融合理论计算和中子散射技术研究四种NASICON结构化合物的传导离子占位无序和协同输运问题

NASICON-structured compounds have received widespread attention as a class of solid electrolytes or electrode systems due to their superior thermal stability, chemical stability and fast and simple synthesis processes. Possessing more conduction ions site-occupancies, owning high and low temperature phase and withstanding repeated intercalation reaction of conduction ions when used as an electrode are the typical structural features of these compounds. The crystal structural data published so far are mainly based on X-ray diffraction and do not take into account the effects of factors such as temperature and the concentration of conduction ions; It is of great importance to investigate the consequent conduction ions site-occupancy disorder and their cooperative transport for the property improvement of NASICON-structured compounds. In this project, we will investigate the conduction ions site-occupancy disorder and their cooperative transport in Na3Zr2Si2PO12, LiTi2(PO4)3, NaTi2(PO4)3, Na3V2(PO4)3 by combining bond valence sum calculation, first-principles calculation, molecular dynamics simulation, neutron powder diffraction and inelastic and quasi-elastic neutron scattering experiments, revealing the relationship between crystal structure and dynamics behaviors with the ion conductivity and discharge voltage platform, developing the dynamic performance control method of conduction ions based on site-occupancy disorder and cooperative transport effects.

因较好的热稳定性、化学稳定性及快速简单的合成工艺，NASICON结构化合物作为一类固态电解质或电极体系已受到广泛关注。具有较多的传导离子可占据位置、存在高低温相且作电极使用时可反复承受传导离子的脱嵌反应是这类化合物的典型晶体结构特征。目前公布的晶体结构数据主要基于X射线衍射且没有考虑到温度和传导离子浓度等因素的影响；研究据此引起的传导离子占位无序和协同输运对于优化NASICON结构化合物性能具有重要意义。本项目拟通过融合键价和计算、第一性原理计算、分子动力学模拟、中子粉末衍射、非弹性和准弹性中子散射实验研究Na3Zr2Si2PO12、LiTi2(PO4)3、NaTi2(PO4)3和Na3V2(PO4)3等四种NASICON结构化合物中的传导离子占位无序和协同输运问题，揭示晶体结构和离子电导率及放电电压等动力学行为之间的关联规律，发展基于占位无序和协同输运效应的传导离子动力学性能调控方法。

围绕NASICON结构化合物离子协同输运机理研究及协同程度的定量刻画和新效应，结合理论计算与实验表征，首次发现Na3Zr2Si2PO12中存在一个新的高能Na位置(Na5位)，计算其能垒证实Na+离子倾向于多离子高-低能位协同输运；基于通过计算载流子占位信息获得协同跳跃率，开发了一套基于具有框架结构离子导体的第一性原理分子动力学计算结果进行离子协同分析程序并已授权软件著作权；融合自主开发软件计算结果与实验试样表征揭示了NaV2(PO4)3体系中M1和M2位置Na+/Zn2+混占现象，Zn2+的嵌入激活了M1位置的Na+形成Na+/Zn2+高-低能位协同输运，其室温离子电导率为27 mS·cm-1，由此提出异种异价离子协同输运有利于提高其作为Zn离子电池正极倍率和循环性能的新效应；藉此，开发考虑传导离子间相互作用键价和计算离子输运通道的软件；系统性呈现了无序现象和协同效应在NASICON结构化合物中的微观输运物理图像；基于Ewald 求和设计出电化学储能材料长程静电作用模拟软件；通过分析直接和间接分解产物的电导率以动态确定其分解途径提出固体电解质电化学稳定窗口(ESW)预测方法，识别1270种潜在固体电解质，对筛选出328固体电解质ESW高通量计算，提出6种具有4 V以上ESW的新型氟化物固体电解质；通过综述离子输运微观物理图像，强调揭示电解质结构和离子电导率及输运过程等动力学行为之间的科学规律，对于发展基于离子输运微观物理图像的传导离子动力学性能调控的重要性。发表在Advanced Materials等SCI论文12篇，国内核心期刊2篇，已被他引215次，获“中国物理学会最有影响论文一等奖”；授权软件著作权9项；国内外学术会议邀请报告15次；举办上海材料基因组工程研究院2021学术年会；申请人获国家自然科学联合基金重点项目资助；已培养博/硕士2/7名，在读博/硕士2/4名。