Meng Gu A/Prof.

Education and Work Experience:

Associate Professor, Department of Materials Science and Engineering, 

Southern University of Science and Technology (SUSTech), China, 2017-now

Materials Scientist,  The Dow Chemical Company  USA, 2014 - 2017 

Postdoc Researcher, Environmental Molecular Sciences Laboratory, 

Pacific Northwest National Laboratory, USA, Nov. 2011 – Feb. 2014

Ph.D in Materials science and Engineering: 

Advisor -Professor Nigel D. Browning & Yayoi Takamura

Thesis: Atomic scale characterization of complex oxide thin films; 

University of California-Davis (UC Davis), USA, Sep.2008-Nov. 2011

Bachelor of Engineering in Materials Science and Engineering

Shanghai Jiao Tong University  China, Sep. 2004 – Jun. 2008

movies:

mov1_介孔硅空心球的锂化过程

mov2_孔硅空心球的去锂化过程

mov3_鸡蛋黄壳结构的硅碳复合材料锂化过程

mov4_硅碳复合碳纤维锂化过程中的裂开

mov5_WO3薄膜电极原子尺度下观测锂化过程中的晶体向非晶化演变过程

mov6_催化剂纳米颗粒在基体上的原位表征

mov7_三维元素分析技术检测Ni不均匀分布对电池性能的影响

Research Projects:

Project I:  In-situ Transmission electron microscopy analysis of secondary ion batteries  

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Nano-battery experiments inside a TEM. The setup of in-situ TEM open cell using ionic liquid as electrolyte (a); open cell approach using Li2O as solid electrolyte (b); and liquid cell approach (c) (Gu et al, Nano Lett., 2013, 13 (12), pp 6106–6112)

Description: In situ transmission electron microscopy (TEM) studies of lithium ion batteries using an open-cell configuration have helped us to gain fundamental insights into the structural and chemical evolution of the electrode materials in real time. I have creatively applied in-situ TEM analysis to the study of anode materials such as Si-C composite, Si-conductive polymer composite, Ge, TiO2, Li4Ti5O12, SnO2, etc in Li-ion and Na-ion batteries. Novel functional/failure mechanism of these materials are revealed as a result. Furthermore, I have developed an open-cell technique to allow atomic scale characterization of the detailed phase evolution of WO3 electrode materials in real time. The reaction mechanism between the intercalation process and conversion reaction are made clear by atomic scale imaging.   

Last but not least, we developed an operando TEM electrochemical liquid cell to see solid electrolyte interphase layer, providing the configuration of a real battery and in a relevant liquid electrolyte. To demonstrate this novel technique, we studied the lithiation/delithiation behavior of single Si nanowires. Some of lithiation/delithation behaviors of Si obtained using the liquid cell are consistent with the results from the open-cell studies. However, we also discovered new insights different from the open cell configuration—the dynamics of the electrolyte and, potentially, a future quantitative characterization of the solid electrolyte interphase layer formation and structural and chemical evolution.

Project IIInvestigation of novel nano-structures for Li-ion and all solid state batteries 

Description: Maximizing the usage of renewable energy will reduce our reliance on dwindling natural resources and environmental pollution. Batteries are an important enabling technology for renewable energy, portable electronics, and modern transportation systems such as hybrid electric vehicles. However, limitation of current materials has to be overcome if long-life and low-cost batteries are to be built. The establishment of my research focusing on advanced characterization of lithium batteries aligns well with this need of modern technology and with the goals of the energy storage research. We have successfully demonstrated the superior cycling performance of anode materials, such as mesoporous Si foam, mesoprous Si hollow spheres, Si-C yolk-shell, Si-conductive polymer. In addition, we successfully identified the failure mechanism of Li-rich layered cathode materials and improved their performance by controlling the synthesis conditions and apply AlF3 coatings.  

Going beyond traditional Li-ion batteries, we focus on all solid state batteries. All-solid-state batteries present us with opportunities of designing safer energy storage devices with high voltage and long cycle life for ultrathin electronics, implantable medical devices, smart windows, and even electric vehicles. Currently, the all-solid-state Li-ion batteries are fabricated using thin film deposition methods, of which the magnetron sputtering/atomic layer deposition/pulsed laser deposition growth of Li-containing thin film materials shows great advantage for all-solid-state batteries study and fabrication. As shown in the figure below, the 2D all-solid-state batteries can greatly reduce the thickness of electrolyte and electrodes, enhancing the power density. In addition, the 3D design of the all-solid-state batteries utilizes sufficiently high surface area, which allows for high power density and high volumetric energy density.

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Schematic of 2D (a) and 3D design of All-Solid-State batteries

Project III: Heterogeneous Catalysts Synthesis and in-situ TEM Analysis

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     We are actively finding out better catalysts for waste water treatment, waste gas conversion, hydrogen production, bio-mass conversion to oil, etc. We investigate interesting core-shell bi-metallic catalysts, single atom/site catalyst, and emphasize the bonding between the dispersed catalyst ions and matrix materials. With our in-situ TEM capability, we can directly see the changes/dynamics of the catalysts at the nanoscale in high temperature and certain gas environment.     

Project IV:  Development of 3-D chemical imaging technique

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3D EDS tomography showing the distribution of Mn and Ni in Li1.2Ni0.2Mn0.6O2 

Collaborator: Prof. Nigel D Browning, Arda Genc, Khalil Amine, Chongmin Wang

Description:  A variety of approaches are being made to enhance the performance of lithium ion batteries. Incorporating multivalence transition-metal ions into metal oxide cathodes has been identified as an essential approach to achieve the necessary high voltage and high capacity. However, the fundamental mechanism that limits their power rate and cycling stability remains unclear. The power rate strongly depends on the lithium ion drift speed in the cathode. We found the unexpected discovery of a thermodynamically driven, yet kinetically controlled, surface modification in the widely explored lithium nickel manganese oxide cathode material, which may inhibit the battery charge/discharge rate. We found that during cathode synthesis and processing before electrochemical cycling in the cell nickel can preferentially move along the fast diffusion channels and selectively segregate at the surface facets terminated with a mix of anions and cations. This segregation essentially can lead to a higher lithium diffusion barrier near the surface region of the particle. Therefore, it appears that the transition-metal dopant may help to provide high capacity and/or high voltage but can be located in a “wrong” location that may slow down lithium diffusion, limiting battery performance. In this circumstance, limitations in the properties of lithium ion batteries using these cathode materials can be determined more by the materials synthesis issues than by the operation within the battery itself. 

Project V: Interface Physics Study at an epitaxial metal/oxide or oxide/oxide heterojunction                                                                                                                      

Collaborator: Dr. Scott Chambers, Yayoi Takamura, Nigel Browning, Hongliang Zhang, Yingge Du                                         

This project involves the development of next generation spintronic devices, sensors, and low temperature solid oxide fuel cells requires the development of materials with new functional properties not found in conventional bulk materials. A novel route involves harnessing the unexpected physical phenomena that result from the changes in structure and chemistry which occur over nanometer length scales at surfaces and interfaces. The approach of this work utilizes MBE/laser-assisted growth to control interfacial properties with atomic layer precision in combination with state-of-the-art techniques for characterizing the structural and chemical properties. In this way, a full understanding of the origins of new magnetic and electronic properties derived from interfacial mechanisms can be determined.

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STEM & EELS study of superlattices of LSMO/LSTO (J. Appl. Phys. 111, 013911 (2012))

 

We use STEM and EELS and Z contrast image to observe the interface of the superlattice and investigate the structure, the distribution of different atoms and the vacancy of oxygen atoms. The thin film and heterostructures produced are ideally suited for analysis using scanning transmission electron microscopy (STEM). The advantages of STEM over other characterization techniques lies in the ability to combine high angle annular dark field Z contrast imaging with electron energy loss spectroscopy (EELS), thus creating a probe of the local chemical structure across hetero- interfaces with nearly atomic level precision. These EELS spectra have the capability to probe effects such as valence and polar discontinuities, which have been proposed to cause surface and interface phenomena, such as electric conductivity and magnetic property change.  Then comes clearly the relationship between structure and property of the thin films

Teaching at SUSTech

Structure & Characterization of Engineering Materials

Electric, optical, Magnetic Properties of Materials  

Advanced Topics in Electron Microscopy     

Instruments and Group Members at SUSTech

Electron microscopy Pico-center @SUSTech house the most advanced instruments including double Cs-corrected&Mono FEI Themis with super-X EDS and Quantum EELS; Cs-corrected Environmental TEM, Talos with Super-X EDS; and F-30 S/TEM

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Awards:

Microscopy Society of America major award winner:  2015 Albert CREWE Award

1000 Talents - Young Scholar Program 2017 from the CPC Central Committee of China

Additional Academic Contribution Information:

Editorial Board Member for American Journal of Engineering and Applied Sciences   2015-now

Editorial Board Member for Current Nanomaterials   2017-now

 Member of Microscopy Society of America (MSA)

Member of American Chemical Society (ACS)

Member of Materials Research Society (MRS)

Opening:

We have openings for highly-motivated master/PHD students, Research Assistants, Postdocs, Research Assistant Professors with a passion for science. Science is our RELIGION! SUSTech offers highly competitive salaries and benefits to our employees! Please contact gum@sustc.edu.cn

Presentations & Invited talks at International Conferences and Universities:

Microscopy & Microanalysis meeting 2010, Portland, OR

Microscopy & Microanalysis meeting 2011, Nashville, TN

Materials Research Society Spring meeting 2011, San Francisco, CA

Microscopy & Microanalysis meeting 2012, Phoenix, AZ

Microscopy & Microanalysis meeting 2013, Indianapolis 

PNWAVS symposium, Portland OR 2013

Presenter and Organizer of the poster competition, 2012, PNNL, Richland, WA

Materials Research Society Fall meeting 2012, Boston

Session Co-Chair, 2012 Fall meeting of Materials Research Society, PP2: Imaging Chemical Bonding

American Conference on Neutron Scattering 2012 Washington DC

222nd Meeting of ECS — The Electrochemical Society, Hawaii

Workshop of oxides electronics 18, Napa Valley, CA 2011

Atomic Scale Characterization of Complex Oxide Thin Films, PNNL, Richland, WA 2011

Advanced Characterization of Materials Using Electron/Ion Microscopy, Exxon Mobil, NY Nov 2013

Synthesis and Characterization of Batteries, Shanghai Jiao Tong University, April 2014

Advanced Characterization of Materials using Electron/Ion Microscopy, Jan 2014, UC Irvine

Electron Microscopy Characterization of Materials, the University of Nebraska Lincoln, 2014

Advanced Synthesis & Characterization of Energy Storage Materials, March 2014, The University of Hong Kong 

Three Dimensional & in-situ TEM Characterization of Materials, Nov. 2014, IBM, New York 

Renewable energy storage approaches, Columbia University in the City of New York  Aug 2015

Advanced Characterization of Energy Storage Materials Using 3D and in-situ Scanning Transmission Electron Microscopy, Peking University, 9/28/2017 - invited talk

2017 Electron microscopy annual conference of China 2017

Selecte Publications:

1.       Yang He, Meng Gu, et alAtomistic Conversion Reaction Mechanism of WO3 in Secondary Ion Batteries of Li, Na, and Ca, Angewandte Chemie International Edition, 55, 6244-6247  (2016)                  (Co-first author)

2.       Qiangfeng Xiao, Meng Gu, et al, Inward Lithium-Ion Breathing of Hierarchically Porous Silicon Anodes, Nature Communications, 6, Article number: 8844                                             (Co-first author)

3.       Gan, Zhaofeng; Gu, Meng, et al, Direct Mapping of Charge Distribution during Lithiation of Ge Nanowires Using Off-axis Electron Holography, Nano Letters201616 3748-3753                       (Co-first author)

4.       Meng Gu, Yang He, Jianming Zheng, Chongmin Wang, et al, Nanoscale Silicon as Anode for Li-ion Batteries: The Fundamentals, Promise, and Challenges, Nano Energy, 17, 366–383 2015 

5.       Meng Gu, et al, Bending-induced Symmetry Breaking of Lithiation in Germanium Nanowires, Nano Letters, 2014, 14, 4622–4627

6.       Meng Gu, et al, Demonstration of an Electrochemical Liquid Cell for Operando Transmission Electron Microscopy Observation of the Lithiation/Delithiation Behavior of Si Nanowire Battery Anodes, Nano Letters, 2013, 13, 6106-6112 

7.       Meng Gu, et al, Probing the Failure Mechanism of SnO2 Nanowires for Sodium-ion Batteries, Nano Letters, 2013, 13, 5203–5211

8.       Meng Gu, et al, Conflicting roles of Ni in controlling cathode performance in Li-ion batteries, Nano Letters, 12, 5186‐5191(2012)   

9.       Jianming Zheng, Meng Gu, et al, Mitigating Voltage Fade in Cathode Materials by Improving Atomic Level Spatial Uniformity of Chemical Species, Nano Letters 2014, 14, 2628–2635                         (Co-first author)

10.   Jianming Zheng, Meng Gu, et al, Corrosion/Fragmentation of Layered Composite Cathode and Related Capacity/Voltage Fading during Cycling Process, Nano Letters, 13, 3824-3830, 2013            (Co-first author)  

11.   Wang, Zhiguo; Meng, Gu; et al, Electron-Rich Driven Electrochemical Solid-State Amorphization in Li-Si Alloys, Nano Letters 2013 13, 4511–4516                                                   (Co-first author)

12.   Meng Gu, et al, Electronic origin for the phase transition from amorphous LixSi to crystalline Li15Si4, ACS Nano, 2013, 7, 6303–6309 

13.   Meng Gu,,et al, Formation of Spinel Phase in the Layered Composite Cathode in Li‐Ion Batteries, ACS Nano, 2013, 7 , pp 760–767   

14.   Meng Gu, et al, In-situ TEM study of lithiation behavior of silicon nanoparticles attached to and embedded in a carbon matrix, ACS Nano, 2012, 6, pp 8439–8447

15.   Meng Gu, et al, Nanoscale Phase Separation, Cation Ordering, and Surface Chemistry in Pristine Li1.2Ni0.2Mn0.6O2 for Li-Ion Batteries, Chemistry of Materials 2013, 25, pp 2319–2326 

16.   Gao, Qi; Meng, Gu; et al, Direct Evidence of Lithium-induced Atomic Ordering in Amorphous TiO2 Nanotubes, Chemistry of Materials, 2014, 26 (4), pp 1660–1669                                     (Co-first author)

17.   Zheng, Jianming; Gu, Meng; et al, Functioning Mechanism of AlF3 Coating on the Li- and Mn-Rich Cathode Materials, Chemistry of Materials, 26 , 6320-6327 2014                                  (Co-first author)

18.   Meng Gu, et al, Mesoscale Origin of enhanced cycling performance of Si/conductive polymer composite for Li-ion batteries, Scientific Reports, 4, Article number: 3684 (2014)

19.   Meng Gu, W Shi, J Zheng, P Yan, J Zhang, C Wang, Probing the failure mechanism of nanoscale LiFePO4 for Li-ion batteries, Applied Physics Letters 106, 203902

20.   Meng Gu, Zhiguo Wang, Michael Biegalski, Hans M. Christen, Yayoi Takamura, Nigel D. Browning, Antisite defects in La0.7Sr0.3MnO3 and La0.7Sr0.3FeO3, Applied Physics Letters 102, 151911, 2013

21.   Meng Gu, et al, Structural variability in La0.5Sr0.5TiO3+d thin films, Applied Physics Letters 99, 261907, 2011

22.   Meng Gu, Fan Yang, Chengyu Song, Nigel D. Browning, and Yayoi Takamura, Tuning magnetic and transport properties though Strain Engineering in LSMO/LSTO Superlattices, J. Appl. Phys. 111, 084906 (2012)

23.   Meng Gu, et al, Strain relaxation defects in perovskite oxide superlattices, Journal of Materials Research, 27, 1436 (2012)

24.   Meng Gu, et al, Cation uniformity and magnetic properties of La0.7Sr0.3Mn0.5Fe0.5O3 thin films, Journal of Magnetism and Magnetic Materials, 325, 69-74 (2013)

25.   Meng Gu, et al, Preparation and photoluminescence of single crystalline GdVO4:Eu3+ nanorods by hydrothermal conversion of Gd(OH)3 nanorods, Crystal Growth & Design, (2008) 8, 1422-1425