A High Energy Density Asymmetric Supercapacitor from Nano‐architectured Ni(OH)2/Carbon Nanotube Electrodes

The demand for advanced energy storage devices such as supercapacitors and lithium‐ion batteries has been increasing to meet the application requirements of hybrid vehicles and renewable energy systems. A major limitation of state‐of‐art supercapacitors lies in their relatively low energy density compared with lithium batteries although they have superior power density and cycle life. Here, we report an additive‐free, nano‐architectured nickel hydroxide/carbon nanotube (Ni(OH)₂/CNT) electrode for high energy density supercapacitors prepared by a facile two‐step fabrication method. This Ni(OH)₂/CNT electrode consists of a thick layer of conformable Ni(OH)₂ nano‐flakes on CNT bundles directly grown on Ni foams (NFs) with a very high areal mass loading of 4.85 mg cm^?2 for Ni(OH)₂. Our Ni(OH)₂/CNT/NF electrode demonstrates the highest specific capacitance of 3300 F g^?1 and highest areal capacitance of 16 F cm^?2, to the best of our knowledge. An asymmetric supercapacitor using the Ni(OH)₂/CNT/NF electrode as the anode assembled with an activated carbon (AC) cathode can achieve a high cell voltage of 1.8 V and an energy density up to 50.6 Wh/kg, over 10 times higher than that of traditional electrochemical double‐layer capacitors (EDLCs).     

Synthesis and characterization of polypyrrole/graphitic carbon nitride/niobium pentoxide nanocomposite for high-performance energy storage applications

Graphitic carbon nitride (GCN) has been employed as a supercapacitor electrode because of its high carbon-to-nitrogen ratio and flexible structure. However, its low surface area and poor conductivity continue to be obstacles for practical usage. GCN's electrochemical characteristics are enhanced by the hybrid structure it forms with polypyrrole and Nb₂O₅. The synthesized polypyrrole (Ppy)/GCN/niobium pentoxide (Nb₂O₅) (Ppy/GCN/Nb₂O₅) nanocomposite electrode was tested for supercapacitance by cyclic voltammetry (CV) and Alternating current impedance techniques in 6 M Potassium hydroxide(KOH) electrolyte. The Ppy/GCN/Nb₂O₅ is linked to a network of agglomerated GCN and Nb₂O₅ nanoparticles with additional spherical shapes. The specific capacitance of Ppy/GCN/Nb₂O₅ was determined to be 1177 Fg⁻¹ at a current density of 5 Ag⁻¹. The Ppy/GCN/Nb₂O₅ electrode in KOH has average specific energy and specific power densities of 33 Wh kg⁻¹ and 2991 W kg⁻¹, respectively. The electrode showed excellent capacitance-retention ability of 97% after 10,000 cycles. The results demonstrate the high stability and efficient performance of the Ppy/GCN/Nb₂O₅ electrode employed in supercapacitors. The performance of the Ppy/GCN/Nb₂O₅ electrode was found to be superior to those reported for other carbon-based materials.     

磷酸活化炭气凝胶微球的电化学性能研究

以磷酸为活化剂,对炭气凝胶微球在高温下进行活化改性,并用活化产品制作超级电容器的电极。采用扫描电镜、N2物理吸附-脱附等对炭气凝胶微球的形貌结构进行表征,采用循环伏安、恒流充放电、交流阻抗等测定了材料的电化学性能。结果表明,磷酸活化效果温和,不会破坏炭气凝胶微球典型的圆球状外观和三维纳米孔隙结构。经过磷酸活化,炭气凝胶微球的电化学性能得到有效改善,材料的内阻降低,同时比电容提高将近一倍,最高可达184 F/g。     

二次活化活性炭及其在硫酸电解液中的电化学性能

采用二次活化的方法,通过改变活化剂种类、活化剂浓度、活化温度等参数,用商用活性炭制备高比容量活性炭。循环伏安、恒流充放电测试的结果表明,活化剂为65％的H3PO4,活化温度为800℃时,改性活性炭（AC—M）的比电容达到了331F／g。对AC—M进行SEM表征,图像显示活性炭大中孔比例增加。电化学测试表明,In2O3与Bi2O3混合使用抑制析氢效果较好。将AC—M应用于铅炭电池,结果表明,采用AC—M的铅炭电池高倍率部分荷电循环寿命为普通铅蓄电池的3～4倍。     

超级电容器碳基材料研究的进展

超级电容器是一种介于传统电容器和蓄电池之间的储能装置,其以功率密度大,充电速度快,工作温度范围宽,循环使用寿命长和绿色环保等优点,被世界各国广泛关注。通过对超级电容器新型碳电极材料的最新研究进展进行介绍,展望了超级电容器的发展前景,认为超级电容器将不仅对全球性能源问题有着重大突破,还将会带来巨大的经济效益。     

卷绕式超级电容器工作过程热分析

温度作为超级电容器的重要工作参数,对其性能和状态影响很大.该文建立了一种卷绕式圆柱形超级电容器的三维有限元热分析模型,并以2A参考电流进行恒流充放电测试,分析了其内部温度场分布情况.结果表明,最高温度出现在核心区最内层及其附近区域,循环充放电5次后,最高温度为34.5℃,进入稳态后,最高温度达到了42.5℃.进一步讨论了最高温度与充放电电流之间的关系,当充放电电流为4A,循环充放电5次后,最高温度超过60℃,此时需采取一定的冷却措施.该文所作研究可以为研究卷绕式超级电容器工作过程中的内部温度场分布及其结构设计提供思路.     

rGO/CuO/PEDOT nanocomposite formation,its characterisation and electrochemical performances for supercapacitors

ABSTRACT

Supercapacitor properties of rGO, CuO, PEDOT and rGO/CuO at [rGO]_o/[CuO]_o?=?1:1; 1:1.5; 1:2 and rGO/CuO/PEDOT nanocomposite at [rGO]_o/[CuO]_o/[EDOT]_o?=?1:1:1; 1:1:3; 1:1:5 were investigated using chemical reduction of GO and in-situ polymerisation process. SEM-EDX, HRTEM, BET surface area analysis confirm the nanocomposite formations. Nanocomposite materials are also analysed through FTIR-ATR, Raman, TGA-DTA, GCD, CV and EIS. The highest specific capacitance of C _sp?=?156.7 F/g at 2?mV/s is determined as rGO/CuO/PEDOT at [rGO]_o/[CuO]_o/[EDOT]_o?=?1:1:5. In addition, two-electrode supercapacitor device for rGO/CuO/PEDOT at [rGO]_o/[CuO]_o/[EDOT]_o?=?1:1:5 are found to provide a maximum specific energy (E?=?14.15 Wh/kg at 20?mA) and specific power (P?=?24730 W/kg at 50?mA), electrical serial resistance (ESR?=?13.33 Ω) with good capacity retention after 3000 cycles. An equivalent circuit model of LR1(CR2)(QR3) is proposed to interpret the EIS data. The supercapacitor performance of the rGO/CuO/PEDOT nanocomposite electrode indicates the synergistic effect of hybrid supercapacitors.     

MnO2氧化法制备高电容保持率PANI-Co3O4

以二氧化锰(MnO2)为氧化剂,通过化学原位聚合法将溶剂热法制备的四氧化三钴(Co3O4)与聚苯胺(PAM)复合,得到PANI-Co3O4复合材料.对产物进行SEM、XRD、循环伏安和恒流充放电测试.Co3O4为立方晶型,被大量纤维状的PANI包襄着.制备的PANI-Co3O4复合材料的比电容较高,循环性能良好.在电流...     

基于系统辨识的电化学超级电容器建模

各种不同类型电化学超级电容器的工作机理有较大区别,为克服机理分析法不适合机理复杂系统的建模和通用性差的缺点,提出一种基于系统辨识方法建立的电化学超级电容器模型。首先计算确定辨识实验数据的采样周期和长度,并采用小波分析对其进行滤波处理;针对模型结构辨识问题,利用行列式比定阶法确定模型阶次,然后在此基础上辨识模型参数;最后对模型进行仿真分析和验证。结果表明,文中建模方法可行有效,所建立的模型可以准确描述超级电容器的特性,同时待辨识数据经过小波滤波处理后可以有效提高模型精度。     

孤岛模式下基于快速储能投退机制的微电网多源协调控制

针对小型微电网,提出了单刀双掷开关和快速储能等集成安装在微电网公共连接点处的方案.在此基础上,提出微源综合并网控制模型和基于本地信息的自我决策模型(快速储能模型、后备电源模型),实现了响应速度快但容量较小的快速储能与容量较大但响应速度较慢(或需要一定启动时间)的后备电源之间不依赖于通信的多源协调控制.利用PSCAD/EMTDC软件建立了仿真系统,以超级电容(作为快速储能)和微型燃气轮机(作为后备电源)为例对所提控制策略进行了验证,实现了微源在微电网进入孤岛过程中的主动控制及在孤岛运行模式下的自治运行.