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obtain many insights by tracking physical-geometrical evolution during operation. Atomic force microscopy (AFM) is a promising technique to map such geometrical evolution but is constrained by the slower image acquisition times (~min). An additional challenge is to configure AFM for the unique electrochemical environment of operating cells. Guangyi Shang, Zhuanfang Bi, and colleagues from Beihang University and Singapore University of Technology and Design have advanced AFM to break these constraints and provide meaningful imaging for fast-charging battery materials. The study was recently published in the Review of Scientific Instruments (doi:10.1063/5.0024425). The researchers combined advances in AFM in other scientific disciplines to extend the capabilities of AFM to study electrochemical systems. They borrowed high-speed AFM to improve the image acquisition time from a few minutes to a few seconds. In this setting, a smaller cantilever (i.e., AFM probe) is used since it has a higher resonant frequency, lower spring constant and allows for faster scans. The downside of such a cantilever is its small dimensions. The researchers developed a custom optical detection
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• VOLUME 45 • DECEMBERIP2020 • mrs.org/bulletin Downloaded MRS fromBULLETIN https://www.cambridge.org/core. address: 212.119.46.136, on 13 Dec 2020 at 15:38:42, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1557/mrs.2020.309
NEWS & ANALYSIS MATERIALS NEWS properties, pressure, etc.” In his opinion, the group has done a nice job of expanding the electrochemical research community’s characterization toolbox by integrating a handful of these relevant measurement parameters with their recently developed “electrochemical highspeed AFM.” The utility of the new tool to track the nanoscopic structure of electrochemically active material as a function of both time and electrochemical
potential is well conveyed in their article, as well as the video provided in the supplemental material. Larson is curious to see the future work that follows. The researchers are excited about various future investigations for this technique. Other positive electrode materials such as lithium iron phosphate and lithium nickel manganese cobalt oxide will be studied, particularly over larger voltage windows where they have been known to
undergo morphological changes. Another interesting possibility is to study negative electrode materials like graphite and silicon, which are known to show side reactions and volume expansion. Such in situ imaging studies will finally allow researchers to verify degradation predictions of physics-based battery models, especially at faster rates relevant to nextgeneration batteries. Aashutosh Mistry
way: “Qiang Zhu, a PhD student working on the project, found that by loading the Trigonal prismatic cage pores with different solvents, including molecule enables new type of 3D covalent organic framework dimethylformamide, the COF structure changed.” Another PhD student, Xue Wang
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