湖南大学“天马材料研究论坛”第170期
题 目：Ion Transport in Lithium-Ion Conducting Solid Electrolytes:Oxides and Composites
报告人：郭新 教授/博导（华中科技大学）
地 点：工程实验大楼240、244 多媒体报告厅
时 间： 2019年10月28日（周一）下午 2:30
主持人：丁元力 教授
邀请人：材料科学与工程学院
承办人：材料学院“天马材料研究论坛”日常工作小组
报告人简介：
郭新，华中科技大学材料学院教授，中国固态离子学会理事，国际期刊 “Solid State Ionics”编委，国际固态离子学会（International Society for Solid State Ionics）学术奖评审委员。回国前任德国于利希研究中心（Research Center Juelich）终身高级研究员，之前，他曾在德国马普固体研究所（Max Planck Institute for Solid State Research）从事研究工作多年。2005年获美国陶瓷协会Ross Coffin Purdy Award。在国际学术会议（如MRS, E-MRS, ECS, MS&T, SSI等）及国际著名高校和研究机构（如麻省理工学院、斯坦福大学、瑞士联邦工学院、德国马普研究所等）作过数十场邀请报告，并担任分会主席。在包括“Science”的学术期刊发表论文百余篇。研究领域可概括为“固态离子导体与混合导体及其在能源、信息与环境等领域的应用”，具体研究领域有: 1.固态电池，2.类脑器件及脑启发式人工智能，3.气敏传感器及人工嗅觉，4.功能器件的3D打印。
报告摘要：
A few issues about the ion transport in oxide ceramics with garnet and perovskite structures, and oxide-polymer composites are discussed in this talk, including:
1. Ionic conduction in Li7La3Zr2O12 (LLZO) garnets, and the strategy to enhance the ionic conductivity by proper doping. Herein, the influence of Ga doping on the properties of LLZO garnets is investigated, with the determined concentration and mobility of lithium ions shedding light on the origin of the high conductivity of Li7-3xGaxLa3Zr2O12.
2. The surface property of LLZO garnets. Without any surface modification, Li2CO3-free LLZO shows an intrinsic “lithiophilicity” characteristic, which leads to a continuous and tight Li/LLZO interface, resulting in an ultra-low interfacial resistance of 49 Ω cm2 and a homogenous current distribution in the charge/discharge processes. Consequently, the current density for the stable Li plating/stripping in LLZO increases to 900 μA cm-2 at 60 °C.
3. Physical origin of the low grain boundary conductivity of Li3xLa0.67-x□0.33-2xTiO3 (LLTO, 0.12 ≤ 3x ≤ 0.50, □ represents the A-site vacancy). Although the bulk conductivity of LLTO perovskites reaches the level of 10-3 S/cm, the grain boundary conductivity is orders of magnitude lower; the origin of the low grain boundary conductivity should be understood as a prerequisite to improve the overall conductivity.
4. Ionic conduction in oxide-polymer composites. Oxide-polymer composites, in which oxide nanoparticles are dispersed in the polymer matrix, show higher flexibility than ceramic oxides, meanwhile the ionic conductivity, ionic transference number and electrochemical stability are much higher than those of polymers. We use the LLZO-PEO composite as a model system and develop a conduction model based on the two-phase mixture theory.
