The rapid development of flexible electronic devices requires the design of flexible energy-storage devices. Lithium-sulfur(Li-S) batteries are attracting much interest due to their high energy density. Therefore, fle...The rapid development of flexible electronic devices requires the design of flexible energy-storage devices. Lithium-sulfur(Li-S) batteries are attracting much interest due to their high energy density. Therefore, flexible Li-S batteries with high areal capacity are desired. Herein, we fabricated freestanding reduced graphene oxide-sulfur(RGO@S) composite films with a cross-linked structure using a blade coating technique, followed by a subsequent chemical reduction. The porous cross-linked structure endows the composite films with excellent electrochemical performance. The batteries based on RGO@S composite films could exhibit a high discharge capacity of 1381 m Ah/g at 0.1 C and excellent cycle stability. Furthermore, the freestanding composite film possesses excellent conductivity and high mechanical strength. Therefore, they can be used as the cathodes of flexible Li-S batteries. As a proof of concept, soft-packaged Li-S batteries were assembled and remained stable electrochemical performance under different bending states.展开更多
Archimedes number(Ar)is the most important parameter characterizing the fluid-particle two-phase-flow system,which determines the ratio of terminal velocity of single particle to minimum gas velocity for fluidization,...Archimedes number(Ar)is the most important parameter characterizing the fluid-particle two-phase-flow system,which determines the ratio of terminal velocity of single particle to minimum gas velocity for fluidization,and then the possibility of two fluidized systems being similar in fast-fluidization flow-regime.After brief revisit of the scaling laws reported in literatures,the problem/limitations of missing Ar were revealed/identified.Starting from Glicksman's full set scaling laws,new simplified four identities scaling laws for mesoscale similarity were derived.They were confirmed,also,by the unified model for fast fluidization dynamics established by the present author and his co-workers.When the new criteria were applied for scaling-down a high-temperature CFB combustor to a cold-air model,about one tenth semi-spontaneous scaling for bed size was identified and declared.With this benefit,scaling down from a large CFB combustor,of 15 m in diameter,to a 1/20 cold model was demonstrated successfully.Further simplification was also conducted to the beds using same gas and particles for partial/macroscale similarity.With guidance of the unified model,the simplest scaling laws having two similitude identities were obtained.And this is coincident well with Qi and Zhu's empirical correlation,deduced from dozens more literature data sets and their own.展开更多
Pressure fluctuation data measured in a series of fluidized beds with diameters of 0.05, 0.1, 0.29, 0.60 and 1.56 m showed that the maximum amplitude or standard deviation increased with increasing the superficial gas...Pressure fluctuation data measured in a series of fluidized beds with diameters of 0.05, 0.1, 0.29, 0.60 and 1.56 m showed that the maximum amplitude or standard deviation increased with increasing the superficial gas velocity and static bed height for relatively shallow beds and became insensitive to the increase in static bed height in relatively deep beds. The amplitude appeared to be less dependent on the measurement location in the dense bed. Predictions based on bubble passage, bubble eruption at the upper bed surface and bed oscillation all failed to explain all observed trends and underestimated the amplitude of pressure fluctuations, suggesting that the global pressure fluctuations in gas-solids bubbling fluidized beds are the superposition of local pressure variations, bed oscillations and pressure waves generated from the bubble formation in the distributor region, bubble coalescence during their rise and bubble eruption at the upper bed surface.展开更多
基金supported by the National Natural Science Foundation of China(21573116 , 51822205 , 21875121 and 51602218)Ministry of Science and Technology of China(2017YFA0206701)+1 种基金Ministry of Education of China(B12015)the Young Thousand Talents Program
文摘The rapid development of flexible electronic devices requires the design of flexible energy-storage devices. Lithium-sulfur(Li-S) batteries are attracting much interest due to their high energy density. Therefore, flexible Li-S batteries with high areal capacity are desired. Herein, we fabricated freestanding reduced graphene oxide-sulfur(RGO@S) composite films with a cross-linked structure using a blade coating technique, followed by a subsequent chemical reduction. The porous cross-linked structure endows the composite films with excellent electrochemical performance. The batteries based on RGO@S composite films could exhibit a high discharge capacity of 1381 m Ah/g at 0.1 C and excellent cycle stability. Furthermore, the freestanding composite film possesses excellent conductivity and high mechanical strength. Therefore, they can be used as the cathodes of flexible Li-S batteries. As a proof of concept, soft-packaged Li-S batteries were assembled and remained stable electrochemical performance under different bending states.
基金support from the National Natural Science Foundation of China(grant No.52076138),。
文摘Archimedes number(Ar)is the most important parameter characterizing the fluid-particle two-phase-flow system,which determines the ratio of terminal velocity of single particle to minimum gas velocity for fluidization,and then the possibility of two fluidized systems being similar in fast-fluidization flow-regime.After brief revisit of the scaling laws reported in literatures,the problem/limitations of missing Ar were revealed/identified.Starting from Glicksman's full set scaling laws,new simplified four identities scaling laws for mesoscale similarity were derived.They were confirmed,also,by the unified model for fast fluidization dynamics established by the present author and his co-workers.When the new criteria were applied for scaling-down a high-temperature CFB combustor to a cold-air model,about one tenth semi-spontaneous scaling for bed size was identified and declared.With this benefit,scaling down from a large CFB combustor,of 15 m in diameter,to a 1/20 cold model was demonstrated successfully.Further simplification was also conducted to the beds using same gas and particles for partial/macroscale similarity.With guidance of the unified model,the simplest scaling laws having two similitude identities were obtained.And this is coincident well with Qi and Zhu's empirical correlation,deduced from dozens more literature data sets and their own.
文摘Pressure fluctuation data measured in a series of fluidized beds with diameters of 0.05, 0.1, 0.29, 0.60 and 1.56 m showed that the maximum amplitude or standard deviation increased with increasing the superficial gas velocity and static bed height for relatively shallow beds and became insensitive to the increase in static bed height in relatively deep beds. The amplitude appeared to be less dependent on the measurement location in the dense bed. Predictions based on bubble passage, bubble eruption at the upper bed surface and bed oscillation all failed to explain all observed trends and underestimated the amplitude of pressure fluctuations, suggesting that the global pressure fluctuations in gas-solids bubbling fluidized beds are the superposition of local pressure variations, bed oscillations and pressure waves generated from the bubble formation in the distributor region, bubble coalescence during their rise and bubble eruption at the upper bed surface.
