(6t) Hierarchical Nanostructured and Polymeric Materials for Energy Storage and Conversion

Hierarchical Nanostructured and Polymeric Materials for Energy Storage and Conversion

Zheng Chen, Postdoctoral Fellow

Stanford University

Research Background:

Facing fossil-fuel shortage and ecological deterioration, humankind has been diligently seeking for clean, safe and renewable energy sources to offset the diminishing availability or to take place of fossil fuels. At the same time, new strategies to increase energy-use efficiency, reduce fossil-fuel consumption and decrease CO₂ emission, is highly demanded. These essential needs have made energy storage and conversion a critical component in the creation of sustainable society. At the forefront of such endeavor is to develop high-performance materials to store charges, catalyze reactions and convert energy. My research interests focus on designing and synthesizing new materials based on fundamental principles of these processes. The goal is to enhance the capability and efficiency of materials in various energy-related applications.

PhD Dissertation: “Rational Material Architecture Design for Better Energy Storage”

Advisor: Prof. Yunfeng Lu, Chemical and Biomolecular Engineering, University of California, Los Angeles

Postdoctoral Project: “Novel Polymeric Materials for High-Performance Energy Storage”

Advisors: 1) Prof. Zhenan Bao, Chemical Engineering, Stanford University; 2) Prof. Yi Cui, Materials Science and Engineering, Stanford University

Research Experience:

My PhD research focused on designing and fabricating multifunctional nanoarchitectures by integrating distinct material structures and properties to address the kinetics limitation of traditional materials. Different types of energy storage architectures were investigated and compared with conventional structures to demonstrate such design concepts.  As model systems, “hierarchically porous spherical carbon particles” with graphitized structures, “interpenetrating oxide nanowire/CNT network”, “self-assembled ultrafine nanocrystals/CNTs” were designed and fabricated using various approaches.  The microstructures were carefully analyzed and electrochemical reaction kinetics was systematically studied.  It was demonstrated that thick electrodes with high charge capacity, high rate performance and cycling stability rely on functional architecture that simultaneously provides high electronic conductivity, easy ion diffusion, abundant surface actives sites and robust structure and interfaces.

My postdoc research is to understand and utilize novel properties of polymer materials for energy storage devices. Polymeric materials can offer a variety of functions such as good electronic and ionic conductivity, mechanical flexibility, stretchability and self-healing capability. These properties are of great interest for electronic and energy-related applications. In next-generation high-energy lithium-ion batteries, their electrode active materials (e.g., silicon, sulfur) suffer from mechanical and electronic degradation, which limits the battery capacity and cycling life time. In my research, novel functional polymers were used to solve some of the most critical issues related to high-energy materials. Specifically, a dynamic hydrogen-bonding based self-healing polymer is developed to effectively coat and bond onto silicon particle surface, which can maintain good electronic conductivity and mechanical integrity in electrodes over repeatedly charging/discharging. In addition, conducting polymer hydrogels were designed to make flexible electrodes and produce graphitic carbon with record-high surface area.  Thermal responsive polymers were used to improve the battery’s safe property.  Our polymer approach provides novel platform to renovate electrode structure and improve battery performance by tuning their structures and compositions.

With the synthetic capability and fundamental understanding of charge transport of energy materials, my future research will focus on materials development for advanced energy applications: 1) Precise synthesis of new materials for large scale energy storage, CO₂ conversion and membrane, and 2) Understanding charge transport behavior on electrochemical interfaces.

Selected Publications:

1. John W. F. To,† Zheng Chen,† HongbinYao, Jiajun He, Kwanpyo Kim, Ho-Hsiu Chou, Lijia Pan, Jennifer Wilcox, Yi Cui and Zhenan Bao,* Ultra-High Surface Area Three-Dimensional Porous Graphitic Carbon from Conjugated Polymeric Molecular Framework, ACS Central Science, 2015, in press (DOI:10.1021/acscentsci.5b00149). (co-first author)
2. Zheng Chen, Chao Wang, Jeffrey Lopez, Zhenda Lu, Yi Cui*, Zhenan Bao*, High-Areal-Capacity Silicon Electrodes with Low-Cost Silicon Particles Based on Spatial Control of Self-Healing Binder, Advanced Energy Materials, 2015, DOI:10.1002/aenm.201401826.
3. Zheng Chen, Yin Yuan, Huihui Zhou, Xiaolei Wang, Zhihua Gan*, Fosong Wang^* and Yunfeng Lu^*, 3D Nanocomposite Architectures from Carbon-Nanotube-Threaded Nanocrystals for High-Performance Electrochemical Energy Storage, Advanced Materials, 2014, 26, 339-345.
4. Zheng Chen, John W. F. To, Chao Wang, Zhenda Lu, Nan Liu, Alex Chortos, Lijia Pan, Fei Wei, Yi Cui* and Zhenan Bao*, A Three-Dimensionally Interconnected Carbon Nanotube-Conducting Polymer Hydrogel Network for High-Performance Flexible Battery Electrodes, 2014, Advanced Energy Materials, 2014, 4: 1400207.
5. Yanhua Cheng,† Zheng Chen,† Meifang Zhu*, Yunfeng Lu*, Polymer-Assisted Assembly of Oxide Particles and Carbon Nanotubes for High-Performance Flexible Battery Anode, Advanced Energy Materials, 2014, DOI: 10.1002/aenm.201401207. (co-first author)
6. Chao Wang, Hui Wu, Zheng Chen, Matthew T. McDowell, Yi Cui*, and Zhenan Bao*, Enabling Stable Operation for Silicon Microparticle Anodes for High Energy Lithium Ion Batteries using Self-healing Chemistry, Nature Chemistry, 2013, 5, 1042-1048.
7. Zheng Chen, Dieqing Zhang, Xiaolei Wang, Xilai Jia, Fei Wei, Hexing Li* and Yunfeng Lu^*, High-Performance Energy Storage Architectures from Carbon Nanotubes and Nanocrystals Building Blocks, Advanced Materials, 2012, 24, 2030-2036.
8. Zheng Chen, Veronica Augustyn, Xilai Jia, Qiangfeng Xiao, Bruce Dunn^* and Yunfeng Lu^*, High-Performance Sodium-ion Pseudocapacitors Based on Hierarchically Porous Nanowire Composites, ACS Nano, 2012, 6(5), 4319-4327.
9. Xilai Jia,† Zheng Chen,† Arnold Suwarnasarn, Benjamin M. Wu, Fei Wei^* and Yunfeng Lu^*, High-Performance Flexible Lithium-Ion Electrodes Based on Robust Network Architecture, Energy Environ. Sci., 2012, 5, 6845-6849. (co-first author)
10. Zheng Chen, Jing Wen, Chunzhu Yan, Lynn Rice, Hiesang Sohn, Mei Cai^*, Bruce Dunn and Yunfeng Lu^*, High-Performance Supercapacitors Based on Hierarchically Porous Graphite Particles, Advanced Energy Materials, 2011,1, 551-556.
11. Zheng Chen, Veronica Augustyn, Jing Wen, Yuewei Zhang, Meiqing Shen^*, Bruce Dunn^* and Yunfeng Lu^*, High-Performance Supercapacitors Based on Intertwined CNT/V₂O₅ Nanowire Nanocomposites, Advanced Materials, 2011, 23, 791-795.
12. Zheng Chen, Yaochun Qin, Ding Weng, Qiangfeng Xiao, Yiting Peng, Xiaolei Wang, Hexing Li^*, Fei Wei^* and Yunfeng Lu^*, Design and Synthesis of Hierarchical Nanowire Composites for Electrochemical Energy Storage, Advanced Functional Materials, 2009, 19(21), 3420-3426.