Carbon materials have shown remarkable usefulness in facilitating the performance of insulating sulfur cathode for lithium–sulfur batteries owing to their excellent conductivity and porous structure. However,the anxi...Carbon materials have shown remarkable usefulness in facilitating the performance of insulating sulfur cathode for lithium–sulfur batteries owing to their excellent conductivity and porous structure. However,the anxiety is the poor affinity toward polar polysulfides due to the intrinsic nonpolar surface of carbon.Herein, we report a direct pyrolysis of the mixture urea and boric acid to synthesize B/N–codoped hierarchically porous carbon nanosheets(B–N–CSs) as efficient sulfur host for lithium–sulfur battery. The graphene–like B–N–CSs provides high specific surface area and porous structure with abundant micropores(1.1 nm) and low–range mesopores(2.3 nm), thereby constraining the sulfur active materials within the pores. More importantly, the codoped B/N elements can further enhance the polysulfide confinement through strong Li–N and B–S interaction based on the Lewis acid–base theory. These structural superiorities significantly suppress the shuttle effect by both physical confinement and chemical interaction, and promote the redox kinetics of polysulfide conversion. When evaluated as the cathode host, the S/B–N–CSs composite displays the excellent performance with a high reversible capacity up to 772 m A h g–1 at 0.5 C and a low fading rate of ^0.09% per cycle averaged upon 500 cycles. In particular, remarkable stability with a high capacity retention of 87.1% can be realized when augmenting the sulfur loading in the cathode up to 4.6 mg cm^(-2).展开更多
A bifunctional heterogeneous catalyst containing two mutually incompatible acidic and basic sites, which exhibits cooperative catalytic behavior in the aldol condensation of acetone and various aldehydes, was synthesi...A bifunctional heterogeneous catalyst containing two mutually incompatible acidic and basic sites, which exhibits cooperative catalytic behavior in the aldol condensation of acetone and various aldehydes, was synthesized by postgrafting of 1,5,7- triazabicyclo[4.4.0] dec-5-ene （TBD, a sterically hindered organic base） onto AI-MCM-41 molecular sieve. 2009 Xiao Bing Lu. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.展开更多
frustrated Lewis pair(FLP)是一个最近出现的新名词,指分子内或混合体系中同时具有路易斯酸和路易斯碱两个位点,由于空间位阻较大而使得这两个位点不能结合形成路易斯酸碱加合物,从而具有独特的反应活性。建议译为"受阻路易斯酸碱...frustrated Lewis pair(FLP)是一个最近出现的新名词,指分子内或混合体系中同时具有路易斯酸和路易斯碱两个位点,由于空间位阻较大而使得这两个位点不能结合形成路易斯酸碱加合物,从而具有独特的反应活性。建议译为"受阻路易斯酸碱对"。展开更多
基金financial support of the National Natural Science Foundation of China (Grant No. 21263016, 21363015, 51662029, 21863006)the Youth Science Foundation of Jiangxi Province (Grant No. 20192BAB216001)the Key Laboratory of Jiangxi Province for Environment and Energy Catalysis (20181BCD40004)。
文摘Carbon materials have shown remarkable usefulness in facilitating the performance of insulating sulfur cathode for lithium–sulfur batteries owing to their excellent conductivity and porous structure. However,the anxiety is the poor affinity toward polar polysulfides due to the intrinsic nonpolar surface of carbon.Herein, we report a direct pyrolysis of the mixture urea and boric acid to synthesize B/N–codoped hierarchically porous carbon nanosheets(B–N–CSs) as efficient sulfur host for lithium–sulfur battery. The graphene–like B–N–CSs provides high specific surface area and porous structure with abundant micropores(1.1 nm) and low–range mesopores(2.3 nm), thereby constraining the sulfur active materials within the pores. More importantly, the codoped B/N elements can further enhance the polysulfide confinement through strong Li–N and B–S interaction based on the Lewis acid–base theory. These structural superiorities significantly suppress the shuttle effect by both physical confinement and chemical interaction, and promote the redox kinetics of polysulfide conversion. When evaluated as the cathode host, the S/B–N–CSs composite displays the excellent performance with a high reversible capacity up to 772 m A h g–1 at 0.5 C and a low fading rate of ^0.09% per cycle averaged upon 500 cycles. In particular, remarkable stability with a high capacity retention of 87.1% can be realized when augmenting the sulfur loading in the cathode up to 4.6 mg cm^(-2).
基金support by a Foundation for the Author of National Excellent Doctoral Dissertation of China(No.FANEDD,200759)the Outstanding Young Scientist Foundation of NSFC(No.20625414)
文摘A bifunctional heterogeneous catalyst containing two mutually incompatible acidic and basic sites, which exhibits cooperative catalytic behavior in the aldol condensation of acetone and various aldehydes, was synthesized by postgrafting of 1,5,7- triazabicyclo[4.4.0] dec-5-ene （TBD, a sterically hindered organic base） onto AI-MCM-41 molecular sieve. 2009 Xiao Bing Lu. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
