MnO2/碳纳米球电化学超级电容器电极材料的制备与性能研究

利用水热法合成了纳米棒状的MnO_2/碳纳米球(CNPs)作为电化学超级电容器的电极材料.利用场发射扫描电镜(FESEM)、X射线衍射光谱分析(XRD)对样品的微观形貌、物相进行分析;利用循环伏安法和恒电流充放电测试材料的电化学性能.结果表明:纳米棒状MnO_2/CNPs复合材料具有良好的电化学性能.在0.1 A/g的电流密度,1 mol/L Na_2SO_4电解液中,电极材料的比电容高达305.6 F/g,远高于纯碳球的比电容(49.3 F/g),当电流密度增至5 A/g时,材料的比电容为235 F/g,比电容仍能保持76.9%.     

Systematically controlled synthesis of rGO/nano-MnO_x materials for supercapacitors

The effects of hydrothermal production conditions on crystal forms,morphology and electrochemical performance of in situ reduced graphene oxide/manganese oxides(r GO/Mn O_x)hybrid electrode materials were studied.The XRD/SEM results show that the ratio of precursors,reaction temperature and type of solvent significantly affected the crystal form obtained and nano-structure of MnO_x.Varied precursor ratios of KMnO_4:GO(5:1,7:1,9:1 and 11:1)yielded the hybrids of rGO/Mn_7O_(13)5H_2O,rGO/β-MnO_2,rGO/Mn_(98)O_2,and rGO/K_(0.27)MnO_2(H_2O)_(0.54),respectively,having corresponding nano structures of nano-sheets composed petal-like shape,petal-like shape based nano-wire clusters,petal-like shape with backwardly arched top and bigger mesoporous petal-like nano structures.Hybrid prepared precursor with the ratio of 5:1 exhibited the highest specific capacitance of 320 F/g at 0.2 A/g and the smallest diffusion impedance.However,hybrid prepared precursor with the ratio of 7:1 presented the lowest electron transfer impedance.Varying hydrothermal treatment temperatures(140,160 and 200℃)yielded hybrids:rGO/MnO(OH),rGO/Mn_(0.91)O_(1,82)(H_2O)_(0.18),and rGO/Mn_7O_(13)5H_2O,respectively.The nano structures of the hybrids were nano-sheets having petal-like mesoporous structure,but having larger dimensions as temperature increase.The hybrid prepared at 160℃ showed the highest specific capacitance of 214 F/g at a current density of 0.2 A/g and the lowest solution resistance of1.61Ω,whiles,the hybrid prepared at 140℃ inferred the best cyclic reversibility.     

分级多孔纳米炭纤维的结构及电容性能

以酚醛树脂为碳源、PVP为纺丝助剂、纳米MgO颗粒为模板剂,通过静电纺丝法制得酚醛树脂基纳米炭纤维,经过炭化、KOH活化、酸洗后得到分级多孔纳米炭纤维,利用SEM、XRD、XPS、拉曼光谱仪及氮气吸脱附实验,对所制多孔纳米炭纤维的结构和形貌进行表征,并将其作为模拟电容器的电极,利用循环伏安、恒电流充放电及交流阻抗方法测试了材料的电化学性能。结果表明,KOH活化引入了数量可观的微孔,所得纳米炭纤维表现出明显的"微孔-中孔-大孔"分级孔分布的特点,其比表面积达到1058.4m~2/g,总孔容为1.64cm~3/g。电化学测试结果表明,所制分级多孔纳米炭纤维在6mol/L KOH电解液中显示出优异的电容性能,在0.2A/g的电流密度下,其放电比容量达到198F/g,在20A/g电流密度下,电容保持率达到65%。     

MnO_2@NiCo_2O_4核-壳异质结构的构筑及电化学性能和催化性能

采用2步水热法制备出1种以NiCo_2O_4纳米线为核,MnO_2纳米颗粒为壳的三维结构MnO_2@NiCo_2O_4@Ni-foam复合材料。通过X射线衍射(XRD),扫描电子显微镜(SEM)对复合催化剂的结构和形貌进行表征;通过循环伏安法(CV),恒流充放电性能(GCD)和电化学阻抗谱(EIS)来进行表征复合材料的电化学性能;通过O_3催化降解装置对复合材料的催化性能进行研究。结果表明:MnO_2@NiCo_2O_4@Ni-foam复合材料在频率范围为0.1～10 000 Hz时阻抗较低;通过降解实验发现,MnO_2@NiCo_2O_4@Ni-foam对O_3的降解率高于50%,表现出良好的催化效果。这表明MnO_2@NiCo_2O_4@Ni-foam复合材料在降解O_3,净化空气方面有广阔的应用前景。     

混合型电容器研究进展

混合型电容器是一种介于超级电容器和二次电池之间的新型储能装置,是现代电子、交通等行业理想的动力电源.根据电极组合的不同,将混合型电容器分为以下三种类型,它们分别是双电层电容器电极与法拉第电容器电极的组合、传统二次电池电极与双电层电容器电极的组合以及电解电容器的阴极与超级电容器电极的组合.混合型电容器与传统超级电容器相比,在能量密度和工作电压上均得到了较大的提高.着重介绍几种性能优异的混合型电容器及其未来的发展趋势.     

Flexible micro-supercapacitors fabricated from MnO2 nanosheet/graphene composites with black phosphorus additive

Supercapacitors are widely used for powering flexible/wearable electronics owing to their excellent charge storage capabilities. In this study, MnO₂ nanosheets were grown on the surface of graphene using a simple water bath method to prepare graphene/MnO₂ composites for fabricating supercapacitors. In addition, two-dimensional black phosphorus was introduced as an additive into the electronic ink based on the as-prepared graphene/MnO₂ composites. The characterization and electrochemical analyses results showed that adding black phosphorus considerably improved the capacitive performance of the material, yielding a high specific capacitance of 241.5 ?F ?g^-1 at 0.1 ?A ?g^-1 and an impressive rate capability improvement from 52.5% to 80.3%. Then the micro-supercapacitor having an area-specific capacitance of 20.15 ?mF ?cm^-2 at a scanning rate of 2 ?mV ?s^-1 was utilized to demonstrate the practical applicability of this material. To further evaluate the practical applicability of this micro-supercapacitor, the micro-supercapacitor was integrated with a flexible thin-film pressure sensor on paper and cloth through screen printing.     

Preparation and electrochemical properties of carbon-coated LiFePO4 hollow nanofibers

Carbon-coated LiFePO₄ hollow nanofibers as cathode materials for Li-ion batteries were obtained by coaxial electrospinning. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Brunauer–Emmett–Teller specific surface area analysis, galvanostatic charge–discharge, and electrochemical impedance spectroscopy (EIS) were employed to investigate the crystalline structure, morphology, and electrochemical performance of the as-prepared hollow nanofibers. The results indicate that the carbon-coated LiFePO₄ hollow nanofibers have good long-term cycling performance and good rate capability: at a current density of 0.2C (1.0C = 170 mA·g-1) in the voltage range of 2.5–4.2 V, the cathode materials achieve an initial discharge specific capacity of 153.16 mAh·g-1 with a first charge–discharge coulombic efficiency of more than 97%, as well as a high capacity retention of 99% after 10 cycles; moreover, the materials can retain a specific capacity of 135.68 mAh·g-1, even at 2C.     

凝胶聚合物电解质MnO2/AC电容器的研究

采用液相氧化法制备了MnO2超级电容器电极材料,以MnO2为正极材料,活性炭(AC)为负极材料,丙烯腈作聚合物单体,碳酸二甲酯(DMC)与碳酸乙烯酯(EC)的混和液作增塑剂,高氯酸锂为支持电解质,采用内聚合法制备PAN基凝胶聚合物电解质MnO2/AC混合电容器.通过循环伏安、交流阻抗、恒流充放电等测试方法对混合电容器的电化学性能进行了测试.结果表明:混合电容器的工作电压为2.5 V,比容量为27.3 F/g(i=0.5 mA/cm2),比同电解质体系的AC/AC电容器提高约48.21%.     

同槽电解生成锰和二氧化锰

分别采用预电解法,Mn(NO₃)₂热解,热解-预电解方式制备MnO2覆层Ti电极,并分别作为电解二氧化锰的阳极,硫酸锰-硫酸为电解液,研究不同的电流密度、温度、酸度对电解二氧化锰电流效率的影响.研究表明：采用热解-预电解法制备的Ti-MnO₂电极,抗钝化能力强,表面致密,MnO₂覆层与Ti基结合牢固,适合作为电解阳极使用.采用盐桥,素烧瓷,玻璃纤维作为阴阳极隔膜,阳极采用上述Ti-MnO₂电极,使用经过抛光的不锈钢作为阴极,在同一电解槽中同时电解生成电解MnO₂和金属锰,较佳条件下阳极和阴极电流效率分别能达到90%和60%,产品符合质量要求.     

影响聚吡咯铝电解电容器漏电流的因素及改进措施

利用电化学沉积的方法在腐蚀并赋能的铝箔试样表面合成了聚吡咯，并制备了聚吡咯铝电解电容器。在聚吡咯被覆的过程中，由于聚合溶液的毛细现象使电容器的阴极与阳极之间形成了微小的电气通路，另外聚合溶液对铝氧化膜有一定的腐蚀作用，导致氧化膜的缺陷增加，这两种情况是聚吡咯电解电容漏电流增加的根本原因。研究发现，采用合适的阻断材料和缩短聚合时间均可以有效地降低它们的影响。通过热重－差热分析，说明了在贮存过程中环境对这种电容器漏电流的影响，并提出了保持该电容器长期性能稳定的措施。     

电解质支持型固体氧化物燃料电池的制备及其工作稳定性

利用固相反应法制备固体氧化物燃料电池（SOFC)的复合阳极材料NiO-ScSZ和复合阴极材料（La_0.8Sr_0.2）_0.98MnO₃(LSM), 并对组装的电解质支持型单电池NiO-ScSZ-LSM进行I V性能测试, 其输出电压每0.2 A为0.9 V. 在外加恒定电流密度(0.2 A/cm²)的条件下, 利用电化学测试仪测试该电池的总电压为每1 000 h衰减0.02 V. 电流遮断法解析表明, 该单电池电压衰减主要为阴极过电压所致.     

无电解电容的宽范围输入电压半桥LLC数控开关电源设计

目前半桥LLC谐振电源中大多采用电解电容进行滤波,针对电解电容的电解液挥发产生的寿命低缺点。本设计采用了高寿命的CBB电容来代替电解电容进行滤波。但CBB电容容值低,滤波效果差,带来电压纹波大,输入电压范围宽的问题,因此本设计以STM32作为主控芯片,采用变频控制(PFM)与变脉宽控制(PWM)相结合的控制方法解决这一问题。经试验验证,本设计在使用CBB电容代替电解电容,宽输入电压范围的情况下,能够在一定的电压纹波内达到稳压效果,可以实现电源的高寿命。     

Characteristics of electric double layer in different aqueous electrolyte solutions for supercapacitors

Aiming to find suitable electrolytes for electric double layer capacitor (EDLC),the relationship between the formation velocity of electric double layer and the specific capacitance in different electrolyte (H 2 SO 4,KOH,KCl,NH 4 Cl,and LiOH) solutions was investigated by cyclic voltammetry and AC impedance with varying frequency and potential,which was also analyzed based on Stern model and Gouy-Chapman diffusion layer model.It shows that the capacitance is positively correlated with the formation velocity of the electric double layers,which is affected by the type of ions applied,the concentration of the electrolyte solution,and the potential and frequencies as well.The electrolyte solutions of 6 mol/L KOH and 4 mol/L H 2 SO 4 provide the largest capacitance,reaching 214 and 186 μF/cm 2,respectively.Both 6 mol/L KOH and 4 mol/L H 2 SO 4 solutions are suitable electrolytes for EDLC applications using Pt as electrodes.     

Influence of graphene microstructures on electrochemical performance for supercapacitors

The influence of variant graphenes on electrochemical performance for supercapacitors was studied comparatively and systematically by using SEM, FTIR and Raman spectroscopy, cyclic voltammetry (CV), galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS). The results revealed that: 1) the nitrogen-doped graphene (N-G) electrode exhibited the highest specific capacitance at the same voltage scan rate; 2) the specific capacitance of the N-G reached up to 243.5 F/g at 1 A/g, while regular graphite oxide (GO) was 43.5 F/g and reduced graphene oxide (rGO) was 67.9 F/g; 3) N-G exhibited the best supercapacitance performance and the superior electrochemical properties, which made it an ideal electrode material for supercapacitors.     

A study on nano-sized NiO electrodes doping with C and Co prepared by electrochemical deposition-sintering processes and their capacitance performance

In the present work, it was studied that nanoosized NiO electrodes doping with C and Co were prepared by electrochemical deposition in an ethanol solution containing nickel nitrate and cobalt nitrate and sintering processes. The capacitance performance of such electrodes was also studied. The results reveal that samples obtained by electrochemical deposition first on a porous nickel cathode in an ethanol solution contain 0.5 mol/L nitrates, in which Ni(NO3)2 and Co(NO3)2 were mixed in a molar proportion of 8 : 2. After sintering at 300℃ for 2 h, they exhibited the best performance. XRD analysis illustrates that the essential phase of the product is NiO doping with certain content of C and Co. The particles of product imaged a spherical morphology with sizes of 20---30 nm in diameter, and with an average crystal size of 4--5 nm. The capacitance measurement of the simulating C/NiO capacitors indicates that a single electrode can reach as high as 410.0 F/g, and still maintain the value of 323 F/g after 30 recycles showed as a stabilized value with increasing recycles, when it was discharged at a current of 5 mA.     

泡沫镍上原位生长CoMn2O4多级空心纳米球作为超级电容器电极材料的电化学性能研究

采用水热法结合空气气氛中的热处理过程,在泡沫镍（NF）表面生长了锰酸钴（CoMn₂O₄）多级空心纳米球,通过X射线衍射仪（XRD）、场发射扫描电镜（FE-SEM）和X射线光电子能谱（XPS）等测试手段对纳米球进行了表征.在三电极电化学测量系统中,0.1Co²⁺-250电极材料在5 mA·cm^-2时的面积比电容高达6 184 mF·cm^-2.以0.1Co²⁺-250为正极,商用活性炭（AC）为负极组装而成的混合超级电容器,在1.6 mW·cm^-2时的最大能量密度为0.112 mWh·cm^-2.即使在功率密度为16 mW·cm^-2时,能量密度仍达到0.064 mWh·cm^-2.在2 mA·cm^-2的电流密度下,经过10 000次充放电循环后,电容保持了初始值的93%.因其优越的电化学性能和低成本的便捷合成方法,CoMn₂O₄多级空心纳米球作为电极材料具有重要的应用前景.     

Direct growth of Fe3O4-MoO2 hybrid nanofilm anode with enhanced electrochemical performance in neutral aqueous electrolyte

To enhance the electrochemical energy storage performance of supercapacitors(SCs), the current researches are general directed towards the cathode materials. However, the anode materials are relatively less studied. In the present work, Fe_3O_4-MoO_2(FO-MO) hybrid nano thin film directly grown on Ti substrate is investigated, which is used as high-performance anode material for SCs in Li_2SO_4 electrolyte with the comparison to pristine Fe_3O_4 nanorod array. The areal capacitance of FO-MO hybrid electrode was initially found to be 65.0 m F cm~(-2)at 2 m Vs~(-1)and continuously increased to 260.0% after 50 cycles of activation. The capacitance values were considerably comparable or higher than many reported thinfilm iron oxide-based anodes in neutral electrolyte. With the protection of MoO_2 shell, the FO-MO electrode developed in this study also exhibited excellent cyclic stability(increased to 230.8% after 1000cycles). This work presents a promising way to improve the electrochemical performance of iron oxidebased anodes for SCs.     

无定形纳米级MnO2电极材料的制备及其准电容性能

 采用化学沉淀法制备了无定形纳米级粉末MnO₂电极材料,运用X射线衍射(XRD)、X射线光电子能谱(XPS)、热重分析和充放电容量测量法及循环伏安等方法对MnO₂制备、准电容形成机理进行了理论探讨.使用0.1 mol/L Na₂SO₄为电解液、烧结温度为80℃时能得到比电容最大的MnO₂材料,其实际电容约为136 F/g.     

基于超级电容的B/KNO3激光点火数值模拟

为了研究B/KNO₃（硼/硝酸钾）药剂基于超级电容驱动的激光点火规律,建立了从超级电容驱动激光二极管到激光辐照加热药剂全过程的激光点火时域模型,分析了放电电压和超级电容容值及等效电阻对激光点火延时的影响,基本揭示了基于超级电容的B/KNO₃激光点火特性和规律.仿真结果表明,随超级电容放电电压、容值的增加及超级电容等效电阻的减小,激光输出功率与能量均显著增加,激光点火延迟时间缩短,点火能量显著下降.仿真结果可为基于超级电容的激光快速点火设计提供依据及技术支撑.     

基于Li2MnO3的富锂类高比容量锂离子电池正极材料的研究进展

综述了近几年来基于Li2MnO3的高比容量二元和三元富锂类锂离子电池正极材料的研究进展.重点讨论了富锂材料zLi2MnO3.(1-z)LiMO2(0相似文献