Bromine-based flow batteries(Br-FBs)are well suitable for stationary energy storage owing to their high energy density and low cost.However,their power density and lifespan are limited by relatively low reaction kinet...Bromine-based flow batteries(Br-FBs)are well suitable for stationary energy storage owing to their high energy density and low cost.However,their power density and lifespan are limited by relatively low reaction kinetics of Br_(2)/Br-couple and serious self-discharge caused by bromine migration.Herein,lamella-like porous carbon nitride nanosheets(PCNS)with adsorption and spatial confinement effects are used to modify cathodes for Br-FBs.The large specific surface area and plentiful N-containing groups enable PCNS with excellent adsorption capacity,which captures bromine species into the pores on PCNS layers.The captured bromine species is subsequently confined in PCNS interlayers due to the strong interaction between bromine species and N-containing groups,thus effectively depressing bromine diffusion/migration.Moreover,the strong bromine adsorption capacity significantly improves the electrochemical activity of PCNS.Consequently,a zinc-bromine flow battery(ZBFB)employing PCNS-modified cathode achieves a high current density of 180 m A cm^(-2),with an ultra-high coulombic efficiency of 99.22%.It also exhibits better self-discharge performance and a long cycle life of 500 cycles.Furthermore,a complexing agent-free ZBFB is successfully realized based on the superior bromineentrapping/retaining capacity of the PCNS-modified cathode.Consequently,this work provides a promising strategy toward electrode modifications for high-performance and long-lifespan Br-FBs.展开更多
Hydrogels are among the most promising biologic materials in recent technology with numerous desired applications,including serving as biosensors,drug delivery vehicles,and tissue-engineered products for cell matrices...Hydrogels are among the most promising biologic materials in recent technology with numerous desired applications,including serving as biosensors,drug delivery vehicles,and tissue-engineered products for cell matrices.However,they often dehydrate,and become stiff and brittle in air,causing loss of flexibility and functions.Several layered structures have been proven to increase the strength,toughness,and even flexibility of these materials,which might provide a new clue for the sustenance of the flexibility of drying gels.Herein,we report a novel solvent-dehydrated hydrogel engineering approach,aimed to change the inner structure and keep the flexibility of a dehydrated hydrogel in the air via solvent-induced dehydration,for example,acetonedehydrated polyacrylic acid hydrogel.This flexible dry gel could be folded,twisted,and stretched without any damage due to the assumed lamella-like structures,contrary to dry gels without these microstructures or those with porous structures,which retain brittle consistency.The flexible dry gel also exhibited excellent self-healing capability with the assistance of solvents.Fascinatingly,this flexible gel film displayed strain-visualizing paper writing/erasing performance properties,with water acting as invisible ink.Thus,this fabricated flexible hydrogel film might function as confidential information storage material.Our current approach is versatile,hence applicable to other hydrogels,and provides insight into the engineering of other functional gels for extended future applications.展开更多
The rod-like assembly from BAB block copolymer with hydrophilic middle block A in aqueous solution was described. The copolymer used is polystyrene (PS)39-b-poly(4-vinylpyridine)(P4VP)98-b-PS39 (the subscripts are the...The rod-like assembly from BAB block copolymer with hydrophilic middle block A in aqueous solution was described. The copolymer used is polystyrene (PS)39-b-poly(4-vinylpyridine)(P4VP)98-b-PS39 (the subscripts are the average polymerization degree of corresponding blocks) triblock copolymer with Mw/Mn = 1.15. The aggregates were characterized by transmission electron microscopy and atomic force microscopy. The dependence of rod-like aggregate formation on solvents, pH, and polymer concentrations was investigated. The rod-like aggregates were formed when using dioxane as initial solvent, while spherical micelles were formed using DMF. Elevating pH values from 4 to 5 to 7 and decreasing initial copolymer concentrations from 1.5 wt% to 1.0 wt% to 0.5 wt% were favorable for the formation of well-defined rod-like aggregates. In addition, the bicontinuous rods and lamellae were observed when preparing colloid solutions in appropriate conditions.展开更多
基金supported by CAS Strategic Leading Science&Technology Program(A)(XDA21070100)CAS Engineering Laboratory for Electrochemical Energy Storage(KFJ-PTXM-027)+1 种基金DICP funding(DICP I202026 DICP I201928)Liaoning Natural Science Foundation(2021-MS-024)。
文摘Bromine-based flow batteries(Br-FBs)are well suitable for stationary energy storage owing to their high energy density and low cost.However,their power density and lifespan are limited by relatively low reaction kinetics of Br_(2)/Br-couple and serious self-discharge caused by bromine migration.Herein,lamella-like porous carbon nitride nanosheets(PCNS)with adsorption and spatial confinement effects are used to modify cathodes for Br-FBs.The large specific surface area and plentiful N-containing groups enable PCNS with excellent adsorption capacity,which captures bromine species into the pores on PCNS layers.The captured bromine species is subsequently confined in PCNS interlayers due to the strong interaction between bromine species and N-containing groups,thus effectively depressing bromine diffusion/migration.Moreover,the strong bromine adsorption capacity significantly improves the electrochemical activity of PCNS.Consequently,a zinc-bromine flow battery(ZBFB)employing PCNS-modified cathode achieves a high current density of 180 m A cm^(-2),with an ultra-high coulombic efficiency of 99.22%.It also exhibits better self-discharge performance and a long cycle life of 500 cycles.Furthermore,a complexing agent-free ZBFB is successfully realized based on the superior bromineentrapping/retaining capacity of the PCNS-modified cathode.Consequently,this work provides a promising strategy toward electrode modifications for high-performance and long-lifespan Br-FBs.
基金This study is supported financially by the National Natural Science Foundation of China(21425314,21501184,21434009,21421061,and 21504098)the Top-Notch Young Talents Program of China,Beijing Municipal Science&Technology Commission(Z161100000116037)Youth Innovation Promotion Association,CAS(2017036).F.Z.designed and performed all the experiments.S.W.codesigned the experiments.Z.G.,M.Y.,S.L.,Y.S.,J.F.,and J.M.conducted or supported the experiments for characterization.J.Z.conducted the thermodynamic analysis of the hydrogel in poor solvent.F.Z.,L.J.,P.W.,and S.W.analyzed the data.F.Z.and S.W.wrote the article.
文摘Hydrogels are among the most promising biologic materials in recent technology with numerous desired applications,including serving as biosensors,drug delivery vehicles,and tissue-engineered products for cell matrices.However,they often dehydrate,and become stiff and brittle in air,causing loss of flexibility and functions.Several layered structures have been proven to increase the strength,toughness,and even flexibility of these materials,which might provide a new clue for the sustenance of the flexibility of drying gels.Herein,we report a novel solvent-dehydrated hydrogel engineering approach,aimed to change the inner structure and keep the flexibility of a dehydrated hydrogel in the air via solvent-induced dehydration,for example,acetonedehydrated polyacrylic acid hydrogel.This flexible dry gel could be folded,twisted,and stretched without any damage due to the assumed lamella-like structures,contrary to dry gels without these microstructures or those with porous structures,which retain brittle consistency.The flexible dry gel also exhibited excellent self-healing capability with the assistance of solvents.Fascinatingly,this flexible gel film displayed strain-visualizing paper writing/erasing performance properties,with water acting as invisible ink.Thus,this fabricated flexible hydrogel film might function as confidential information storage material.Our current approach is versatile,hence applicable to other hydrogels,and provides insight into the engineering of other functional gels for extended future applications.
文摘The rod-like assembly from BAB block copolymer with hydrophilic middle block A in aqueous solution was described. The copolymer used is polystyrene (PS)39-b-poly(4-vinylpyridine)(P4VP)98-b-PS39 (the subscripts are the average polymerization degree of corresponding blocks) triblock copolymer with Mw/Mn = 1.15. The aggregates were characterized by transmission electron microscopy and atomic force microscopy. The dependence of rod-like aggregate formation on solvents, pH, and polymer concentrations was investigated. The rod-like aggregates were formed when using dioxane as initial solvent, while spherical micelles were formed using DMF. Elevating pH values from 4 to 5 to 7 and decreasing initial copolymer concentrations from 1.5 wt% to 1.0 wt% to 0.5 wt% were favorable for the formation of well-defined rod-like aggregates. In addition, the bicontinuous rods and lamellae were observed when preparing colloid solutions in appropriate conditions.
