Single-crystal Ni-rich cathodes are a promising candidate for high-energy lithium-ion batteries due to their higher structural and cycling stability than polycrystalline materials.However,the phase evolution and capac...Single-crystal Ni-rich cathodes are a promising candidate for high-energy lithium-ion batteries due to their higher structural and cycling stability than polycrystalline materials.However,the phase evolution and capacity degradation of these single-crystal cathodes during continuous lithation/delithation cycling remains unclear.Understanding the mapping relationship between the macroscopic electrochemical properties and the material physicochemical properties is crucial.Here,we investigate the correlation between the physical-chemical characteristics,phase transition,and capacity decay using capacity differential curve feature identification and in-situ X-ray spectroscopic imaging.We systematically clarify the dominant mechanism of phase evolution in aging cycling.Appropriately high cut-off voltages can mitigate the slow kinetic and electrochemical properties of single-crystal cathodes.We also find that second-order differential capacity discharge characteristic curves can be used to identify the crystal structure disorder of Ni-rich cathodes.These findings constitute a step forward in elucidating the correlation between the electrochemical extrinsic properties and the physicochemical intrinsic properties and provide new perspectives for failure analysis of layered electrode materials.展开更多
LiMnOand LiNiAlyMnO(x= 0.50;y = 0.05-0.50) powders have been synthesized via facile solgel method using Behenic acid as active cheiating agent.The synthesized samples are subjected to physical characterizations such...LiMnOand LiNiAlyMnO(x= 0.50;y = 0.05-0.50) powders have been synthesized via facile solgel method using Behenic acid as active cheiating agent.The synthesized samples are subjected to physical characterizations such as thermo gravimetric analysis(TG/DTA),X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),field-emission scanning electron microscopy(FESEM),transmission electron microscopy(TEM) and electrochemical studies viz.,galvanostatic cycling properties,electrochemical impedance spectroscopy(EIS) and differential capacity curves(dQ/dE).Finger print XRD patterns of LiMnOand LiNiAlMnOfortify the high degree of crystallinity with better phase purity.FESEM images of the undoped pristine spinel illustrate uniform spherical grains surface morphology with an average particle size of 0.5 μm while Ni doped particles depict the spherical grains growth(50nm) with ice-cube surface morphology.TEM images of the spinel LiMnOshows the uniform spherical morphology with particle size of(100 nm) while low level of Al-doping spinel(LiNio.5Alo.05Mn1.45O4) displaying cloudy particles with agglomerated particles of(50nm).The LiMnOsamples calcined at 850℃ deliver the discharge capacity of 130 mAh/g in the first cycle corresponds to 94%coiumbic efficiency with capacity fade of 1.5 mAh/g/cycle over the investigated 10 cycles.Among all four dopant compositions investigated,LiNiAlMnOdelivers the maximum discharge capacity of 126 mAh/g during the first cycle and shows the stable cycling performance with low capacity fade of 1 mAh/g/cycle(capacity retention of 92%) over the investigated 10 cycles.Electrochemical impedance studies of spinel LiMnOand LiNiAlMnOdepict the high and low real polarization of 1562 and 1100 Ω.展开更多
There is a wide range of oesophageal diseases,the most general of which are inflammation,injury and tumours,and treatment methods are constantly being developed and updated.With an increasingly comprehensive understan...There is a wide range of oesophageal diseases,the most general of which are inflammation,injury and tumours,and treatment methods are constantly being developed and updated.With an increasingly comprehensive understanding of stem cells and their characteristics of multilineage differentiation,self-renewal and homing as well as the combination of stem cells with regenerative medicine,tissue engineering and gene therapy,stem cells are playing an important role in the treatment of a variety of diseases.Mesenchymal stem cells have many advantages and are most commonly applied;however,most of these applications have been in experimental studies,with few related clinical trials for comparison.Therefore,the methods,positive significance and limitations of stem cells in the treatment of oesophageal diseases remain incompletely understood.Thus,the purpose of this paper is to review the current literature and summarize the efficacy of stem cells in the treatment of oesophageal diseases,including oesophageal ulceration,acute radiation-induced oesophageal injury,corrosive oesophageal injury,oesophageal stricture formation after endoscopic submucosal dissection and oesophageal reconstruction,as well as gene therapy for oesophageal cancer.展开更多
LiMn<sub>2</sub>O<sub>4</sub> and LiCu<sub>x</sub>Cr<sub>y</sub>Mn<sub>2-x-y</sub>O<sub>4</sub> (x = 0.50;y = 0.05 - 0.50) powders have been synt...LiMn<sub>2</sub>O<sub>4</sub> and LiCu<sub>x</sub>Cr<sub>y</sub>Mn<sub>2-x-y</sub>O<sub>4</sub> (x = 0.50;y = 0.05 - 0.50) powders have been synthesized via sol-gel method for the first time using Myristic acid as chelating agent. The synthesized samples have been taken to physical and electrochemical characterization such as thermo gravimetric analysis (TG/DTA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and electrochemical characterization viz., electrochemical galvanostatic cycling studies, electrochemical impedance spectroscopy (EIS) and differential capacity curves (dQ/dE). XRD patterns of LiMn<sub>2</sub>O<sub>4</sub> and LiCu<sub>x</sub>Cr<sub>y</sub>Mn<sub>2-x-y</sub>O<sub>4</sub> confirm high degree of crystallinity with good phase purity. FESEM image of undoped pristine spinel lucidly depicts cauliflower morphology with good agglomerated particle size of 50 nm while 0.5-Cu doped samples depict the pebbles morphology. TEM images of the spinel LiMn<sub>2</sub>O<sub>4</sub> and LiCu<sub>0.5</sub>Cr<sub>0.05</sub>Mn<sub>1.45</sub>O<sub>4</sub> authenticate that all the synthesized particles via sol-gel method are nano-sized (100 nm) with spherical surface and cloudy particles morphology. The LiMn<sub>2</sub>O<sub>4</sub> samples calcined at 850℃ deliver the high discharge capacity of 130 mA·h/g with cathodic efficiency of 88% corresponds to 94% columbic efficiency in the first cycle. Among all four compositions studied, LiCu<sub>0.5</sub>Cr<sub>0.05</sub>Mn<sub>1.45</sub>O<sub>4</sub> delivers 124 mA·h/g during the first cycle and shows stable performance with a low capacity fade of 1.1 mA·h/g cycle over the investigated 10 cycles.展开更多
文摘Single-crystal Ni-rich cathodes are a promising candidate for high-energy lithium-ion batteries due to their higher structural and cycling stability than polycrystalline materials.However,the phase evolution and capacity degradation of these single-crystal cathodes during continuous lithation/delithation cycling remains unclear.Understanding the mapping relationship between the macroscopic electrochemical properties and the material physicochemical properties is crucial.Here,we investigate the correlation between the physical-chemical characteristics,phase transition,and capacity decay using capacity differential curve feature identification and in-situ X-ray spectroscopic imaging.We systematically clarify the dominant mechanism of phase evolution in aging cycling.Appropriately high cut-off voltages can mitigate the slow kinetic and electrochemical properties of single-crystal cathodes.We also find that second-order differential capacity discharge characteristic curves can be used to identify the crystal structure disorder of Ni-rich cathodes.These findings constitute a step forward in elucidating the correlation between the electrochemical extrinsic properties and the physicochemical intrinsic properties and provide new perspectives for failure analysis of layered electrode materials.
基金support given under the "Brain Pool Program of the Korean Federation of Science and Technology Societies" (KOFST), Republic of South Koreasupported by the Human Resources Development Program (No. 20124010203270) of the Korea Institute of Energy Technology EvaluationPlanning (KETEP) grant funded by the Korea Government Ministry of Trade, Industry and Energy
文摘LiMnOand LiNiAlyMnO(x= 0.50;y = 0.05-0.50) powders have been synthesized via facile solgel method using Behenic acid as active cheiating agent.The synthesized samples are subjected to physical characterizations such as thermo gravimetric analysis(TG/DTA),X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),field-emission scanning electron microscopy(FESEM),transmission electron microscopy(TEM) and electrochemical studies viz.,galvanostatic cycling properties,electrochemical impedance spectroscopy(EIS) and differential capacity curves(dQ/dE).Finger print XRD patterns of LiMnOand LiNiAlMnOfortify the high degree of crystallinity with better phase purity.FESEM images of the undoped pristine spinel illustrate uniform spherical grains surface morphology with an average particle size of 0.5 μm while Ni doped particles depict the spherical grains growth(50nm) with ice-cube surface morphology.TEM images of the spinel LiMnOshows the uniform spherical morphology with particle size of(100 nm) while low level of Al-doping spinel(LiNio.5Alo.05Mn1.45O4) displaying cloudy particles with agglomerated particles of(50nm).The LiMnOsamples calcined at 850℃ deliver the discharge capacity of 130 mAh/g in the first cycle corresponds to 94%coiumbic efficiency with capacity fade of 1.5 mAh/g/cycle over the investigated 10 cycles.Among all four dopant compositions investigated,LiNiAlMnOdelivers the maximum discharge capacity of 126 mAh/g during the first cycle and shows the stable cycling performance with low capacity fade of 1 mAh/g/cycle(capacity retention of 92%) over the investigated 10 cycles.Electrochemical impedance studies of spinel LiMnOand LiNiAlMnOdepict the high and low real polarization of 1562 and 1100 Ω.
基金the Special Distinguished Younger Funding at the Second Affiliated Hospital of Harbin Medical University.
文摘There is a wide range of oesophageal diseases,the most general of which are inflammation,injury and tumours,and treatment methods are constantly being developed and updated.With an increasingly comprehensive understanding of stem cells and their characteristics of multilineage differentiation,self-renewal and homing as well as the combination of stem cells with regenerative medicine,tissue engineering and gene therapy,stem cells are playing an important role in the treatment of a variety of diseases.Mesenchymal stem cells have many advantages and are most commonly applied;however,most of these applications have been in experimental studies,with few related clinical trials for comparison.Therefore,the methods,positive significance and limitations of stem cells in the treatment of oesophageal diseases remain incompletely understood.Thus,the purpose of this paper is to review the current literature and summarize the efficacy of stem cells in the treatment of oesophageal diseases,including oesophageal ulceration,acute radiation-induced oesophageal injury,corrosive oesophageal injury,oesophageal stricture formation after endoscopic submucosal dissection and oesophageal reconstruction,as well as gene therapy for oesophageal cancer.
文摘LiMn<sub>2</sub>O<sub>4</sub> and LiCu<sub>x</sub>Cr<sub>y</sub>Mn<sub>2-x-y</sub>O<sub>4</sub> (x = 0.50;y = 0.05 - 0.50) powders have been synthesized via sol-gel method for the first time using Myristic acid as chelating agent. The synthesized samples have been taken to physical and electrochemical characterization such as thermo gravimetric analysis (TG/DTA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and electrochemical characterization viz., electrochemical galvanostatic cycling studies, electrochemical impedance spectroscopy (EIS) and differential capacity curves (dQ/dE). XRD patterns of LiMn<sub>2</sub>O<sub>4</sub> and LiCu<sub>x</sub>Cr<sub>y</sub>Mn<sub>2-x-y</sub>O<sub>4</sub> confirm high degree of crystallinity with good phase purity. FESEM image of undoped pristine spinel lucidly depicts cauliflower morphology with good agglomerated particle size of 50 nm while 0.5-Cu doped samples depict the pebbles morphology. TEM images of the spinel LiMn<sub>2</sub>O<sub>4</sub> and LiCu<sub>0.5</sub>Cr<sub>0.05</sub>Mn<sub>1.45</sub>O<sub>4</sub> authenticate that all the synthesized particles via sol-gel method are nano-sized (100 nm) with spherical surface and cloudy particles morphology. The LiMn<sub>2</sub>O<sub>4</sub> samples calcined at 850℃ deliver the high discharge capacity of 130 mA·h/g with cathodic efficiency of 88% corresponds to 94% columbic efficiency in the first cycle. Among all four compositions studied, LiCu<sub>0.5</sub>Cr<sub>0.05</sub>Mn<sub>1.45</sub>O<sub>4</sub> delivers 124 mA·h/g during the first cycle and shows stable performance with a low capacity fade of 1.1 mA·h/g cycle over the investigated 10 cycles.