High performance pliable supercapacitor fabricated using activated carbon nanospheres intercalated into boron nitride nanoplates by pulsed laser ablation technique

Pliable supercapacitor, yielding specific capacitance (C_s) and energy density as high as 348 F g⁻¹ and 48.3 Wh Kg⁻¹ respectively was fabricated using modified activated carbon electrodes. The nanospheres of activated carbon (AC) were anchored on the nanoplates of boron nitride (BN) by employing the facile technique of pulsed laser ablation in liquid (PLAL) using 532 nm focused laser beam. Four different variants of electrode materials were synthesized by varying the weight percentage (1%, 3%, 5% and 10%) of BN in AC in the PLAL precursor solution. The morphological characteristics, the elemental composition and the structural analysis of the synthesized electrode materials were studied respectively by FESEM, XPS and XRD. The morphological studies indicated that the PLAL synthesis of the electrode materials resulted in proper intercalation of carbon nanospheres into BN nanoplates, which resulted in the observed enhanced performance of the fabricated supercapacitor. Four supercapacitors in this work were fabricated using the four variants of synthesized electrode materials in conjunction with gel polymer electrolyte (GPE). GPE are well known for their non-corrosive nature and best sealing ability to avoid any leakage that results in increasing the cycle life of the device. The performance of the fabricated supercapacitors was evaluated using cyclic voltammetry (CV), galvanostatic charge discharge (GCD) measurement and electrochemical impedance spectroscopy (EIS). The results indicate that the supercapacitor fabricated using 3% BN in AC as electrode material manifested the best specific capacitance and energy density. Also it was found that the supercapacitor maintained 85% of its initial capacitance even after 5000 charge/discharge cycles.     

Enhanced energy density of asymmetric supercapacitors via optimizing negative electrode material and mass ratio of negative/positive electrodes

An asymmetric supercapacitor based on manganese dioxide/Au/nickel foam (MANF) electrode as positive electrode and graphene or commercial activated carbons (AC) as negative electrode was fabricated. The effect of different negative electrode materials and mass ratios of negative/positive electrodes on the electrochemical properties of the asymmetric supercapacitor was carefully investigated. The results suggest that the mass ratio of negative/positive electrode has a significant impact on the specific capacitance of the asymmetric supercapacitor. Especially, it is found that the optimal mass ratio of the negative/positive electrode is slightly lower than that calculated according to charge balance. On the other hand, the asymmetric supercapacitor with commercialized AC as negative electrode possesses higher specific capacitance and better rate capability than that of the asymmetric supercapacitor with graphene as negative electrode. The negative material has slight impact on the cycle stability of the asymmetric supercapacitor. In addition, the optimized asymmetric supercapacitor with MANF composite as positive electrode and AC as negative electrode can obtain an energy density as high as 65.9 Wh?kg^?1 at a power density of 180 W?kg^?1 and a cell voltage of 1.8 V in the neutral Na₂SO₄ aqueous solution.     

Scalable activated carbon/graphene based supercapacitors with improved capacitance retention at high current densities

Scalable, highly stable supercapacitor electrodes were developed from the mixture of a tea factory waste based activated carbon (AC) and a low-cost electrochemical exfoliated graphene (EEG). The hybrid electrodes showed notably enhanced stability at high current densities. The AC sample was prepared by chemical method and exposed to a further heat treatment to enhance electrochemical performance. Graphene used in the preparation of hybrid electrodes was obtained by direct electrochemical exfoliation of graphite in an aqueous solution. Detailed structural characterization of AC, EEG, and hybrid material was performed. The original electrochemical performances of AC and EEG were examined in button size cells using an aqueous electrolyte. The hybrid materials were prepared by mixing AC and EEG at different mass percentage ratios, and tested as supercapacitor electrodes under the same conditions. Capacitance stability of the electrodes developed from AC:EEG (70:30) at high currents increased by about 45% compared to the original AC. The highest gravimetric capacitance (110 F/g) was achieved by this hybrid electrode. The hybrid electrode was scaled up to the pouch size and tested using an organic electrolyte. The organic electrolyte was preferred for scaling up due to its wider voltage ranges. The pouch cell had a gravimetric capacitance of 85 F/g and exhibited as good performance as the coin cell in the organic electrolyte.     

离子液体电解质种类对活性炭电极超级电容器电化学性能的影响

本文将经水蒸气二次活化的椰壳活性炭（W-AC）作为电极材料,选择1-乙基-3甲基咪唑四氟硼酸盐（[EMIM]BF₄）作为电解质,结果表明W-AC电极的比电容量远高于未活化的椰壳活性炭（R-AC）.使用循环伏安、恒电流充放电、交流阻抗等方法研究了不同种类离子液体电解质对超级电容器电化学性能的影响.不同阴阳离子组成的离子液体作为电解质,直接影响超级电容器的电化学性能. 研究表明,由EMIM⁺和BMIM⁺阳离子与BF₄^-、TFSI^-阴离子构成的离子液体电解质较适用于W-AC电极. 其中在[EMIM]BF₄电解质中,单片电极的比电容量可高达153 F·g^-1;在1-丁基-3-甲基-咪唑四氟硼酸盐（[BMIM]BF₄）电解质中电位窗可达3.5V,能量密度可高达57 Wh·kg^-1.本研究对于构筑高性能超级电容器离子液体的选择提供参考,以满足不同应用领域需求.     

MoS2 incorporated carbon allotropes (activated carbon,graphene, MWCNT) as electrodes in symmetric supercapacitors

Symmetric supercapacitor devices were fabricated from MoS₂ incorporated carbon allotropes such as activated carbon (AC)/MoS₂, graphene/MoS₂ and MWCNT/MoS₂. The device performance was evaluated using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). The electrochemical properties of the devices fabricated from carbon allotropes (activated carbon, graphene, MWCNT) were remarkably enhanced to above 50% by the incorporation MoS₂ phases. Out of the three fabricated devices, electrochemical performance of AC/MoS₂ as found to be superior. The specific capacitance and energy density of this device is 216 ​F/g and 6.2 ​Wh/Kg respectively with excellent higher rate capability and longer cyclic durability. The devices fabricated from graphene/MoS₂ and MWCNT/MoS₂ has exhibited a specific capacitance value of 202 ​F/g and 161 ​F/g with an energy density value of 5.68 ​Wh/Kg and 3.95 ​Wh/Kg respectively.     

A hierarchical porous carbon membrane from polyacrylonitrile/polyvinylpyrrolidone blending membranes: Preparation,characterization and electrochemical capacitive performance

Novel hierarchical porous carbon membranes were fabricated through a simple carbonization procedure of well-defined blending polymer membrane precursors containing the source of carbon polyacrylonitrile (PAN) and an additive of polyvinylpyrrolidone (PVP), which was prepared using phase inversion method. The as-fabricated materials were further used as the active electrode materials for supercapacitors. The effects of PVP concentration in the casting solution on structure feature and electrochemical capacitive performance of the as-prepared carbon membranes were also studied in detail. As the electrode material for supercapacitor, a high specific capacitance of 278.0 F/g could be attained at a current of 5 mA/cm² and about 92.90% capacity retention could be maintained after 2000 charge/discharge cycles in 2 mol/L KOH solution with a PVP concentration of 0.3 wt% in the casting solution. The facile hierarchical pore structure preparation method and the good electrochemical capacitive performance make the prepared carbon membrane particularly promising for use in supercapacitor.     

A hierarchical porous carbon membrane from polyacrylonitrile/polyvinylpyrrolidone blending membranes:Preparation,characterization and electrochemical capacitive performance

Novel hierarchical porous carbon membranes were fabricated through a simple carbonization procedure of well-defined blending polymer membrane precursors containing the source of carbon polyacrylonitrile （PAN） and an additive of polyvinylpyrrolidone （PVP）, which was prepared using phase inversion method. The as-fabricated materials were further used as the active electrode materials for supercapacitors. The effects of PVP concentration in the casting solution on structure feature and electrochemical capacitive performance of the as-prepared carbon membranes were also studied in detail. As the electrode material for supercapacitor, a high specific capacitance of 278.0 F/g could be attained at a current of 5 mA/cm2 and about 92.90% capacity retention could be maintained after 2000 charge/discharge cycles in 2 mol/L KOH solution with a PVP concentration of 0.3 wt% in the casting solution. The facile hierarchical pore structure preparation method and the good electrochemical capacitive performance make the prepared carbon membrane particularly promising for use in supercapacitor.     

WO3/碳布柔性非对称超级电容器的组装及性能研究

以超级电容器的电极材料制备、性质研究及对组装的非对称超级电容器的性能研究为核心内容,提高超级电容器电化学性能为主要目的,采用水热合成法在碳布基底上合成三氧化钨/碳布和活化后的碳布为超级电容器的电极材料。采用SEM、XRD表征方法对制备的材料进行了形貌表征及物相分析;使用上海辰华电化学工作站对电极材料进行了循环伏安、恒流充放电、交流阻抗等电化学性能测试. 最终得到以三氧化钨/碳布为正极材料、活化后的碳布为负极材料组装成不对称柔性电容器,进行电化学测试,其电位窗口提高到0~1.6 V,电流密度61.9 mA·cm^-2时,电容达到58.96 F·cm-2,功率密度0.48 W·cm^-2时,能量密度为20.36 mWh·cm^-2,同时在电流密度8 mA·cm^-2时,循环3000次时表现出良好的循环性能,相较于对称型超级电容器,倍率性能更加优异.     

电解质浓度和温度对活性炭电容性能的影响

采用循环伏安、交流阻抗和恒流充放电技术考察了电解质浓度和温度对活性炭电容性能的影响. 活性炭电容器在0.1、0.5、1.0和6.0 mol·L^-1 KOH溶液中性能测试结果表明: 活性炭在高浓度电解质中具有高电容和低内阻, 但电位窗口较窄; 电容和内阻与KOH浓度的对数成正比. 活性炭电容在不同温度(20、40、80 °C)的性能测试结果表明: 高温能够增加电容和降低内阻, 但是却加速了长期充放电过程中电容的衰减.     

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.     

氧化锰表面改性活性炭电极材料的电化学特性

用Mn(NO3)2溶液浸渍-高温热解法对普通活性炭进行表面改性处理以改善其电化学性能. 采用氮气吸附、SEM、XRD等方法研究改性活性炭的比表面积、孔结构、形貌和氧化锰的晶体结构; 用循环伏安、恒流充放电、交流阻抗等电化学方法研究了改性活性炭电极构成的电化学电容器的性能. 结果表明, Mn(NO3)2热解产生的多价态氧化锰有法拉第赝电容效应, 尤其是立方晶形结构的α-Mn2O3, 与活性炭的双电层电容构成了复合电容, 因而改性炭材料的比电容有明显的提高, 其质量比电容达到254 F·g-1, 比未改性炭的165 F·g-1提高了54%. 改性炭电极电化学电容器具有优异的充放电可逆性和稳定性, 而且等效串联电阻较小, 只有0.40 Ω; 经2000次循环的长期测试, 容量保持率几乎达到100%.     

Electrodeposited NiSe_2 on carbon fiber cloth as a flexible electrode for high-performance supercapacitors

A flexible electrode of nickel diselenide/carbon fiber cloth(NiSe_2/CFC) is fabricated at room temperature by a simple and efficient electrodeposition method. Owing to NiSe_2 character of nanostructure and high conductivity, the as-synthesized electrodes possess perfect pseudocapacitive property with high specific capacitance and excellent rate capability. In three-electrode system, the electrode specific capacitance of the NiSe_2/CFC electrode varies from 1058 F g~(-1) to 996.3 F g~(-1) at 2 A g~(-1) to 10 A g~(-1) respectively, which shows great rate capability. Moreover, the NiSe_2 electrode is assembled with an active carbon(AC) electrode to form an asymmetric supercapacitor with an extended potential window of 1.6 V. The asymmetric supercapacitor possesses an excellent energy density 32.7 Wh kg~(-1) with a power density 800 W kg~(-1) at the current density of 1 A g~(-1). The nanosheet array on carbon fiber cloth with high flexibility, specific capacitance and rate capacitance render the NiSe_2 to be regarded as the promising material for the high performance superconductor.     

Facile synthesis of high electrical conductive CoP via solid-state synthetic routes for supercapacitors

Co-P precursor was prepared by a mechanical alloying method and then is controlled to synthesis of Co P phase through an annealing method. The optimal conditions of ball milling and annealing temperature are investigated. The Co P exhibits higher electrical conductivity than graphite and cobalt oxide, showing excellent pseudocapacitive properties due its high electrical conductivity which can result in a fast electron transfer in high rate charge–discharge possess. The as-obtained Co P electrode achieves a high specific capacitance of 447.5 F/g at 1 A/g, and displays an excellent rate capability as well as good cycling stability. Besides, the asymmetric supercapacitor(ASC) based on the Co P as the positive electrode and activated carbon(AC) as the negative electrode was assembled and displayed a high rate capability(60%of the capacitance is retained when the current density increased from 1 A/g to 12 A/g), excellent cycling stability(96.7% of the initial capacitance is retained after 5000 cycles), and a superior specific energy of19 Wh/kg at a power density of 350.8 W/kg. The results suggest that the Co P electrode materials have a great potential for developing high-performance electrochemical energy storage devices.     

活性炭二次活化对其电化学容量的影响

为进一步提高作为电化学超级电容器电极材料活性炭的电化学容量, 采用KOH作为二次活性剂, 将所得活性炭进行二次化学活化处理, 从而得到二次活化活性炭. 将原始活性炭材料与二次活化活性炭材料都分别经过系列处理, 组装成电化学超级电容器进行电化学性能测试. 测试结果表明, 二次活化活性炭材料的电化学容量达到145.0 F·g-1(有机电解液), 远远大于原活性炭材料的容量(45.0 F·g-1). 为研究二次活化活性炭材料电化学容量大幅提高的原因, 将这两种材料分别进行微观结构数据测试, 包括比表面积、N2吸脱附等温曲线和孔径分布. 研究结果表明, 二次活化处理大大增加了二次活化活性炭材料在孔径为2-3 nm的中孔分布, 从而证实对于有机电解液, 电极材料在2-3 nm的中孔对其电化学容量的提高具有重要意义.     

互通多孔碳/二氧化锰纳米复合材料的原位水热合成及电化学性能

以互通多孔碳（IPC）为载体，水热条件下在碳表面原位反应生成纳米结构的二氧化锰（MnO₂），制备互通多孔碳/二氧化锰纳米（IPC/MnO₂）复合电极材料. 采用扫描电镜（SEM），透射电镜（TEM），X射线衍射（XRD），热重分析（TGA）对其结构进行表征；采用循环伏安法、恒流充放电和交流阻抗对其电化学性能进行研究. 结果表明：生成的MnO₂均匀地负载在碳的表面，形成多层次结构，并且随着温度的升高IPC表面负载的MnO₂由纳米颗粒变为纳米片状结构；MnO₂纳米片具有典型的K-Birnessite 型晶体结构；复合物中MnO₂的含量约为34%（w）. 在100 ℃制备的IPC/MnO₂复合材料在三电极系统中最高比电容达到了411 F·g^-1；随着反应温度的升高,比容量先增长后基本保持不变. 以IPC/MnO₂为正极，活性炭（AC）为负极，1 mol·L^-1 Na₂SO₄溶液为电解液组装成IPC/MnO₂//AC 混合超级电容器，发现IPC/MnO₂电极的电容器其电位窗口从1 V扩展到1.8 V，容量可达86F·g^-1，且表现出良好的电容特性和大电流放电性能.     

互通多孔碳/二氧化锰纳米复合材料的原位水热合成及电化学性能

以互通多孔碳（IPC）为载体，水热条件下在碳表面原位反应生成纳米结构的二氧化锰（MnO₂），制备互通多孔碳/二氧化锰纳米（IPC/MnO₂）复合电极材料. 采用扫描电镜（SEM），透射电镜（TEM），X射线衍射（XRD），热重分析（TGA）对其结构进行表征；采用循环伏安法、恒流充放电和交流阻抗对其电化学性能进行研究. 结果表明：生成的MnO₂均匀地负载在碳的表面，形成多层次结构，并且随着温度的升高IPC表面负载的MnO₂由纳米颗粒变为纳米片状结构；MnO₂纳米片具有典型的K-Birnessite 型晶体结构；复合物中MnO₂的含量约为34%（w）. 在100 ℃制备的IPC/MnO₂复合材料在三电极系统中最高比电容达到了411 F·g^-1；随着反应温度的升高,比容量先增长后基本保持不变. 以IPC/MnO₂为正极，活性炭（AC）为负极，1 mol·L^-1 Na₂SO₄溶液为电解液组装成IPC/MnO₂//AC 混合超级电容器，发现IPC/MnO₂电极的电容器其电位窗口从1 V扩展到1.8 V，容量可达86F·g^-1，且表现出良好的电容特性和大电流放电性能.     

互通多孔碳/二氧化锰纳米复合材料的原位水热合成及电化学性能

以互通多孔碳（IPC）为载体,水热条件下在碳表面原位反应生成纳米结构的二氧化锰（MnO₂）,制备互通多孔碳/二氧化锰纳米（IPC/MnO₂）复合电极材料. 采用扫描电镜（SEM）,透射电镜（TEM）,X射线衍射（XRD）,热重分析（TGA）对其结构进行表征;采用循环伏安法、恒流充放电和交流阻抗对其电化学性能进行研究. 结果表明：生成的MnO₂均匀地负载在碳的表面,形成多层次结构,并且随着温度的升高IPC表面负载的MnO₂由纳米颗粒变为纳米片状结构;MnO₂纳米片具有典型的K-Birnessite 型晶体结构;复合物中MnO₂的含量约为34%（w）. 在100 ℃制备的IPC/MnO₂复合材料在三电极系统中最高比电容达到了411 F·g^-1;随着反应温度的升高,比容量先增长后基本保持不变. 以IPC/MnO₂为正极,活性炭（AC）为负极,1 mol·L^-1 Na₂SO₄溶液为电解液组装成IPC/MnO₂//AC 混合超级电容器,发现IPC/MnO₂电极的电容器其电位窗口从1 V扩展到1.8 V,容量可达86F·g^-1,且表现出良好的电容特性和大电流放电性能.     

互通多孔碳/二氧化锰纳米复合材料的原位水热合成及电化学性能

以互通多孔碳（IPC）为载体，水热条件下在碳表面原位反应生成纳米结构的二氧化锰（MnO₂），制备互通多孔碳/二氧化锰纳米（IPC/MnO₂）复合电极材料. 采用扫描电镜（SEM），透射电镜（TEM），X射线衍射（XRD），热重分析（TGA）对其结构进行表征；采用循环伏安法、恒流充放电和交流阻抗对其电化学性能进行研究. 结果表明：生成的MnO₂均匀地负载在碳的表面，形成多层次结构，并且随着温度的升高IPC表面负载的MnO₂由纳米颗粒变为纳米片状结构；MnO₂纳米片具有典型的K-Birnessite 型晶体结构；复合物中MnO₂的含量约为34%（w）. 在100 ℃制备的IPC/MnO₂复合材料在三电极系统中最高比电容达到了411 F·g^-1；随着反应温度的升高,比容量先增长后基本保持不变. 以IPC/MnO₂为正极，活性炭（AC）为负极，1 mol·L^-1 Na₂SO₄溶液为电解液组装成IPC/MnO₂//AC 混合超级电容器，发现IPC/MnO₂电极的电容器其电位窗口从1 V扩展到1.8 V，容量可达86F·g^-1，且表现出良好的电容特性和大电流放电性能.     

互通多孔碳/二氧化锰纳米复合材料的原位水热合成及电化学性能

以互通多孔碳（IPC）为载体，水热条件下在碳表面原位反应生成纳米结构的二氧化锰（MnO₂），制备互通多孔碳/二氧化锰纳米（IPC/MnO₂）复合电极材料. 采用扫描电镜（SEM），透射电镜（TEM），X射线衍射（XRD），热重分析（TGA）对其结构进行表征；采用循环伏安法、恒流充放电和交流阻抗对其电化学性能进行研究. 结果表明：生成的MnO₂均匀地负载在碳的表面，形成多层次结构，并且随着温度的升高IPC表面负载的MnO₂由纳米颗粒变为纳米片状结构；MnO₂纳米片具有典型的K-Birnessite 型晶体结构；复合物中MnO₂的含量约为34%（w）. 在100 ℃制备的IPC/MnO₂复合材料在三电极系统中最高比电容达到了411 F·g^-1；随着反应温度的升高,比容量先增长后基本保持不变. 以IPC/MnO₂为正极，活性炭（AC）为负极，1 mol·L^-1 Na₂SO₄溶液为电解液组装成IPC/MnO₂//AC 混合超级电容器，发现IPC/MnO₂电极的电容器其电位窗口从1 V扩展到1.8 V，容量可达86F·g^-1，且表现出良好的电容特性和大电流放电性能.     

互通多孔碳/二氧化锰纳米复合材料的原位水热合成及电化学性能

以互通多孔碳（IPC）为载体,水热条件下在碳表面原位反应生成纳米结构的二氧化锰（MnO₂）,制备互通多孔碳/二氧化锰纳米（IPC/MnO₂）复合电极材料. 采用扫描电镜（SEM）,透射电镜（TEM）,X射线衍射（XRD）,热重分析（TGA）对其结构进行表征;采用循环伏安法、恒流充放电和交流阻抗对其电化学性能进行研究. 结果表明：生成的MnO₂均匀地负载在碳的表面,形成多层次结构,并且随着温度的升高IPC表面负载的MnO₂由纳米颗粒变为纳米片状结构;MnO₂纳米片具有典型的K-Birnessite 型晶体结构;复合物中MnO₂的含量约为34%（w）. 在100 ℃制备的IPC/MnO₂复合材料在三电极系统中最高比电容达到了411 F·g^-1;随着反应温度的升高,比容量先增长后基本保持不变. 以IPC/MnO₂为正极,活性炭（AC）为负极,1 mol·L^-1 Na₂SO₄溶液为电解液组装成IPC/MnO₂//AC 混合超级电容器,发现IPC/MnO₂电极的电容器其电位窗口从1 V扩展到1.8 V,容量可达86F·g^-1,且表现出良好的电容特性和大电流放电性能.