碳纳米管在锂离子电池正极中的应用研究

以碳纳米管及Supper-p/KS-6作为正极导电剂分别制作了锂离子电池。利用SEM研究了电池电极的显微结构,并对电池的电化学性能进行了综合评价。结果表明,与Supper-p/KS-6导电剂相比,碳纳米管导电剂有效降低了电池内阻,显著提高了电池在大倍率情况下的性能,并改善了电池的循环性能:内阻从120 m降到了100 m,10.0C(C为放电倍率)及15.0C时的放电容量分别为0.5C时的90.4%和80.7%,500次循环后的容量保持率达89.0%。     

尖晶石型LiMn_(2-x)Ga_xO_4的合成及电化学性能研究

为了提高锂离子电池尖晶石锰酸锂正极材料的循环性能和倍率性能,采用柠檬酸辅助溶胶-凝胶法制备了LiMn2–xGaxO4(x=0,0.02,0.05,0.07)正极材料。研究了Ga掺杂对所制材料性能的影响。结果表明:制得的LiMn2–xGaxO4具有单一的尖晶石结构。当Ga3+掺杂量为x=0.05时,LiMn2–xGaxO4首次放电比容量为117.1 mAh/g,经过95次循环后,放电容量保持率高达97.9%;在高倍率4C条件下,首次放电比容量为100.9 mAh/g,30次循环后放电比容量为102.4 mAh/g,具有优异的倍率性能。     

镍钴酸锂的空气气氛下高温固相合成

通过改进马弗炉结构,在空气气氛下合成了LiNi0.7Co0.3O2锂离子二次电池正极材料。利用XRD、SEM和循环充放电测试等手段,研究了材料结构与电化学性能之间的关系。实验电池以C/3的电流倍率在2.7~4.2V进行恒流充放电循环,电池首次充电比容量与放电比容量分别为181mAh/g和157mAh/g,库仑效率为86.7%。经过15次循环后,放电比容量趋于稳定,库仑效率保持在98%以上。循环40次,放电比容量为122mAh/g。     

面密度对锂离子电池快充性能的影响研究

面密度是影响锂离子电池快充性能的主要因素之一。采用扫描电子显微镜、X射线衍射仪及粒度分析表征正负极材料形貌和结构,研究不同面密度镍钴锰酸锂/石墨锂离子电池的内阻、倍率性能、循环寿命和安全性能。结果表明,电池的内阻随着面密度的增加而增大,正极面密度从190 g/m~2提高到340 g/m~2,电池均呈现出良好的5C快速充放电性能和安全性能。正极面密度不超过280 g/m~2时,电池依然保持优异的10C快速充放电性能,容量达到1C倍率的93.4%以上。正极面密度为250 g/m~2的电池展示出最佳的5C倍率充放电寿命,2000次充放电后的容量保持率高达98.1%。而正极面密度为340 g/m~2的电池5C倍率充放电寿命衰减较快。     

可弯曲锂离子电池电化学性能的研究

以Li Ni1/3Co1/3Mn1/3O2为正极,石墨为负极;采用卷绕和叠片工艺制备理论容量为300 m Ah可弯曲锂离子电池。通过测试首次充放电效率、循环寿命和内阻等方法对电池电化学性能进行研究。实验结果表明:卷绕式单颗锂离子电池首次放电容量为67.0 m Ah(0.1C倍率),首次充放电效率为89.33%,并联成内阻为48 mΩ,循环300周后容量保持率为85.35%。叠片式电池首次放电容量为400.8 m Ah(0.1C倍率),首次充放电效率为93.49%,内阻为45 mΩ,循环300周后容量保持率为92.68%。     

高性能碳纳米管复合Fe3O4锂离子电池负极材料研究

通过添加碳纳米管共沉淀的方法制备了Fe3O4-CNTs复合材料。研究发现,CNTs不仅可以降低复合材料作为锂离子电池负极的阻抗,而且对活性物质Fe3O4起到很好的支撑作用,极大地提高了Fe3O4在充放电过程中的电化学稳定性。在0.5 A/g的电流密度下Fe3O4-CNTs循环200圈后的放电比容量保持在1406 mAh/g。在10 A/g的大电流密度下循环,第100圈时Fe3O4-CNTs的放电比容量稳定在230 mAh/g左右。循环至第9999圈时,Fe3O4-CNTs的比容量下降至179 mAh/g,只损失了50 mAh/g,充放电效率高达99.98%。Fe3O4-CNTs复合材料在大电流密度超长循环的背景下表现出优异的性能,对负极材料的开发有重要的意义。     

锂离子电池混合正极材料LiNi0.5Co0.2Mn0.3O2/LiFePO4电化学性能研究

采用湿法球磨制备了锂离子电池用混合正极材料LiNi0.5Co0.2Mn0.3O2/LiFePO4。通过X射线衍射(XRD)和扫描电镜(SEM)表征了材料的结构和形貌,采用恒流充放电测试、循环伏安测试(CV)和电化学阻抗谱测试(EIS)方法研究了混合正极材料LiNi0.5Co0.2Mn0.3O2/LiFePO4的电化学性能。结果表明：混合正极材料LiNi0.5Co0.2Mn0.3O2/LiFePO4的晶体结构完好,碳包覆的纳米LiFePO4颗粒较好地包覆在LiNi0.5Co0.2Mn0.3O2表面。含质量分数15% LiFePO4的混合正极材料LiNi0.5Co0.2Mn0.3O2/LiFePO4电化学性能优良,0.2C首次充放电比容量为181.40 mAh?g–1,首次充放电效率为90.79%;1.0C循环50次后放电比容量为169.89 mAh?g–1,容量保持率为97.80%;3.0C循环5次后的放电比容量为162.22 mAh?g–1,容量保持率仍有89.43%;60 ℃高温存储7 d后,容量保持率和容量恢复率分别为86.48%和97.32%。     

LiAl_(0.03)Mn_(1.97)O_4的流变相辅助微波合成及电化学性能

采用流变相辅助微波合成法,制备了结晶度好、纯度高的尖晶石相的锂离子电池正极材料LiAl0.03Mn1.97O4。对其进行了XRD分析和SEM研究,并与传统固相法制备的LiMn2O4和LiAl0.03Mn1.97O4进行了比较。结果表明,该合成法制备的LiAl0.03Mn1.97O4具有优良的电化学性能,用这种材料制造的电池具有比较高的首次放电容量(115 mAh/g)以及良好的可逆性和循环性能,25次循环后比容量几乎不变,保持在115 mAh/g左右。     

LiFePO_4/膨胀石墨复合材料的制备及性能

采用机械球磨法合成LiFePO_4/膨胀石墨复合材料,讨论了膨胀石墨不同添加量对复合材料电化学性能的影响。运用扫描电镜、四探针测试和恒流充放电等对材料的表面形貌、电阻率和电化学性能进行了研究。结果表明:当膨胀石墨的添加量为质量分数1.0%时,其电化学性能最优异,0.2C放电比容量可达到164.2mAh/g,1.0C循环60次后,其放电比容量仍有151.6mAh/g,3.0C充放电后,其容量保持率仍有89.6%。     

V2O5(TiO2)/S复合材料作锂电池正极的性能研究

为了改善锂硫电池的循环性能,将单质硫分别与纳米金属氧化物(V2O5,TiO2)机械混合。用XRD对材料的晶体结构进行了表征。通过循环伏安、交流阻抗和电池性能的对比,对材料的电化学性能进行了分析。结果表明:采用V2O5改性的硫材料,首次放电比容量达844.68 mAh.g–1,样品循环容量衰减明显改善,30次后比容量保持在696.71 mAh.g–1。而TiO2/S复合材料,初始放电比容量为578.21 mAh.g–1,30次循环后比容量为347.71 mAh.g–1。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.     

Call for Papers

正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks