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Improved electrochemical performances of yttrium oxyfluoride-coated Li[Li0.2Mn0.54Ni0.13Co0.13]O2 for lithium ion batteries

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Journal of Energy Chemistry 2018年第4期27卷 1239-1246页

作者： Yaxin Hao Fangning Yang Didi Luo Jianhua Tian zhongqiang shan School of Chemical Engineering and Technology Tianjin UniversityTianjin 300350.China The 18th Research Institute of China Electronics Technology Group Corporation Tianjin 300384.China

The Li-rich layered oxides show a higher discharge capacity over 250 mAh/g and have been developed into a promising positive material for lithium ion batteries. A rare earth metal oxyfluoride YOF-coated Li[Lio.2Mno.54Ni0.13Co0.13]O2 composites have been synthesized by a simple wet chem- ical method. Crystal structure, micro-morphology and element valence of the pristine and YOF-coated Li[Li0.2Mn0.54Ni0.13Co0.13]O2 materials are characterized by XRD, SEM, TEM, and XPS. The results indicate that all materials exhibit a typical layered structure, and are made up of small and homogenous parti- cles ranging from 100 nm to 200 nm. In addition, YOF layer with a thickness of approximately 3-8 nm is precisely coated on the surface of the Li[Li0.2Mn0.54Ni0.13Co0.13]02. Constant current charge/discharge tests at various current densities show that the electrochemical performance of 2 wt% YOF-coated Li[Li0.2Mn0.54Ni0.13Co0.13]O2 has been improved significantly. 2 wt% YOF-coated Li[Li0.2Mn0.54Ni0.13Co0.13]O2 delivers the highest discharge capacity of 250.4 mAh/g at 20 mA/g among all the samples, and capacity retention of 87% after 100 charge/discharge cycles at 200 mA/g while that of the pristine one is only 81.6%. The superior electrochemical performance of 2wt% YOF-coated sample is ascribed to YOF coating layer, which could not only reduce side reactions between the electrode and liquid electrolyte, but also promote lithium ion migration.

关键词： Li[Li0.2 Mn0.54 Ni0.13 Co0.13]O2 YOF-coated Cathode material Lithium ion battery

Study about thermal runaway behavior of high specific energy density Li-ion batteries in a low state of charge

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Journal of Energy Chemistry 2021年第1期30卷 20-27,I0002页

作者： Shiqiang Liu Tianyi Ma Zhen Wei Guangli Bai Huitian Liu Dapeng Xu zhongqiang shan Fang Wang School of Chemical Engineering and Technology Tianjin UniversityTianjin 300350China Tianjin Key Laboratory of Evaluation Technology for Electric Vehicles China Automotive Technology and Research Center Co.Ltd.(CATARC)Tianjin 300300China

Lithium-ion batteries are widely used in electric vehicles and electronics, and their thermal safety receives widespread attention from consumers. In our study, thermal runaway testing was conducted on the thermal stability of commercial lithium-ion batteries, and the internal structure of the battery was analyzed with an in-depth focus on the key factors of the thermal runaway. Through the study of the structure and thermal stability of the cathode, anode, and separator, the results showed that the phase transition reaction of the separator was the key factor affecting the thermal runaway of the battery for the condition of a low state of charge.

关键词： Lithium-ion battery Thermal runaway State of charge Thermal stability

Hydrogen Bonding-Assisted Synthesis of Silica/Oxidized Mesocarbon Microbeads Encapsulated in Amorphous Carbon as Stable Anode for Optimized/Enhanced Lithium Storage

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Transactions of Tianjin University 2020年第1期26卷 13-21页

作者： Zongjie Cao Huitian Liu Wenlong Huang Peng Chen Yuansheng Liu Yu Yu zhongqiang shan Shuxian Meng School of Chemical Engineering and Technology Tianjin University

The practical application of silica-based composites as an alternative to commercial graphite anode materials is hampered by their large volumetric expansion,poor conductivity,and low Coulombic *** this work,a novel silica/oxidized mesocarbon microbead/amorphous carbon(SiO2/O’MCMB/C)hierarchical structure in which SiO2 is sandwiched between spherical graphite and amorphous carbon shell was succes sfully fabricated through hydrogen bonding-assisted self-assembly and post-carbon coating *** obtained three-layer hierarchical structure effectively accommodates the volumetric expansion of SiO2 and significantly enhances the electronic conductivity of composite ***,the outer layer of amorphous carbon effectively increases the diffusion rate of lithium ions and promotes the formation of stable SEI *** a result,the SiO2/O’MCMB/C composite exhibits superior electrochemical performance with a reversible capacity of 459.5 mA h/g in the first cycle,and the corresponding Coulombic efficiency is 62.8%.After 300 cycles,the capacity climbs to around 600 mA h/*** synthetic route provides an efficient method for preparing SiO2 supported on graphite with excellent electrochemical performance,which is likely to promote its commercial applications.

关键词： Hydrogen bonding Silica Oxidized mesocarbon microbead Anode material

Fe的掺杂对LiMnPO4材料电化学性能的影响

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高技术通讯 2012年第10期22卷 1103-1108页

作者：曾福娣单忠强田建华天津大学应用化学系天津300072

采用高温固相法合成了Fe掺杂（掺杂的质量分数分别为0，0．05，0．1，0．15，0．2）的LiMnPO4材料，利用X射线衍射（XRD）分析、透射电镜（TEM）对材料进行了物相和形貌表征，利用充放电测试和循环伏安测量方法研究了材料的电化学性能... 详细信息

采用高温固相法合成了Fe掺杂（掺杂的质量分数分别为0，0．05，0．1，0．15，0．2）的LiMnPO4材料，利用X射线衍射（XRD）分析、透射电镜（TEM）对材料进行了物相和形貌表征，利用充放电测试和循环伏安测量方法研究了材料的电化学性能。结果表明，掺杂后的材料电化学性能远优于未掺杂材料。各掺杂材料36次循环之后有较高的容量保持率；0．1C充放电时掺杂量为0．05的材料首次放电比容量最大，达到155．5mAh／g，且其各倍率下的电化学性能都优于其它掺杂材料。用循环伏安法计算出了Li＋的扩散系数，结果显示．掺杂后的材料具有相对较大的扩散系数。

关键词：锂离子电池磷酸锰锂固溶体电化学性能扩散系数

一种能够抑制锂枝晶的锂金属电池电解液润湿性添加剂

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精细化工 2021年第10期38卷 2103-2110,2124页

作者：徐继开刘元生单忠强天津大学化工学院天津300350

将氟代有机溶剂2,2,3,3-四氟丙基甲基丙烯酸酯(TFPMA)作为双功能添加剂引入碳酸酯电解液体系,考察了TFPMA质量分数对增大润湿性的影响。采用交流阻抗、恒流充放电等测试了添加TFPMA后的锂金属电池性能。采用SEM和XPS表征了循环后的锂金... 详细信息

将氟代有机溶剂2,2,3,3-四氟丙基甲基丙烯酸酯(TFPMA)作为双功能添加剂引入碳酸酯电解液体系,考察了TFPMA质量分数对增大润湿性的影响。采用交流阻抗、恒流充放电等测试了添加TFPMA后的锂金属电池性能。采用SEM和XPS表征了循环后的锂金属电极表面。结果表明,1.0%(质量分数,下同)TFPMA的添加使电解液与隔膜间的接触角从54°降至44°,内阻从6.15Ω降至1.94Ω,Li-LiFePO_(4)电池在5 C电流密度下的比容量从66 mA·h/g提升至80 mA·h/g,1 C电流密度下的恒电流循环在100圈时还保持99%以上的库仑效率。TFPMA还促进了Li+的均匀沉积和优良固体电解质界面膜的形成,抑制了锂枝晶,电解液添加了1.0%TFPMA后,Li-Cu电池可以循环100圈以上,而库仑效率没有发生较大下降。循环后电极的SEM图表明,添加了1.0%TFPMA电解液的锂金属负极表面沉积更加平整,有较少的锂枝晶生成。

关键词：锂金属电池电解液润湿性氟代有机溶剂添加剂锂枝晶抑制有机电化学

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多孔兰尼镍作单质硫载体的锂硫电池性能

复合材料学报 2018年第5期35卷 1269-1278页

作者：朱希田建华刘肖燕单忠强天津大学化工学院天津300350

提出以导电多孔兰尼镍(RNi)为锂硫电池中单质S的新载体材料,探究了S/RNi复合材料在溶剂法、研磨高温法及球磨高温法下的电化学性能差异。结果表明,溶剂法制备的S/RNi复合材料的电化学性能最好。预处理后的RNi为海绵状的导电多孔结构,孔... 详细信息

提出以导电多孔兰尼镍(RNi)为锂硫电池中单质S的新载体材料,探究了S/RNi复合材料在溶剂法、研磨高温法及球磨高温法下的电化学性能差异。结果表明,溶剂法制备的S/RNi复合材料的电化学性能最好。预处理后的RNi为海绵状的导电多孔结构,孔径分布在12.5~50nm之间。SEM和XRD表明,溶剂法制备的S/RNi复合材料具备良好的孔结构,单质S颗粒较小,均匀分布在深层孔结构中,S与RNi充分接触。其首次放电比容量达到1 479mAh/g,经过200次充放电循环后放电比容量保持在765mAh/g,库伦效率约为99%。其循环性能也优于传统S/C复合材料。溶剂法制备的S/RNi复合材料的循环稳定性和高倍率性能得益于RNi的导电性及对单质S的物理和化学吸附。

关键词：锂硫电池兰尼镍(RNi) 单质硫吸附制备方法

地震叠前反演方法预测页岩脆性指数在南川地区的应用

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地质学刊 2018年第2期42卷 291-297页

作者：单中强中国石化股份有限公司华东分公司勘探开发研究院江苏南京210011

页岩气的有效开发依赖水平井的压裂效果,而页岩脆性是影响页岩压裂的关键因素。通过对比分析现有的3种脆性指数计算方法,即矿物脆性指数计算法、岩石力学脆性指数计算法、基于多元回归脆性指数计算法,优选基于多元回归的脆性指数计算法... 详细信息

页岩气的有效开发依赖水平井的压裂效果,而页岩脆性是影响页岩压裂的关键因素。通过对比分析现有的3种脆性指数计算方法,即矿物脆性指数计算法、岩石力学脆性指数计算法、基于多元回归脆性指数计算法,优选基于多元回归的脆性指数计算法计算五峰—龙马溪组(简称龙马溪组)页岩储层脆性指数。以四川盆地东部南川地区龙马溪组海相页岩气为例,利用南川地区三维地震资料叠前反演方法,获取多元回归脆性指数计算方程所需的参数,预测页岩脆性指数。结果表明,在已有钻井矿物脆性指标约束下,叠前反演法计算的脆性指数平面预测效果较好,且与实际压裂数据具有较好的一致性,能够满足南川地区页岩气勘探开发的需要。

关键词：页岩脆性指数预测方法三维地震叠前反演南川地区四川盆地