A novel gel-like process has been developed for synthesizing LiaNi0.8Co0.2O2 powders, using citric acid as a chelating agent. This process improves the homogeneity of constituent cation and enhances their reactivity ...A novel gel-like process has been developed for synthesizing LiaNi0.8Co0.2O2 powders, using citric acid as a chelating agent. This process improves the homogeneity of constituent cation and enhances their reactivity in the obtained precursor. The results of electrochemical test demonstrated that these materials exhibited excellent electrochemical properties. Its initial capacity reached 181.6 mAh/g and reversible efficiency at the first cycle is about 88.6%.展开更多
The study on the criteria used to distinguish floc sedimentation and gel-like network sedimentation of cohesive fine-grained sediment in a turbulent flow has rarely been carried out. In this preliminary study, we deri...The study on the criteria used to distinguish floc sedimentation and gel-like network sedimentation of cohesive fine-grained sediment in a turbulent flow has rarely been carried out. In this preliminary study, we derive three criteria to distinguish these two different sedimentation phases by considering the comparison of the time that a characteristic floc takes to settle through mean distance between characteristic flocs and the time that it takes to move through the same distance under the influence of a turbulent flow. These criteria incorporate physical and chemical factors that have been verified to have some influences on the sediment flocculation in some published literatures, and a simple analysis result is found to be consistent with our qualitative understandings of flocculation phenomenon of cohesive fine-grained sediment.展开更多
It is known that large amounts of residual lignin are generated in the pulp and paper industry.A new alternative for Kraft lignin valorization,which consists of first a chemical modification using a diisocyanate and t...It is known that large amounts of residual lignin are generated in the pulp and paper industry.A new alternative for Kraft lignin valorization,which consists of first a chemical modification using a diisocyanate and then the efficient dispersion in castor oil to achieve stable gel-like systems,is proposed in this work.Rheological properties and microstructure of these materials were determined by means of small amplitude oscillatory shear tests and viscous flow measurements and atomic force microscopy observations,respectively.Moreover,both standardized penetration tests and tribological assays,usually performed in the lubricant industry,were carried out to evaluate the performance characteristics as lubricating greases.Linear viscoelasticity functions are affected by the lignin/diisocyanate ratio and thickener concentration.The thermorheological response evidenced a softening temperature of around 105°C.The microstructure of these gel-like dispersions is composed of interconnected thin fibers,homogeneously distributed in castor oil.Moreover,the NCO-functionalized lignin gel-like dispersions studied show lower friction coefficients than traditional lubricating greases.展开更多
Owing to the potential ability of metal nanoparticles to enhance the performance of energy storage devices,their catalytic performance has been studied by many researchers.However,a limited number of suitable characte...Owing to the potential ability of metal nanoparticles to enhance the performance of energy storage devices,their catalytic performance has been studied by many researchers.However,a limited number of suitable characterization techniques does not allow fully elucidating their catalytic mechanism.Herein,high‐accuracy operando magnetometry is employed to investigate the catalytic properties of a cobalt oxide electrode for lithium‐ion batteries fabricated by magnetron sputtering.Using this technique,the magnetic responses generated by the Co‐catalyzed reversible formation and decomposition of a polymer/gel‐like film are successfully detected.A series of CoO/Co films are prepared by magnetron sputtering in different environments at various sputtering times to study the influence of Co content and film thickness on their catalytic properties.It is clearly demonstrated that increasing the Co content enhances the magnetic signal associated with the catalysis process.Furthermore,decreasing the electrode thickness increases the area affected by the catalytic reactions,which in turn enhances the corresponding magnetic responses.The obtained results experimentally confirm the catalytic activity of Co metal nanoparticles and provide a scientific guidance for designing advanced energy storage devices.This work also shows that operando magnetometry is a versatile technique for studying the catalytic effects of transition metals.展开更多
文摘A novel gel-like process has been developed for synthesizing LiaNi0.8Co0.2O2 powders, using citric acid as a chelating agent. This process improves the homogeneity of constituent cation and enhances their reactivity in the obtained precursor. The results of electrochemical test demonstrated that these materials exhibited excellent electrochemical properties. Its initial capacity reached 181.6 mAh/g and reversible efficiency at the first cycle is about 88.6%.
文摘The study on the criteria used to distinguish floc sedimentation and gel-like network sedimentation of cohesive fine-grained sediment in a turbulent flow has rarely been carried out. In this preliminary study, we derive three criteria to distinguish these two different sedimentation phases by considering the comparison of the time that a characteristic floc takes to settle through mean distance between characteristic flocs and the time that it takes to move through the same distance under the influence of a turbulent flow. These criteria incorporate physical and chemical factors that have been verified to have some influences on the sediment flocculation in some published literatures, and a simple analysis result is found to be consistent with our qualitative understandings of flocculation phenomenon of cohesive fine-grained sediment.
文摘It is known that large amounts of residual lignin are generated in the pulp and paper industry.A new alternative for Kraft lignin valorization,which consists of first a chemical modification using a diisocyanate and then the efficient dispersion in castor oil to achieve stable gel-like systems,is proposed in this work.Rheological properties and microstructure of these materials were determined by means of small amplitude oscillatory shear tests and viscous flow measurements and atomic force microscopy observations,respectively.Moreover,both standardized penetration tests and tribological assays,usually performed in the lubricant industry,were carried out to evaluate the performance characteristics as lubricating greases.Linear viscoelasticity functions are affected by the lignin/diisocyanate ratio and thickener concentration.The thermorheological response evidenced a softening temperature of around 105°C.The microstructure of these gel-like dispersions is composed of interconnected thin fibers,homogeneously distributed in castor oil.Moreover,the NCO-functionalized lignin gel-like dispersions studied show lower friction coefficients than traditional lubricating greases.
文摘Owing to the potential ability of metal nanoparticles to enhance the performance of energy storage devices,their catalytic performance has been studied by many researchers.However,a limited number of suitable characterization techniques does not allow fully elucidating their catalytic mechanism.Herein,high‐accuracy operando magnetometry is employed to investigate the catalytic properties of a cobalt oxide electrode for lithium‐ion batteries fabricated by magnetron sputtering.Using this technique,the magnetic responses generated by the Co‐catalyzed reversible formation and decomposition of a polymer/gel‐like film are successfully detected.A series of CoO/Co films are prepared by magnetron sputtering in different environments at various sputtering times to study the influence of Co content and film thickness on their catalytic properties.It is clearly demonstrated that increasing the Co content enhances the magnetic signal associated with the catalysis process.Furthermore,decreasing the electrode thickness increases the area affected by the catalytic reactions,which in turn enhances the corresponding magnetic responses.The obtained results experimentally confirm the catalytic activity of Co metal nanoparticles and provide a scientific guidance for designing advanced energy storage devices.This work also shows that operando magnetometry is a versatile technique for studying the catalytic effects of transition metals.
