Designing Advanced In Situ Electrode/Electrolyte Interphases for Wide Temperature Operation of 4.5 V Li||LiCoO2 Batteries

High-energy-density batteries with a LiCoO₂ (LCO) cathode are of significant importance to the energy-storage market, especially for portable electronics. However, their development is greatly limited by the inferior performance under high voltages and challenging temperatures. Here, highly stable lithium (Li) metal batteries with LCO cathode, through the design of in situ formed, stable electrode/electrolyte interphases on both the Li anode and the LCO cathode, with an advanced electrolyte, are reported. The LCO cathode can deliver a high specific capacity of ≈190 mAh g⁻¹ and show greatly improved cell performances under a high charge voltage of 4.5 V (even up to 4.55 V) and a wide temperature range from −30 to 55 °C. This work points out a promising approach for developing Li||LCO batteries for practical applications. This approach can also be used to improve the high-voltage performance of other batteries in a broad temperature range.     

The Role of Electron Localization in Covalency and Electrochemical Properties of Lithium-Ion Battery Cathode Materials

Following the fundamental research conducted by J. B. Goodenough, the important role of electron localization induced by elemental substitution is studied. The size and electron negativity of host and substituting ions are two important factors in tuning material properties such as local structure and transition metal (TM) oxygen covalency. However, another factor, electron localization, which is widely studied in catalyst research but largely overlooked for battery materials, deserves systematic studies. A combined investigation using synchrotronbased X-ray spectroscopy and theoretical calculations is carried out on the Li-Co-Mn-O model system in which the substituting cation Mn⁴⁺, with its 3d³ electronic structure, is used as a promoter for electron localization. Results indicate that electron localization greatly influences the Co O bond by making it less covalent, which increases the delithiation voltage. It is also found that during charge/discharge, electron localization tends to make TM K-edge X-ray absorption near edge spectroscopy (XANES) spectra show a more “rigid shift” behavior while electron delocalization makes the XANES exhibit a “shape change.” It clearly explains why the K-edge XANES data of some TM oxides show no “rigid shift” while the nominal valence states changed. This work highlights the importance of electron localization with guidance for XANES interpretation.     

基于边缘对应的三维颅骨自动非刚性配准方法

针对三维颅骨模型在初始姿态相差较大以及存在较多缺失情况下自动配准困难的问题,提出一种基于边缘对应的三维颅骨非刚性自动配准方法。首先对待配准三维颅骨进行边缘提取,获得所有孔洞的边缘;然后根据边缘长度以及边缘间最短距离自动识别边缘类型,建立待配准颅骨和参考颅骨在边缘上的对应;之后对待配准颅骨的初始位置和姿态进行调整,实现粗配准;最后通过两次一致点漂移（CPD）算法逐步实现两个颅骨从边缘区域至所有区域的精确配准。实验结果表明,与常用的基于迭代最近点（ICP）和薄板样条函数（TPS）相结合的三维颅骨自动配准方法相比,该方法对姿态、位置、分辨率以及缺损具有更强的鲁棒性,并且配准效率更高。     

用MATLAB实现维吾尔语广播新闻敏感词检索系统

首先,用MATLAB开发一个敏感词检索系统;然后,用该系统对语音信号来自于新疆广播电台网站的维吾尔语新闻60分节目语音进行连续敏感词检索;最后,对识别结果进行分析并提出提高正识率的思路．     

High‐Voltage Charging‐Induced Strain,Heterogeneity, and Micro‐Cracks in Secondary Particles of a Nickel‐Rich Layered Cathode Material

Nickel‐rich layered materials LiNi_1‐x‐yMn_xCo_yO₂ are promising candidates for high‐energy‐density lithium‐ion battery cathodes. Unfortunately, they suffer from capacity fading upon cycling, especially with high‐voltage charging. It is critical to have a mechanistic understanding of such fade. Herein, synchrotron‐based techniques (including scattering, spectroscopy, and microcopy) and finite element analysis are utilized to understand the LiNi_0.6Mn_0.2Co_0.2O₂ material from structural, chemical, morphological, and mechanical points of view. The lattice structural changes are shown to be relatively reversible during cycling, even when 4.9 V charging is applied. However, local disorder and strain are induced by high‐voltage charging. Nano‐resolution 3D transmission X‐ray microscopy data analyzed by machine learning methodology reveal that high‐voltage charging induced significant oxidation state inhomogeneities in the cycled particles. Regions at the surface have a rock salt–type structure with lower oxidation state and build up the impedance, while regions with higher oxidization state are scattered in the bulk and are likely deactivated during cycling. In addition, the development of micro‐cracks is highly dependent on the pristine state morphology and cycling conditions. Hollow particles seem to be more robust against stress‐induced cracks than the solid ones, suggesting that morphology engineering can be effective in mitigating the crack problem in these materials.     

Review of Recent Development of In Situ/Operando Characterization Techniques for Lithium Battery Research

The increasing demands of energy storage require the significant improvement of current Li‐ion battery electrode materials and the development of advanced electrode materials. Thus, it is necessary to gain an in‐depth understanding of the reaction processes, degradation mechanism, and thermal decomposition mechanisms under realistic operation conditions. This understanding can be obtained by in situ/operando characterization techniques, which provide information on the structure evolution, redox mechanism, solid‐electrolyte interphase (SEI) formation, side reactions, and Li‐ion transport properties under operating conditions. Here, the recent developments in the in situ/operando techniques employed for the investigation of the structural stability, dynamic properties, chemical environment changes, and morphological evolution are described and summarized. The experimental approaches reviewed here include X‐ray, electron, neutron, optical, and scanning probes. The experimental methods and operating principles, especially the in situ cell designs, are described in detail. Representative studies of the in situ/operando techniques are summarized, and finally the major current challenges and future opportunities are discussed. Several important battery challenges are likely to benefit from these in situ/operando techniques, including the inhomogeneous reactions of high‐energy‐density cathodes, the development of safe and reversible Li metal plating, and the development of stable SEI.     

面向维吾尔语关键词检索的等宽切词算法

该文提出了面向维吾尔语关键词检索的两种切词算法,并给出MATLAB实现的算法代码及详细说明;在同等条件下对两种算法的切词效果和关键词识别效率进行对比分析;提出两种算法的优化方法和构想。     

>维吾尔语广播新闻敏感词检索系统的研究

维吾尔语广播新闻敏感词检索系统是以HMM为基础。在MATLAB平台上设计实现的。该系统的特点包括 1.由于维吾尔语敏感词数量不多,该系统语音语料库很小。2.由于广播新闻中的发音较为标准规范,在识别中避免了说话人发音上的不规范,这有利于语音识别系统性能的提高。3.由于选择词素为识别基元,易于识别基元端点检测。