泡沫镍负载球状NiCo_2O_4电极的制备及超级电容性能研究

采用水热法在泡沫镍上生长了球状钴酸镍(NiCo_2O_4)电极材料,利用扫描电镜(SEM)观测了纳米球的表面形貌,利用X射线衍射(XRD)分析了纳米球的结构,通过循环伏安、恒流充放电测试了电极的超级电容性能。结果表明:球状NiCo_2O_4直径500~600nm,均匀生长在泡沫镍骨架上,球状之间存在空隙,可以增大与电解液的接触面积。在电流密度为1A/g,NiCo_2O_4/泡沫镍复合电极放电比电容为970F/g,循环1000次后比电容仍保持在844F/g,放电比容量保持率为82.5%,具有优异的超级电容性能。     

纳米纤维素/Fe3O4纳米球的原位合成及其电化学性能

利用实验室自制茶梗纳米纤维素原位合成纳米纤维素(CNC)/四氧化三铁(Fe_3O_4)纳米球,并对其粒径大小、结晶性质、磁性性能和电化学性能进行分析表征。结果表明,通过原位合成法所制得CNC/Fe_3O_4纳米球,粒子间分散性良好,直径约为10～30 nm;CNC/Fe_3O_4纳米球具有磁化强度34.9 A·m~2/kg的磁特性;CNC/Fe_3O_4纳米球表现出良好的电化学性能,CNC/Fe_3O_4电极的比电容主要是Fe_3O_4产生的赝电容,在电流密度0.03 A/g时,比容量可达30.14 F/g,在0.04 A/g电流密度下,经过500次充放电后容量保持率为78.76%。CNC/Fe_3O_4电极中离子的扩散为Warburg机理。     

MnO2/NiCo2O4复合材料的控制合成及其电化学性能研究

采用两步合成法制备了MnO_2/NiCo_2O_4核壳结构纳米棒,使用场发射扫描电子显微镜、X射线衍射和电化学工作站研究了其形貌特征和电化学性能。研究结果表明,在α-MnO_2纳米棒上生长了均匀的NiCo_2O_4纳米片,这种核壳结构纳米棒所制备的电极在充放电电流密度为0.5A/g时比电容达到了434F/g,明显比纯α-MnO_2的比电容(256F/g)高,循环测试2 000次后,比电容保留量为91.8%,表现出了优秀的电化学性能,具有广阔的应用前景。     

“一步法”合成NiCo_2S_4纳米阵列高性能能量存储器件电极的研究

通过简单的"一步低温原位合成"法成功制备出了以泡沫镍为基底的具有自支撑结构的分层三维网络的NiCo_2S_4纳米阵列,采用SEM、XRD对产物的微观结构进行表征,并对其进行电化学性能测试。结果表明,由于这种独特的分层网络结构,该NiCo_2S_4纳米阵列不仅能够为能量存储提供大量的电化学活性位点,而且拥有良好的电子传递性能,NiCo_2S_4@泡沫镍电极在20 m A/cm~2的电流密度下,面积比电容可达到10.15 F/cm~2,且当电流密度增大到100 m A/cm~2时,面积电容仍然为7.29 F/cm~2,显示出优异的电容保持率;当NiCo_2S_4负载量是14.8 mg时,电流密度为20 m A/cm~2,充放电5 000次,电容保持率是72.5%,显示出NiCo_2S_4@泡沫镍电极良好的循环稳定性。     

Co_3O_4纳米片/碳微球复合物的制备及其超级电容器性能研究

利用简单的低温水热法和后续高温煅烧,将Co_3O_4纳米片成功的生长在碳微球表面。X-射线衍射(XRD)和场发射扫描电镜(FE-SEM)测试表明,Co_3O_4纳米片自组装呈疏松状包覆于碳微球表面,纳米片之间相互交织形成三维多孔结构,丰富的孔道极有利于电解质离子在电极材料活性物质中的迁移和渗透。将其作为工作电极,表现出较高的电容性能,电流密度为1A/g时比电容达184F/g,当电流密度达5A/g时电容保持率为82.6%,电极材料具有良好的倍率特性。     

水热合成法制备超级电容器用二氧化锰薄膜电极

采用简单的水热合成法制备了基于石墨基底的多孔α-MnO2薄膜电极。用X射线衍射(XRD)、扫描电镜(SEM)、能谱仪(EDS)、BET氮气吸附法和热重分析(TG)对产物进行表征,结果表明,沉积得到了由纳米棒交织而成的网络结构的α-MnO2薄膜。用循环伏安法和恒流充放电法对其电化学性能进行研究,结果显示,在1mol·L-1Na2SO4溶液中,电流密度为1A·g-1时,α-MnO2薄膜的比电容可达到229F·g-1,该电极材料在2A·g-1的电流密度下进行2000次循环,电极容量的衰减仅为2%。     

分级多孔活性炭的KOH再活化法制备及其电化学性能

首先利用水热法以葡萄糖为碳源合成炭微球,然后采用KOH再活化法将炭微球制备成分级多孔活性炭,最后测试并表征其作为超级电容器电极材料的电化学性能。结果表明:KOH再活化法具有扩孔和再造孔的双重作用,可获得具有较高的比表面积、合适的分级多孔结构和良好的石墨化程度的分级多孔活性炭材料;在Na2SO4中性电解液中,在电流密度为1 A/g时,分级多孔活性炭材料的比电容可达209 F/g,表现出优异的电化学性能。     

聚酰亚胺基氮掺杂碳电极材料的制备及电化学性能研究

由于氮掺杂多孔碳材料不仅保留原有材料的高比表面积、高孔隙率和发达的孔道结构等优势,还兼具杂原子良好的润湿性能和导电性,被广泛应用于超级电容器电极材料的研究。以均苯四甲酸二酐(PMDA)和4,4′-二氨基二苯醚(ODA)为原料,通过水热法,在高温高压的条件下,分子链进行“自上而下”的折叠,形成三维纳米微球结构。借助对纳米球的高温热解,使氮元素保留在碳材料中,得到含有大量微孔和介孔结构的掺杂氮碳微球。当碳化温度达到800℃时,PI碳球具有709.39m²/g的高比表面积和良好的氮掺杂率,很大程度上提高了此类电极材料的比电容和润湿性能。电化学测试表明,当扫描速率为0.5A/g时,电极材料能够达到253.6F/g的比电容,且在电流密度达到10A/g时,电极材料的电容保持率为59.6%。同时,在循环10000次后,比电容保持率出现涨幅达到105%,具有优异的循环稳定性。综上,通过自组装和氮掺杂的有效结合,制备的3D氮掺杂多孔碳微球具有理想的电化学性能,为制备超级电容器电极材料提供了一种可供参考的工艺。     

超薄二氧化锰@碳纳米球复合材料的制备及电容特性

本工作采用液相沉淀法制备了二氧化锰@碳纳米球电极材料,通过碳纳米球复合的方式对二氧化锰进行改性。经XRD分析可知,合成的材料以水钠锰矿的形式存在;由TEM和SEM分析可知,碳纳米球均匀分布在片层状二氧化锰的表面,使其更加饱满充实。由电化学测量可知,适量碳纳米球的引入明显提高了材料的电化学性能,在二氧化锰复合碳纳米球摩尔分数为100%时,所得材料拥有最佳比容量,即在1 A·g~(-1)电流密度下放电比容量为166.3 F·g~(-1),当电流密度增加到10 A·g~(-1)时,材料的比容量仍能保持在135.9 F·g~(-1),经历2 000次循环后电容保持率高达95.1%,说明材料具有优异的倍率特性和较高的稳定性。这可能是由于引入碳纳米球后提高了水钠锰矿的导电性,从而增加了其活性位点的数量。     

ZnFe_2O_4纳米粒子-石墨烯复合材料制备和超级电容器性能

为提高ZnFe_2O_4的电化学性能,采用一步溶剂热法合成ZnFe_2O_4纳米粒子-石墨烯复合材料,对其进行X射线衍射、扫描电子显微镜、透射电子显微镜表征和电化学性能分析。结果表明:该方法可防止二维层状结构石墨烯团聚,把ZnFe_2O_4颗粒粒径控制在纳米级且均匀地附着到石墨烯片层上;复合材料呈现二维层状结构,比表面积达到180 m~2/g,有效增加活性位点数量;当电流密度为1 A/g时,复合材料电极的比电容达到180.9 F/g,电化学性能优于纯ZnFe_2O_4电极。     

NiS2/三维多孔石墨烯复合材料作为超级电容器电极材料的电化学性能

选用合适的软模板,通过简便的一步溶剂热法成功制备了NiS₂/三维多孔石墨烯（3D rGO）复合材料。利用FESEM、TEM、XPS和电化学工作站对样品的表面形貌、元素价态和电化学性能进行表征。结果表明:制备的NiS₂/3D rGO复合材料存在石墨烯三维堆叠的孔道结构,且具备较大的比表面积,为57.51 m2g-1。电化学测试表明,在1 Ag-1的电流密度下NiS₂/3D rGO复合材料的比电容高达1 116.7 Fg-1,而且当电流密度增加到5 Ag-1时NiS₂/3D rGO复合材料的比电容为832.2 Fg-1,比电容保持率为1 Ag-1时的74.5%。在4 Ag-1电流密度下,经过1 000次循环后,NiS₂/3D rGO复合材料的比电容仍能保持91.2%。因此,NiS₂/3D rGO复合材料可作为一种理想的超级电容器电极材料。      

中空Cu_7S_4纳米立方的制备及其电化学电容性能

本文以化学沉淀法制备出立方体Cu_2O,以Cu_2O为模板用水热离子交换法制备出纳米Cu_7S_4。利用X-射线衍射仪(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)对Cu_7S_4进行测试,结果显示Cu_7S_4具有中空立方体结构,平均尺寸在550nm左右。使用三电极体系,采用循环伏安法、恒流充放电、电化学阻抗谱和循环稳定性分析研究了Cu_7S_4的电化学性能。测试结果表明,当电流密度为1A·g~(-1)时,Cu_7S_4的比电容为275F·g~(-1)。在电流密度为4A·g~(-1)时,Cu_7S_4循环1000次仍能保留94.8%的比电容,展示出良好的循环性能。     

超级电容器用CeO_2-MnO/3D石墨烯复合材料的制备

以西瓜瓜瓤为碳源,采用两步碳化法制备三维石墨烯(3D-Fiberbased Graphene,3D G)材料,并使用水热法制备了CeO_2-MnO/3DG复合材料,以期获得比电容高,循环寿命好的石墨烯超级电容器电极材料。结果表明:3DG材料具有较高比表面积,最高可达到332m~2·g~(-1)。CeO_2-MnO/3DG复合材料具有三维导电网络结构,金属氧化物颗粒在石墨烯片层间生长均匀,粒径在10nm左右。电化学测试结果显示:在0.5 mol·L~(-1)的Na_2SO_4溶液中,电流密度1A·g~(-1),当摩尔比MnO∶CeO_2=4∶1,复合负载量在80%时得到的CeO_2-MnO/3D G复合材料拥有最高比电容,达308.5F·g~(-1),经过1 000次循环充放电测试比电容保持率为95.5%。CeO_2-MnO/3DG复合材料电化学性能的提高主要是因为两种金属氧化物复合负载与石墨烯的协同作用。     

Facile one-pot synthesis of NiCo<Subscript>2</Subscript>O<Subscript>4</Subscript> hollow spheres with controllable number of shells for high-performance supercapacitors

In this work,single-and double-shelled NiCo2O4 hollow spheres have been synthesized in situ by a one-pot solvothermal method assisted by xylose,followed by heat treatment.Employed as supercapacitor electrode materials,the double-shelled NiCo2O4 hollow spheres exhibit a remarkable specific capacitance (1,204.4 F·g-1 at a current density of 2.0 A·g-1) and excellent cycling stability (103.6％ retention after 10,000 cycles at a current density of 10 A·g-1).Such outstanding electrochemical performance can be attributed to their unique internal morphology,which provides a higher surface area with a larger number of active sites available to interact with the electrolyte.The versatility of this method was demonstrated by applying it to other binary metal oxide materials,such as ZnCo2O4,ZnMn2O4,and CoMn2O4.The present study thus illustrates a simple and general strategy for the preparation of binary transition metal oxide hollow spheres with a controllable number of shells.This approach shows great promise for the development of next-generation high-performance electrochemical materials.     

Metal-organic framework derived hierarchical NiCo2O4 triangle nanosheet arrays@SiC nanowires network/carbon cloth for flexible hybrid supercapacitors

To overcome the disadvantages of traditional powder electrodes,such as the insufficient performance,the aggregation of active materials,and the complex fabrication process,rationally constructing free-standing electrode materials with hierarchical architecture is an effective and promising method,which could further improve the electrochemical properties.Herein,using metal-organic framework nanoar-rays (MOFNAs) as self-sacrificial templates and SiC nanowires (SiCNWs) network as nanoscale conductive skeletons,we successfully fabricated the hierarchical core-shell SiCNws@NiCo2O4NAs on carbon cloth (CC)substrate.Taking advantages of structural merits,such as hierarchical porous triangle-like NiCo2O4NAs,the interwoven SiCNWs network and conductive CC substrate,when evaluated as a binder-free superca-pacitor electrode,the CC/SiCNWs@NiCo2O4NAs shows a high specific capacitance of 1604.7 F g-1 (specific capacity of 222.9 mA h g-1) at 0.5 A g 1,good rate performance,and excellent cycling stability.Signifi-cantly,the hybrid supercapacitor assembled with CC/SiCNWs@NiCo2O4NAs as the cathode and MOF derived CC/SiCNWs@CNAs as the anode,could deliver a high specific density of 49.9 W h kg-1 at a specific power of 800 W kg-1,stable cycling performance,and good flexibility.Impressively,this feasible strategy for fabricating hierarchical structure displays great potential in the field of energy storage.     

Feather-like NiCo2O4 self-assemble from porous nanowires as binder-free electrodes for low charge transfer resistance

The unique feather-like arrays composing of ultrathin secondary nanowires are fabricated on nickel foam (NF) through a facile hydrothermal strategy. Thus, the enhancement of electrochemical properties especially the low charge transfer resistance strongly depends on more active sites and porosity of the morphology. Benefiting from the unique structure, the optimized NiCo₂O₄ electrode delivers a significantly lower charge transfer resistance of 0.32 Ω and a high specific capacitance of 450 F·g⁻¹ at 0.5 A·g⁻¹, as well as a superior cycling stability of 139.6% capacitance retention. The improvement of the electrochemical energy storage property proves the potential of the fabrication of various binary metal oxide electrodes for applications in the electrochemical energy field.     

Construction of hierarchical three-dimensional interspersed flower-like nickel hydroxide for asymmetric supercapacitors

Low-cost and easily obtainable electrode materials are crucial for the application of supercapacitors.Nickel hydroxides have recently attracted intensive attention owning to their high theoretical specific capacitance,high redox activity,low cost,and eco-friendliness.In this study,novel three-dimensional (3D) interspersed flower-like nickel hydroxide was assembled under mild conditions.When ammonia was used as the precipitant and inhibitor and CTAB was used as an exfoliation agent,the obtained exfoliated ultrathin Ni(OH)2 nanosheets were assembled into 3D interspersed flower-like nickel hydroxide.In this novel 3D structure,the ultrathin Ni(OH)2 nanosheets not only provided a large contact area with the electrolyte,reducing the polarization of the electrochemical reaction and providing more active sites,but also reduced the concentration polarization in the electrode solution interface.Consequently,the utilization efficiency of the active material was improved,yielding a high capacitance.The electrochemical performance was improved via promoting the electrical conductivity by mixing the as-synthesized Ni(OH)2 with carbon tubes (N-4-CNT electrode),yielding excellent specific capacitances of 2,225.1 F·g-1 at 0.5 A·g-1 in a three-electrode system and 722.0 F·g-1 at 0.2 A·g-1 in a two-electrode system.The N-4-CNT//active carbon (AC) device exhibited long-term cycling performance (capacitance-retention ratio of 111.4％ after 10,000 cycles at 5 A·g-1) and a high specific capacitance of 180.5 F·g-1 with a high energy density of 33.5 W·h·kg-1 and a power density of 2,251.6 W·kg-1.     

Facile solvothermal synthesis of NiFe2O4 nanoparticles for high-performance supercapacitor applications

We report a green and facile approach for the synthesis of NiFe₂O₄ (NF) nanoparticles with good crystallinity. The prepared materials are studied by various techniques in order to know their phase structure, crystallinity, morphology and elemental state. The BET analysis revealed a high surface area of 80.0 m²·g⁻¹ for NF possessing a high pore volume of 0.54 cm³·g⁻¹, also contributing to the amelioration of the electrochemical performance. The NF sample is studied for its application in supercapacitors in an aqueous 2 mol·L⁻¹ KOH electrolyte. Electrochemical properties are studied both in the three-electrode method and in a symmetrical supercapacitor cell. Results show a high specific capacitance of 478.0 F·g⁻¹ from the CV curve at an applied scan rate of 5 mV·s⁻¹ and 368.0 F·g⁻¹ from the GCD analysis at a current density of 1 A·g⁻¹ for the NF electrode. Further, the material exhibited an 88% retention of its specific capacitance after continuous 10000 cycles at a higher applied current density of 8 A·g⁻¹. These encouraging properties of NF nanoparticles suggest the practical applicability in high-performance supercapacitors.     

Self‐Assembled Nickel Pyrophosphate‐Decorated Amorphous Bimetal Hydroxides 2D‐on‐2D Nanostructure for High‐Energy Solid‐State Asymmetric Supercapacitor

To obtain a supercapacitor with a remarkable specific capacitance and rate performance, a cogent design and synthesis of the electrode material containing abundant active sites is necessary. In present work, a scalable strategy is developed for preparing 2D‐on‐2D nanostructures for high‐energy solid‐state asymmetric supercapacitors (ASCs). The self‐assembled vertically aligned microsheet‐structured 2D nickel pyrophosphate (Ni₂P₂O₇) is decorated with amorphous bimetallic nickel cobalt hydroxide (NiCo‐OH) to form a 2D‐on‐2D nanostructure arrays electrode. The resulting Ni₂P₂O₇/NiCo‐OH 2D‐on‐2D array electrode exhibits peak specific capacity of 281 mA hg^?1 (4.3 F cm^?2), excellent rate capacity, and cycling stability over 10 000 charge–discharge cycles in the positive potential range. The excellent electrochemical features can be attributed to the high electrical conductivity and 2D layered structure of Ni₂P₂O₇ along with the Faradic capacitance of the amorphous NiCo‐OH nanosheets. The constructed Ni₂P₂O₇/NiCo‐OH//activated carbon based solid‐state ASC cell operates in a high voltage window of 1.8 V with an energy density of 78 Wh kg^?1 (1.065 mWh cm^?3) and extraordinary cyclic stability over 10 000 charge–discharge cycles with excellent energy efficiency (75%–80%) over all current densities. The excellent electrochemical performance of the prepared electrode and solid‐state ASC device offers a favorable and scalable pathway for developing advanced electrodes.