Non-volatile, Li-doped ion gel electrolytes for flexible WO₃-based electrochromic devices

Yun, Tae Yong,Li, Xinlin,Bae, Jaehyun,Kim, Se Hyun,Moon, Hong Chul Elsevier 2019 Materials & Design Vol.162 No.-

<P><B>Abstract</B></P> <P>Flexible electrochromic devices (ECDs) based on Li-doped ion gels and tungsten trioxide (WO<SUB>3</SUB>) are demonstrated. Colored ECDs cannot be produced using conventional ion gels comprised of copolymers and room temperature ionic liquids (RTILs) due to a lack of cations that can be inserted into WO<SUB>3</SUB>. Based on considerations of the coloration mechanism, we developed Li-doped ion gels and applied these to devices. The effects of Li salt concentration are systematically examined, with respect to device dynamics, coloration efficiency, and transmittance contrast. In addition, the coloration/bleaching switching stability of the ECD produced using optimal Li salt content is investigated. The ECD exhibits distinct colored and bleached states even after 24 h operation in air. Using the described Li-doped ion gel electrolytes, flexible WO<SUB>3</SUB> ECDs were successfully demonstrated with good bending stability and no electrolyte leakage.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Non-volatile, Li-doped ion gel electrolytes are designed for flexible WO<SUB>3</SUB>-based ECDs. </LI> <LI> ECDs exhibit low voltage operation (–0.9 V) and large transmittance contrast (~85%) between colored and bleached states. </LI> <LI> Electrolyte leakage is not observed in flexible ECDs containing Li-doped gel electrolyte when bending deformation is applied. </LI> <LI> Flexible ECDs maintain ~90.3 and ~84.5% of initial optical transmittance and coloration efficiency after 1000 bending tests. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Effect of Li Content on the Surface Film Formed on the Binary Mg–Li Alloys in NaCl Solution

Chuanqiang Li,Dahui Liang,Yejia Lin,Yong Dong,Binqing Shi,Changjian Yan,Zhengrong Zhang 대한금속·재료학회 2024 METALS AND MATERIALS International Vol.30 No.1

The surface film formed on the Mg–Li alloys with different Li content in 0.1 M NaCl solution were investigated via electrochemicaltesting, morphologies observation and chemical composition analysis in this work. The results revealed that thesurface film of Mg–14Li alloy (L14: body centred cubic (BCC)) possessed higher electrical resistivity and remained a highertolerating over-potential (0.1 V vs. open circuit potential) than those of Mg–4Li (L4: hexagonal closed-packed (HCP)) andMg–7.5Li (L7: HCP+BCC), resulting in a better corrosion performance. After 24 h immersion in NaCl solution, the wholesurface film of L14 remained undamaged and displayed weave-like and dense characteristic, while both L4 and L7 present aseverely damaged film. The cross-sectional details illustrated typical two layers of surface film formed on L14 with the outerlayer of ~ 1.5 μm and inner layer of ~ 2.5 μm in thickness, whilst only one layer of film with less than 2.5 μm in thicknesswas observed on L4 and L7. At last, combining analysis of X-ray diffraction, energy dispersive X-ray spectrometry, X-rayphotoelectron spectroscopy and transmission electron microscope confirmed the composition of outer layer of surface filmon the L14 contains much more Mg(OH)2 and Li-containing compounds, and the porous Mg(OH)2 film can be sealed by theLi-containing compounds, which is very different the single Mg(OH)2 film on the traditional magnesium and L4/L7 alloys. As a result, the best protective function of the surface film on the L14 alloy contribute to its high corrosion resistance.

White-Matter Hyperintensities and Lacunar Infarcts Are Associated with an Increased Risk of Alzheimer’s Disease in the Elderly in China

Shuai Ye,Shuyang Dong,Jun Tan,Le Chen,Hai Yang,Yang Chen,Zeyan Peng,Yingchao Huo,Juan Liu,Mingshan Tang,Yafei Li,Huadong Zhou,Yong Tao 대한신경과학회 2019 Journal of Clinical Neurology Vol.15 No.1

Background and Purpose This study investigated the contribution of white-matter hyperintensities (WMH) and lacunar infarcts (LI) to the risk of Alzheimer’s disease (AD) in an elderly cohort in China. Methods Older adults who were initially cognitively normal were examined with MRI at baseline, and followed for 5 years. WMH were classified as mild, moderate, or severe, and LI were classified into a few LI (1 to 3) or many LI (≥4). Cognitive function was assessed using the Mini Mental State Examination and the Activities of Daily Living scale. Results Among the 2,626 subjects, 357 developed AD by the end of the 5-year follow-up period. After adjusting for age and other potential confounders, having only WMH, having only LI, and having both WMH and LI were associated with an increased risk of developing AD compared with having neither WMH nor LI. Moderate and severe WMH were associated with an increased risk of developing AD compared with no WMH. Furthermore, patients with many LI had an increased risk of developing AD compared with no LI. Conclusions Having moderate or severe WMH and many LI were associated with an increased risk of developing AD, with this being particularly striking when both WMH and LI were present.

CNT@Ni@Ni-Co silicate core-shell nanocomposite: a synergistic triple-coaxial catalyst for enhancing catalytic activity and controlling side products for Li-O₂ batteries

Li, Ziwei,Yang, Junghoon,Agyeman, Daniel Adjei,Park, Mihui,Tamakloe, Wilson,Yamauchi, Yusuke,Kang, Yong-Mook The Royal Society of Chemistry 2018 Journal of Materials Chemistry A Vol.6 No.22

<P>A great challenge in the application of carbon-based materials to Li-O2 batteries is to prevent the formation of carbonate-based side products, thereby extending the cycle life of Li-O2 batteries. Herein, for the first time, CNT@Ni@NiCo silicate core-shell nanocomposite is designed and used as a cathode catalyst in Li-O2 batteries. This nanocomposite shows a promising electrochemical performance with a discharge capacity of 10 046 mA h gcat<SUP>−1</SUP> and a low overpotential of 1.44 V at a current density of 200 mA gcat<SUP>−1</SUP>, and it can sustain for more than 50 cycles within the voltage range of 2-4.7 V. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) characterizations prove that the formation of Li2CO3 and other side products are prevented, likely due to the encapsulation of CNTs by NiCo silicates and Ni nanoparticles, which may help decompose the side products. Finally, the synergistic effects, which are contributed by the high electrical conductivity of CNTs, high surface area, the high oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activities of NiCo silicate, and the simple decomposition of side products by Ni nanoparticles enable outstanding performance of the CNT@Ni@NiCo silicate core-shell nanocomposite as a cathode catalyst for Li-O2 batteries.</P>

Critical Descriptor for the Rational Design of Oxide-Based Catalysts in Rechargeable Li–O₂ Batteries: Surface Oxygen Density

Zheng, Yongping,Song, Kyeongse,Jung, Jaepyeong,Li, Chenzhe,Heo, Yoon-Uk,Park, Min-Sik,Cho, Maenghyo,Kang, Yong-Mook,Cho, Kyeongjae American Chemical Society 2015 Chemistry of materials Vol.27 No.9

<P>Li-O-2 batteries provide high-capacity energy storage, but for aprotic Li-O-2 batteries, it is reported that the charge-discharge efficiency is ultimately limited by the crystal growth of insoluble Li2O2 on the porous cathode. Catalysts have been reported to improve the nucleation and morphology of Li2O2, which helps achieve high energy densities. We provide a new insight into the catalytic mechanism of the oxygen reduction reaction (ORR) in aprotic Li-O-2 batteries the oxygen sites on the surface play a more important role than the exposed metal sites via a study based on the density functional theory (DFT) examining alpha-MnO2 surfaces. Lithium ions from electrolytes are found to interact with the surface oxygen sites and form surface lithium sites, facilitating further growth of Li2O2. A larger number of initial growth points with uniform distribution makes Li2O2 well dispersed, forming small particles, which benefit both the ORR and oxygen evolution reactions (OER). This design concept for oxygen sites has been successfully validated by the real Li-O-2 cell experiments with alpha-MnO2 nanowire cathodes.</P>

The effect of S-functionalized and vacancies on V2C MXenes as anode materials for Na-ion and Li-ion batteries

Ya-Meng Li,Yong-Liang Guo,Zhao-Yong Jiao 한국물리학회 2020 Current Applied Physics Vol.20 No.2

The electrochemical properties of V2C and V2CT2 (T = O, S) MXenes with and without vacancy as anode materials for Na-ion and Li-ion batteries, have been studied using first-principles calculation. The present results indicate that the adsorption strength of Li-ion and Na-ion on V2CS2 are less than that of O-functionalized, together with a lower diffusion barrier. Simultaneously, V2CS2 monolayer exhibits lower open-circuit voltage (OCV) values of 0.72 and 0.49 V for Li- and Na-ion, respectively. Interestingly, the presence of atomic vanadium vacancy on V2CS2 monolayer exerts more prominent effects on enhancing adsorption strength than that of carbon vacancy for Li-ion and Na-ion, but with an exception for the diffusion of Li-ion and Na-ion on V2CS2 monolayer. The finding suggests that the V2CS2 monolayer is expected to be a potential candidate as anode material for Li-ion and Na-ion battery due to its lower open-circuit voltages and diffusion barriers.

Promising Carbon Matrix Derived from Willow Catkins for the Synthesis of SnO2/C Composites with Enhanced Electrical Performance for Li-Ion Batteries

Yong Li,Yun Zhao,Canliang Ma,Yongxiang Zhao 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.08

Willow catkins as a kind of seasonal biomass are harmful to human health in terms of causing respiratory ailments and skin anaphylaxis every spring. To explore the high-value utilization of willow catkins, in this study, we attempt to develop a kind of tin-based anode materials with willow catkin derived carbon (WCC) as the matrix. A designed solvent-thermal method involving thiourea as stabilizer and acetone–H2O mixture as solvent has been employed to fabricate SnO2–WCC composites, which exhibit uniform deposition of well-dispersed SnO2 nanoparticles on the surface of WCC. As an anode material for lithium-ion batteries (LIBs), the SnO2–WCC composite delivered a stable discharge capacity of 565mAh g -1 at 100mA g -1 after 70 cycles and a good rate capability of 349mAh g -1 at 1000mA g -1. The high dispersity of SnO2 nanoparticles and high conductivity of WCC are both believed to contribute to the excellent electrochemical performances. These results suggest the potential of willow catkins derived carbonaceous materials applied in anode materials of LIBs and shed light on the creation of advanced carbon materials from other biomass materials towards energy storage applications.

A photosensitizer-conjugated magnetic iron oxide/gold hybrid nanoparticle as an activatable platform for photodynamic cancer therapy

Li,Nurunnabi, Md,Nafiujjaman, Md,Jeong, Yong Yeon,Lee, Yong-kyu,Huh, Kang Moo The Royal Society of Chemistry 2014 Journal of Materials Chemistry B Vol.2 No.19

Impact of electrolyte additives (alkali metal salts) on the capacitive behavior of NiO-based capacitors

Yong Zhang,Lizhen Wang,Aiqin Zhang,Yanhua Song,Xiaofeng Li,Xingbing Wu,Peipei Du,Lv Yan 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.2

To improve the specific capacitance and energy density of electrochemical capacitor, nanostructured NiO was prepared by high temperature solid-state method as electrode material. The crystal structure and morphology of as-parepared NiO samples were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Cyclic voltammetry (CV) measurement was applied to investigate the specific capacitance of the NiO electrode. Furthermore,a novel mixed electrolyte consisting of NaOH, KOH, LiOH and Li_2CO_3 was prepared for the NiO capacitor,and the component and concentration of the four different electrolytes was examined by orthogonal test. The results showed that the NiO sample has cubic structure with nano-size particles, and the optimal composition of the electrolyte was: NaOH 2 mol L^(−1), KOH 3 mol L^(−1), LiOH 0.05 mol L^(−1), and Li_2CO_3 0.05 mol L^−1. At a scan rate of 10 mV s^(−1), the fabricated capacitor exhibits excellent electrochemical capacitive performance, while the specific capacitance and the energy density were 239 F g^(−1) and 85 Wh kg^(−1), which was higher than one-component electrolyte.

Hot Deformation Behavior and Recrystallization Mechanism in an As-Cast CoNi-Based Superalloy

Yong Guan,Yongchang Liu,Zongqing Ma,Huijun Li,Hongyao Yu 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.6

The hot deformation behavior of as-cast CoNi-based superalloy was investigated by means of hot compression tests. Thecorresponding microstructure evolution after hot deformation was examined by optical microscope, as well as the TEMtechnique. The constitutive equation and processing map as a function of deformation temperature and strain rate were developed. Results show that the efficiency peak of the processing map is 0.38 at the temperature of 1130 °C and the strain rate of0.01 s−1. The discontinuous dynamic recrystallization (DDRX) related to the strain-induced grain boundary migration (SIBM)is the dominant recrystallization mechanism during hot working. Meanwhile, the DRX also occurs by forming sub-grainsaround MC carbides and shear band. In addition, the existence of fine γ′ precipitates are found to retard the recrystallization.