An innovative spongy nanographene （SG） shell for a silicon substrate was prepared by low-temperature chemical vapor deposition on a hierarchical nickel nanotemplate. The SG-functionalized silicon （Si@SG） composite...An innovative spongy nanographene （SG） shell for a silicon substrate was prepared by low-temperature chemical vapor deposition on a hierarchical nickel nanotemplate. The SG-functionalized silicon （Si@SG） composite shows outstanding properties, which may be helpful to overcome issues affecting current silicon anodes used in lithium ion batteries such as poor conductivity, large volume expansion and high mass transfer resistance. The hierarchical nanographene shell exhibits elastic, sponge-like features that allow it to self-adaptively change its volume to accommodate the volume expansion of silicon. In addition, the porous, spongy framework containing randomly stacked graphene nanosheets presents low diffusion barriers and provides sufficiently free and short-haul channel segments to allow the fast migration of Li and electrolyte ions. The unique properties of the present silicon anode result in excellent electrochemical performances in terms of long-term cycling stability （95% capacity retention after 510 cycles）, rate performance, and cycling behavior for high mass loadings at different current densities.展开更多
A new analysis method based on serial sectioning and three-dimensional（3 D）reconstruction was developed to characterize the mineral microstructure of iron ore sinter.Through the 3 Dreconstruction of two types of iro...A new analysis method based on serial sectioning and three-dimensional（3 D）reconstruction was developed to characterize the mineral microstructure of iron ore sinter.Through the 3 Dreconstruction of two types of iron ore sinters,the morphology and distribution of minerals in three-dimensional space were analyzed,and the volume fraction of minerals in a 3 Dimage was calculated based on their pixel points.In addition,the microhardness of minerals was measured with a Vickers hardness tester.Notably,different mineral compositions and distributions are obtained in these two sinters.The calcium ferrite in Sinter 1 is dendritic with many interconnected pores,and these grains are crisscrossed and interwoven;the calcium ferrite in Sinter 2 is strip shaped and interweaves with magnetite,silicate and columnar pores.The calculated mineral contents based on a two-dimensional region are clearly different among various layers.Quantitative analysis shows that Sinter 1 contains a greater amount of calcium ferrite and hematite,whereas Sinter 2 contains more magnetite and silicate.The microhardness of minerals from highest to lowest is hematite,calcium ferrite,magnetite and silicate.Thus,Sinter 1 has a greater tumbler strength than Sinter 2.展开更多
文摘An innovative spongy nanographene （SG） shell for a silicon substrate was prepared by low-temperature chemical vapor deposition on a hierarchical nickel nanotemplate. The SG-functionalized silicon （Si@SG） composite shows outstanding properties, which may be helpful to overcome issues affecting current silicon anodes used in lithium ion batteries such as poor conductivity, large volume expansion and high mass transfer resistance. The hierarchical nanographene shell exhibits elastic, sponge-like features that allow it to self-adaptively change its volume to accommodate the volume expansion of silicon. In addition, the porous, spongy framework containing randomly stacked graphene nanosheets presents low diffusion barriers and provides sufficiently free and short-haul channel segments to allow the fast migration of Li and electrolyte ions. The unique properties of the present silicon anode result in excellent electrochemical performances in terms of long-term cycling stability （95% capacity retention after 510 cycles）, rate performance, and cycling behavior for high mass loadings at different current densities.
基金financial support from the National Natural Science Foundation of China(51474164)the China Postdoctoral Science Foundation(2016M602378)
文摘A new analysis method based on serial sectioning and three-dimensional（3 D）reconstruction was developed to characterize the mineral microstructure of iron ore sinter.Through the 3 Dreconstruction of two types of iron ore sinters,the morphology and distribution of minerals in three-dimensional space were analyzed,and the volume fraction of minerals in a 3 Dimage was calculated based on their pixel points.In addition,the microhardness of minerals was measured with a Vickers hardness tester.Notably,different mineral compositions and distributions are obtained in these two sinters.The calcium ferrite in Sinter 1 is dendritic with many interconnected pores,and these grains are crisscrossed and interwoven;the calcium ferrite in Sinter 2 is strip shaped and interweaves with magnetite,silicate and columnar pores.The calculated mineral contents based on a two-dimensional region are clearly different among various layers.Quantitative analysis shows that Sinter 1 contains a greater amount of calcium ferrite and hematite,whereas Sinter 2 contains more magnetite and silicate.The microhardness of minerals from highest to lowest is hematite,calcium ferrite,magnetite and silicate.Thus,Sinter 1 has a greater tumbler strength than Sinter 2.
