Effect of Zn2+ and F- Co-Modification on the Structure and Electrochemical Performance of Li4Ti5O12 Anode Material

Aijia Wei,Wen Li,Lihui Zhang,Xiaohui Li,Xue Bai,Zhenfa Liu 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2017 NANO Vol.12 No.5

Zn2+ and F- ions are successfully used to modify pure Li4Ti5O12 via a co-precipitation method followed by calcination at 400℃ for 5 h in an Ar atmosphere in order to further investigate the reaction mechanism of the fluoride modification process. Zn2+ and F- co-modified Li4Ti5O12 samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and electrochemical measurements. After the modification process, no ZnF2 coating layer is formed on the surface of Li4Ti5O12, instead, F- ions react with Li4Ti5O12 to generate a new phase, composed of a small amount of anatase TiO2, rutile TiO2, LiF, and Zn2+ ions are suspected to form a ZnO coating layer on Li4Ti5O12 particles. The electrolyte reduction decomposition is suppressed in Zn2+ and F- co-modified Li4Ti5O12 due to the ZnO coating layer. 1 wt.% Zn2+ and F- co-modified Li4Ti5O12 exhibits the best rate capability, which leads to a charge capacity of 236.7, 227.8, 222.1, 202.7, 188.9 and 150.7 mAh g -1 at 0.2C, 0.5C, 1C, 3C, 5C and 10C, respectively, between 0 V and 3 V. Furthermore, 1 wt.% Zn2+ and F- comodified Li4Ti5O12 exhibits 96.0% charge capacity retention at 3C rate after 200 cycles, which is significantly higher than that of pure Li4Ti5O12 (78.4%).

In-situ PECVD-enabled graphene-V₂O₃ hybrid host for lithium–sulfur batteries

Song, Yingze,Zhao, Wen,Wei, Nan,Zhang, Li,Ding, Feng,Liu, Zhongfan,Sun, Jingyu Elsevier 2018 Nano energy Vol.53 No.-

<P><B>Abstract</B></P> <P>Lithium–sulfur (Li–S) batteries have been regarded as promising candidates for current energy-storage technologies due to their remarkable advantages in energy density and theoretical capacity. However, one of the daunting challenges remained for advanced Li–S systems thus far deals with the synchronous suppression of polysulfide (LiPS) shuttle and acceleration of redox kinetics. Herein, a cooperative interface bridging adsorptive V<SUB>2</SUB>O<SUB>3</SUB> and conductive graphene is constructed <I>in-situ</I> by virtue of direct plasma-enhanced chemical vapor deposition (PECVD), resulting in the design of a novel V<SUB>2</SUB>O<SUB>3</SUB>-graphene hybrid host to synergize the LiPS entrapment and conversion. The redox kinetics and electrochemical performances of thus-derived cathodes were accordingly enhanced owing to the smooth adsorption-diffusion-conversion of LiPSs even at a sulfur mass loading of 3.7 mg cm<SUP>–2</SUP>. Such interfacial engineering offers us a valuable opportunity to gain insight into the comprehensive regulation of LiPS anchoring ability, electrical conductivity and ion diffusive capability in hybrid hosts on suppressing the LiPS shuttle and propelling the redox kinetics. Our devised PECVD route might pave a new route toward the facial and economic design of hetero-phased multi-functional hosts for high-performance Li–S systems.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Graphene-V<SUB>2</SUB>O<SUB>3</SUB> hybrid host was designed <I>in-situ</I> based on PECVD route. </LI> <LI> Thus-derived cathode showed a low capacity decay of merely 0.046% per cycle at 2 C after 1000 cycles. </LI> <LI> Cathodes with a relatively high sulfur mass loading (3.7 mg cm<SUP>–2</SUP>) were fabricated. </LI> <LI> The smooth adsorption-diffusion-conversion of polysulfides was thoroughly probed <I>via</I> experimental studies and DFT simulations. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

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.

Improved lithium storage performance of CeO2-decorated SrLi2Ti6O14 material as an anode for Li-ion battery

Ying Li,Hong-Yan Liu,Ling-Na Shi,Yan-Rong Zhu,Ting-Feng Yi 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.101 No.-

In this work, the CeO2-decorated SrLi2Ti6O14 anode was successfully prepared through a solid-state process. The space-charge effect induced by the internal adsorption of ions on the CeO2 surface can easilyresult in a formation of an excellent conductive interfacial layer between CeO2 and SrLi2Ti6O14. The goodelectrical contact between CeO2 and SrLi2Ti6O14 offers more active sites for the electrolyte storage andredox reaction, and promotes the intercalation/deintercalation of lithium ions, and thus improves therate performance and cycle stability. Due to its unique structure and composition, the CeO2-decoratedSrLi2Ti6O14 composites exhibit high reversible capacities, good cycle performance and outstanding rateperformance. Especially, the CeO2 (5 wt%)-decorated SrLi2Ti6O14 anode shows the most excellent electrochemicalperformance, which delivers a large charge capacity of 121.3 mAh g 1 and a capacity retentionof 94.48% after 100 cycles at 0.5 A g 1. However, the corresponding charge capacity and capacity retentionof pristine SrLi2Ti6O14 are 100.5 mAh g 1 and 86.77%, respectively. The CeO2(5 wt%)-decoratedSrLi2Ti6O14 with enhanced rate capacity, cycle stability and structural stability is a potential electrodematerial candidate for Li-ion battery.

The Effects of ESG Performance on Export Intensity of Korean Firms

Yongshang Liu(Yongshang Liu),Sung-Hwan Kim(Sung-Hwan Kim),Xinyu Li(Xinyu Li) 한국무역연구원 2022 무역연구 Vol.18 No.6

Purpose – This study examines whether the export intensity of firms listed in the Korean market is affected by environmental, social and governance (ESG) ratings. We test whether the environmental, social, and governance (ESG) performance in ratings of Korean firms can improve their export intensity in the global markets. Design/Methodology/Approach – In this study, we introduce ESG ratings, export intensity and other control variables in the models using unbalanced panel data of 1,974 firms listed on the KOSPI and KOSDAQ Exchange between 2012 and 2021 from a merged dataset of the KIS-VALUE and TS-2000 databases. We apply the fixed effects model (FEMs) after applying the Hausman and Lagrangian multiplier tests. Also, we apply instrument variable regressions (IV regressions) to control endogeneity in ESG ratings affected by other factors introduced. Findings – First, higher ESG ratings of the firms have a significantly negative effect on export intensity, which is inconsistent with the results of the previous research (Herding and Poncet, 2014). Second, ESG ratings of chaebol firms do not significantly reduce export intensity. The results might be due to the less severe constraints in chaebol firms by ESG costs. (Chaney, 2008; Shi Xin-Zheng and Xu Zhu-Feng, 2018). Third, each ESG rating, E, S, and G individually, shows a significantly negative effect on export intensity for only non-chaebol firms, while such an effect for chaebol firms is not statistically significant. Fourth, using the instrument variable regression, we have verified the result that ESG performance has a negative effect on firms' export intensity. Research Implications – This study is the first to examine the relationship between the ESG ratings of Korean firms and their export intensity, whose result is different from that of a prior study regarding Chinese firms (Wu Qing-Lan, Chen Gui-Fu, Han Jing and Wu Li-Yan, 2022). The negative effects of ESG ratings in Korea on exports for non-chaebol firms suggest that higher ESG ratings of Korean firms are not favorably accepted by their counterparts in the global markets while their efforts to get or enhance higher ratings incurring more expenses might hurt their competence in the global markets. Such negative effects of ESG ratings are not clearly observed for chaebol affiliated firms.

Synchronous immobilization and conversion of polysulfides on a VO₂-VN binary host targeting high sulfur load Li-S batteries

Song, Yingze,Zhao, Wen,Kong, Long,Zhang, Li,Zhu, Xingyu,Shao, Yuanlong,Ding, Feng,Zhang, Qiang,Sun, Jingyu,Liu, Zhongfan The Royal Society of Chemistry 2018 ENERGY AND ENVIRONMENTAL SCIENCE Vol.11 No.9

<P>Lithium-sulfur (Li-S) batteries are deemed as one of the most promising next-generation energy storage systems. However, their practical application is hindered by existing drawbacks such as poor cycling life and low Coulombic efficiency due to the shuttle effect of lithium polysulfides (LiPSs). We herein present an <I>in situ</I> constructed VO2-VN binary host which combines the merits of ultrafast anchoring (VO2) with electronic conducting (VN) to accomplish smooth immobilization-diffusion-conversion of LiPSs. Such synchronous advantages have effectively alleviated the polysulfide shuttling, promoted the redox kinetics, and hence improved the electrochemical performance of Li-S batteries. As a result, the sulfur cathode based on the VO2-VN/graphene host exhibited an impressive rate capability with ∼1105 and 935 mA h g<SUP>−1</SUP> at 1C and 2C, respectively, and maintained long-term cyclability with a low capacity decay of 0.06% per cycle within 800 cycles at 2C. More remarkably, favorable cyclic stability can be attained with a high sulfur loading (13.2 mg cm<SUP>−2</SUP>). Even at an elevated temperature (50 °C), the cathodes still delivered superior rate capacity. Our work emphasizes the importance of immobilization-diffusion-conversion of LiPSs toward the rational design of high-load and long-life Li-S batteries.</P>

Vanadium Dioxide-Graphene Composite with Ultrafast Anchoring Behavior of Polysulfides for Lithium-Sulfur Batteries

Song, Yingze,Zhao, Wen,Zhu, Xingyu,Zhang, Li,Li, Qiucheng,Ding, Feng,Liu, Zhongfan,Sun, Jingyu American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.18

<P>The lithium-sulfur (Li-S) battery has been deemed as one of the most promising energy-storage systems owing to its high energy density, low cost, and environmental benignancy. However, the capacity decay and kinetic sluggishness stemming from polysulfide shuttle effects have by far posed a great challenge to practical performance. We herein demonstrate the employment of low-cost, wet-chemistry-derived VO<SUB>2</SUB> nanobelts as the effective host additives for the graphene-based sulfur cathode. The VO<SUB>2</SUB> nanobelts displayed an ultrafast anchoring behavior of polysulfides, managing to completely decolor the polysulfide solution in 50 s. Such a fast and strong anchoring ability of VO<SUB>2</SUB> was further investigated and verified by experimental and theoretical investigations. Benefitting from the synergistic effect exerted by VO<SUB>2</SUB> in terms of chemical confinement and catalytic conversion of polysulfides, the Li-S batteries incorporating VO<SUB>2</SUB> and graphene manifested excellent cycling and rate performances. Notably, the batteries delivered an initial discharge capacity of 1405 mAh g<SUP>-1</SUP> when cycling at 0.2 C, showed an advanced rate performance of ∼830 mAh g<SUP>-1</SUP> at 2 C, and maintained a stable cycling performance at high current densities of 1, 2, and 5 C over 200 cycles, paving a practical route toward cost-effective and environmentally benign cathode design for high-energy Li-S batteries.</P> [FIG OMISSION]</BR>

Facile and controllable synthesis of nitrogen self-doped chitosan-derived carbon for high-performance Li-ion batteries

Xia Wentao,Cheng Miao,Hu Jing,Liu Qianqian,Wei Tao,Wang Ruirui,Li Wanfei,Liu Bo 한국탄소학회 2024 Carbon Letters Vol.34 No.1

N-doping content and configurations have a significant effect on the electrochemical performance of carbon anodes. Herein, we proposed a simple method to synthesize highly N self-doped chitosan-derived carbon with controllable N-doping types by introducing 2ZnCO3·3Zn(OH)2 into the precursor. The as-synthesized NC-CS/2ZnCO3·3Zn(OH)2 electrode exhibited more than twice the reversible capacity (518 mAh g−1 after 100 cycles at 200 mA g−1) compared to the NC-CS electrode, superior rate performance and outstanding cycling stability. The remarkable improvement should be mainly attributed to the increase of N-doping content (particularly the pyrrolic-N content), which provided more active sites and favored Li+ diffusion kinetics. This study develops a cost-effective and facile synthesis route to fabricate high-performance N self-doped carbon with tunable doping sites for rechargeable battery applications.

Carbon-coated SnO₂@C with hierarchically porous structures and graphite layers inside for a high-performance lithium-ion battery

Li, Yao,Zhu, Shenmin,Liu, Qinglei,Gu, Jiajun,Guo, Zaiping,Chen, Zhixin,Feng, Chuanliang,Zhang, Di,Moon, Won-Jin The Royal Society of Chemistry 2012 Journal of materials chemistry Vol.22 No.6

<P>A high-performance anode material was prepared from a hierarchically structured activated carbon which contains <I>in situ</I> graphene and nano-graphite. The activated carbon was immersed in a solution of SnCl<SUB>2</SUB>·2H<SUB>2</SUB>O and subjected to ultrasound. As a result, nanoparticles of SnO<SUB>2</SUB> were uniformly deposited on the surface of the activated carbon. The composite material was then coated with a thin layer of carbon by soaking it in a sucrose solution, followed by carbonization of the adsorbed sucrose at 500 °C. The resulting composite showed an outstanding high-rate cycling performance that can deliver an initial discharge capacity of 1417 mAh g<SUP>−1</SUP> and maintain a discharge capacity of more than 400 mAh g<SUP>−1</SUP> after 100 cycles at a high current density of 1000 mA g<SUP>−1</SUP>. This outstanding electrochemical performance is likely to be related to a unique combination of the excellent electrical conductivity of the activated carbon with graphite layers formed inside, its hierarchical pore structure which enhances lithium-ion transportation, and the carbon coating which alleviates the effects of volume changes, shortens the distance for Li<SUP>+</SUP> diffusion, facilitates the transmission of electrons, and keeps the structure stable.</P> <P>Graphic Abstract</P><P>Carbon-coated SnO<SUB>2</SUB>@C nanocomposite with hierarchically porous structures and graphite layers inside was prepared by ultrasound and hydrothermal treatment, which showed an outstanding high-rate cycling performance for lithium-ion battery. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c1jm14290a'> </P>

Effect of CeO2 addition on crystallization and thermophysical properties of Li2O-ZnO-SiO2 glass-ceramics

Ruixue Li,Qian Zhang,Xingliang Peng,Weizhen Liu 한양대학교 세라믹연구소 2020 Journal of Ceramic Processing Research Vol.21 No.1

The effect of CeO2 addition on crystallization and thermo-physical properties of lithium zinc silicate (LZS) glasses containingLi2O-ZnO-SiO2-Al2O3-Na2O-P2O5 was investigated. The changes of CeO2 contents (2-8 wt.%) had an obvious influence on thetransition temperatures (Tg) and crystallization temperatures (Tc) of LZS glass-ceramics, and they increased with CeO2 contentincreasing. According to XRD analysis, CeO2 promoted the formation of cristobalite and β-spodumene crystals, and β-spodumene increased obviously. As the CeO2 content increasing, the microstructure and microhardness (being 6.88 Gpa at 880oC) of glass-ceramics had great changes. The average thermal expansion coefficient (20 - 450 oC) showed first increasing thendecreasing, having a wide range. The maximum of thermal expansion coefficient was obtained when the glass-ceramicscontained 4 wt.% CeO2, being 175×10−7 K−1 (at 700 oC) and 178×10−7 K−1 (at 880 oC) respectively. Excellent thermo-physicalproperties indicate the glass has greater potential application, such as being used as sealing glass.