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| 2. |
- Li, Qi, 1990, et al.
(författare)
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A Study on Storage Characteristics of Pristine Li-rich Layered Oxide Li1.20Mn0.54Co0.13Ni0.13O2: Effect of Storage Temperature and Duration
- 2015
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Ingår i: Electrochimica Acta. - 0013-4686. ; 154, s. 249-158
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Tidskriftsartikel (refereegranskat)abstract
- Lithium-ion batteries always suffer from serious capability decay, especially when stored at high temperature and/or for prolonged duration. In this work, electrochemical performance for Li-rich layered oxides Li1.20Mn0.54Co0.13Ni0.13O2 was systematically investigated as a function of temperature and duration. Plenty of techniques like SEM, EDS, EIS, ARC, Raman, XRD, and XPS were utilized to characterize the structures, valence states, compositions, particle sizes, and morphologies of the layered oxides with varying temperature and duration. The results reveal that room temperature storage may alter surface kinetics, but hardly influence the electrochemical performance. While in the case of high temperature storage in pristine state, cycling stability is highly dependent on the storage duration. The degradation mechanism at high temperature storage with prolonged duration is demonstrated to be the accumulation of surface species like LiF/LixPFyOz initiated by the strong reactions between LiPF6 electrolyte and electrode. The results reported here may shed light on predicting electrochemical performance by surface analysis and also provide vital hints on enhancing the high-temperature storage stability of Li-rich layered oxides.
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| 3. |
- Li, Qi, 1990, et al.
(författare)
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Balancing stability and specific energy in Li-rich cathodes for lithium ion batteries: a case study of a novel Li–Mn–Ni–Co oxide
- 2015
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Ingår i: Journal of Materials Chemistry. - 1364-5501 .- 0959-9428. ; 3:19, s. 10592-10602
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Tidskriftsartikel (refereegranskat)abstract
- Lithium batteries for UPS, portable electronics and electrical vehicles rely on high-energy cathodes. Li-rich manganese-rich oxide (xLi2MnO3·(1 − x)LiMO2, M = transition metals) is one of the few materials that might meet such a requirement, but it suffers from poor energy retention due to serious voltage and/or capacity fade, which challenges its applications. Here we show that this challenge can be addressed by optimizing the interactions between the components Li2MnO3 and LiMO2 in the Li-rich oxide (i.e. stabilizing the layered structure through Li2MnO3 and controlling Li2MnO3 activation through LiMO2). To realize this synergistic effect, a novel Li2MnO3-stabilized Li1.080Mn0.503Ni0.387Co0.030O2 was designed and prepared using a hierarchical carbonate precursor obtained by a solvo/hydro-thermal method. This layered oxide is demonstrated to have a high working voltage of 3.9 V and large specific energy of 805 W h kg−1 at 29 °C as well as impressive energy retention of 92% over 100 cycles. Even when exposed to 55 °C, energy retention is still as high as 85% at 200 mA g−1. The attractive performance is most likely the consequence of the balanced stability and specific energy in the present material, which is promisingly applicable to other Li-rich oxide systems. This work sheds light on harnessing Li2MnO3 activation and furthermore efficient battery design simply through compositional tuning and temperature regulation.
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| 4. |
- Lv, Wanzhi, et al.
(författare)
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Lipoxin A4 attenuation of endothelial inflammation response mimicking pancreatitis-induced lung injury
- 2013
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Ingår i: Experimental Biology and Medicine. - : SAGE Publications. - 1535-3702 .- 1535-3699. ; 238:12, s. 1388-1395
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Tidskriftsartikel (refereegranskat)abstract
- Lipoxins (LXs) and their analogues are known to display potent anti-inflammatory actions. Previously, we reported that lipoxin A4 (LXA4) possessed powerful anti-inflammatory properties in acute pancreatitis in rats and that it may ameliorate the concomitant acute lung injury by reducing cytokine generation and inhibiting neutrophil activation. Considering that the vascular endothelium plays an important role during adherence, migration and activation of leukocytes, the present study was designed to investigate the effects of LXA4 on the inflammatory response induced by tumor necrosis factor a (TNF-alpha) in human pulmonary microvascular endothelial cells (HPMECs) and explore the potential mechanisms involved in these processes. We found that LXA4 markedly down-regulated the expression of monocyte chemotactic protein-1 (MCP-1), E-selectin, and interleukin-6 (IL-6) mRNA, as well as intercellular adhesion molecule-1 (ICAM-1) in TNF-alpha-exposed HPMECs. Moreover, LXA4 inhibited the phosphorylation and nuclear translocation of nuclear factor-kappa B/p65 (NF-kappa B/p65) and phosphorylation of p38 mitogen-activated protein kinase (p38 MAPK) in HPMECs following TNF-alpha stimulation. Heme oxygenase-1 (HO-1), a cytoprotective enzyme, was up-regulated by LXA4 in both non- and TNF-alpha-stimulated HPMECs. In conclusion, the protective effects of LXA4 to ALI may be executed through inhibition inflammation pathways of NF-kappa B and p38 MAPK and up-regulation of cytoprotective HO-1.
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| 5. |
- Xie, Dongjiu, et al.
(författare)
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Improved Cycling Stability of Cobalt-free Li-rich Oxides with a Stable Interface by Dual Doping
- 2016
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Ingår i: Electrochimica Acta. - 0013-4686. ; 196, s. 505-516
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Tidskriftsartikel (refereegranskat)abstract
- Li-rich cobalt-free oxides, popularly used as a cathode with high capacity in lithium ion battery, always suffer from poor cycling stability between 2.0 and 4.8 V vs Li+/Li, especially when cycled at high temperatures (>50 °C). To overcome this issue, Na+ and Al3+ dual-doped NaxLi1.2-xMn0.6-xAlxNi0.2O2 Li-rich cathode is prepared in this study. It is shown that the side reactions between cathode and electrolyte during cycling are suppressed. The improved cycling performance is observed for all of the doped samples, among which the sample with x = 0.03 exhibits the highest capacity retention of 86.1% after 200 cycles between 2.0 and 4.8 V at 2C (1C = 200 mA g−1) and shows a remarkable cycling stability, even at a high temperature of 55 °C (a capacity retention of 92.2% after 100 cycles). Moreover, the average voltage of the sample with x = 0.03 after 100 cycles at 0.5C remains at 3.11 V with a retention ratio of 86.6%. This work provides a new strategy to develop Li-rich cobalt-free cathodes with excellent cycling stability for lithium ion batteries at high temperatures.
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