Synthesis of full concentration gradient cathode studied by high energy X-ray diffraction

Li, Yan,Xu, Rui,Ren, Yang,Lu, Jun,Wu, Huiming,Wang, Lifen,Miller, Dean J.,Sun, Yang-Kook,Amine, Khalil,Chen, Zonghai Elsevier 2016 Nano energy Vol.19 No.-

<P><B>Abstract</B></P> <P>Nickel-rich metal oxides have been widely pursued as promising cathode materials for high energy-density lithium-ion batteries. Nickel-rich lithium transition metal oxides can deliver a high specific capacity during cycling, but can react with non-aqueous electrolytes. In this work, we have employed a full concentration gradient (FCG) design to provide a nickel-rich core to deliver high capacity and a manganese-rich outer layer to provide enhanced stability and cycle life. <I>In situ</I> high-energy X-ray diffraction was utilized to study the structural evolution of oxides during the solid-state synthesis of FCG lithium transition metal oxide with a nominal composition of LiNi<SUB>0.6</SUB>Mn<SUB>0.2</SUB>Co<SUB>0.2</SUB>O<SUB>2</SUB>. We found that both the pre-heating step and the sintering temperature were critical in controlling phase separation of the transition metal oxides and minimizing the content of Li<SUB>2</SUB>CO<SUB>3</SUB> and NiO, both of which deteriorate the electrochemical performance of the final material. The insights revealed in this work can also be utilized for the design of other nickel-rich high energy-density cathode materials.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Solid-state synthesis of FCG cathode is investigated by <I>in situ</I> XRD. </LI> <LI> Covariance analysis and Rietveld refinement are used to analyze the HEXRD data. </LI> <LI> Synthetic optimization of FCG cathode with excellent electrochemical performance. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Benefit from the covariance analysis and Rietveld refinement of <I>in situ</I> HEXRD data during the solid state synthesis, we can optimized the solid state synthesis conditions in a short time. And the full concentration gradient cathode composites (nickel-rich core and manganese-rich outer layer) with excellent electrochemical performance are obtained.</P> <P>[DISPLAY OMISSION]</P>

Formation and Inhibition of Metallic Lithium Microstructures in Lithium Batteries Driven by Chemical Crossover

Li, Wangda,Kim, Un-Hyuck,Dolocan, Andrei,Sun, Yang-Kook,Manthiram, Arumugam American Chemical Society 2017 ACS NANO Vol.11 No.6

<P>The formation of metallic lithium microstructures in the form of dendrites or mosses at the surface of anode electrodes (e.g., lithium metal, graphite, and silicon) leads to rapid capacity fade and poses grave safety risks in rechargeable lithium batteries. We present here a direct, relative quantitative analysis of lithium deposition on graphite anodes in pouch cells under normal operating conditions, paired with a model cathode material, the layered nickel-rich oxide LiNi0.61Co0.12Mn0.27O2, over the course of 3000 charge discharge cycles. Secondary-ion mass spectrometry chemically dissects the solid electrolyte interphase (SEI) on extensively cycled graphite with virtually atomic depth resolution and reveals substantial growth of Li-metal deposits. With the absence of apparent kinetic (e.g., fast charging) or stoichiometric restraints (e.g., overcharge) during cycling, we show lithium deposition on graphite is triggered by certain transition-metal ions (manganese in particular) dissolved from the cathode in a disrupted SEI. This insidious effect is found to initiate at a very early stage of cell operation (<200 cycles) and can be effectively inhibited by substituting a small amount of aluminum (similar to 1 mol %) in the cathode, resulting in much reduced transition-metal dissolution and drastically improved cyclability. Our results may also be applicable to studying the unstable electrodeposition of lithium on other substrates, including Li metal.</P>

Nano/Microstructured Silicon-Graphite Composite Anode for High-Energy-Density Li-Ion Battery

Li, Peng,Hwang, Jang-Yeon,Sun, Yang-Kook American Chemical Society 2019 ACS NANO Vol.13 No.2

<P>With the ever-increasing demand for lithium-ion batteries (LIBs) with higher energy density, tremendous attention has been paid to design various silicon-active materials as alternative electrodes due to their high theoretical capacity (ca. 3579 mAh g<SUP>-1</SUP>). However, totally replacing the commercially utilized graphite with silicon is still insurmountable owing to bottlenecks such as low electrode loading and insufficient areal capacity. Thus, in this study, we turn back to enhanced graphite electrode through the cooperation of modified silicon via a facile and scalable blending process. The modified nano/microstructured silicon with boron doping and carbon nanotube wedging (B-Si/CNT) can provide improved stability (88.2% retention after 200 cycles at 2000 mA g<SUP>-1</SUP>) and high reversible capacity (∼2426 mAh g<SUP>-1</SUP>), whereas the graphite can act as a tough framework for high loading. Owing to the synergistic effect, the resultant B-Si/CNT-graphite composite (B-Si/CNT@G) shows a high areal capacity of 5.2 mAh cm<SUP>-2</SUP> and excellent cycle retention of 83.4% over 100 cycles, even with ultrahigh active mass loading of 11.2 mg cm<SUP>-2</SUP>,which could significantly surpass the commercially used graphite electrode. Notably, the composite also exhibits impressive application in Li-ion full battery using 2 mol % Al-doped full-concentration-gradient Li[Ni<SUB>0.76</SUB>Co<SUB>0.09</SUB>Mn<SUB>0.15</SUB>]O<SUB>2</SUB> (Al2-FCG76) as the cathode with excellent capacity retention of 82.5% even after 300 cycles and an outstanding energy density (8.0 mWh cm<SUP>-2</SUP>) based on the large mass loading of the cathode (12.0 mg cm<SUP>-2</SUP>).</P> [FIG OMISSION]</BR>

Antimony Selenide Nanorods Decorated on Reduced Graphene Oxide with Excellent Electrochemical Properties for Li-Ion Batteries

Wang, Xia,Wang, Hong,Li, Qiang,Li, Hongsen,Xu, Jie,Zhao, Guoxia,Li, Hongliang,Guo, Peizhi,Li, Shandong,Sun, Yang-kook The Electrochemical Society 2017 Journal of the Electrochemical Society Vol.164 No.13

<P>A promising anode material for lithium-ion batteries (LIBs) consisting of Sb2Se3 nanorods and reduced graphene oxide (rGO) sheets has been prepared by an effective solvothermal approach. The synergetic effect between Sb2Se3 nanorods and rGO matrix provides not only high conductivity paths and strong electron contact interface, but also alleviates the volume change of Sb2Se3 nanorods, resulting in excellent lithium-storage performance. When tested as an anode material for LIBs, a high capacity of 868.30 mAh g(-1) can be retained after 100 cycles at 200 mA g(-1). Even at 2000 mA g(-1), a satisfactory capacity of 430.40 mAh g(-1) after long 550 cycles can be delivered. Ex situ X-ray diffraction study suggests that the Sb2Se3/rGO composite follows the combined Li+ intercalation, conversion reaction and alloying reaction mechanism. These features suggest the Sb2Se3/rGO composite a viable choice for application as an anode material in high-performance LIBs. (C) 2017 The Electrochemical Society. All rights reserved.</P>

Superior lithium/potassium storage capability of nitrogen-rich porous carbon nanosheets derived from petroleum coke

Li, Peng,Hwang, Jang-Yeon,Park, Sang-Min,Sun, Yang-Kook The Royal Society of Chemistry 2018 Journal of Materials Chemistry A Vol.6 No.26

<P>Tremendous attention has been paid to carbon-based anodes for lithium-ion and potassium-ion batteries. Nevertheless, conferring high energy storage properties using carbon-based anodes is still challenging. In this work, petroleum coke-based nitrogen-doped porous carbon nanosheets (N-PCSs) were prepared using carbon nitride (g-C3N4) as both a template and nitrogen source and tested as advanced anode materials. The as-obtained N-PCSs constructed through an <I>in situ</I> solid-state approach possess both high capacity and excellent cycling stability. High capacities were obtained for Li-ion and K-ion batteries (407 mA h g<SUP>−1</SUP> after 500 cycles at 3720 mA g<SUP>−1</SUP> and 206 mA h g<SUP>−1</SUP> after 300 cycles at 1000 mA g<SUP>−1</SUP>, respectively); these are some of the best capacities for carbon-based electrode materials and could be ascribed to the unique microstructure of the anodes, <I>i.e.</I>, nanosheet morphology, developed porosity, ultrahigh nitrogen doping, and a high level of disorder. Meanwhile, this study represents a milestone for high-value utilization of petroleum coke and other kinds of heavy oil.</P>

Li-Water Battery with Oxygen Dissolved in Water as a Cathode

Kim, Jae-Kwang,Yang, Wei,Salim, Jason,Ma, Chao,Sun, Chunwen,Li, Jianqi,Kim, Youngsik The Electrochemical Society 2014 Journal of the Electrochemical Society Vol.161 No.3

<P>In this work, we demonstrate a lithium-water battery that uses oxygen dissolved in water as a cathode, Sr<SUB>0.95</SUB>Ce<SUB>0.05</SUB>CoO<SUB>3-δ</SUB> (SCCO)-copper nanoparticles as an efficient bifunctional catalyst, and with hybrid electrolytes. The SCCO-Cu composite catalyst exhibits an efficient and stable bifunctional catalytic activity, especially for the OER. The round-trip efficiency of the cell with SCCO-Cu nanoparticles catalyst reaches 84.1%, close to that of the 50% Pt/carbon-black catalyst (87.2%). The improved performance of the SCCO-Cu catalyst can be ascribed to the synergetic effect of SCCO and copper. The preliminary results demonstrate that the rechargeable lithium-water battery with oxygen dissolved in water flow can be achieved with high efficient and low cost oxide catalyst. This can be a good candidate for a large stationary energy storage system (ESS) with a low-cost.</P>

Aprotic and Aqueous Li–O₂ Batteries

Lu, Jun,Li, Li,Park, Jin-Bum,Sun, Yang-Kook,Wu, Feng,Amine, Khalil American Chemical Society 2014 Chemical reviews Vol.114 No.11

<P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/chreay/2014/chreay.2014.114.issue-11/cr400573b/production/images/medium/cr-2013-00573b_0033.gif'></P>

CdSe@ZnS/ZnS quantum dots loaded in polymeric micelles as a pH-triggerable targeting fluorescence imaging probe for detecting cerebral ischemic area

Yang, Hong Yu,Fu, Yan,Jang, Moon-Sun,Li, Yi,Yin, Wen Ping,Ahn, Tae Kyu,Lee, Jung Hee,Chae, Heeyeop,Lee, Doo Sung Elsevier 2017 Colloids and surfaces. B, Biointerfaces Vol.155 No.-

<P><B>Abstract</B></P> <P>High photoluminescence (PL) quantum yield (QY), photostability CdSe@ZnS/ZnS core/multishell quantum dots (CM-QDs) were first applied for bioimaging. The solubility, stability and biocompatible of the fluorescence imaging probes were constructed by self-assembly of CM-QDs and pH-responsive methoxy poly(ethylene glycol)-poly(β-amino ester/amidoamine)-dodecylamine (mPEG-PAEA-DDA) multiblock copolymers. The resulting CM-QDs-loaded mPEG-PAEA-DDA micelles (CM-QDs-PEG-PAEA-DDA) exhibited lower cell cytotoxicity and higher fluorescence intensity than the core/shell CdSe@ZnS QDs-encapsulated mPEG-PAEA-DDA micelles (CS-QDs-PEG-PAEA-DDA). Moreover, the in vivo fluorescence imaging ability confirmed that the CM-QDs-PEG-PAEA-DDA can be employed as a pH-triggerable targeting imaging probe for detection of a rat bearing cerebral ischemia disease. Therefore, we believed that the CM-QDs-PEG-PAEA-DDA may be the next generation of fluorescence imaging probes for targeted diagnosis acidic pathological areas, using pH as a stimulus.</P> <P><B>Highlights</B></P> <P> <UL> <LI> CdSe@ZnS/ZnS QDs are synthesized and first applied for bioimaging. </LI> <LI> mPEG-PAEA-DDA copolymer showed pH-responsive property and the hydrolysis stability. </LI> <LI> CM-QDs-PEG-PAEA-DDA exhibited lower toxicity and higher fluorescent intensity. </LI> <LI> CM-QDs-PEG-PAEA-DDA has ability to target image for acidic brain ischemic area. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Cholinesterases inhibition studies of biological active compounds from the rhizomes of <i>Alpinia officinarum</i> Hance and <i>in silico</i> molecular dynamics

Lee, Ji Sun,Kim, Jang Hoon,Han, Yoo Kyong,Ma, Jin Yeul,Kim, Young Ho,Li, Wei,Yang, Seo Young Elsevier 2018 INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES Vol.120 No.2

<P><B>Abstract</B></P> <P>Six diarylheptanoids (<B>1</B>–<B>6</B>) and two flavonoids (<B>7</B> and <B>8</B>) derived from <I>Alpinia officinarum</I> were evaluated for their ability to inhibit acetylcholinesterase. Compound <B>1</B> showed the highest degree of inhibition, with an IC<SUB>50</SUB> of approximately 2 μM, followed by moderate degrees of inhibition by <B>2</B>, <B>4</B> and <B>7</B>, with IC<SUB>50</SUB> values ranging from 20 to 40 μM. The remaining isolated compounds <B>3</B>, <B>5</B>, <B>6</B> and <B>8</B> had IC<SUB>50</SUB> values greater than 50 μM. Enzyme kinetic studies showed that the compounds with high or moderate activity were competitive inhibitors, anchored to the active site of acetylcholinesterase. In particular, compounds <B>1</B> and <B>2</B> were docked at slightly different positions from those occupied by <B>4</B> and <B>7</B>. Furthermore, molecular dynamics studies showed that compound <B>1</B> maintained its interactions with residues Thr74 and Phe295 throughout the simulation trajectory. Our findings suggest that compound <B>1</B> is a potential therapeutically relevant inhibitor of acetylcholinesterase.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Six diarylheptanoids (<B>1</B>–<B>6</B>) and two flavonoids (<B>7</B> and <B>8</B>) were isolated from <I>Alpinia officinarum</I>. </LI> <LI> Compound <B>1</B> showed acetylcholinesterase inhibitory activity with IC<SUB>50</SUB> value of approximately 2 μM. </LI> <LI> Compounds <B>1</B>, <B>2</B>, <B>4</B>, and <B>7</B> inhibited the catalytic reaction of acetylcholinesterase as competitive mode. </LI> <LI> Computational simulation study suggested the predicted binding position of the compound <B>1</B> with catalytic site of receptor. </LI> </UL> </P>

Selection of Reference Genes for Real-time Quantitative PCR Normalization in the Process of Gaeumannomyces graminis var. tritici Infecting Wheat

Li-hua Xie,Xin Quan,Jie Zhang,Yan-yan Yang,Run-hong Sun,Ming-cong Xia,Bao-guo Xue,Chao Wu,Xiao-yun Han,Ya-nan Xue,Li-rong Yang 한국식물병리학회 2019 Plant Pathology Journal Vol.35 No.1

Gaeumannomyces graminis var. tritici is a soil borne pathogenic fungus associated with wheat roots. The accurate quantification of gene expression during the process of infection might be helpful to understand the pathogenic molecular mechanism. However, this method requires suitable reference genes for transcript normalization. In this study, nine candidate reference genes were chosen, and the specificity of the primers were investigated by melting curves of PCR products. The expression stability of these nine candidates was determined with three programs-geNorm, Norm Finder, and Best Keeper. TUBβ was identified as the most stable reference gene. Furthermore, the exopolygalacturonase gene (ExoPG) was selected to verify the reliability of TUBβ expression. The expression profile of ExoPG assessed using TUBβ agreed with the results of digital gene expression analysis by RNA-Seq. This study is the first systematic exploration of the optimal reference genes in the infection process of Gaeumannomyces graminis var. tritici.