The dynamic evolution of aggregated lithium dendrites in lithium metal batteries

Lithium (Li) metal anodes promise an ultrahigh theoretical energy density and low redox potential,thus being the critical energy material for next-generation batteries.Unfortunately,the formation of Li den-drites in Li metal anodes remarkably hinders the practical applications of Li metal anodes.Herein,the dynamic evolution of discrete Li dendrites and aggregated Li dendrites with increasing current densities is visualized by in-situ optical microscopy in conjunction with ex-situ scanning electron microscopy.As revealed by the phase field simulations,the formation of aggregated Li dendrites under high current den-sity is attributed to the locally concentrated electric field rather than the depletion of Li ions.More specif-ically,the locally concentrated electric field stems from the spatial inhomogeneity on the Li metal surface and will be further enhanced with increasing current densities.Adjusting the above two factors with the help of the constructed phase field model is able to regulate the electrodeposited morphology from aggregated Li dendrites to discrete Li dendrites,and ultimately columnar Li morphology.The methodol-ogy and mechanistic understanding established herein give a significant step toward the practical appli-cations of Li metal anodes.     

Effect of supports on the redox performance of pyrite cinder in chemical looping combustion

Chemical looping combustion (CLC) is a clean and efficient flame-free combustion technology,which combust the fuels by lattice oxygen from a solid oxygen carrier with inherent CO2 capture.The develop-ment of oxygen carriers with low cost and high redox performance is crucial to the whole efficiency of CLC process.As the solid by-product from the sulfuric acid production,pyrite cinder presented excellent redox performance as an oxygen carrier in CLC process.The main components in pyrite cinder are Fe2O3,CaSO4,Al2O3 and SiO2 in which Fe2O3 is the active component to provide lattice oxygen.In order to sys-tematic investigate the functions of supports (CaSO4,Al2O3 and SiO2) in pyrite cinder,three oxygen car-riers (Fe2O3-CaSO4,Fe2O3-Al2O3 and Fe2O3-SiO2) were prepared and evaluated in this study.The results showed that Fe2O3-CaSO4 displayed high redox activity and cycling stability in the multiple redox cycles.However,both Fe2O3-Al2O3 and Fe2O3-SiO2 experienced serious deactivation during redox reactions.It indicated that the inert Fe-Si solid solution (Fe2SiO4) was formed in the spent Fe2O3-SiO2 sample,which decreased the oxygen carrying capacity of this sample.The XPS results showed that the oxygen species on the surface of Fe2O3-CaSO4 could be fully recovered after the 20 redox cycles.It can be concluded that CaSO4 is the key to the high redox activity and cycling stability of pyrite cinder.     

彭水水电站2、3号机组下导轴承摆度偏大原因分析

水轮发电机组振摆偏大会严重影响机组设备的安全稳定运行,机组振摆偏大一般是多个原因叠加的结果,给原因分析和检修处理带来一定的困难.以彭水水电站2、3号机组下导轴承摆度偏大现象为例,通过分析影响下导摆度的水力、机械、电磁3个因素,结合机组在线监测系统的频谱分析和主轴状态等工具,逐项排除可能引起下导轴承摆度偏大的次要原因,最终得出机组轴线偏折和空气间隙偏小且分布不均匀是造成2、3号机组下导轴承摆度偏大的主要原因,为后续机组缺陷分析、运行方式调整、检修周期项目制定提供依据,进一步优化机组运行工况,提高设备安全性和可靠性,也为实现机组状态检修积累经验,奠定基础,为类似电站和机组解决导轴承摆度问题提供参考.     

锌铝镁镀层钢板前处理与电泳性能研究

以镀锌钢板作为对比,考察锌铝镁钢板涂装前处理和电泳性能.结果显示:锌铝镁钢板的脱脂性能与镀锌钢板相近,磷化膜外观、膜重、覆盖率和结晶尺寸与镀锌钢板差异较小,电泳漆膜外观、膜厚、附着力和耐冲击性与镀锌钢板一致,但电泳漆膜的杯突极限性能和划线循环腐蚀性能优于镀锌钢板.     

负荷功率模型的最优特征选择研究

负荷功率呈现时空多样的变化特性,其影响因素众多,构建负荷功率模型的关键之一是确定模型的输入特征量。文中着重研究短期负荷功率模型的特征选择,旨在从历史负荷、气象、日期等众多特征中选出最优特征集。首先,采用最大信息系数、基于支持向量机的递归特征消除法和随机森林3种不同特征选择方法分别对输入特征集进行选择;然后,根据对比分析结果提出基于遗传算法的最优特征集搜索策略,选定XGBoost预测模型的误差指标作为适应性函数进行迭代优化搜索;最终,确定负荷功率模型的最优特征输入集。采用某地区220 kV变电站母线负荷数据进行算例分析,对比各方法所选特征集作为功率模型输入得到的负荷预测效果,验证了文中方法的有效性和准确性。     

Crude Wax Extracted from Rice Bran Oil Improves Oleogel Properties and Oxidative Stability

Crude wax extracted from rice bran oil (RBO) is used to improve the oleogel properties and oxidative stability of RBO. The effect of crude rice bran wax (CrBW) on the formation characteristics and oxidative stability of oleogels is discussed. The results show that oleogels can be formed with 7.0 wt% CrBW at 20 °C. As the concentration of CrBW increases from 7.0 to 11.0 wt%, the hardness and solid fat content (SFC) of the oleogels increase significantly, and the oleogels are primarily β' crystals. Moreover, oleogel crystals formed with 5 and 7 wt% CrBW are flocculent; when the amount included is 9%, the oleogel crystals are transformed into long dendrites, and the density rises. After 90 days of storage at 20 °C, the peroxide value of oleogels formed with 9.0 wt% CrBW slowly rises from 3.21 to 6.52 mmol kg⁻¹. Practical Applications: Oleogels prepared here by CrBW and RBO are an innovative structural lipid without trans fats. Useful information on the rich fats and nutrients in CrBW is provided, which reduces the production cost and improves the industrial production capacity.     

无机超细粉体改性锂离子电池隔膜的研究进展

综述了近年来无机超细粉体改性锂离子电池隔膜的研究进展,首先介绍了已在锂电隔膜改性上商业应用的Al₂O₃和AlOOH对传统聚烯烃膜和新型静电纺丝膜的改性方法和改性效果,随后又对常规无机材料TiO₂和SiO₂粉体对锂电隔膜的改性进行了叙述,最后对BN等非常规隔膜改性无机材料进行了简介;总结和讨论了无机材料改性后隔膜的组分、结构和性能对锂离子电池综合性能的影响,并对其无机材料改性锂电池隔膜的未来发展趋势进行了展望。     

Microstructure Evolution and Tensile Properties of a Selectively Laser Melted CoNi-Base Superalloy

Metallurgical and Materials Transactions A - A high $$\gamma ^{\prime }$$ volume fraction CoNi-base superalloy with roughly equal amounts of cobalt and nickel was successfully processed through...     

碳质金矿中碳质物及其“劫金”机理研究进展

碳质金矿是重要的难处理金矿资源之一,碳质物“劫金”是金浸出率低下的主要原因。碳质物组分复杂,不同组分的碳质物的“劫金”能力和“劫金”行为存在差异,磨矿和浸出环节对碳质物的“劫金”能力也会产生影响,这些因素均能直接影响金的浸出率。通过系统总结碳质金矿中碳质物在组成特征、“劫金”机理及“劫金”能力的影响因素等方面的研究进展,对碳质物“劫金”机理现有研究工作的不足及未来研究方向进行了探讨,为碳质金矿碳质物劫金机理及预处理工艺的研究提供了重要参考。