Al2O3包覆Li1.2Mn0.54Ni0.13Co0.13O2富锂正极材料的电化学性能

用溶胶凝胶法制备了Li_1.2Mn_0.54Ni_0.13Co_0.13O₂富锂锰基正极材料,用均匀沉淀法对其进行不同比例Al₂O₃的表面包覆改性,并对其进行XRD、TEM表征和电化学性能分析。结果表明,包覆后的材料保持了原来的层状结构,Al₂O₃均匀地包覆在材料颗粒表面形成纳米级包覆层。在0.1C、2.0~4.8 V条件下Al₂O₃包覆量(质量分数)为0.7%的正极材料首次放电容量为251.3 mAh/g,首次库仑效率达到76.1%,100次循环后容量保持率达92.9%。包覆Al₂O₃抑制了循环过程中的电压衰减,适量的Al₂O₃包覆使正极材料的电化学性能提高。     

一种适用于配电自动化通信网络的网络管理解决方案

通信网络是配电自动化系统的关键组成部分。本文提出了一种为双光纤环网结构的配电自动化通信网络设计的网络管理解决方案,并介绍了SNMP代理软件在Rabbit2000芯片中的实现方法。本文提出的解决方案对于其它形式的配电自动化通信网络的管理具有很强的参考价值。     

低温液相化学法在合成单分散纳米微粒中的应用

单分散纳米微粒的获得,为进一步研究某一特定尺寸的纳米微粒的各种性质提供了方便.单分散纳米微粒比多分散纳米微粒具有更显著的性能,更适合于应用.国内外在这方面开展了大量的研究工作,主要报道了低温液相化学法在合成单分散金属纳米颗粒、单分散半导体纳米颗粒、单分散复合氧化物纳米颗粒、单分散聚合物纳米微球、单分散核壳结构复合纳米微粒等方面的应用情况.     

人工鱼的认知建模方法研究

“人工鱼”利用人工生命方法创作计算机动画。为了进一步提高动画角色的智能水平,将人工智能方法学引入到“人工鱼”系统中,建立认知模型,控制人工动物的行为,使人工动物成为更加自主的和智能的角色。该文介绍了认知建模的概念、特点,给出人工鱼的认知建模方法研究的主要内容和模型结构。     

Pd-Ag alloy hollow nanostructures with interatomic charge polarization for enhanced electrocatalytic formic acid oxidation

Formic acid oxidation is an important electrocatalytic reaction in protonexchange membrane (PEM) fuel cells, in which both active sites and species adsorption/activation play key roles. In this study, we have developed hollow Pd-Ag alloy nanostructures with high active surface areas for application to electrocatalytic formic acid oxidation. When a certain amount of Ag is incorporated into a Pd lattice, which is already a highly active material for formic acid oxidation, the electrocatalytic activity can be significantly boosted. As indicated by theoretical simulations, coupling between Pd and Ag induces polarization charges on Pd catalytic sites, which can enhance the adsorption of HCOO* species. As a result, the designed electrocatalysts can achieve reduced Pd usage and enhanced catalytic properties at the same time. This study represents an approach that simultaneously fabricates hollow structures to increase the number of active sites and utilizes interatomic interactions to tune species adsorption/activation towards improved electrocatalytic performance.

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Synthesis of Inorganic–Organic 2D CdSe Slab‐Diamine Quantum Nets

Porous semiconductors attract great interest due to their unique structural characteristics of high surface area as well as their intrinsic optical and electronic properties. In this study, synthesis of inorganic–organic 2D CdSe slabs‐diaminooctane (DAO) porous quantum net structures is demonstrated. It is found that the hybrid 2D CdSe‐DAO lamellar structures are disintegrated into porous net structures, maintaining an ultrathin thickness of ≈1 nm in CdSe slabs. Furthermore, the CdSe slabs in quantum nets show the highly shifted excitonic transition in the absorption spectrum, demonstrating their strongly confined electronic structures. The possible formation mechanism of this porous structure is investigated with the control experiments of the synthesis using n‐alkyldiamines with various hydrocarbon chain lengths and ligand exchange of DAO with oleylamine. It is suggested that a strong van der Waals interaction among long chain DAO may exert strong tensile stress on the CdSe slabs, eventually disintegrating slabs. The thermal decomposition of CdSe‐DAO quantum nets is further studied to form well‐defined CdSe nanorods. It is believed that the current CdSe‐DAO quantum nets will offer a new type of porous semiconductors nanostructures under a strong quantum‐confinement regime, which can be applied to various technological areas of catalysts, electronics, and optoelectronics.     

A Double‐Buffering Strategy to Boost the Lithium Storage of Botryoid MnOx/C Anodes

Transition metal oxides (TMOs) are regarded as promising candidates for anodes of lithium ion batteries, but their applications have been severely hindered by poor material conductivity and lithiated volume expansion. As a potential solution, herein is presented a facile approach, by electrospinning a manganese‐based metal organic framework (Mn‐MOF), to fabricate yolk–shell MnO_x nanostructures within carbon nanofibers in a botryoid morphology. While the yolk–shell structure accomodates the lithiated volume expansion of MnO_x, the fiber confinement ensures the structural integrity during charge/discharge, achieving a so‐called double‐buffering for cyclic volume fluctuation. The formation mechanism of the yolk–shell structure is well elucidated through comprehensive instrumental characterizations and cogitative control experiments, following a combined Oswald ripening and Kirkendall process. Outstanding electrochemical performances are demonstrated with prolonged stability over 1000 cycles, boosted by the double‐buffering design, as well as the “breathing” effect of lithiation/delithiation witnessed by ex situ imaging. Both the fabrication methodology and electrochemical understandings gained here for nanostructured MnO_x can also be extended to other TMOs toward their ultimate implementation in high‐performance lithium ion batteries (LIBs).     

保护气氛下反应烧结MoSi_2/Al_2O_3复合陶瓷

以金属Mo粉、Si粉和Al粉为原料,采用反应烧结法制备MoSi_2/Al_2O_3陶瓷复合材料,有效增强其室温韧性和强度,并揭示其电阻率随烧结温度变化规律。利用XRD和SEM分析不同温度烧结后MoSi_2/Al_2O_3复合材料试样的物相组成和微观结构;研究不同烧结温度下试样的力学和电学性能。结果表明:在氩气保护气氛下1 200℃时,MoSi_2/Al_2O_3陶瓷复合材料的各项性能较好,其显气孔率为20.7%,体积密度为4.8g/cm~3,断裂韧性值为9.72MPa·m1/2,电阻率为6.0×10~(-2)Ω·cm。所制备的MoSi_2/Al_2O_3陶瓷复合材料物相结构主要由Al_2O_3包覆MoSi_2形成的连续包覆相组成,组织结构均匀。烧结温度为1 200℃时,MoSi2导电相由弥散分布变成相互连接的网络状分布,且Al_2O_3包覆MoSi_2导电相的包覆层变薄,包裹的MoSi_2颗粒之间易于突破包覆相而互相连通,有助于降低电阻率。