Design and Preparation of Graphene/Fe2O3 Nanocomposite as Negative Material for Supercapacitor

The development of high specific capacitance electrode materials with high efficiency, scalability and economic feasibility is significant for the application of supercapacitors, however, the synthesis of electrode material still faces huge challenges. Herein, graphene(G)/Fe₂O₃ nanocomposite was prepared via a simple hydrothermal method connected with subsequent thermal reduction process. Scanning electron microscopy(SEM) and transmission electron microscopy(TEM) results showed rod-like Fe₂O₃ nanoparticles were prepared and well-dispersed on graphene layers, providing a rich active site and effectively buffering the aggregation of Fe₂O₃ nanoparticles in the process of electrochemical reaction. The specific capacitance of the obtained G/Fe₂O₃ nanocomposite as negative electrode for supercapacitor was 378.7 F/g at the current density of 1.5 A/g, and the specific capacitance retention was 88.76% after 3000 cycles. Furthermore, the asymmetric supercapacitor(ASC) was fabricated with G/Fe₂O₃ nanocomposite as negative electrode, graphene as positive electrode, which achieved a high energy density of 64.09 W∙h/kg at a power density of 800.01 W/kg, maintained 30.07 W∙h/kg at a power density of 8004.89 W/kg, and retained its initial capacitance by 78.04% after 3000 cycles. The excellent result offered a promising way for the G/Fe₂O₃ nanocomposite to be applied in high energy density storage systems.     

MoS_2@Co_9S_8蛋黄壳复合材料的制备及其电化学性能

近年来,过渡金属硫化物已成为锂离子电池理想的负极材料之一。其中,MoS_2具有的独特二维层状结构使得其能够让Li+在电化学反应中可逆地嵌入和脱出,且拥有较高的理论储锂容量(670 m A·h/g)而受到广泛关注。但MoS_2作为典型的半导体材料,电导率低下且在锂离子嵌入-脱出的过程中会发生较大程度的体积收缩膨胀,所以具有较差的倍率性能和循环性能,限制了其商业化的使用。很多研究通过优化MoS_2结构或与其它导电材料复合来克服上述缺陷。Co_9S_8具有较高的电导率,但由于其迟缓的离子传输动力学表现出低的首次库仑效率及较差的循环稳定性,基于此,将MoS_2与Co_9S_8结合利用二者协同效应来提高复合材料的电化学性能。本文采用溶剂热与气相沉积法制备得MoS_2@Co_9S_8蛋黄结构复合材料电极。MoS_2与Co_9S_8均匀分布于整个蛋黄壳结构,这有利于电子和锂离子的快速传输,从而有效地提升了电极的循环性能和倍率性能。其次,蛋黄壳的空穴有效缓解了在充放电过程中的体积膨胀,及其活性位点有效缩短了离子和电子的传输距离,提高了电极反应动力学并获得高比容量。MoS_2@Co_9S_8蛋黄壳复合物的循环性能与倍率性能在同等条件下均高于Co_9S_8和MoS_2,在电流密度为0.2 A/g下循环500圈后,放电容量仍能维持在631.5 m A·h/g。     

Enhanced electrochemical performance and mechanism study of AgLi1/3Sn2/3O2 for lithium storage

AgLi_1/3Sn_2/3O₂ with delafossite structure is prepared by treating Li₂SnO₃ with molten AgNO₃ and it exhibits improved electrochemical performance compared to Li₂SnO₃.     

BC/CoNi2S4@PPy柔性复合电极材料的制备及电化学性能

本文采用溶剂热、原位聚合和真空抽滤相结合的方法制备了用于超级电容器的细菌纤维素/镍钴硫化物/聚吡咯(BC/CoNi2S4@PPy)柔性电极材料,通过X 射线衍射、场发射扫描电镜、红外光谱、氮气吸脱附、拉伸强度和接触角表征了材料的形貌结构、组成、机械性能和亲水性,并采用循环伏安法和恒电流充放电测试了复合材料的电化学性能....     

TiO_2包覆Co_9S_8的制备及其电化学储氢性能

目前,寻找新型能源成为解决能源和环境问题的关键,氢能以其高效能、无污染等优点成为研究重点。其中,开发具有高储氢量和优异循环稳定性的新材料是利用氢能的重要研究方向。近些年,Co_9S_8凭借其优良的电化学储氢性能和较高的储氢容量成为目前研究热点,但其抗粉化性能仍有待于进一步提高。本文采用溶胶凝胶法和煅烧法得到了不同质量分数TiO_2包覆Co_9S_8的电极材料,利用X射线粉末衍射(XRD)、扫描电子显微镜(SEM)和电化学测试系统分析包覆材料组成与性能,研究不同质量分数的TiO_2对材料电化学储氢性能的影响。结果表明,当TiO_2质量分数为3%时,产物的储氢性能和循环稳定性最好,最大储氢容量(质量分数)为2.03%,且经过30次充放电后,其放电容量仍能保持在60%。     

Recent advances in electrocatalysts for non-aqueous Li-O2 batteries

As one of the next-generation energy-storage devices,Li-O₂ battery has become the main research direction for the academic researchers due to its characteristics of environmental friendship,relatively simple structures,high energy density of 3500 Wh/kg and low cost.However,Li-O₂ battery cannot be commercialized on a large scale because of the challenging issues including high-efficient electro-catalysts,membranes,Li-based anode and so on.In this review,we focused on the recent development of electrocatalyst materials as cathodes for the non-aqueous Li-O₂ batteries which are relatively simpler than other Li-O₂ batteries' structures.Electrocatalysts were summarized including noble metals,nano-carbon materials,transition metals and their hybrids.We points out that the challenges of preparation high-efficient catalysts not only require high catalytic activity and conductivity,but also have novel nanoarchitectures with large interface and porous volume for LiOx storage.Furthermore,the further investigation of reaction mechanism and advanced in situ analysis technologies are welcome in the coming work.     

High performance hybrid supercapacitor based on hierarchical MoS2/Ni3S2 metal chalcogenide

Herein, we synthesized hierarchical MoS₂/Ni₃S₂ structures as electrode materials grown on nickel foam by a facile hydrothermal strategy. The hierarchical MoS₂/Ni₃S₂ structures show high specific capacitance.     

Performance of PbO2/activated carbon hybrid supercapacitor with carbon foam substrate

PbO₂/activated carbon（AC） hybrid supercapacitor in H₂SO₄ with a carbon foam current collector is studied.The PbO₂/AC hybrid is designed with electrodeposited PbO₂ thin film as positive electrode to match with AC negative electrode.The discharge curve shows capacitive characteristics between 1.88 V and 0.65 V.The hybrid system exhibits excellent energy and power performance,with specific energy of 43.6 Wh/kg at a power density of 654.2 W/kg.The use of carbon foam current collector ensures stability of the PbO₂ electrode in H₂SO₄ environment.After 2600 deep cycles at 15 C high rate of charge/discharge,the capacity remains nearly unchanged from its initial value.     

三氧化钼——一种新型有机系钠离子储能器件负极材料

由于锂资源短缺,我们尝试使用三氧化钼作为钠离子储能装置负极材料。通过一种简单的方法合成了三氧化钼,使用XRD、SEM和TEM等测试手段对其物性进行了表征。利用三氧化钼作为有机系钠离子储能器件的负极材料,通过循环伏安和恒流充放电测试探讨了负极材料的储钠机理。以三氧化钼(MoO3)作为负极材料,活性炭(AC)和石墨(graphite)作为正极材料,组装成新型的电化学储能器件,研究了两种器件在1mol/L NaPF6的碳酸丙烯酯(PC)中的电化学性能。两种器件的电压范围分别为0~3.2V和0~3.5V,能量密度最高可分别达到31.6和53 Wh/kg,长循环性能远远优于AC/AC对称电容器。此种储能装置有望成为锂离子电池的一个很好的替代。     

尖晶石型过渡金属硫化物CuCo2S4与MoS2复合材料的制备及电催化析氢性能

通过简单的三步水热法实现尖晶石型过渡金属硫化物CuCo₂S₄与MoS₂的复合, 以三维多孔泡沫镍(NF)为基底, 制得自支撑催化电极MoS₂@CuCo₂S₄-Ni₃S₂/NF. 高分辨透射电子显微镜(HRTEM)、 X射线衍射(XRD)、 X射线光电子能谱(XPS)、 扫描电子显微镜(SEM)及透射电子显微镜(TEM)表征结果表明, MoS₂纳米片层密集均匀地生长在CuCo₂S₄-Ni₃S₂纳米棒表面, 并形成多级核壳结构. 其碱性条件下(1 mol/L KOH)的电催化析氢性能研究结果表明, MoS₂与CuCo₂S₄的复合和特殊形貌的构筑有效提高了电化学活性面积和电子传导效率, 达到10, 100和300 mA/cm²电流密度分别仅需116, 231和282 mV的过电位, 经2000次循环伏安扫描后, 100 mA/cm²电流密度所对应的过电位仅增大6%, 展现出优异的电催化析氢催化活性及较好的稳定性.     

Flexible asymmetric supercapacitor with high energy density based on optimized MnO2 cathode and Fe2O3 anode

A flexible asymmetric supercapacitor is assembled using MnO₂ nanosheets/carbon fabric and Fe₂O₃/carbon fabric electrodes. By optimizing the reaction condition of the two electrodes, the device shows high energy densities and excellent flexibility.     

链状Cs_8Mn_4Sn_4Se_(16)和[Ni(1,2-dap)_3]_2Cd_2Sn_2S_8(1,2-dap:1,2-丙二胺)的溶剂热合成与表征

采用溶剂热法,在1,4-丁二胺中合成以碱金属为客体阳离子的硫属锡酸盐Cs_8Mn_4Sn_4Se_(16)(1)及1,2-丙二胺(1,2-dap)配位的过渡金属为客体阳离子的硫属锡酸盐[Ni(1,2-dap)_3]_2Cd_2Sn_2S_8(2)。并采用单晶X射线、紫外可见漫反射、热重分析-差示扫描量热分析(TG-DSC)等手段进行表征。结果表明,化合物1为正交晶系,空间群为Fddd;化合物2为正交晶系,空间群为Cmcm;且结构中均包含Sn Q4(Q=S,Se)四面体与TMQ_4(TM=Mn,Cd)四面体通过共边而成的一维(1-D)阴离子链,紫外可见漫反射分析表明,化合物1、2的禁带宽度分别为1.70和2.21 e V,具有半导体性质。且TG-DSC测试显示化合物1、2在一定温度下具有一定的稳定性。     

皱褶表面介孔镍钴硫化物微球的制备及其超电性能

通过一步水热法分别合成了α-NiS、Co₃S₄和CoNi₂S₄纳米介孔电极材料,并研究了其电化学性能。 X射线衍射(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)研究表明,介孔硫化物是由单相纳米颗粒堆叠组装而成,其中二元系的CoNi₂S₄由纳米片自组装形成了具有皱褶表面的微球形貌。 电化学性能研究表明,二元系的CoNi₂S₄比α-NiS、Co₃S₄具有更高的比电容、更佳的倍率特性和优异的循环稳定性。 在扫描速率为5 mV/s时,CoNi₂S₄材料在6 mol/L KOH电解液中比电容高达1678.3 F/g,优于α-NiS (787.4 F/g)和Co₃S₄(1532.7 F/g),在扫描速率从5 mV/s增加到100 mV/s时,其电容保持率为45.8%,比α-NiS(30.2%)和Co₃S₄(29.3%)高出约15%。 在15A/g的电流密度下,经过900次循环充-放电后,二元系的CoNi₂S₄的电容仍保持在96.3%,库伦效率保持在94.3%左右,说明镍钴双金属硫化物具有优异的循环稳定性能和充放电可逆性。     

Ni3S2@碳纳米管复合材料的制备及其储钠性能

采用一步固相煅烧工艺制备了碳纳米管原位封装Ni₃S₂纳米颗粒（Ni₃S₂@CNT）,并研究了其作为钠离子电池（SIBs）负极材料的电化学性能. 通过X射线衍射（XRD）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）、循环伏安测试、恒流充放电以及交流阻抗等研究了Ni₃S₂@CNT的物相结构、形貌特征以及电化学性能. 电化学测试表明,材料在100 mA·g ^-1电流密度下,放电容量可以达到541.6 mAh·g ^-1,甚至在2000 mA·g ^-1的大电流密度下其放电比容量也可以维持在274.5 mAh·g ^-1. 另外,材料在100 mA·g ^-1电流密度下,经过120周充放电循环后其放电和充电比容量仍然可以保持在374.5 mAh·g ^-1和359.3 mAh·g ^-1,说明其具有良好倍率性能和循环稳定性能. 良好的电化学性能归因于这种独特的碳纳米管原位封装Ni₃S₂纳米颗粒结构. 碳纳米管不但可以提高复合材料的导电性,也可以缓冲Ni₃S₂纳米颗粒在反复充放电过程中产生的体积膨胀效应,明显改善了Ni₃S₂@CNT负极复合材料的电化学性能.     

CoNi2S4上电沉积NiS用于柔性固态非对称超级电容器

采用一种在CoNi2S4上电沉积NiS的有效方法来改善钴/镍硫化物的性能。CoNi2S4@NiS电极材料在1 A·g^-1时比电容达到1433 F·g^-1,并具有很好的倍率性能。CoNi2S4@NiS和还原氧化石墨烯组装成的柔性固态非对称超级电容器的能量密度在功率密度为800 W·kg^-1时达到36.6 Wh·kg^-1,并且在10000次充放电后表现出良好的循环性能,循环保持率达87.8%。     

SnS2/graphene nanocomposite: A high rate anode material for lithium ion battery

In this work,via a facile solvothermal route,we synthesized an anode material for lithium ion batteries(LIBs)—SnS_2 nanoparticle/graphene(SnS_2 NP/GNs) nanocomposite.The nanocomposite consists of SnS_2nanoparticles with an average diameter of 4 nm and graphene nanosheets without restacking.The SnS_2 nanoparticles are firmly anchored on the graphene nanosheets.As an anode material for LIBs,the nanocomposite exhibits good Li storage performance especially high rate performance.At the high current rate of 5,10,and 20 A/g,the nanocomposite delivered high capacities of 525,443,and 378 mAh/g,respectively.The good conductivity of the graphene nanosheets and the small particle size of SnS_2contribute to the electrochemical performance of SnS_2 NP/GNs.     

Synthesis of spherical nanoparticles of Cu2L2O5 (L=Ho, Er) from W/O microemulsions

Nanoparticles of Cu₂L₂O₅ (L=Ho, Er) (15–25 nm in size) were synthesised by the intermediate use of W/O microemulsions. In this process the aqueous cores of water/cetyltrimethylammonium bromide/n-octane/1-butanol microemulsions were used as microreactors for the precipitation of Cu₂Ho₂(CO₃)₄(OH)₂ (25–30 nm) and Cu₂Er₂(CO₃)₄(OH)₂ (10–40 nm) as precursors. These mixed salts were separated and further decomposed to the corresponding mixed oxides at 900°C for 16 h. All solids were characterised by scanning and transmission electron microscopy, IR, XRPD, ICP-OES, TGA, XPS measurements and elemental analyses.     

A wide potential window aqueous supercapacitor based on LiMn<Subscript>2</Subscript>O<Subscript>4</Subscript>–rGO nanocomposite

Aqueous supercapacitors based on neutral solutions have the advantages of high-ionic conductivity, being environmentally friendly, safe, and low cost. However, the operating potential window for most aqueous electrolytes is far lower than that of organic electrolytes that are commonly used in commercial supercapacitors. In this work, we report on the fabrication of a wide potential window, high-energy aqueous asymmetric supercapacitor, without sacrificing power, by using a nanostructured LiMn₂O₄/reduced graphene oxide (LMO–rGO) nanocomposite. We synthesized the uniformly distributed LMO in the LMO–rGO nanocomposite using a co-precipitation route followed by a low-temperature hydrothermal treatment. In a three-electrode cell setup, the specific capacitance of the LMO–rGO nanocomposite electrode at 1 A/g (1.2 mA/cm²) is 268.75 F/g (258 mF/cm²), which shows a dramatic improvement over the sum of the specific capacitances of pristine LMO (162.5 F/g) and pure rGO (29.94 F/g) electrodes in their relative ratios, when used alone. This finding suggests a synergistic coupling of LMO and rGO in the nanocomposite. We also assembled the LMO–rGO nanocomposite, as the positive electrode, with activated carbon, as the negative electrode, into an asymmetric cell configuration. The device shows an ultra-wide potential window of 2.0 V in a neutral aqueous Li₂SO₄ electrolyte, with a maximum energy density of 29.6 Wh/kg (which approaches the commercial lead-acid batteries), power density of up to 7408 W/kg, and an excellent cycle life (5% loss after 6000 cycles). These findings confirm that an LMO–rGO nanocomposite is a promising material to meet the demands of real world energy storage.     

Synthesis of core-shell structured Au@Bi2S3 nanorod and its application as DNA immobilization matrix for electrochemical biosensor construction

The core-shell structured Au@Bi2S3 nanorods have been prepared through direct in-situ growth of Bi2S3 at the surface of pre-synthesized gold nanorods.The product was characterized by X-ray diffraction,transmission electron microscopy and energy-dispersive X-ray spectroscopy.Then the obtained Au@Bi2S3 nanorods were coated onto glassy carbon electrode to act as a scaffold for fabrication of electrochemical DNA biosensor on the basis of the coordination of-NH2 modified on 5’-end of probe DNA and Au@Bi2S3.Electrochemical characterization assays demonstrate that the Au@Bi2S3 nanorods behave as an excellent electronic transport channel to promote the electron transfer kinetics and increase the effective surface area by their nanosize effect.The hybridization experiments reveal that the Au@Bi2S3 matrix-based DNA biosensor is capable of recognizing complementary DNA over a wide concentration ranging from 10 fmol/L to 1 nmol/L.The limit of detection was estimated to be 2 fmol/L(S/N=3).The biosensor also presents remarkable selectivity to distinguish fully complementa ry sequences from basemismatched and non-complementary ones,showing great promising in practical application.     

On the electronic structure of [W(WS4)2]

The ground-state electronic structure of W₃S₈²⁻ has been calculated using the relativistic SCF-MS-X method. The results confirm a formal oxidation state of +2 for the central tungsten atom and a + 6 oxidation state for the terminal ones. A W---|W σ bond is detected within the 7a_1g molecular orbital leading to a W---|W bond order of 1/2. The energy order of the X MOs of ligand field interest, localized on the central metal ion, is explained based on the simple angular overlap approach taking into consideration the W---|W interactions.