印第安纳大学-普渡大学印第安纳波利斯联合分校Jian Xie教授做客第299期化苑讲坛

报告题目：Making Li-Metal Electrodes Rechargeable by Controlling the Direction of Dendrite Growth

报 告 人 ：Prof. Jian Xie

报告时间：2017年11月9日（周四）上午10:00

报告地点：化学楼二楼一号会议室

邀 请 人 ：解孝林教授

报告人简介：

Dr. Xie is a professor of Mechanical Engineering at the Purdue School of Engineering Indianapolis (IUPUI campus). He has published more than 55 journal papers, 4 issued patents and 11 patents applications, 2 book chapters and he has been awarded more than $4.86 million research grants within 8 years. He served as review board members for more than 12 journals including the well known “Nature”. He also serves as the panelist of the review panel for US National Science Foundation (NSF), Advanced Research Project Agency-Energy (ARPA-E), Fuel Cell Technology Office of US Department of Energy (DOE), Canadian National Science Foundation (CNSF) for grant proposal review and evaluation. He has been served as the session chair for Polymer Electrolyte Fuel Cells Symposium in the Electrochemical Society Meeting for more than 5 years. Before joining the university, he was a principal research scientist at Battelle Memorial Institute and worked on fuel cell R&D as well as Li-ion batteries and artificial lung. Prior to Battelle, as the program manager and senior electrochemical engineer at Cabot Corp, Dr. Xie worked extensively on catalyst development for fuel cells. Dr. Xie spent four years at Los Alamos National Laboratory on fuel cell research covering from membrane electrolytes, catalysts, membrane electrode assembly (MEA) to durability of fuel cells. As a system engineer, Dr. Xie was in charge of developing electric propulsion system for Electric Vehicle (EV) and Hybrid EV at General Motors Advanced Technology Vehicle, Indianapolis Technical Center. Dr. Xie received his PhD in chemistry from Miami University, U.S.A. and BS in chemical engineering (emphasis on electrochemical engineering) from Tianjin University, China.

报告内容：

The long-standing issue of Li dendrite formation and growth during the repeated plating/stripping processes prevents the high specific capacity/energy Li metal from being used as the anode in practical applications for batteries. We have developed a novel and unique method to transform the low-dimensional, fiber-like structured Li into a higher-dimensional Li with a dense layer by controlling the dendrite growth direction. This was achieved by simultaneously growing Li dendrites from two opposite directions until they meet, which caused the growth along the protrusion direction to stop and restart in a perpendicular direction. After several cycles, the dendrites grew into a dense Li layer. A battery separator coated with functionalized nanocarbon (FNC) was used to realize such control. Forming such a dense Li layer effectively alleviate the SEI formation from the dendrites which in turn, greatly reduces the decomposition of electrolyte as well as the drying-out of Li metal battery cells. SEM and in situ TEM proved the working principles. The Li metal was studied for three different electrolyte systems: carbonates (LiPF6 in EC/EMC and LiClO4 in EC/PC) and ethers (LiTFSI in DOL/DME) for long term cycling, Columbic efficiency and AC impedance in a Li/LiFePO4 coin cell configuration, showing excellent cycle life (>800 cycle with 80% initial capacity), improved efficiency, and reduced solid electrolyte interphase (SEI) formation. This method not only provides a universal rechargeable Li metal anode for practical batteries (Li-metal oxides, Li-polymer, Li-Air, and Li-S), but it also opens a new avenue for solving the dendrite issues of other alkali metals such as Na and K.