Capsule shells have been successfully fabricated from water-soluble chitosan(WSC)with the addition of alginate and Gembili starch.WSC was synthesized from crab shell chitosan by depolymerization reaction.The capsule s...Capsule shells have been successfully fabricated from water-soluble chitosan(WSC)with the addition of alginate and Gembili starch.WSC was synthesized from crab shell chitosan by depolymerization reaction.The capsule shells were made with the composition of WSC:Alginate,2:1,3:1 and 4:1(w/w)with and without the addition of Gembili starch.Gembili starch was added with a ratio of Alginate:Starch,1:1(w/w).The capsule shell properties were evaluated according to Indonesian Pharmacopoeia standard.The solubility test showed that the capsule shells were comply with the standard.The highest degrees of swelling in water and HCl 0.1 N solution were 491.93%and 410.51%,respectively.The highest degradation percentages in water and HCl 0.1 N solution were 57.80%and 21.44%,respectively.The observation of physical appearance indicated that the capsule shell with WSC:Alginate:Starch in ratio of 3:1:1 has appearance close to commercial capsule shell.展开更多
Reasonable construction of sulfur host with high conductivity,large sulfur storage gap,strong chemical adsorption,and fast oxidation–reduction kinetics of polysulfide is very significant for its practical use in lith...Reasonable construction of sulfur host with high conductivity,large sulfur storage gap,strong chemical adsorption,and fast oxidation–reduction kinetics of polysulfide is very significant for its practical use in lithium-sulfur batteries(LSBs).In this paper,the surface modification of MIL-88A(Fe)is carried out by Dawson-type polyoxometalate(POM),and a hollow capsule shell material with P_(2)W_(18),Fe_(3)O_(4),and C components is synthesized by the subsequent carbonization process.When applied as the sulfur host,the hollow capsule shell material can efficiently improve the conductivity of sulfur electrode and restrain the volumetric change of active sulfur while charging and discharging.On this foundation,electrochemical analysis and density functional theory(DFT)calculation show that the P_(2)W_(18)on the outer layer of the capsule shell have effective electrocatalytic activity and potent chemical bond on the lithium polysulfides(LiPSs),which is helpful to block the shuttle effect.Therefore,the as-assembled LSBs display the outstanding specific capacity and prominent cycle stability.Specifically,it delivers an excellent reversible capacity of 1063 mAh/g after 100 cycles of charge–discharge at a rate of 0.5 C,accounting for a preservation by 96%in comparison to that of the initial cycle.Moreover,even after 2000 cycles at 1 C,the reversible specific capacity of 585 mAh/g can still be maintained with an average decay rate of only 0.021%.展开更多
文摘Capsule shells have been successfully fabricated from water-soluble chitosan(WSC)with the addition of alginate and Gembili starch.WSC was synthesized from crab shell chitosan by depolymerization reaction.The capsule shells were made with the composition of WSC:Alginate,2:1,3:1 and 4:1(w/w)with and without the addition of Gembili starch.Gembili starch was added with a ratio of Alginate:Starch,1:1(w/w).The capsule shell properties were evaluated according to Indonesian Pharmacopoeia standard.The solubility test showed that the capsule shells were comply with the standard.The highest degrees of swelling in water and HCl 0.1 N solution were 491.93%and 410.51%,respectively.The highest degradation percentages in water and HCl 0.1 N solution were 57.80%and 21.44%,respectively.The observation of physical appearance indicated that the capsule shell with WSC:Alginate:Starch in ratio of 3:1:1 has appearance close to commercial capsule shell.
基金the financial support from the National Natural Science Foundation of China (No. 21971085)the Natural Science Foundation of Shandong Province (No. ZR2019MB004, China)
文摘Reasonable construction of sulfur host with high conductivity,large sulfur storage gap,strong chemical adsorption,and fast oxidation–reduction kinetics of polysulfide is very significant for its practical use in lithium-sulfur batteries(LSBs).In this paper,the surface modification of MIL-88A(Fe)is carried out by Dawson-type polyoxometalate(POM),and a hollow capsule shell material with P_(2)W_(18),Fe_(3)O_(4),and C components is synthesized by the subsequent carbonization process.When applied as the sulfur host,the hollow capsule shell material can efficiently improve the conductivity of sulfur electrode and restrain the volumetric change of active sulfur while charging and discharging.On this foundation,electrochemical analysis and density functional theory(DFT)calculation show that the P_(2)W_(18)on the outer layer of the capsule shell have effective electrocatalytic activity and potent chemical bond on the lithium polysulfides(LiPSs),which is helpful to block the shuttle effect.Therefore,the as-assembled LSBs display the outstanding specific capacity and prominent cycle stability.Specifically,it delivers an excellent reversible capacity of 1063 mAh/g after 100 cycles of charge–discharge at a rate of 0.5 C,accounting for a preservation by 96%in comparison to that of the initial cycle.Moreover,even after 2000 cycles at 1 C,the reversible specific capacity of 585 mAh/g can still be maintained with an average decay rate of only 0.021%.
