多孔金属电极基体材料

简要介绍了电池用多孔金属电极基体材料的主要类型及其特点、基本性能要求和制备方法 ,旨在提供改善该材料制备工艺的线索和强化其性能及性能关系研究的必要。

超级电容器过渡金属氧化物电极材料研究进展

与传统电容器相比,超级电容器具有循环性能优异、大倍率充放电特性好、能快速充放电和环境友好等优点,目前在众多领域中都受到了研究者的关注.超级电容器电极材料主要包括3大类,即碳基电极材料、过渡金属氧化物电极材料及导电聚合物电极材料.鉴于超级电容器具有广阔的应用前景,综述了超级电容器过渡金属氧化物电极材料的研究现状,并对其今后可能的发展方向进行探讨.

A review of anode materials for sodium ion batteries

Lithium-ion batteries(LIBs)are used in electric vehicles and portable smart devices,but lithium resources are dwindling and there is an increasing demand which has to be catered for.Sodium ion batteries(SIBs),which are less costly,are a promising replacement for LIBs because of the abundant natural reserves of sodium.The anode of a SIB is a necessary component of the battery but is less understood than the cathode.This review outlines the development of various types of anodes,including carbonbased,metallic and organic,which operate using different reaction mechanisms such as intercalation,alloying and conversion,and considers their challenges and prospects.Strategies for modifying their structures by doping and coating,and also modifying the solid electrolyte interface are discussed.In addition,this review also discusses the challenges encountered by the anode of SIBs and the solutions.

p型GaN基器件的欧姆接触

宽带隙的GaN具有优良的物理和化学性质,己成为半导体领域研究的热点之一。p型GaN的欧姆接触问题制约了GaN基器件的进-步发展。本文首先介绍了欧姆接触的原理及评价方法,详细讨论了实现良好的p型GaN欧姆接触的主要方法是采取表面处理技术、选择合适的金属电极材料和进行热退火处理,以及研究进展情况。最后指出目前存在的问题并提出今后的研究方向。

Geometric optimization of electrostatic fields for stable levitation of metallic materials

Experimental and computational methods are used to optimize the electrostatic field for levitating metallic materials.The calculated launch voltage increases linearly with the distance between top and bottom electrodes.The combination of a larger top electrode diameter with a smaller bottom diameter may enhance the levitation ability because the electric field intensity near the levitated sample is strengthened.Top convex and bottom concave electrodes can guarantee good levitation stability but decrease the levitation force.The design of bottom electrode is crucial to attain not only a stable levitation state but also a higher levitation capability.As a measure characterizing the intrinsic levitation ability of various materials,the product of density and diameter of levitated samples can be used to determine the launch voltage for counteracting gravity according to a power relationship.

Porous carbon matrix-encapsulated MnO in situ derived from metalorganic frameworks as advanced anode materials for Li-ion capacitors

Conversion-type anode materials hold great potential for Li+storage applications owing to their high specific capacity,while large volume expansion and poor electrical conductivity limit their rate and cycling performances.Herein,a bimetal ZnMn-based metal-organic framework(ZnMn-MOF)is engineered for in situ conversion of MnO-encapsulated porous carbon(MnO/PC)composite.The templating and activation effects of coordinated Zn endow the converted PC matrix with a highly porous structure.This enhances the compatibility of PC matrix with MnO particles,resulting in the full encapsulation of MnO particles in the PC matrix.More significantly,the PC matrix provides enough void space to buffer the volume change,which fully wraps the MnO without crack or fracture during repeated cycling.As a result,MnO/PC shows high charge storage capability,extraordinary rate performance,and long-term cycling stability at the same time.Thus MnO/PC exhibits high delithiation capacities of 768mA h g^(-1)at 0.1Ag^(-1)and 487mA h g^(-1)at a high rate of 0.7Ag^(-1),combined with an unattenuated cycling performance after 500 cycles at 0.3Ag^(-1).More significantly,MnO/PC demonstrates a well-matched performance with the capacitive activated carbon electrode in a Li-ion capacitor(LIC)full cell.LIC demonstrates a high specific energy of 153.6W h kg^(-1)at 210W kg^(-1),combined with a specific energy of 71.8W h kg^(-1)at a high specific power of 63.0kW kg^(-1).

NiCoSe2/Ni3Se2 lamella arrays grown on N-doped graphene nanotubes with ultrahigh-rate capability and long-term cycling for asymmetric supercapacitor

In this paper, we report a one-step electrodeposited synthesis strategy for directly growing NiCoSe2/Ni3Se2 lamella arrays(LAs) on N-doped graphene nanotubes(N-GNTs) as advanced free-standing positive electrode for asymmetric supercapacitors. Benefiting from the synergetic contribution between the distinctive electroactive materials and the skeletons, the as-constructed N-GNTs@NiCoSe2/Ni3-Se2LAs present a specific capacitance of ~1308 F g^-1 at a current density of 1 A g^-1. More importantly, the hybrid electrode also reveals excellent rate capability(~1000 F g^-1 even at 100 A g^-1) and appealing cycling performance(~103.2% of capacitance retention over 10,000 cycles). Furthermore, an asymmetric supercapacitor is fabricated by using the obtained N-GNTs@NiCoSe2/Ni3Se2LAs and active carbon(AC) as the positive and negative electrodes respectively,which holds a high energy density of 42.8 W h kg^-1 at 2.6 k W kg^-1, and superior cycling stability of ~94.4% retention over 10,000 cycles. Accordingly, our fabrication technique and new insight herein can both widen design strategy of multicomponent composite electrode materials and promote the practical applications of the latest emerging transition metal selenides in next-generation high-performance supercapacitors.

Carbon-emcoating architecture boosts lithium storage of Nb_(2)O_(5)

Intercalation transition metal oxides (ITMO)have attracted great attention as lithium-ion battery negative electrodes due to high operation safety,high capacity and rapid ion intercalation.However,the intrinsic low electron conductivity plagues the lifetime and cell performance of the ITMO negative electrode.Here we design a new carbon-emcoating architecture through single CO_(2)activation treatment as demonstrated by the Nb_(2)O_(5)/C nanohybrid.Triple structure engineering of the carbon-emcoating Nb_(2)O_(5)/C nanohybrid is achieved in terms of porosity,composition,and crystallographic phase.The carbon-embedding Nb_(2)O_(5)/C nanohybrids show superior cycling and rate performance compared with the conventional carbon coating,with reversible capacity of 387 m A h g(-1)at 0.2 C and 92%of capacity retained after 500cycles at 1 C.Differential electrochemical mass spectrometry(DEMS) indicates that the carbon emcoated Nb_(2)O_(5)nanohybrids present less gas evolution than commercial lithium titanate oxide during cycling.The unique carbon-emcoating technique can be universally applied to other ITMO negative electrodes to achieve high electrochemical performance.