu Baoheng Gan Shuyu Zhao Hui Wang Congju Li Jie Wang 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(1)
The graphene with 3D porous network structure is directly laser‐induced on polyimide sheets at room temperature in ambient environment by an inexpensive and one‐step method, then transferred to silicon rubber substrate to obtain highly stretchable, transparent, and flexible electrode of the all‐solid‐state planar microsupercapacitors. The electrochemical capacitance properties of the graphene electrodes are further enhanced by nitrogen doping and with conductive poly(3,4‐ethylenedioxythiophene) coating. With excellent flexibility, stretchability, and capacitance properties, the planar microsupercapacitors present a great potential in fashionable and comfortable designs for wearable electronics. 相似文献
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Yongting Qiu Mingzhen Hou Jingchang Gao Haili Zhai Haimin Liu Mengmeng Jin Xiang Liu Linfei Lai 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(45)
Cost‐effective synthesis of carbon nanospheres with a desirable mesoporous network for diversified energy storage applications remains a challenge. Herein, a direct templating strategy is developed to fabricate monodispersed N‐doped mesoporous carbon nanospheres (NMCSs) with an average particle size of 100 nm, a pore diameter of 4 nm, and a specific area of 1093 m2 g?1. Hexadecyl trimethyl ammonium bromide and tetraethyl orthosilicate not only play key roles in the evolution of mesopores but also guide the assembly of phenolic resins to generate carbon nanospheres. Benefiting from the high surface area and optimum mesopore structure, NMCSs deliver a large specific capacitance up to 433 F g?1 in 1 m H2SO4. The NMCS electrodes–based symmetric sandwich supercapacitor has an output voltage of 1.4 V in polyvinyl alcohol/H2SO4 gel electrolyte and delivers an energy density of 10.9 Wh kg?1 at a power density of 14014.5 W kg?1. Notably, NMCSs can be directly applied through the mask‐assisted casting technique by a doctor blade to fabricate micro‐supercapacitors. The micro‐supercapacitors exhibit excellent mechanical flexibility, long‐term stability, and reliable power output. 相似文献
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Zhiqiang Niu Weiya Zhou Xiaodong Chen Jun Chen Sishen Xie 《Advanced materials (Deerfield Beach, Fla.)》2015,27(39):6002-6008
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Huichao Liu Sheng Zhu Yu Zhang Hua Song Ying Zhang Yunzhen Chang Wenjing Hou Gaoyi Han 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(40):2204119
Heteroatom-doped porous carbon materials with distinctive surface properties and capacitive behavior have been accepted as promising candidates for supercapacitor electrodes. Currently, the researches mainly focus on developing facile synthetic method and unveiling the structure-activity relationship to further elevate their capacitive performance. Here, the B, N co-doped porous carbon sheet (BN-PCS) is constructed by one-pot pyrolysis of agar in KCl/KHCO3 molten salt system. In this process, the urea acts as directing agent to guide the formation of 2D sheet morphology, and the decomposition of KHCO3 and boric acid creates rich micro- and mesopores in the carbon framework. The specific capacitance of optimized BN-PCS reaches 361.1 F g−1 at a current density of 0.5 A g−1 in an aqueous KOH electrolyte. Impressively, the fabricated symmetrical supercapacitor affords a maximum energy density of 43.5 Wh kg−1 at the power density of 375.0 W kg−1 in 1.0 mol L−1 TEABF4/AN electrolyte. It also achieves excellent long-term stability with capacitance retention of 91.1% and Columbic efficiency of 100% over 10 000 cycles. This study indicates one-pot molten salt method is effective in engineering advanced carbon materials for high-performance energy storage devices. 相似文献
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Zhuangnan Li Srinivas Gadipelli Yuchen Yang Zhengxiao Guo 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(44)
Graphene‐oxide (GO) based porous structures are highly desirable for supercapacitors, as the charge storage and transfer can be enhanced by advancement in the synthesis. An effective route is presented of, first, synthesis of three‐dimensional (3D) assembly of GO sheets in a spherical architecture (GOS) by flash‐freezing of GO dispersion, and then development of hierarchical porous graphene (HPG) networks by facile thermal‐shock reduction of GOS. This leads to a superior gravimetric specific capacitance of ≈306 F g−1 at 1.0 A g−1, with a capacitance retention of 93% after 10 000 cycles. The values represent a significant capacitance enhancement by 30–50% compared with the GO powder equivalent, and are among the highest reported for GO‐based structures from different chemical reduction routes. Furthermore, a solid‐state flexible supercapacitor is fabricated by constructing the HPG with polymer gel electrolyte, exhibiting an excellent areal specific capacitance of ≈220 mF cm−2 at 1.0 mA cm−2 with exceptional cyclic stability. The work reveals a facile but efficient synthesis approach of GO‐based materials to enhance the capacitive energy storage. 相似文献
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Zenan Yu Julian Moore Jean Calderon Lei Zhai Jayan Thomas 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(39):5289-5295
Cable‐shaped supercapacitors (SCs) have recently aroused significant attention due to their attractive properties such as small size, lightweight, and bendability. Current cable‐shaped SCs have symmetric device configuration. However, if an asymmetric design is used in cable‐shaped supercapacitors, they would become more attractive due to broader cell operation voltages, which results in higher energy densities. Here, a novel coil‐type asymmetric supercapacitor electrical cable (CASEC) is reported with enhanced cell operation voltage and extraordinary mechanical‐electrochemical stability. The CASECs show excellent charge–discharge profiles, extraordinary rate capability (95.4%), high energy density (0.85 mWh cm−3), remarkable flexibility and bendability, and superior bending cycle stability (≈93.0% after 4000 cycles at different bending states). In addition, the CASECs not only exhibit the capability to store energy but also to transmit electricity simultaneously and independently. The integrated electrical conduction and storage capability of CASECS offer many potential applications in solar energy storage and electronic gadgets. 相似文献
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《Advanced Materials Technologies》2017,2(7)
This work presents a scalable method to produce robust all‐solid electric double layer capacitors (EDLCs), compatible with roll‐to‐roll processes and structural laminate composite fabrication. It consists in sandwiching and pressing an ionic liquid‐based polymer electrolyte membrane between two carbon nanotube (CNT) fiber sheet electrodes at room temperature, and laminating with ordinary plastic film. This fabrication method is demonstrated by assembling large‐area devices of up to 100 cm2 with electrodes fabricated in‐house, as well as with commercial CNT fiber sheets. Freestanding flexible devices operating at 3.5 V exhibit 28 F g−1 of specific capacitance, 11.4 W h kg−1 of energy density, and 46 kW kg−1 of power density. These values are nearly identical to control samples with pure ionic liquid. The solid EDLCs could be repeatedly bent and folded 180° without degradation of their properties, with a reversible 25% increase in energy density in the bent state. Devices produced using CNT fiber electrodes with a higher degree of orientation and therefore better mechanical properties show similar electrochemical properties combined with composite specific strength and modulus of 39 and 577 MPa SG−1 for a fiber mass fraction of 11 wt%, similar to a structural thermoplastic and with higher specific strength than copper. 相似文献
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Benxuan Li Shijie Zhan Haolan Wang Bo Hou Gehan A. J. Amaratunga 《Advanced Materials Technologies》2020,5(9)
Flexible capacitors are a promising power source for foldable and biological electronic devices. Although various materials and device structures have been explored, they are still limited by low energy densities and slow rate capabilities compared to their rigid counterparts. Here, asymmetric carbon nanohorns are proposed as an active material to fabricate flexible solid‐state carbon wire (CW)‐based electrochemical supercapacitors (ss‐CWECs) which exhibit high power density and ultra‐low cutoff frequency. By controlling the electric arc reaction at low temperature (77 K), asymmetric single‐wall carbon nanohorns (SWCNHs) are synthesized with high yield. Based on microscopy and electrochemical characterization, the fundamental reaction mechanism in polyvinyl‐based electrolyte system is elucidated, as being associated with deprotonation reaction at acid, base, and elevated temperature conditions. Additionally, by using activated carbon, multi‐walled carbon nanotubes, and SWCNHs as hybrid electrode materials (5:1:1), remarkable specific length capacitance of 48.76 mF cm−1 and charge–discharge stability (over 2000 times cycles) of ss‐CWECs are demonstrated, which are the highest reported to date. Furthermore, a high‐pass filter for eliminating ultra‐low electronic noise is demonstrated, which enables an optical Morse Code communication system to be operated. Current results confirm the SWCNHs as promising materials for high‐performance soft electronics and energy storage applications. 相似文献
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《Advanced Materials Interfaces》2018,5(5)
Graphene‐based nanocomposites are characterized by high mechanical strength, excellent electrical conductivity, and outstanding thermal and chemical stability. Additionally, the combination of versatile functionalization chemistry and simplicity of large‐scale synthesis makes graphene ideal for electrode materials for energy storage devices. To improve the electrochemical performance even further, recent research has focused on the preparation of porous graphene structures, either by creating holes in the graphene sheets or by assembling them into a 3D porous framework. Porous graphene and reduced graphene oxide allow for rapid ion diffusion and display high real surface area. In this review paper, the conventional methods for the preparation of porous graphene are summarized and recent progress in porous graphene‐based nanomaterials for electrochemical energy storage devices is discussed. 相似文献
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Ruling Huang Meiling Huang Xiaofeng Li Fei An Nikhil Koratkar Zhong‐Zhen Yu 《Advanced materials (Deerfield Beach, Fla.)》2018,30(21)
The development of fully foldable energy storage devices is a major science and engineering challenge, but one that must be overcome if next‐generation foldable or wearable electronic devices are to be realized. To overcome this challenge, it is necessary to develop new electrically conductive materials that exhibit superflexibility and can be folded or crumpled without plastic deformation or damage. Herein, a graphene film with engineered microvoids is prepared by reduction (under confinement) of its precursor graphene oxide film. The resultant porous graphene film can be single folded, double folded, and even crumpled, but springs back to its original shape without yielding or plastic deformation akin to an elastomeric scaffold after the applied stress is removed. Even after thermal annealing at ≈1300 °C, the folding performance of the porous graphene film is not compromised and the thermally annealed film exhibits complete foldability even in liquid nitrogen. A solid‐state foldable supercapacitor is demonstrated with the porous graphene film as the device electrode. The capacitance performance is nearly identical after 2000 cycles of single‐folding followed by another 2000 cycles of double folding. 相似文献
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Shude Liu Ying Yin Musheng Wu Kwan San Hui Kwun Nam Hui Chu‐Ying Ouyang Seong Chan Jun 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(4)
Molybdenum disulfide (MoS2) is a promising electrode material for electrochemical energy storage owing to its high theoretical specific capacity and fascinating 2D layered structure. However, its sluggish kinetics for ionic diffusion and charge transfer limits its practical applications. Here, a promising strategy is reported for enhancing the Na+‐ion charge storage kinetics of MoS2 for supercapacitors. In this strategy, electrical conductivity is enhanced and the diffusion barrier of Na+ ion is lowered by a facile phosphorus‐doping treatment. Density functional theory results reveal that the lowest energy barrier of dilute Na‐vacancy diffusion on P‐doped MoS2 (0.11 eV) is considerably lower than that on pure MoS2 (0.19 eV), thereby signifying a prominent rate performance at high Na intercalation stages upon P‐doping. Moreover, the Na‐vacancy diffusion coefficient of the P‐doped MoS2 at room temperatures can be enhanced substantially by approximately two orders of magnitude (10?6–10?4 cm2 s?1) compared with pure MoS2. Finally, the quasi‐solid‐state asymmetrical supercapacitor assembled with P‐doped MoS2 and MnO2, as the positive and negative electrode materials, respectively, exhibits an ultrahigh energy density of 67.4 W h kg?1 at 850 W kg?1 and excellent cycling stability with 93.4% capacitance retention after 5000 cycles at 8 A g?1. 相似文献
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Planar micro‐supercapacitors are attractive for system on chip technologies and surface mount devices due to their large areal capacitance and energy/power density compared to the traditional oxide‐based capacitors. In the present work, a novel material, niobium nanowires, in form of vertically aligned electrodes for application in high performance planar micro‐supercapacitors is introduced. Specific capacitance of up to 1 kF m?2 (100 mF cm?2) with peak energy and power density of 2 kJ m?2 (6.2 MJ m?3 or 1.7 mWh cm?3) and 150 kW m?2 (480 MW m?3 or 480 W cm?3), respectively, is achieved. This remarkable power density, originating from the extremely low equivalent series resistance value of 0.27 Ω (2.49 µΩ m2 or 24.9 mΩ cm2) and large specific capacitance, is among the highest for planar micro‐supercapacitors electrodes made of nanomaterials. 相似文献