A facile synthesis of hierarchical porous carbon derived from renewable lignin for high-performance supercapacitor

In this work, we proposed a facile one-pot pyrolysis method to conveniently manufacture lignin-derived carbon materials with graded porous construction for use in supercapacitors. The renewable lignin was selected as precursor, while the potassium citrate was used as a pore-forming agent. The properties of the prepared lignin-derived carbon (LAC) and the performance for supercapacitor application were thoroughly evaluated. The LAC at optimal preparation conditions shows a layered porous structure with a large specific surface area of 3174 cm² g⁻¹ and pore volume of 2.796 cm³ g⁻¹, where the specific capacitance reach to 241 F g⁻¹ at 1 A g⁻¹ scan rate in 6 M KOH electrolyte solution. At the same time, the specific capacitance remains at 220 F g⁻¹ even at an excessive scan velocity of 20 A g⁻¹, while the capacitance retention is still close to 91.3%. The capacitance retention rate is stable above 95% after 10,000 charge/discharge cycles, which shows the desired long-time stability. All these results demonstrate the outstanding properties of the new prepared LAC material and the considerable application potential in the field of electrical energy storage.     

From interpenetrating polymer networks to hierarchical porous carbons for advanced supercapacitor electrodes

A novel and effective strategy to fabricate hierarchical porous carbons for supercapacitors is developed via in-situ activation of interpenetrating polymer networks obtained from simultaneous polymerization of the monomers for two polymeric networks.     

Lignin-derived hierarchical porous carbon for high-performance supercapacitors

Journal of Solid State Electrochemistry - Lignin as the second most abundant natural polymer was applied to prepare a hierarchical porous carbon (HPC) for supercapacitors (SCs). Direct activation...     

Dual template method to prepare hierarchical porous carbon nanofibers for high-power supercapacitors

Hierarchical porous carbon nanofibers serving as electrode materials are prepared through carbonization and hydrofluoric acid treatment of polyacrylonitrile-based electrospinning involving dual templates. The hierarchical porous structures are synergistically tailored by varying template contents in the spinning solution. The carbon nanofibers prepared from the electrospinning of polyacrylonitrile containing 15/15 wt.% polymethylmethacrylate/tetraethyl orthosilicate exhibit the largest specific surface area (699 m² g^?1) and microporous volume (0.196 cm³ g^?1). In 6 M KOH electrolyte, a symmetrical supercapacitor equipped with the hierarchical porous carbon nanofibers demonstrates its high-end specific capacitance of 170 F g^?1, superior rate capability, and high-power density output up to 14.7 kW kg^?1. Cycling evolution indicates capacitance fading is only 5.8 % of initial capacitance at a current density of 1 A g^?1 even after 8,000 cycles. The excellent electrochemical performances of the carbon nanofiber are mainly ascribed to the optimized pore size distributions of both micropores and mesopores and the unique hierarchical pore structures possessed by abundant micropores.     

三维多孔碳纳米管-还原氧化石墨烯复合气凝胶应用于高性能对称超级电容器

以羟基化的碳纳米管(CNT-OH)和自制的氧化石墨烯(GO)为原料,通过氧化还原自组装的水热合成策略制备了碳纳米管-还原氧化石墨烯(CNTs-rGO)三维气凝胶,并探究了水热温度对三维气凝胶的影响,利用扫描电子显微镜(SEM)、X射线衍射(XRD)、拉曼光谱(Raman)和X射线光电子能谱(XPS)对材料的结构、形貌进行了表征,并对其进行电化学性能测试。其中,在140℃下合成的气凝胶CNTs-rGO展示了最佳的电化学性能,在1 A·g^-1电流密度下的比电容高达294.65 F·g^-1,循环伏安曲线在50 mV·s^-1扫速下的形状仍然近似于矩形,展示了良好的可逆性。将其作为正极和负极材料组装的对称超级电容器在功率密度为249.8 W·kg^-1时的最大能量密度为3.744 Wh·kg^-1,在1 A·g^-1下循环10 000次后,其电容保持率和库仑效率均约为100%。优异的电化学性能主要归因于CNTs-rGO复合材料疏松多孔的三维立体结构,这保证了离子的快速运输,同时CNTs和rGO的交联结构提高了电导率,充分发挥了CNTs和rGO的化学和电学性能。     

三维多孔碳纳米管-还原氧化石墨烯复合气凝胶应用于高性能对称超级电容器

以羟基化的碳纳米管(CNT-OH)和自制的氧化石墨烯(GO)为原料,通过氧化还原自组装的水热合成策略制备了碳纳米管-还原氧化石墨烯(CNTs-rGO)三维气凝胶,并探究了水热温度对三维气凝胶的影响,利用扫描电子显微镜(SEM)、X射线衍射(XRD)、拉曼光谱(Raman)和X射线光电子能谱(XPS)对材料的结构、形貌进行了表征,并对其进行电化学性能测试。其中,在140℃下合成的气凝胶CNTs-rGO展示了最佳的电化学性能,在1 A·g^-1电流密度下的比电容高达294.65 F·g^-1,循环伏安曲线在50 mV·s^-1扫速下的形状仍然近似于矩形,展示了良好的可逆性。将其作为正极和负极材料组装的对称超级电容器在功率密度为249.8 W·kg^-1时的最大能量密度为3.744 Wh·kg^-1,在1 A·g^-1下循环10 000次后,其电容保持率和库仑效率均约为100%。优异的电化学性能主要归因于CNTs-rGO复合材料疏松多孔的三维立体结构,这保证了离子的快速运输,同时CNTs和rGO的交联结构提高了电导率,充分发挥了CNTs和rGO的化学和电学性能。     

High-capacity porous carbons prepared by KOH activation of activated carbon for supercapacitors

High-performance supercapacitor electrode materials are prepared from the commercially available activated carbon （AC） through a facile and low-cost chemical activation method. The obtained results show that AC activated by KOH with an alkali/carbon ratio of 6/1 （ACK6） possesses a specific surface area of 3405 m^2/g, a large pore volume of 2.01 cm^3/g, and exhibits the highest initial specific capacitance of 335 F/g at the current density of 0.5 A/g in 6 mol/L KOH, and 85% coloumbic efficiency for 5000 cycles at 20 mV/s.     

Facilely prepared polypyrrole-graphene oxide-sodium dodecylbenzene sulfonate nanocomposites by in situ emulsion polymerization for high-performance supercapacitor electrodes

The layered polypyrrole-graphene oxide-sodium dodecylbenzene sulfonate (PPyGO-SDBS) nanocomposites were facilely fabricated via an in situ emulsion polymerization method with the assistance of SDBS as dopant and stabilizer. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and electrochemical performance were employed to analyze the structure and the characteristics of the composites. The results showed that SDBS played an important role in improving the electrochemical performance of the PPyGO-SDBS, by dispersing the PPy between the layers of the GO. The obtained PPyGO-SDBS exhibited remarkable performance as an electrode material for supercapacitors, with a specific capacitance as high as 483 F g^?1 at a current density of 0.2 A g^?1 when the mass ratio of pyrrole to GO was 80:20. The attenuation of the specific capacitance was less than 20 % after 1,000 charge–discharge processes, supporting the idea that PPy inserted successfully into the GO interlayers. The excellent electrochemical performance seemed to arise from the synergistic effect between the PPy and the GO and the dispersion of the PPy induced by SDBS.     

Facile synthesis of nanoporous CuS nanospheres for high-performance supercapacitor electrodes

In recent years, development of high-performance supercapacitor electrode materials has stimulated a great deal of scientific research. The electrochemical performance of a supercapacitor strongly depends on its material structures. Herein, we report a simple strategy for high-performance supercapacitors by building pseudocapacitive CuS nanospheres with nanoporous structures, nanosized walls(10 nm) and relatively large specific surface area of 65 m~2/g. This electrode demonstrates excellent electrochemical performance including a maximum specific capacitance of 814 F/g at 1 A/g, significant rate capability of 42% capacitance retention at an ultrafast rate of 50 A/g, and outstanding long-term cycling stability at various current densities. The remarkable electrochemical performance of as-prepared nanoporous CuS nanospheres electrode has been attributed to its unique structures that plays a key role in providing short ion and electron diffusion pathways, facilitated ion transport and more active sites for electrochemical reactions. This work sheds a new light on the metal sulfides design philosophy, and demonstrates that nanoporous CuS nanospheres electrode is a promising candidate for application in high-performance supercapacitors.     

Shapeable carbon fiber networks with hierarchical porous structure for high-performance Zn-I2 batteries

Aqueous rechargeable zinc-iodine batteries(ZIBs)emerging as a promising energy storage alternative have attracted con-siderable attention.However,ZIBs still suf...     

Synthesis of MnO2/N-doped ultramicroporous carbon nanospheres for high-performance supercapacitor electrodes

We demonstrate a simple and highly efficient strategy to synthesize MnO₂/nitrogen-doped ultramicroporous carbon nanospheres (MnO₂/N-UCNs) for supercapacitor application. MnO₂/N-UCNs were fabricated via a template-free polymerization of resorcinol/formaldehyde on the surface of phloroglucinol/terephthalaldehyde colloids in the presence of hexamethylenetetramine, followed by carbonization and then a redox reaction between carbons and KMnO₄. As-prepared MnO₂/N-UCNs exhibits regular ultramicropores, high surface area, nitrogen heteroatom, and high content of MnO₂. A typical MnO₂/N-UCNs with 57 wt.% MnO₂ doping content (denoted as MnO₂(57%)/N-UCNs) makes the most use of the synergistic effect between carbons and metal oxides. MnO₂(57%)/N-UCNs as a supercapacitor electrode exhibits excellent electrochemical performance such as a high specific capacitance (401 F/g at 1.0 A/g) and excellent charge/discharge stability (86.3% of the initial capacitance after 10,000 cycles at 2.0 A/g) in 1.0 mol/L Na₂SO₄ electrolyte. The well-designed and high-performance MnO₂/N-UCNs highlight the great potential for advanced supercapacitor applications.     

Preparation of activated carbon from polyaniline by zinc chloride activation as supercapacitor electrodes

Activated carbon for supercapacitor electrode was prepared from polyaniline using chemical activation with ZnCl₂. The morphology, surface chemical composition, and surface area of the as-prepared carbon materials were investigated by scanning electron microscope, atomic force microscopy, X-ray photoelectron spectroscopy, and Brunauer–Emmett–Teller measurement, respectively. Electrochemical characteristics were evaluated by cyclic voltammograms, galvanostatic charge/discharge, and electrochemical impedance spectroscopy tests in 6.0 mol L⁻¹ KOH aqueous solution. The electrochemical measurements showed that ZnCl₂ activation led to better capacitive performances. The activated carbon presented a high-specific gravimetric capacitance of 174 F g⁻¹, with rectangular cyclic voltammetry curves at a scan rate of 2 mV s⁻¹, and it remained 93% even at a high scan rate of 50 mV s⁻¹. These demonstrated that activated carbon would be a promising electrode material for supercapacitors.

     

Preparation of activated carbon from polyaniline by zinc chloride activation as supercapacitor electrodes

Activated carbon for supercapacitor electrode was prepared from polyaniline using chemical activation with ZnCl₂. The morphology, surface chemical composition, and surface area of the as-prepared carbon materials were investigated by scanning electron microscope, atomic force microscopy, X-ray photoelectron spectroscopy, and Brunauer–Emmett–Teller measurement, respectively. Electrochemical characteristics were evaluated by cyclic voltammograms, galvanostatic charge/discharge, and electrochemical impedance spectroscopy tests in 6.0?mol?L^?? KOH aqueous solution. The electrochemical measurements showed that ZnCl₂ activation led to better capacitive performances. The activated carbon presented a high-specific gravimetric capacitance of 174?F?g^??, with rectangular cyclic voltammetry curves at a scan rate of 2?mV?s^??, and it remained 93% even at a high scan rate of 50?mV?s^??. These demonstrated that activated carbon would be a promising electrode material for supercapacitors.     

Activated carbon prepared from polyaniline base by K2CO3 activation for application in supercapacitor electrodes

An activated carbon was prepared from a polyaniline base using K₂CO₃ as an activating agent. The morphology, surface chemical composition, and surface area of the as-prepared carbon materials were investigated by scanning electron microscope, X-ray photoelectron spectroscopy, and Brunauer?CEmmett?CTeller measurement, respectively. Electrochemical properties of the as-prepared sample were studied by cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy measurements in 6?mol?L^?1 KOH aqueous solution. Compared with the non-activated carbon, activated carbon showed superior capacitive performance. The activation carbon presented a high specific gravimetric capacitance of 210?F?g^?1. The good electrochemical performance of the activated carbon was ascribed to well-developed micropores, high surface area, the presence of nitrogen and oxygen functional groups, and larger pore volume.     

Synthesis and electrochemical performance of high surface area hierarchical porous carbon with ultrahigh mesoporosity for high-performance supercapacitors

Journal of Solid State Electrochemistry - Hierarchical porous carbons (HPCs) with both high Brunauer–Emmett–Teller (BET) surface area and high mesoporosity have been synthesized by...     

Thin, bendable electrodes consisting of porous carbon nanofibers via the electrospinning of polyacrylonitrile containing tetraethoxy orthosilicate for supercapacitor

In the present study, electrically conducting carbon nanofiber (CNF) mats were produced by incorporating tetraethoxy orthosilicate (TEOS) into polyacrylonitrile (PAN) via electrospinning. A simple thermal treatment was applied to the electrospun nanofibers to create ultramicropores that could accommodate a large number of ions were formed on the surface of the CNFs, removing the need for a time-consuming activation step. The Si/CNF composites showed high capacitance and energy/power density values due to the formation of ultramicropores and the introduction of heteroatoms.     

Enhanced electrochemical performance of straw-based porous carbon fibers for supercapacitor

The efficient utilization of natural biomass as renewable raw materials is of importance. We herein prepared porous carbon fibers (PCFs) by activation of the extracted cellulose microfibers from the agriculture byproduct of corn straw. Different from the porous carbons (PCs) by directly activating straw, the obtained PCFs had typical one-dimensional morphology with high surface area (2013 m² g^?1) and large pore volume (1.27 cm³ g^?1). The influence of the ZnCl₂/cellulose mass ratio on the electrochemical performance was studied, and the optimized PCF(1:1) possessed a much higher specific capacitance than the PC(1:1) sample, which was attributed to the improved specific surface area as well as the fiber-like morphology where it had short ion diffusion route and small interfacial resistance in comparison to PCs. PCFs have a high specific capacitance of 230 F g^?1 at 0.5 A g^?1, and 183 F g^?1 was retained at 20 A g^?1 (79.6%), revealing an excellent rate capability. The assembled symmetrical supercapacitor exhibited a wide potential window of 1.8 V, small electrochemical impedance, and superior cycle performance. Moreover, a high energy density of 16.0 Wh kg^?1 was obtained at a power density of 450.4 W kg^?1, which was preserved of 6.9 Wh kg^?1 at a high power density of 14,194.3 W kg^?1.     

Excellent electrochemical performance of nitrogen-enriched hierarchical porous carbon electrodes prepared using nano-CaCO3 as template

Recently, tremendous research efforts have been concentrated on developing high-performance electrode materials to meet the ever-increasing energy and power demands in supercapacitors. Herein, we presented a high-capacity supercapacitor material based on nitrogen-enriched hierarchical porous carbons (NHPCs) synthesized by the carbonization of melamine formaldehyde resins using eco-friendly and inexpensive nano-CaCO₃ as template. The effects of carbonization temperature and template content on the porous structure and electrochemical characteristics were compared and discussed in detail. The prepared NHPCs possessed large surface area up to 834 m² g^?1 and high nitrogen content up to 20.94 wt %. As electrode material for supercapacitors, NHPCs exhibited superior electrochemical performances with high specific capacitance (190 F g^?1 at 20 A g^?1), outstanding rate capability (80 %), and excellent cycling stability (over 2,000 cycles at 5 A g^?1) in 1 M sulfuric acid media. The excellent electrochemical performances are due to the synergic effects of unique hierarchical porous microstructure, abundant nitrogen and oxygen functionalities, as well as high degree of graphitization framework.     

A high-performance hybrid supercapacitor with Li4Ti5O12-C nano-composite prepared by in situ and ex situ carbon modification

In this work, we report on the synthesis of in situ and ex situ carbon-modified Li₄Ti₅O₁₂-C (LTO-C) nano-composite and its application in a hybrid supercapacitor constructed using activated carbon (AC) and LTO-C nano-composite as positive and negative electrodes, respectively. The hybrid capacitors are characterized by galvanostatic charge–discharge, cycle life testing, and electrochemical impedance spectroscopy. The results reveal that the AC/LTO-C hybrid capacitors exhibit high rate capability and long cycle life. In the potential range of 1.5–3.0 V, the AC/LTO-C hybrid system can deliver a specific capacitance of 83 F?g^?1 based on the total mass of AC and LTO-C electrodes at a current density of 60 mA g^?1 (2 C rate). At a higher discharge rate of 980 mA g^?1 (32 C), the capacity is 68 F?g^?1, about 82?% of that at 2 C rate. After 9,000 deep cycles at 32 C, the hybrid capacitor still maintains 84?% of its initial capacitance. The specific energy of such hybrid system is 20 Wh kg^?1, which is at least twice that of an AC/AC system. Combining the high energy density with power capability, the AC/LTO-C hybrid supercapacitor has demonstrated high performance for applications needing high power output.