锂离子电池低温性能改善研究进展

锂离子电池因其能量密度高,循环寿命长等优点已成为新型动力电池领域的研究热点,但其温度特性尤其是低温性能较差制约着锂离子电池的进一步使用.本文综述了锂离子电池低温性能的研究进展,系统地分析了锂离子电池低温性能的主要限制因素.从正极、电解液、负极三个方面讨论了近年来研究者们提高电池低温性能的改性方法.并对提高锂离子电池低温性能的发展方向进行了展望.国家重点研发计划(No.2018YFB010400);;福建省高校产学合作项目(No.2018H6020)资

可变光衰减器中高斯光束的衍射特性研究

应用傅里叶变换法计算了高斯光束经光衰减器的挡光片阻挡后产生的衍射特性,给出了近似的衍射光强分布表达式。根据表达式,绘制了衍射光能量分布图,并实际测试了准直器出射光通过挡光片后的衍射光强分布。对比了数值计算和实际测试结果,最后对结果进行了讨论

Research Progresses in Improvement for Low Temperature Performance of Lithium-Ion Batteries

锂离子电池因其能量密度高，循环寿命长等优点已成为新型动力电池领域的研究热点，但其温度特性尤其是低温性能较差制约着锂离子电池的进一步使用. 本文综述了锂离子电池低温性能的研究进展，系统地分析了锂离子电池低温性能的主要限制因素. 从正极、电解液、负极三个方面讨论了近年来研究者们提高电池低温性能的改性方法. 并对提高锂离子电池低温性能的发展方向进行了展望.Lithium-ion batteries (LIBs) have become a new research hotspot due to their high energy density and long service life. However, the temperature characteristics, especially the poor performance at low temperatures, have seriously limited their wider applications. In this report, the research progresses in the low temperature performance of LIBs are reviewed. The main existing limitations of LIBs at low temperatures were systematically analyzed, and followed by discussion on the recent improvements in low temperature performances by developing novel cathode, electrolyte, and anode materials. The developments for improving the low temperature performance of LIBs are prospected. The three most important factors that influence the low temperature electrochemical performance of LIBs are as follows: 1) a reduced ion conductivity of the electrolyte and solid electrolyte interface (SEI) film formed on the electrode/electrolyte interface; 2) increased charge-transfer resistances at both the cathode and anode electrolyte- electrode interfaces; 3) slow lithium diffusion in the electrodes. The above three points lead to high polarization and lithium deposition, which may cause problems in terms of performance, reliability and safety of the cell. The key point is to provide expedite paths for the transport of lithium ions and electrons at low temperatures. All the influential aspects, such as cathode, electrolyte,and anode, should be considered to improve the low temperature performance of LIBs. The low temperature electrolyte can be obtained by adjusting the relative compositions, and species of the solvent, salt, and additive. The conductivity of electrolyte can be improved by adding low melting point cosolvents and salts. In addition, use of electrolyte additives forming low impedance interface film is one of the most economic and effective methods to improve the low temperature performance. And the structure of electrode materials can be optimized by doping, coating and decreasing the particle size, which can ensure sufficient conductivity and shorten diffusion path length for lithium ions and electrons. Managing the electrolyte and developing electrodes are efficient methods to improve the low temperature performance. Future studies should be focused on achieving high performance lithium-ion battery materials.国家重点研发计划（No. 2018YFB010400）和福建省高校产学合作项目（No. 2018H6020）资助作者联系地址：1.多氟多化工股份有限公司，河南 焦作 454150; 2. 厦门大学化学化工学院/能源学院，福建 厦门 361005; 3. 多氟多(焦作)新能源科技有限公司，河南 焦作454150Author's Address: 1. Do-fluoride Chemicals Co., Ltd, Jiaozuo 454150, Henan, China; 2. College of Chemistry and Chemical Engineering/College of energy, Xiamen University, Xiamen 361005, Fujian China 3. Do-Fluoride Jiaozuo New Energy Technology CO., Ltd, Jiaozuo 454150, Henan, China通讯作者E-mail：[email protected]; yyang@xmu. edu. c

新疆喀什地下水浅埋区弃荒地表层土壤积盐与地下水的关系[J]

为了研究新疆喀什地下水浅埋区弃荒地表层土壤积盐与地下水的定量关系,对试验区自然状况下的土壤含水量、表层土壤含盐量、地下水埋深、地下水矿化度和潜水蒸发量进行了原位监测,模拟了潜水蒸发量与地下水埋深的关系,定量分析了弃荒地自然条件下地下水埋深、地下水矿化度对土壤表层盐分的影响,建立了表层土壤含盐量与地下水埋深、地下水矿化度的经验模型。结果表明:在5~50 cm土层,土壤质量含水率随土层深度增加而增大;地下水埋深、地下水矿化度对表层土壤盐分有显著的影响,当地下水埋深为定值时,表层土壤含盐量与地下水矿化度呈线性正相关;当地下水矿化度为定值时,表层土壤含盐量与地下水埋深呈线性负相关;土壤盐分表聚现象明显..

不同入渗水头条件下壤砂土的一维垂直入渗特性/One-dimensional vertical infiltration characteristics of loamy sand at different infiltration heads[J]

通过室内垂直入渗试验,分析了入渗水头对新疆喀什市塔什库尔干县壤砂土一维垂直水分入渗特性的影响.结果表明:累计入渗量与时间的关系符合Kostiakov-Lewis模型和Philip模型,其模型参数A值和吸渗率S随入渗水头的增大而增大,呈良好的线性关系,入渗系数与入渗指数随入渗水头增加呈相反的变化趋势;湿润锋推进距离与时间呈幂函数关系,参数m值随着入渗水头增加而增大,参数n在数值上等于第10个单位时间末和第1个单位时间末湿润锋推进距离比值的常用对数;累计入渗量与湿润锋呈线性关系,其斜率等于湿润区平均含水率与初始含水率之差,且随入渗水头的增大而增大

一种电导率指标测可溶性盐分含量新方法/A NEW METHOD TO DETERMINE SOIL SOLUBLE SALT USING ELECTRICAL CONDUCTIVITY INDEX[J]

土壤可溶性盐的定量研究是确定土壤盐渍化程度和改良土壤的关键步骤之一[1-2].在土壤农化分析土壤可溶性盐中,常用全盐量和1∶5土水质量比浸提液的电导率指标来描述土壤可溶性盐含量的状况.在测定土壤可溶性盐的过程中,在室内是让土壤中的可溶性盐充分溶解后测定浸提液的电导率,而在一定的土壤含水量的条件下,尤其在干旱区,在室内测定的土壤可溶性盐的含量与野外测得的结果有差别.用土壤浸提液的浓度来描述土壤可溶性盐含量,该参数具有很强的可比性[3-4]

JUNO Sensitivity on Proton Decay p→νˉK+p\to \bar\nu K^+ Searches

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this paper, the potential on searching for proton decay in $p\to \bar\nu K^+$ mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits to suppress the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar\nu K^+$ is 36.9% with a background level of 0.2 events after 10 years of data taking. The estimated sensitivity based on 200 kton-years exposure is $9.6 \times 10^{33}$ years, competitive with the current best limits on the proton lifetime in this channel

JUNO sensitivity on proton decay p → ν K + searches*

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this study, the potential of searching for proton decay in the $p\to \bar{\nu} K^+$ mode with JUNO is investigated. The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits suppression of the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar{\nu} K^+$ is 36.9% ± 4.9% with a background level of $0.2\pm 0.05({\rm syst})\pm$$0.2({\rm stat})$ events after 10 years of data collection. The estimated sensitivity based on 200 kton-years of exposure is $9.6 \times 10^{33}$ years, which is competitive with the current best limits on the proton lifetime in this channel and complements the use of different detection technologies