Improved high-rate performance and cycling stability of 1D LiFePO4 nanorods by a facile annealing process

To alleviate the main limitations of lithium ion diffusion rate and poor electronic conductivity for LiFePO4 cathode material, it is desirable to synthesize nano-size LiFePO4 material due to its enhanced electronic and lithium ion transport rates and thus an improved high-rate performance. However, our previous synthesized LiFePO4 nanorods only exhibited low high-rate and slightly unstable cycle performance. Possible reasons are the poor crystallization and Fe2+ oxidation of LiFePO4 nanorods prepared by hydrothermal method. In this paper, LiFePO4 nanorods were simply dealt with at 700 ℃ for 4 h under the protection of Ar and H2 mixture gas. The electrochemical properties of LiFePO4/Li cells were investigated by galvanostatic test and cyclic voltammetry(CV). The experimental results indicated that the annealed LiFePO4 nanorods delivered an excellent cycling stability and obviously improved capacity of 150 mA·h·g-1 at 1C, and even 122 mA·h·g-1 at 5C.     

正极添加CNTs对MH /Ni电池高倍率性能的影响

对正极中添加多壁碳纳米管(CNTs)的MH／Ni电池的高倍率放电性能进行了研究。结果表明：正极中添加少量CNTs的Ni／MH电池具有优异的高倍率放电性能。利用正极中添加少量CNTs制成的标准AA型电池的内阻在14mΩ左右；在高倍率放电条件下电池有更高的放电平台，3C放电中值电压在1．167V左右，5C放电中值电压在1．108V左右；电池循环容量保持率也高于正极中不加CNTs的电池。随着循环次数的增加，正极中添加少量CNTs的电池内阻升高幅度较小。     

Nanocellulose-Carboxymethylcellulose Electrolyte for Stable,High-Rate Zinc-Ion Batteries

Aqueous Zn ion batteries (ZIBs) are one of the most promising battery chemistries for grid-scale renewable energy storage. However, their application is limited by issues such as Zn dendrite formation and undesirable side reactions that can occur in the presence of excess free water molecules and ions. In this study, a nanocellulose-carboxymethylcellulose (CMC) hydrogel electrolyte is demonstrated that features stable cycling performance and high Zn²⁺ conductivity (26 mS cm⁻¹), which is attributed to the material's strong mechanical strength (≈70 MPa) and water-bonding ability. With this electrolyte, the Zn-metal anode shows exceptional cycling stability at an ultra-high rate, with the ability to sustain a current density as high as 80 mA cm⁻² for more than 3500 cycles and a cumulative capacity of 17.6 Ah cm⁻² (40 mA cm⁻²). Additionally, side reactions, such as hydrogen evolution and surface passivation, are substantially reduced due to the strong water-bonding capacity of the CMC. Full Zn||MnO₂ batteries fabricated with this electrolyte demonstrate excellent high-rate performance and long-term cycling stability (>500 cycles at 8C). These results suggest the cellulose-CMC electrolyte as a promising low-cost, easy-to-fabricate, and sustainable aqueous-based electrolyte for ZIBs with excellent electrochemical performance that can help pave the way toward grid-scale energy storage for renewable energy sources.     

Analysis for Microscopic Hyperbolic Two-Step Heat Transfer Problems

This work analyzes the heat transfer problems in thin metal films using the microscopic hyperbolic two-step model. It is necessary in dealing with such problems to solve a set of the coupled energy equations or an equation containing higher-order mixed derivatives in both time and space. This present numerical scheme eliminates the coupling between energy equations with the Laplace transform technique and leads to a second-order governing differential equation in the transform domain. Afterward, the transformed second-order governing differential equation is discretized by the control volume scheme. To demonstrate the efficiency and accuracy of the present numerical scheme, a comparison between the present numerical results and the analytical solution is made. Theoretical insight into the hyperbolic two-step heat conduction is provided. Results show that the thermal propagation velocity is finite and is independent of the coupling factor and the volumetric heat capacity ratio between electrons and the lattice.     

高速率通信网络下时变系统的有限时域H∞控制

针对高速率通信网络和Round-Robin（RR）协议影响下网络化时变系统的有限时域[H∞]控制问题，考虑到系统中存在乘性噪声、随机时滞和量化效应，提出了一种基于观测器的有限时域[H∞]控制器的设计方法。利用李雅普诺夫稳定性理论和线性矩阵不等式（Linear Matrix Inequality，LMI）技术得到有限时域[H∞]控制器存在的充分条件。基于锥补线性化（Cone Complementarity Linearization，CCL）方法通过求解一组递归矩阵不等式得到观测器和控制器参数。所设计的控制器保证闭环网络化时变系统在给定的时域内稳定，且满足预定的[H∞]性能指标。数值仿真验证了所提方法的有效性。     

Filament-activated chemical vapour deposition of nitride thin films

We have applied the novel method of hot filament-activated chemical vapour deposition (HFCVD) for low-temperature deposition of a variety of nitride thin films. In this paper the results from our recent work on aluminium, silicon and titanium nitride have been reviewed. In the HFCVD method a hot tungsten filament (1500–1850°C) was utilised to decompose ammonia in order to deposit nitride films at low substrate temperatures and high rates. The substrate temperatures ranged from 245 to 600°C. The film properties were characterised by a number of analytical and optical methods. The effect of various deposition conditions on film properties was studied. All the films obtained were of high chemical purity and had very low or no detectable tungsten contamination from the filament metal.     

高效反硝化分段组合式反应器运行性能

氮素污染是水体富营养化的主要诱因之一,反硝化技术是氮素污染控制的有效手段。采用模拟废水,研究了反硝化分段组合式反应器(CAR)的脱氮除碳性能。实验结果表明,CAR具有很高的容积效能,在进水NO₃^--N浓度为964.7 mg·L^-1、水力停留时间为0.86 h条件下,硝氮去除速率(NRR)为26.8 kg·(m³·d)^-1,COD去除速率(CRR)为93.76 kg·(m³·d)^-1,NRR高于文献报道的最高值,CRR也达到文献报道的领先水平。CAR具有良好的运行稳定性,在反应器的效能上升阶段和效能稳定阶段,出水基质浓度的变异系数比和极差分别小于9.85和9.07,出水pH的相对标准差小于1。CAR运行性能出众的原因是它能持留浓度高(MLVSS高于17 g·L^-1)、活性强(最大比活性为1.573 g NO₃^--N·(g VSS)^-1·d^-1)的颗粒污泥。     

从蓄电池常数n值看密封铅酸蓄电池的大电流性能

用一元线性回归法测得密封铅酸蓄电池的蓄电池常数n值,它比浸液式蓄电池低得多,说明了密封蓄电池的大电流性能较好.     

Floating Filters for Particle Removal in Sewage Treatment

This paper describes experiments which were carried out on a high-rate secondary-treatment plant which incorporate a moving-bed biofilm and floating filter. The same cylindrically shaped plastic elements were used both as a biofilm carrier and as a filter medium in the floating filter.