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Park, Gwi Ok,Yoon, Jeongbae,Park, Eunjun,Park, Su Bin,Kim, Hyunchul,Kim, Kyoung Ho,Jin, Xing,Shin, Tae Joo,Kim, Hansu,Yoon, Won-Sub,Kim, Ji Man American Chemical Society 2015 ACS NANO Vol.9 No.5
<P>To monitor dynamic volume changes of electrode materials during electrochemical lithium storage and removal process is of utmost importance for developing high performance lithium storage materials. We herein report an <I>in operando</I> probing of mesoscopic structural changes in ordered mesoporous electrode materials during cycling with synchrotron-based small angel X-ray scattering (SAXS) technique. <I>In operando</I> SAXS studies combined with electrochemical and other physical characterizations straightforwardly show how porous electrode materials underwent volume changes during the whole process of charge and discharge, with respect to their own reaction mechanism with lithium. This comprehensive information on the pore dynamics as well as volume changes of the electrode materials will not only be critical in further understanding of lithium ion storage reaction mechanism of materials, but also enable the innovative design of high performance nanostructured materials for next generation batteries.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2015/ancac3.2015.9.issue-5/acsnano.5b01378/production/images/medium/nn-2015-013783_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn5b01378'>ACS Electronic Supporting Info</A></P>
Glazer, Matthew P.B.,Wang, Junjie,Cho, Jiung,Almer, Jonathan D.,Okasinski, John S.,Braun, Paul V.,Dunand, David C. Elsevier 2017 Journal of Power Sources Vol.367 No.-
<P><B>Abstract</B></P> <P>Volume changes associated with the (de)lithiation of a nanostructured Ni<SUB>3</SUB>Sn<SUB>2</SUB> coated nickel inverse opal scaffold anode create mismatch stresses and strains between the Ni<SUB>3</SUB>Sn<SUB>2</SUB> anode material and its mechanically supporting Ni scaffold. Using <I>in operando</I> synchrotron x-ray diffraction measurements, elastic strains in the Ni scaffold are determined during cyclic (dis)charging of the Ni<SUB>3</SUB>Sn<SUB>2</SUB> anode. These strains are characterized using both the center position of the Ni diffraction peaks, to quantify the average strain, and the peak breadth, which describes the distribution of strain in the measured volume. Upon lithiation (half-cell discharging) or delithiation (half-cell charging), compressive strains and peak breadth linearly increase or decrease, respectively, with charge. The evolution of the average strains and peak breadths suggests that some irreversible plastic deformation and/or delamination occurs during cycling, which can result in capacity fade in the anode. The strain behavior associated with cycling of the Ni<SUB>3</SUB>Sn<SUB>2</SUB> anode is similar to that observed in recent studies on a Ni inverse-opal supported amorphous Si anode and demonstrates that the (de)lithiation-induced deformation and damage mechanisms are likely equivalent in both anodes, even though the magnitude of mismatch strain in the Ni<SUB>3</SUB>Sn<SUB>2</SUB> is lower due to the lower (de)lithiation-induced contraction/expansion.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Lithiation-induced strains quantified in a Ni<SUB>3</SUB>Sn<SUB>2</SUB> inverse opal anode <I>in operando</I>. </LI> <LI> Lithiation induces compressive average strains in Ni inverse opal scaffold. </LI> <LI> Ni inverse opal scaffold strain distribution reversibly broadens upon lithiation. </LI> <LI> Three measured volumes show similar cyclic strain averages and distributions. </LI> <LI> Ni<SUB>3</SUB>Sn<SUB>2</SUB> measured cyclic strains are similar to prior Si inverse opal anode studies. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Directing battery chemistry using side-view operando optical microscopy
S. Jayasubramaniyan,이현욱 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.3
This review highlights recent progress and perspectives on side-view operando optical microscopy (OM) on lithium-ion batteries (LIBs). Side-view operando imaging studies on LIBs offer new insights for understanding the dynamic feature of battery chemistry since the images or movies offer direct visualization of the most realistic conditions. Taking advantage of a fundamentally complete understanding, we have a chance to overcome the formidable challenges of the LIBs. For the realistic demonstration of each part of the battery components, OM has been used to understand direct electrochemical reactions identifying the fundamental failure mechanisms that help overcome the challenges of LIBs. Here, we provide a comprehensive review of our research work in the field of the application of OM for understanding the various challenging aspects of LIBs. Moreover, we highlight that the further utilization of the OM technique towards and beyond the LIBs could lead to the development of next-generation batteries.
김우진,고은교,김소윤,김봉주,노태원 한국물리학회 2019 Current Applied Physics Vol.19 No.4
The instability of iridium oxide at high temperature has long been a bottleneck for in growing pyrochlore iridate thin films in a vacuum chamber. To overcome this problem, we investigated the chemical instability of IrO2 thin films, which are the simplest form of iridate, via in-operando spectroscopic ellipsometry (SE). We observed that IrO2 thin films undergo IrO2 dissociation and IrO3 gas formation depending on the thermodynamic conditions. The chemical kinetics observations of IrO2 were confirmed by ex-situ X-ray diffraction and atomic force microscopy. SE experimental data were compared with models used to describe the evolution of the two chemical reactions. Real-time in-operando SE analysis based on the Maxwell Garnett theory yielded a precise IrO2 dissociation speed for the given thermodynamic conditions. Moreover, the real-time in-operando SE technique allowed us to observe the phase transition from solid IrO2 to gaseous IrO3. This study on the chemical instability of IrO2 at high temperature affords insights into a new method for in-situ pyrochlore iridate and other iridates thinfilm growth.
In Operando Stacking of Reduced Graphene Oxide for Active Hydrogen Evolution
Ling, Ning,Wang, Zhen,Kim, Sera,Oh, Sang Ho,Park, Jong Hyeok,Shin, Hyunjung,Cho, Suyeon,Yang, Heejun American Chemical Society 2019 ACS APPLIED MATERIALS & INTERFACES Vol.11 No.46
<P>Despite the remarkable electronic and mechanical properties of graphene, improving the catalytic activity of the atomically flat, inert, and stable carbon network remains a challenging issue in both fundamental and application studies. In particular, the adsorption of most molecules and ions, including hydrogen (H<SUB>2</SUB> or H<SUP>+</SUP>), on graphene is not favorable, underlining the challenge for an efficient electrochemical catalytic reaction on graphene. Various defects, edges, and functionalization have been suggested to resolve the catalytic issue in graphene, but cost-effectiveness and active catalysis with graphene have not been achieved yet. Here, we introduce dynamic stacking of reduced graphene oxide (rGO) with spontaneously generated hydrogen bubbles to form an efficient electrochemical catalyst with a graphene derivative; the in operando stacking of rGO, without using a high-temperature-based heteroatom doping process or plasma treatment, creates a large catalytic surface area with optimized edges and acidic groups in the rGO. Thus, the uniquely formed stable carbon network achieves active hydrogen evolution with a Tafel slope of 39 mV·dec<SUP>-1</SUP> and a double layer capacitance of 12.41 mF·cm<SUP>-2</SUP>, which breaks the conventional limit of graphene-based catalysis, suggesting a promising strategy for metal-free catalyst engineering and hydrogen production.</P> [FIG OMISSION]</BR>
Liu, Huajun,Dong, Yongqi,Cherukara, Mathew J.,Sasikumar, Kiran,Narayanan, Badri,Cai, Zhonghou,Lai, Barry,Stan, Liliana,Hong, Seungbum,Chan, Maria K. Y.,Sankaranarayanan, Subramanian K. R. S.,Zhou, Hua American Chemical Society 2018 ACS NANO Vol.12 No.5
<P>Memristive devices are an emerging technology that enables both rich interdisciplinary science and novel device functionalities, such as nonvolatile memories and nanoionics-based synaptic electronics. Recent work has shown that the reproducibility and variability of the devices depend sensitively on the defect structures created during electroforming as well as their continued evolution under dynamic electric fields. However, a fundamental principle guiding the material design of defect structures is still lacking due to the difficulty in understanding dynamic defect behavior under different resistance states. Here, we unravel the existence of threshold behavior by studying model, single-crystal devices: resistive switching requires that the pristine oxygen vacancy concentration reside near a critical value. Theoretical calculations show that the threshold oxygen vacancy concentration lies at the boundary for both electronic and atomic phase transitions. Through <I>operando</I>, multimodal X-ray imaging, we show that field tuning of the local oxygen vacancy concentration below or above the threshold value is responsible for switching between different electrical states. These results provide a general strategy for designing functional defect structures around threshold concentrations to create dynamic, field-controlled phases for memristive devices.</P> [FIG OMISSION]</BR>
신예원 ( Yewon Shin ),이민규 ( Mingyu Lee ),이홍경 ( Hongkyung Lee ) 한국공업화학회 2022 공업화학전망 Vol.25 No.4
With the growing popularity of battery-powered mobility, battery safety and performance reliability have been prioritized by battery industries. Despite advanced manufacturing processes of large-scale commercial Li-ion cells, “latent defects” that can accidentally appear due to imbalanced battery design, invisible faults, and extreme operating conditions still threaten performance degradation and battery fire. Hence, it is urgently necessary to detect such latent defects in advance and understand the impacts of cell parameters and operating conditions on the battery failure scenario. For straightforward analysis of commercial cells, real-time, non-invasive visualizing of battery inside and diagnosing battery aging have been recognized through in-operado battery imaging technology based on X-rays, neutrons, and ultrasound which can penetrate the active materials, cell components, and external packaging. Moreover, a battery imaging technique to visualize the current distribution pattern using a magnetic field induced at batteries under external current load has also been proposed. This review will comprehensively discuss the imaging techniques inside the battery from atomic and molecular levels in electrode materials and interfaces to macro-scale battery systems, and examine qualitative case studies and recently unveiled phenomena.