锂磷氧氮(LiPON)固态电解质与Li负极界面特性  

Properties of lithium phosphorus oxynitride(LiPON)solid electrolyte-Li anode interfaces

作　　者：游逸玮 崔建文 张小锋 郑锋 吴顺情[1] 朱梓忠[1] You Yi-Wei;Cui Jian-Wen;Zhang Xiao-Feng;Zheng Feng;Wu Shun-Qing;Zhu Zi-Zhong(Department of Physics,Xiamen University,Xiamen 361005,China)

机构地区：[1]厦门大学物理学系,厦门361005

出　　处：《物理学报》2021年第13期265-272,共8页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11874307);国家重点研发计划(批准号:2016YFA0202601,2016YFB0901502)资助的课题.

摘　　要：近年来,全固态锂离子电池因其高安全性、高能量密度、简单的电池结构等优势成为研究热点.然而电极与电解质的固固界面问题严重影响电池性能的进一步提升,从而受到了广泛关注.本文采用从头算分子动力学对LiPON/Li界面进行了模拟.研究发现,界面处原子互扩散现象明显,并形成薄界面层.相比LiPON体相结构,界面层以Li为中心原子的Li[O_(2)N_(2)],Li[O_(3)N],Li[O_(4)]四面体局域结构占比明显减少,并且界面层Li-O,Li-N,P-O和P-N的平均配位数均有所减小.由于界面层结构和配位数的变化使得Li受到O,N的离子键作用更弱,Li离子扩散过程中受到的阻碍更小.这一点对于LiPON电解质在实际电池应用中的性能起到了积极促进作用.In recent years,all-solid-state thin-film batteries have been used to power low-energy devices such as microchips,smart cards,microelectromechanical systems,wireless sensors,and implantable medical devices.All-solid-state thin-film batteries have become an important research direction of rechargeable solid-state batteries(SSBs).However,the solid-solid interface between electrodes and electrolytes seriously affects the further improvement of battery performance,which has attracted extensive attention.Lithium phosphorus oxynitride(LiPON)was found to be a useful inorganic electrolyte in lithium batteries because of its favorable electrochemical properties.For instance,LiPON has good electrical and chemical stability,negligible electronic conductivity and excellent cyclability as well as ease of integration with thin film battery with an electrochemical stability window.The LiPON can present two states,i.e.amorphous state and crystalline state.Here,we adopt ab initio molecular dynamics to study amorphous-LiPON/Li(100)interface and crystalline-Li2PO_(2)N(100)/Li(100)interface.Our results demonstrate that the atomic inter-diffusion occurs in the interfacial region,forming a thin interfacial layer,and the ionic conductivity is increased after the interface layer has formed.Meanwhile,comparing with the Lipon bulk phase structure,the proportion of Li[O_(2)N_(2)],Li[O_(3)N],and Li[O_(4)]tetrahedral local structure in the interface layer with Li atom as the center decrease obviously,and the average coordination number of Li-O,Li-N,P-O,and P-N in the interfacial layers also decrease in the LiPON/Li interface.Due to the change of structure and coordination number at the interface,the ionic bonds between Li and O,N are weaker,which explains the increase of ionic conductivity at the LiPON/Li interface.Previous experiments showed that element interdiffusion occurs at the LiPON/Li interface and the interface layer is formed,and found that the decrease in impedance of the interface layer can confirm that the ionic conductivity of

关 键 词：固态电解质 锂磷氧氮 界面 结构演化 Li离子扩散 

分 类 号：TM912[电气工程—电力电子与电力传动]