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
For rechargeable aqueous zinc-ion batteries(ZIBs),the design of nanocomposites comprised of electrochemically active materials and carbon materials with novel structures has great prom-ise in addressing the issue of e...For rechargeable aqueous zinc-ion batteries(ZIBs),the design of nanocomposites comprised of electrochemically active materials and carbon materials with novel structures has great prom-ise in addressing the issue of electrical conductivity and structural stability in the electrode materials during electrochemical cycling.We report the production of a novel flexible electrode material,by anchoring MnO_(2) nanosheets on a B,N co-doped carbon nanotube ar-ray(BNCNTs)grown on carbon cloth(BNCNTs@MnO_(2)),which was fabricated by in-situ pyrolysis and hydrothermal growth.The generated BNCNTs were strongly bonded to the surface of the car-bon fibers in the carbon cloth which provides both excellent elec-tron transport and ion diffusion,and improves the stability and dur-ability of the cathode.Importantly,the BNCNTs offer more active sites for the hydrothermal growth of MnO_(2),ensuring a uniform dis-tribution.Electrochemical tests show that BNCNTs@MnO_(2) delivers a high specific capacity of 310.7 mAh g^(−1) at 0.1 A g^(−1),along with excellent rate capability and outstanding cycling stability,with a 79.7% capacity retention after 8000 cycles at 3 A g^(−1).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financial support from projects funded by the National Natural Science Foundation of China(52172038,22179017)the National Key Research and Development Program of China(2022YFB4101600,2022YFB4101601)。
文摘For rechargeable aqueous zinc-ion batteries(ZIBs),the design of nanocomposites comprised of electrochemically active materials and carbon materials with novel structures has great prom-ise in addressing the issue of electrical conductivity and structural stability in the electrode materials during electrochemical cycling.We report the production of a novel flexible electrode material,by anchoring MnO_(2) nanosheets on a B,N co-doped carbon nanotube ar-ray(BNCNTs)grown on carbon cloth(BNCNTs@MnO_(2)),which was fabricated by in-situ pyrolysis and hydrothermal growth.The generated BNCNTs were strongly bonded to the surface of the car-bon fibers in the carbon cloth which provides both excellent elec-tron transport and ion diffusion,and improves the stability and dur-ability of the cathode.Importantly,the BNCNTs offer more active sites for the hydrothermal growth of MnO_(2),ensuring a uniform dis-tribution.Electrochemical tests show that BNCNTs@MnO_(2) delivers a high specific capacity of 310.7 mAh g^(−1) at 0.1 A g^(−1),along with excellent rate capability and outstanding cycling stability,with a 79.7% capacity retention after 8000 cycles at 3 A g^(−1).
