Recent Developments in the Effects of Different Dopants on the Structure and Property of Lithium Titanate Material

Xi-Yang Li,Qian-Lin Chen,Min Yang,Ya-Nan Li,Jing-Bo Ma 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.3

The lithium titanium spinel Li4Ti5O12 has attracted more and more attention as anode materials applied in lithium ion batteries. Li4Ti5O12 material has been found to be able to intercalate lithium ions without deformation of the lattice. However, compared with graphite and other anode materials, the low conductivity of Li4Ti5O12 restricts its charging and discharging rate. Doping is deemed to be a businesslike method to enhance ionic and electronic conductivity of Li4Ti5O12. This paper reviews the effects of Li4Ti5O12 with different doping ions on different crystal lattice states. And it has been found by a summary that the doping objective of doping ions at Li4Ti5O12 is also different. Moreover, the applications of ion doping in different fields of Li4Ti5O12 are prospected.

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.

Effect of the Molar Ratio of Li/Ti and Thermal Treatment on the Electrochemical Performance of Li4Ti5O12–rutile TiO2 Nanocomposite as Anode Materials

Zhen Yang,Xi-Ping Li,Jian Mao 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.8

Li4Ti5O12–rutile TiO2 (LTO–RTO) dual-phase nanocomposite anode materials show excellent electrochemical performance. However, the effects of molar ratio of Li/Ti and thermal treatment on electrochemical properties of the LTO–RTO composite have been rarely reported. In this work, LTO–RTO nanocomposites were prepared by sol-hydrothermal method with different Li/ Ti molar ratios in raw materials and following calcinations at 600℃, 650℃ and 700℃ for the different holding time. The results indicate that with the decrease of Li/Ti molar ratio, the discharge capacity of the LTO–RTO nanocomposite increases at first and then decreases, and the optimal Li/Ti molar ratio is 4:4.77, which was obtained with calcination at 600℃ for 10 h. The effects of calcination temperature and holding time were further investigated. The result demonstrates that the thermal treatment has an obvious influence on the electrochemical performance due to the morphology change in the nanocomposite. The LTO–RTO nanocomposite calcinated at 650℃ for 2 h with a Li/Ti molar ratio of 4:4.77 in raw materials delivers excellent rate capability: the initial discharge capacity is 175.9, 176.3, 170.4, 167.5, 163.3 and 155.6 mA h g-1 at the rate of 0.5, 1, 3, 5, 10 and 20℃ (1 C = 175 mA h g-1), respectively.

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>

Microstructure Evolution and Mechanical Properties of AA2099 Al–Li Alloy with Tailored Li‐Containing Precipitates in Uniaxial Compression at Medium Temperature

Li Hu,Mengdi Li,Weijiu Huang,Xusheng Yang,Fei Guo,Haipeng Dong 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.5

Microstructure characteristics and mechanical behavior of AA2099 Al–Li alloy with no pre-existing Li-containing precipitates(AA2099-1 sample), pre-existing δ′ precipitates (AA2099-2 sample), pre-existing T1phase (AA2099-3 sample) andpre-existing T2phase (AA2099-4 sample) are systematically investigated via isothermal uniaxial compression at 250 °C inthe present study. Experimental results demonstrate that at the onset of plastic deformation, dynamic precipitation of smallsizedT1phase occurs rapidly within AA2099-1 sample, while it will be hindered within AA2099-2 sample. The increasingplastic strain benefits to dynamic precipitation of small-sized T1phase in AA2099-2 sample. Consequently, AA2099-1 andAA2099-2 samples possess similar and intermediate mechanical behaviors. In terms of AA2099-3 sample, the existence oflarge-sized T1phase results in the maximum yielding stress. However, some regions within these large-sized T1precipitatesare suspected to be sheared by cross-slip, leading to the destruction of crystallographic structure and the formation of Almatrix intervals. This aspect is responsible for the gradual degradation in true stress-strain curve after peak stress. As forAA2099-4 sample, dynamic precipitation rarely happens during plastic deformation and the interaction between dislocationand the pre-existing T2phase belongs to Orowan looping, resulting in the minimal mechanical response. Besides,AA2099-1 sample possesses the average minimum deviation angle (MDA) of ~ 16.5° between the loading direction and the<110> crystal direction, whereas AA2099-4 sample owns the average MDA of ~ 7.5°. The difference in MDA is mainlyattributed to δ′ phase and T1phase, which will separately accelerate and postpone the rotation of orientation towards the<110> crystal direction.

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>

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>

In-pile tritium release behavior and the post-irradiation experiments of Li4SiO4 fabricated by melting process

Zhao Linjie,Yang Mao,Xiao Chengjian,Gong Yu,Ran Guangming,Chen Xiaojun,Li Jiamao,Yue Lei,Chen Chao,Hou Jingwei,Wang Heyi,Long Xinggui,Peng Shuming 한국원자력학회 2024 Nuclear Engineering and Technology Vol.56 No.1

Understanding the tritium release and retention behavior of candidate tritium breeder materials is crucial for breeder blanket design. Recently, a melt spraying process was developed to prepare Li4SiO4 pebbles, which were subsequently subjected to the in-pile tritium production and extraction platform in China Mianyang Research Reactor (CMRR) to investigate their in-situ tritium release behavior and irradiation performance. The results demonstrate that HT is the main tritium release form, and adding hydrogen to the purge gas reduces tritium retention while increasing the HT percent in the purge gas. Post-irradiation experiments reveal that the irradiated pebbles darken in color and their grains swell, but the mechanical properties remain largely unchanged. It is concluded that the tritium residence time of Li4SiO4 made by melt spraying method at 467 ◦C is approximately 23.34 h. High-density Li4SiO4 pebbles exhibit tritium release at relatively low temperatures (<600 ◦C) that is mainly controlled by bulk diffusion. The diffusion coefficient at 525 ◦C and 550 ◦C is 1.19 × 10 11 cm2/s and 5.34 × 10 11 cm2/s, respectively, with corresponding tritium residence times of 21.3 hours and 4.7 hours.

Research on Li0.3Na0.18K0.52NO3 promoted Mg20Al-CO3 LDH/GO composites for CO2 capture

Ying Yang,Kai Chen,Liang Huang,Min Li,Taiping Zhang,Mi Zhong,Ping Ning,Junya Wang,Shikun Wen 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.102 No.-

It has been reported that the addition of graphene oxide (GO) can increase the dispersion and heterogeneousnucleation of layered double hydroxide (LDH), thus providing more active sites, which is more conduciveto CO2 adsorption. Herein, we reported alkali metal nitrates ((Li0.3Na0.18K0.52)NO3) promoted LDHand GO composites (LDH/GO) as adsorbents for CO2 capture. The influence of mass ratio of LDH to GO, theimpregnation ratio of alkali metal nitrates, the calcination and adsorption temperature, as well as thecycling stability were investigated systematically. The results indicated that the CO2 capture capacityof LDH/GO composite with 30 mol% (Li0.3Na0.18K0.52)NO3 could reach 4.51 mmol g 1, which was 5.86times higher than LDH/GO1 without loading alkali metal nitrates. Moreover, it had outstanding CO2adsorption capacity in the range from 200 C to 320 C. In addition, the cyclic adsorption and desorptiontest manifested that the CO2 uptake of the material can reach 3.07 mmol g 1 after 22 cycles. We believethat this study will give a significant contribution to fabrication of LDH based composites as CO2 adsorbentsin future study.

Aqueous processing of Li1.075Nb0.625Ti0.45O3 green tapes

Shaochun Li,Yongjuan Geng,Qilong Zhang,Hui Yang 한양대학교 세라믹연구소 2011 Journal of Ceramic Processing Research Vol.12 No.2

An aqueous tape casting of Li1.075Nb0.625Ti0.45O3 (LNT) ceramics was developed using PCA-NH4 as dispersant, PVA as binder and EG as plasticizer. Flexible, defect-free and smooth tapes of LNT were successfully produced. The study focused on obtaining the optimum slurry formulations and on the effects of the processing parameters such as the stability, the rheology on the properties on the tape characteristics. Surface properties of LNT powders in the aqueous suspensions are distinctly influenced by PCA-NH4. The zeta potential measurement showed that the isoelectric point (IEP) of LNT powders in the absence of dispersant corresponds to a pH value of 3.7. The zeta potential values (absolute values) increased with the amount of dispersant and up to its maximum near pH 9-10. The rheology measurements of all the slurries investigated showed the desired shear thinning behavior, indicating that the LNT slurry was homogenous and well stabilized. An optimum formulation for the tape was investigated and it was shown that a high solid loading (50 wt%) would lead to a high relative green density (46.7%). Homogenous, smooth, and defect-free green tapes were successfully obtained by an appropriate slurry formula.