基于P掺杂TiO2/C纳米管负极的高性能锂离子电容器

以磷酸二氢钠(NaH₂PO₄)为磷源, 通过溶剂热法制备了P掺杂的TiO₂/C (P-TiO₂/C)纳米管以改善TiO₂的储锂性能. 电化学测试表明: P-TiO₂/C负极具有高的比容量(在0.1 A•g^-1的电流密度下达到335 mAh•g^-1)、优异的倍率性能(在2.0 A•g^-1的电流密度下为92 mAh•g^-1)及循环性能(在1.0 A•g^-1的电流密度下经过1000次循环后放电比容量仍维持在135 mAh•g^-1). 并且, P-TiO₂/C在2 mV•s^-1时的赝电容贡献约为96%. 由P-TiO₂/C负极和活性炭正极组装的锂离子电容器在250 W•kg^-1的功率密度下能量密度能够达到74.7 Wh•kg^-1. 此外, 该锂离子电容器在10000次循环后比电容保持率约为43%. 此外, 该器件在1.0 A•g^-1下循环10000次后充满电仍可点亮18只红色的LED灯组成的“LIC”字样. 该工作为高性能锂离子电容器TiO₂负极材料的设计提供了思路.     

酚醛树脂热裂解碳为电极的双电层电容器的电化学特性

双电层电容器具有体积小、容量大和价格便宜等特点 ,以活性炭为电极的双电层电容器是具有高度可靠性的特殊电源 ,在许多便携式电子仪器和通讯设备上被用作备用电源 .特别是具有相对大容量的电容器已与标准的铅酸蓄电池组成混合体系 ,应用在电动车辆上 [1] .酚醛树脂经热裂解制备的聚并苯导电材料 PAS是制备双电层电容器电极的最佳材料之一 [2～ 10 ] ,它可以进行 p型和 n型掺杂 ,而且耐化学腐蚀、耐氧化和热稳定性好 .本文通过热裂解酚醛树脂来制备容量大、等效串联电阻小、不使用任何重金属、对环境无污染和不需长时间更换的双电层电容器…     

Synthesis and microstructural TEM investigation of CaCu3Ru4O12 ceramic and thin film

CaCu₃Ru₄O₁₂ (CCRO) is a conductive oxide having the same structure as CaCu₃Ti₄O₁₂ (CCTO) and close lattice parameters. The later compound is strongly considered for high density parallel plates capacitors application due to its so-called colossal dielectric constant. The need for an electrode inducing CCTO epitaxial growth with a clean and sharp interface is therefore necessary, and CCRO is a good potential candidate. In this paper, the synthesis of monophasic CCRO ceramic is reported, as well as pulsed laser deposition of CCRO thin film onto (001) NdCaAlO₄ substrate. Structural and physical properties of bulk CCRO were studied by transmission electron microscopy and electron spin resonance. CCRO films and ceramic exhibited a metallic behavior down to low temperature. CCRO films were (001) oriented and promoted a CCTO film growth with the same orientation.     

A facile approach to the preparation of loose-packed Ni(OH)2 nanoflake materials for electrochemical capacitors

Loose-packed nickel hydroxides were successfully synthesized by a facile chemical precipitation method. Structure characterizations indicate that a nanoflake structure with low crystallinity for the nickel hydroxide samples was obtained. Electrochemical studies were carried out using cyclic voltammetry, chronopotentiometry technology, and alternating current impedance spectroscopy, respectively. A maximum specific capacitance of 2,055F/g could be achieved in 2M aqueous KOH with the potential range of 0 to 0.4V (vs. the saturated calomel electrode) in a half-cell setup configuration for the nanoflake Ni(OH)₂ electrode, suggesting its potential application in the electrode material for electrochemical capacitors. Furthermore, the effect of annealing temperatures on the electrochemical capacitance characteristics has also been systemically explored.     

Challenges Facing Lithium Batteries and Electrical Double‐Layer Capacitors

Energy‐storage technologies, including electrical double‐layer capacitors and rechargeable batteries, have attracted significant attention for applications in portable electronic devices, electric vehicles, bulk electricity storage at power stations, and “load leveling” of renewable sources, such as solar energy and wind power. Transforming lithium batteries and electric double‐layer capacitors requires a step change in the science underpinning these devices, including the discovery of new materials, new electrochemistry, and an increased understanding of the processes on which the devices depend. The Review will consider some of the current scientific issues underpinning lithium batteries and electric double‐layer capacitors.     

新型电极材料Sb掺杂BaSnO_3薄膜的外延生长及其在铁电薄膜电容器中的应用

本文利用脉冲激光沉积技术在SrTiO_3单晶衬底上生长了Sb掺杂BaSnO_3(BSSO)外延薄膜.结构和输运性质测量结果显示BSSO薄膜是一种具有立方钙钛矿结构导电性很好的薄膜材料,80K时呈现金属绝缘体转变,室温下薄膜的电阻率、载流子浓度和迁移率分别为ρ=2.43 mΩcm,n=1.65×1021 cm~(-3)和μ=1.75 cm~2/Vs.以BSSO薄膜为底电极制备了具有比较好电滞回线的Pb(Zr_(0.52)Ti_(0.48))O_3和Bi(Mn_(0.05)Fe_(0.95))O_3铁电电容器,表明BSSO薄膜是一种具有应用前景的新型电极材料.     

Influence of air-oxidation on electric double layer capacitances of multi-walled carbon nanotube electrodes

In this work, air-oxidized multi-walled carbon nanotube (MWCNT) electrodes have been prepared from catalytically grown MWCNTs of high purity and narrow diameter distribution. The experimental results show that air-oxidation modifies the intrinsic structure of individual MWCNTs and a little improves the dispersity of the MWCNTs. The specific capacitances of the electrodes in electric double layer capacitors (EDLCs) based on oxidized MWCNTs are obviously improved through air-oxidation. The specific capacitance of 50 F/g is obtained in the air-oxidized MWCNTs at 600 °C on a single cell device with 35 wt% H₂SO₄ as an electrolyte. This is probably increased BET specific surface area and mesopore volume of the oxidized MWCNT electrode materials of EDLCs. These properties are, therefore highly desirable for the development of electrochemical capacitors with high power and long cycle life.     

Interfacial properties of AlN and oxidized AlN on Si

We report on the characteristics of metal-insulator-semiconductor (MIS) capacitors with aluminum nitride (AlN) as the insulator material. AlN has been grown on (1 1 1) Si by means of molecular beam epitaxy (MBE) and DC magnetron sputtering (SPU). AlN layers have been characterized before and after dry thermal oxidation in O₂. By analyzing changes in morphology and electrical properties, different oxidation mechanisms were identified, due to the crystalline quality difference of the AlN samples. In both cases, oxidation at 1000 °C was beneficial for the electrical characteristics of the MIS structures, presumably due to passivation of atom vacancies. Although AlN was only partially oxidized, the flat-band voltage was reduced and the density of interface traps improved. Dominant conduction mechanism was Poole-Frenkel for the SPU sample, and changed to hopping after oxidation.     

星型建模技术在商业信息系统中的应用

在商场数据仓库构造中，尝试了一种新的增量更新法。在星型模型构造的同时解决了维表的纠错改变和自然改变对数据仓库性能造成的影响。该方法能有效地解决因维表的改变而影响数据仓库性能的问题。