报告题目：Wood-derived Solid Electrolyte for Li-metal batteries:Atomic Structure and Fast Ion Transport Mechanism
报告人：吴其胜School of Engineering, Brown University, USA
Solid-state batteries with lithium metal anodes are attractive for next-generation energy-storage systems with high energy density and safety. But the realization of these promises largely depends on the development of superior ion conductors for the solid-state electrolyte as well as ion-conducting additives for the cathode materials. A research group led by Prof. Liangbing Hu at the University of Maryland, College Park demonstrated that molecule-engineered cellulose nanofibrils through the insertion of copper and lithium ions can be used as a high-performance solid polymer electrolyte that presents record-high ionic conductivity, wide electrochemical stability window, low activation energy, and scalability. The new system, namely Li-Cu-CNF, has the benefit of low cost since the main material sources are wood fibers. In addition, the one-dimensional structure of Li-Cu-CNF also makes it an effective ion-conducting binder for the cathode, and its effective ionic percolation allowed us to fabricate the thickest LiFePO4 solid-state cathode ever reported, suggesting the material’s potential for increasing battery energy density.
Despite the experimental discovery, the origin of the high Li-ion conductivity in the Li-Cu-CNF system remained a mystery. We have developed both quantum and atomistic models to uncover the accurate atomic structures of the Li-Cu-CNF system and the lithium-ion conduction mechanism therein. These understandings cannot be obtained by any currently available experimental techniques. We have unveiled the atomic structures of Li-Cu-CNF very quickly with input from experiments. Through comprehensive density functional theory calculations, classical molecular dynamics simulations, and x-ray absorption spectroscopy modeling, we clearly showed how copper ions connect the cellulose chains and open the channels, which are preconditions for insertion and effective transport of lithium ions in Li-Cu-CNF. More than that, we have proposed that the abundant oxygen-containing functional groups and bound water in the cellulose molecular channels lead to a lithium-ion hopping mechanism that is decoupled from the polymer segmental motion, which is the most fundamental reason that Li-Cu-CNF can deliver the highest lithium-ion conductivity among all the solid polymer electrolytes ever reported during the last four decades. Using molecular dynamics simulations, we have pointed out that the conduction mechanism can also be generalized to cellulose-based sodium-ion and potassium-ion batteries. 
 Chunpeng Yang,#Qisheng Wu,# Weiqi Xie,# …, Yue Qi,* Liangbing Hu*. Nature, 2021, in press.
吴其胜，2013年和2018年于东南大学物理学院分别获得学士学位和博士学位，导师为王金金兰教授。2016-2018年于University of Nebraska-Linclon（内布拉斯加大学林肯分校）联合培养。2018年至今先后于University of New Mexico（新墨西哥大学）、Michigan State University（密歇根州立大学）和Brown University（布朗大学）完成博士后研究。主要研究内容包含二维材料的电子结构计算、分子在过渡金属表面的化学反应过程以及电化学储能和转换装置（锂离子电池）的多尺度模拟。在Nature、JACS、Materials Horizons、JPCL等学术期刊发表文章逾20篇，被引用超过700次（谷歌学术。