Editorial pubs.acs.org/cm
That’s a Wrap: Graphene-Wrapped Magnetite Anodes for Lithium Ion Batteries Newest Members of the Chemistry of Materials’ 1k Club he Chemistry of Materials’ 1k Club is a continuing series of interviews with authors of papers that have been cited 1000 times or more. We were pleased to have the chance to interview Hui-Ming Cheng of the Institute of Metal Research, Chinese Academy of Sciences, the corresponding author of “Graphene-Wrapped Fe3O4 Anode Material with Improved Reversible Capacity and Cyclic Stability for Lithium Ion Batteries”.1 This paper has been cited 1082 times in Web of Science and 1258 times by Google Scholar, as of July 10, 2017. This paper shows the synergistic cooperation between graphene sheets and Fe3O4 nanoparticles; the graphene effectively acts to confine, in a flexible fashion, the Fe3O4 nanoparticles, while the inorganic material prevents restacking and agglomeration of the graphene sheets, as shown in Figure 1. The resulting nanocomposite has excellent cycling stability and rate capability as an anode material for lithium ion batteries. We (CM) asked Dr. Cheng (HMC) to share with us the thoughts and motivation of his team from the Shenyang National Laboratory for Materials Science, Institute of Metal Research of the Chinese Academy of Sciences, and the ARC Centre of Excellence for Functional Nanomaterials, at The University of Queensland, Australia. CM: At what stage of your academic career were you when you submitted this article to Chemistry of Materials? Who were the other 8 authors on the paper, and at what stage were they? Where are they now? HMC: When we submitted this paper to Chemistry of Materials in 2010, the first author, Dr. Guangmin Zhou, was a third year graduate student and just starting his Ph.D. journeythis was his first scientific paper. Dr. Da-Wei Wang was a postdoc at the University of Queensland, Dr. Feng Li was a professor in his third year leading energy storage research, and I (Hui-Ming Cheng) was a professor and the founding director of the Advanced Carbon Materials Division (ACD), Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences (IMR, CAS). Dr. Zhou received his Ph.D from the IMR at CAS in 2014, then worked as a postdoc at UT Austin with Prof. Arumugam Manthiram for one year, and then moved to Stanford University with Prof. Yi Cui, where he is now. Dr. Wang is now a Senior Lecturer in the School of Chemical Engineering at The University of New South Wales. Dr. Li is still working at the IMR CAS. In 2015 he received a China National Fund award for Distinguished Young Scientists and in 2016 was named a highly cited researcher in materials science by Clarivate Analytics (Web of Science). Dr. Cheng has kept the same position at the IMR CAS but recently founded the Low Dimensional Materials and Devices Laboratory at the Tsinghua-Berkeley Shenzhen Institute, Tsinghua University, in 2016. He was elected a member of the Chinese Academy of Sciences in 2013 and has been a highly cited researcher for several years in both materials science and chemistry.
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CM: Given the high citation record of this article, a significant amount of research has been impacted by your findings over the years. Where did you think the field was headed when you wrote this work? In your opinion, how has this particular research field evolved ever since? HMC: Since 2008, there has been an enormous quantity of exploration of graphene materials, stimulated by the pioneering work of Profs. Geim and Novoselov dating back to 2004, for which they were awarded the Nobel Prize in Physics in 2010 for their groundbreaking discoveries. The ACD of the IMR CAS was one of the earliest research groups in China to fabricate high quality graphene by both the liquid exfoliation of natural graphite and chemical vapor deposition and has been doing so since 2007. After a reasonably large quantity of graphene materials was obtained from the oxidation−exfoliation− reduction method, its use in electrochemical energy storage and conversion was our first research choice. We found a large irreversible capacity when pure reduced graphene oxide (rGO) was used as the anode material of lithium ion batteries (LIBs), due to the existence of a large number of oxygen-containing functional groups and defects. Although we obtained negative results, from another viewpoint we thought that the oxygen functional groups and defects in rGO might be good for nucleating and anchoring oxide materials, which have very high capacity but poor electrical conductivity and a large volume change during charge/discharge. The rGO would prevent the volume changes of the oxides and could be used to produce a highly conductive network, both of which are beneficial in obtaining high-performance electrode materials for LIBs. Therefore, we conducted a series of studies on this topic, and this paper is one of them. We have found that chemically exfoliated graphene is a fantastic material platform for constructing highly conductive, flexible, and high-performance hybrid electrodes for LIBs and beyond. This use of graphene in electrochemical energy storage and conversion has inspired many new concepts and opened up new research directions. Following our work, considerable progress has been made thanks to colleagues throughout the world who have been devoted to producing graphene-based composites for electrochemical energy storage and conversion technologies. The beneficial role of graphene in these composites has been intensively investigated, and “synergistic effects” have been highlighted and unveiled. By combining experimental results and first-principles calculations, we have confirmed that oxygen bridges between metal oxides and oxygen functional groups in rGO are the reason for the “synergistic effect”2 and have directly observed the prevention by graphene of volume change in these oxides by in situ transmission electron microscopy.3 This understanding is tremendously important to the research Published: August 22, 2017 6561
DOI: 10.1021/acs.chemmater.7b02905 Chem. Mater. 2017, 29, 6561−6562
Chemistry of Materials
Editorial
Figure 1. Table of contents image from ref 1, graphically showing graphene sheet-wrapped magnetite particles being cycled within the anode of a lithium ion battery.
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community, because it helps in designing and fabricating highperformance electrode materials. The concept has been extended to other graphene-based composites for applications in many fields such as catalysis, sensors, and protection of the environment, in the pursuit of optimal performance. CM: If you had to put your finger on it, what made your paper special? What are you most happy about when you reread this article? HMC: We are not surprised that this paper has aroused so much interest because it was one of the earliest studies to clearly demonstrate the important role of graphene for constructing high-performance composite electrode materials. The unique properties of graphene, including its large surface area, high flexibility, good chemical and thermal stability, wide potential windows, interesting surface chemistry, and extraordinary electrical, thermal, and mechanical properties, make it perfect for electrochemical energy storage and conversion systems. The results in this work gave unambiguous proof that graphene provides a large contact surface for the dispersion of oxide particles, acts as an excellent conductive agent to provide a path for electron transport, and has a “flexible confinement” function for tolerating the volume changes of high-capacity oxide materials, and the porosity formed between the oxide particle and spaced graphene facilitates ion transport. This strategy is not only simple but also universal, and almost everyone can easily reproduce it. We are delighted that this work has served as an important reference for researchers in this field, both from academia and industry, in interpreting or addressing important issues in their own work. CM: What’s your advice to young scientists trying to discover the next breakthrough in materials science? HMC: Try to use new materials in fields that are important for mankind, think of innovative ideas in scientific activity, and find simple yet effective strategies to realize them. Never give up, even when you encounter negative results, because these may inspire new insight and have great impact for other scientific endeavors.
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Views expressed in this editorial are those of the authors and not necessarily the views of the ACS.
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REFERENCES
(1) Zhou, G.; Wang, D.-W.; Li, F.; Zhang, L.; Li, N.; Wu, Z.-S.; Wen, L.; Lu, G.-Q.; Cheng, H.-M. Graphene-Wrapped Fe3O4 Anode Material with Improved Reversible Capacity and Cyclic Stability for Lithium Ion Batteries. Chem. Mater. 2010, 22, 5306−5313. (2) Zhou, G.; Wang, D.-W.; Yin, L.-C.; Li, N.; Li, F.; Cheng, H.-M. Oxygen Bridges between NiO Nanosheets and Graphene for Improvement of Lithium Storage. ACS Nano 2012, 6, 3214−3223. (3) Shan, X.-Y.; Zhou, G.; Yin, L.-C.; Yu, W.-J.; Li, F.; Cheng, H.-M. Visualizing the Roles of Graphene for Excellent Lithium Storage. J. Mater. Chem. A 2014, 2, 17808−17814.
Carlos Toro, Managing Editor Jillian M. Buriak, Editor-in-Chief AUTHOR INFORMATION
ORCID
Jillian M. Buriak: 0000-0002-9567-4328 6562
DOI: 10.1021/acs.chemmater.7b02905 Chem. Mater. 2017, 29, 6561−6562
