Polymer-templated Functional Nanocomposites for Li-ion Batteries, Capacitors, and Ferroelectric Memory Devices
日期：2020/07/22 - 2020/07/22
学术讲座: Polymer-templated Functional Nanocomposites for Li-ion Batteries, Capacitors, and Ferroelectric Memory Devices
主讲人: Dr. Beibei Jiang, Lam Research
时间: 2020年7月22日 （周三）上午9-10点
地点：Zoom
讲座摘要
With the increasing market share of lithium-ion battery-powered electric vehicles, the marketplace desperately needs improvement in traditional battery technology, especially in anode materials, to maximize overall battery performance. The performance of LIBs depends sensitively on the composition as well as structure of the active materials employed for Li storage in the electrodes. Compared with graphite, which is the commercial anode material with theoretical charge capacity of 372 mA h g-1, many anode candidates show much higher theoretical capacity, including silicon (3590 mA h g-1), SnO2 (1494 mA h g-1), Fe3O4 (926 mA h g-1), to name just a few. Electrode materials with nanostructured architecture carry many extra advantages, including (1) high active sites for Li intercalation/deintercalation reactions owning to large surface areas, (2) faster Li insertion/removal rate due to short transport length, (3) better structural stability. As a result, functional nanomaterials in various architectures have been extensively explored due to their attractive electrochemical performance.
Currently, we still lack a versatile approach to design functional nanomaterials with desired functionalities while having a precise control over their size, shape, and architecture. In this study, we developed a versatile and robust polymer-templated approach for synthesizing hybrid nanocomposites with controllable size, shape, morphology, and functionality. This viable polymer-templated approach enables the in-situ synthesis of inorganic nanocrystals in the presence of some rationally designed polymer template by utilizing the interplay between the functional groups (e.g., -COOH) of polymer templates and the inorganic precursors. Two main targeted applications, namely, functional nanocomposites as electrodes for Li-ion batteries and dielectric and ferroelectric nanocomposites for capacitors and ferroelectric memory devices, guide the polymer-templated strategy when designing the polymer templates and selecting the inorganic precursors for crafting the functional nanocomposites.
In order to solve the issues of SnO2-based nanomaterials as anodes for Li-ion batteries, we designed a novel architecture of corn-like nanostructure with protective polydopamine (PDA) coating. The corn-like nanostructure with porosity and high surface area was crafted by capitalizing on rationally designed bottlebrush-like polymer hydroxypropyl cellulose-graft-poly (acrylic acid) (denoted HPC-g-PAA) as template, yielding a corn-like nanostructure with hundreds of SnO2 nanoparticles (D ~ 5 nm) decorated along the nanoscale polymeric backbone. As a result of the synergistic effect of corn-like nanostructure and the protective PDA coating, the PDA-coated corn-like SnO2 electrode exhibited the excellent rate capability, the superior long-term stability for over 300 cycles, and the high Sn→SnO2 reversibility with capacities approaching the theoretical capacity of 1494 mA h g-1. We also developed the ZnFe2O4/carbon nanocomposites composed of ZnFe2O4 nanoparticles encapsulated within the continuous carbon network as advanced anode materials by the polymer-templated approach. For other applications, we designed ferroelectric PVDF-BaTiO3 nanocomposites composed of BaTiO3 nanoparticles or BaTiO3 nanorods with precisely tunable dimensions intimately connected with ferroelectric PVDF by utlizing the amphiphilic star-like or bottlebrush-like PAA-b-PVDF as polymer templates. We can also extend this polymer-templated approach, which offers a new level of tailorability to nanostructured materials, to diverse applications in energy conversion and storage, catalysis, electronics, nanotechnology, and biotechnology.
主讲人简介
Dr. Beibei Jiang received her Ph.D. in Materials Science and Engineering from Georgia Institute of Technology in Dec. 2016. Her dissertation research is focused on designing functional nanocomposites by a polymer-templated method for improving the performance of Li-ion batteries, capacitors, and ferroelectric memory devices. She also holds a M.S. degree in Electrical and Electronics Engineering, focusing on semiconductor materials and devices, flexible electronics, semiconductor fabrication, and interface engineering. She has published 19+ peer reviewed publications in top journals, including 4 first-author papers. She worked as a Senior Materials Analyst after received her Ph.D., focusing on analytical characterization and failure mechanism analysis for Li-ion batteries and semiconductor devices. She is currently working as a R&D engineer in semiconductor industry for emerging memory technology at Lam Research, including 3D DRAM and 3D NAND. Her research interests include novel materials design & synthesis, novel device fabrication method for energy storage and conversion devices, Semiconductor fabrication, emerging memory, flexible electronics, biomaterials, biomedical devices, etc. She is a Georgia Tech Center of Photonics and Electronics (COPE) fellow.