Voltage Decay of Li-Rich Layered Oxides: Mechanism,Modification Strategies,and Perspectives

Li-rich layered oxides (LLOs) have been considered as the most promising cathode materials for achieving high energy density Li-ion batteries. However, they suffer from continuous voltage decay during cycling, which seriously shortens the lifespan of the battery in practical applications. This review comprehensively elaborates and summarizes the state-of-the-art of the research in this field. It is started from the proposed mechanism of voltage decay that refers to the phase transition, microscopic defects, and oxygen redox or release. Furthermore, several strategies to mitigate the voltage decay of LLOs from different scales, such as surface modification, elemental doping, regulation of components, control of defect, and morphology design are summarized. Finally, a systematic outlook on the real root of voltage decay is provided, and more importantly, a potential solution to voltage recovery from electrochemistry. Based on this progress, some effective strategies with multiple scales will be feasible to create the conditions for their commercialization in the future.     

基于分段电容阵列的改进型逐次逼近型ADC

为缩短高速模数转换器(ADC)中高位(MSB)电容建立时间以及减小功耗,提出了一种基于分段式电容阵列的改进型逐次逼近型(SAR)ADC结构,通过翻转小电容阵列代替翻转大电容阵列以产生高位数字码,并利用180 nm CMOS工艺实现和验证了此ADC结构。该结构一方面可以缩短产生高位数码字过程中的转换时间,提高量化速度;另一方面其可以延长大电容的稳定时间,减小参考电压的负载。通过缩小比较器输入对管的面积以减小寄生电容带来的误差,提升高位数字码的准确度。同时,利用一次性校准技术减小比较器的失配电压。最终,采用180 nm CMOS工艺实现该10 bit SAR ADC,以验证该改进型结构。结果表明,在1.8 V电源电压、780μW功耗、有电路噪声和电容失配情况下,该改进型SAR ADC得到了58.0 dB的信噪失真比(SNDR)。     

“高电压工程”课程思政教改探索与实践

针对“高电压工程”课程思政教学改革的要求,分别从教学目标、教学内容、教学方法和考核手段四个方面,挖掘课程中蕴含的思政元素,通过教学创新,有机融入思政内容,使学生不仅学到专业知识,更体会到专业内容蕴含的社会主义核心价值观。最后,通过课堂教学对“高电压工程”课程思政的改革效果进行了实践和检验,为其他电气类专业课的课程思政教学改革提供参考。     

Study of reactive ion etching of Si and SiO2 for CFxCl4−x gases

A parametric study of the etching of Si and SiO₂ by reactive ion etching (RIE) was carried out to gain a better understanding of the etching mechanisms. The following fluorocarbons (FCs) were used in order to study the effect of the F-to-Cl atom ratio in the parent molecule to the plasma and the etching properties: CF₄, CF₃Cl, CF₂Cl₂, and CFCl₃ (FC-14, FC-13, FC-12, and FC-11 respectively). The Si etch rate uniformity across the wafer as a function of the temperature of the wafer and the Si load, the optical emission as a function of the temperature of the load, the etch rate of SiO₂ as a function of the sheath voltage, and the mass spectra for each of the FCs were measured. The temperature of the wafer and that of the surrounding Si load strongly influence the etch rate of Si, the uniformity of etching, and the optical emission of F, Cl, and CF₂. The activation energy for the etching reaction of Si during CF₄ RIE was measured. The etch rate of Si depends more strongly on the gas composition than on the sheath voltage; it seems to be dominated by ion-assisted chemical etching. The etching of photoresist shifted from chemical etching to ion-assisted chemical etching as a function of the F-to-Cl ratio and the sheath voltage. The etch rate of SiO₂ depended more strongly on the sheath voltage than on the F-to-Cl ratio.     

基于定向纳米碳管气体放电的气敏传感器研究

介绍了一种基于定向纳米碳管的气敏传感器,以生长定向纳米碳管的氧化铝模板作为阳极,铝板作为阴极,利用纳米碳管的尖端发射效应,在较低的电压下使气体产生放电现象。通过对纳米碳管在气体中击穿电压和放电电流的测量,实现对气体的定性定量检测。同时纳米碳管气敏传感器还具有体积小、灵敏度高、稳定性好、响应速度快、在常温常压下即可进行检测等优点,具有较好的应用前景。     

Surface analysis of plasma‐treated polydimethylsiloxane by x‐ray photoelectron spectroscopy and surface voltage decay

Surface states of polydimethylsiloxane (PDMS) treated by plasma were investigated by x‐ray photoelectron spectroscopy and surface voltage decay. X‐ray photoelectron spectroscopy confirmed the formation of a silica‐like (SiO_x, x = 3–4) oxidative surface layer. This layer increased in thickness with increasing exposure duration of plasma. Plasma exposure lowers the surface resistivity from 1.78 × 10¹⁴ to 1.09 × 10¹³ Ω □^?1 with increasing plasma treatment time. By measuring the decay time constant of surface voltage, the calculated surface resistivity was compared with the value measured directly by a voltage–current method; good agreement between the two methods was obtained. It was observed that plasma treatment led to a decrease in the thermal activation energy of the surface conduction from 31.0 kJ mol^?1 for an untreated specimen to 21.8 kJ mol^?1 for a plasma‐treated specimen for 1 h. Our results allow the examination of effects of plasma on the electrical properties of PDMS. Copyright © 2003 John Wiley & Sons, Ltd.     

A study for quality evaluation of Taxilli Herba from different hosts based on fingerprint-activity relationship modeling and multivariate statistical analysis

In this study, a fingerprint-activity relationship modeling between chemical fingerprints and antirheumatic activity was established, and multivariate statistical analysis was used to evaluate the quality of Taxilli Herba (TH) from different hosts. Characteristic fingerprints of 20 batches of TH samples were generated by high-performance liquid chromatography coupled with triple quadrupole-time of flight tandem mass spectrometry (HPLC-Triple TOF-MS/MS), and the similarity analysis was calculated based on thirteen common characteristic peaks by hierarchical clustering analysis (HCA). Subsequently, nine efficacy markers were discovered by combining fingerprints and antirheumatic activity through grey correlation analysis (GCA) and bivariate correlation analysis (BCA). Meanwhile, the content of 5 constituents in 9 markers was determined by high-performance liquid chromatography coupled with triple quadrupole-linear ion trap tandem mass spectrometry (HPLC-QTRAP-MS/MS). The comprehensive quality of TH was assessed using multivariate statistical analysis, including principal components analysis (PCA) and technique for order preference by similarity to ideal solution (TOPSIS). The results showed that a high dose of TH extract could markedly ameliorate arthritis damage compared to other doses, with flavonoids playing an important role in the antirheumatic activity. The comprehensive quality of samples from Morus alba L. (SS) was superior to those from Liquidambar formosana Hance (FXS). The present study will demonstrate the markers associated with efficacy, and provide an applicable strategy for more comprehensive quality control and evaluation of TH.     

A comparison of electron ionization mass spectra obtained at 70 eV,low electron energies,and with cold EI and their NIST library identification probabilities

Electron ionization (EI) mass spectra of 46 compounds from several different compound classes were measured. Their molecular ion abundances were compared as obtained with 70‐eV EI, with low eV EI (such as 14 eV), and with EI mass spectra of vibrationally cold molecules in supersonic molecular beams (Cold EI). We further compared these mass spectra in their National Institute of Standards and Technology (NIST) library identification probabilities. We found that

1. Low eV EI is not a soft ionization method, and it has little or no influence on the molecular ion relative abundances for large molecules and those with weak or no molecular ions.
2. Low eV EI for compounds with abundant or dominant molecular ions in their 70 eV mass spectra results in the reduction of low mass fragment ions abundances thereby reducing their NIST library identification probabilities thus rarely justifies its use in real‐world applications.
3. Cold EI significantly enhances the relative abundance of the molecular ions particularly for large compounds; yet, it retains the low mass fragment ions; hence, Cold EI mass spectra can be effectively identified by the NIST library.
4. Different standard EI ion sources provide different 70 eV EI mass spectra. Among the Agilent technologies ion sources, the “Extractor” exhibits relatively abundant molecular ions compared with the “Inert” ion source, while the “High efficiency source” (HES) provides mass spectra with depleted molecular ions compared with the “Inert” ion source or NIST library mass spectra.

These conclusions are demonstrated and supported by experimental data in nine figures and two tables.     

Alloy Temperature Dependence of Offset Voltage and Ohmic Contact Resistance in Thin Base InGaP/GaAs HBTs

研究了薄基区HBT合金温度对残余电压Voffset和欧姆接触电阻Rcontact的影响,给出了薄基区HBT的最佳合金温度区域.用肖特基钳位理论解释了合金温度过高导致Voffset偏大的现象.从晶体管基本物理机制推导出Voffset与集电极、发射极面积比Ac/Ae的关系,并用此解释了U形发射极HBT具有较小Ac/Ae的原因,进一步证明了U型发射极结构的优越性.     

Analytical Model for the Piecewise Linearly Graded Doping Drift Region in LDMOS

提出了体硅LDMOS漂移区杂质浓度分布的一种二维理论模型,根据该模型,如果要使带有场极板的LDMOS得到最佳的性能,那么LDMOS漂移区的杂质浓度必须呈分段线性分布.用半导体专业软件Tsuprem-4和Medici模拟证明了该模型十分有效,根据该模型优化得到的新型LDMOS的击穿电压和导通电阻分别比常规LDMOS增加58.8%和降低87.4%.