P2-type nickel-manganese-based layered oxides are promising cathode materials for sodium-ion batteries(SIBs),but their application is limited by initial specific capacity and anion redox instability.Herein,a P2/O3 bip...P2-type nickel-manganese-based layered oxides are promising cathode materials for sodium-ion batteries(SIBs),but their application is limited by initial specific capacity and anion redox instability.Herein,a P2/O3 biphasic Na0.67Ni0.33Mn0.6Cu0.05Mg0.07Ti0.01O2(Ni33Mn60)was prepared by adjusting the Ni/Mn ratio with as Na0.67Ni0.23Mn0.65Cu0.05Mg0.07Ti0.01O2(Ni23Mn65)matrix and is reported to exhibit high initial discharge capacity,cyclability and rate capability.The density functional theory(DFT)calculation and experimental data prove the enhancement of the Mn3+/Mn4+redox process to improve the specific discharge capacity and the P2/O3biphasic structure to optimize the anion kinetics.The synthesized oxide Ni33Mn60 delivers a high initial discharge specific capacity of 140.21 mAh g-1,a crucial discharge capacity of 76.07 mAh g-1at 10C,a preferable capacity retention rate of 78.97%after 200 cycles at 5C and cycle stability at high voltages above 4.3V.In situ X-ray diffraction(XRD)and galvanostatic intermittent titration technique(GITT)tests show that Ni33Mn60 has reversible structure evolution and fast Na+diffusion kinetics due to the ion effect and unique P2/O3 biphasic structure,respectively.This work provides a new thought about adjusting matrix ratio for the preparation of P2/O3 biphasic cathode materials for advanced SIBs.展开更多
The problem of water and sulfur poisoning in flue gas atmosphere remains a significant obstacle for low-temperature deNOx catalysts.This study investigated the sulfation mechanism of the CoMn2O4/CeTiOx(CMC...The problem of water and sulfur poisoning in flue gas atmosphere remains a significant obstacle for low-temperature deNOx catalysts.This study investigated the sulfation mechanism of the CoMn2O4/CeTiOx(CMCT)catalyst during the selective catalytic reduction of NOx with NH3 under conditions containing H2O and SO2 at 150℃.Employing a comprehensive suite of time-resolved analysis and characterization techniques,the evolution of sulfate species was systematically categorized into three stages:initial rapid surface sulfate accumulation,the transformation of surface sulfates to bulk metal sulfates,and partial sulfates decomposition after the removal of H2O and SO2.These findings indicate that bulk metal sulfates irreversibly deactivate the catalyst by distorting active component lattices and consuming oxygen vacancies,whereas surface sulfates(including ammonium sulfates and surface-coordinated metal sulfates)cause reversible performance loss through decomposition.Furthermore,the competitive adsorption of H2O and SO2 significantly influences the catalytic efficiency,with H2O suppressing SO2 adsorption while simultaneously enhancing the formation of Brönsted acid sites.This research underscores the critical role of sulfate dynamics on catalyst performance,revealing the enhanced SO2 resistance of the Eley-Rideal mechanism facilitated by the Ce-Ti support relative to the Langmuir-Hinshelwood pathway.Collectively,the study unravels the complex interplay of sulfate dynamics influencing catalyst performance and provides potential approaches to mitigate deactivation in demanding atmospheric conditions.展开更多
基金financially supported by the Natural Science Foundation of Jiangsu Province(No.BK20201049)China Postdoctoral Science Foundation(No,2022M711724)+2 种基金the Swedish Energy Agency(Nos.P2022-00055 and P2023-00603)STandUP for EnergyMAX IV Laboratory for time on Balder beamline(No.20240704)
摘要P2-type nickel-manganese-based layered oxides are promising cathode materials for sodium-ion batteries(SIBs),but their application is limited by initial specific capacity and anion redox instability.Herein,a P2/O3 biphasic Na0.67Ni0.33Mn0.6Cu0.05Mg0.07Ti0.01O2(Ni33Mn60)was prepared by adjusting the Ni/Mn ratio with as Na0.67Ni0.23Mn0.65Cu0.05Mg0.07Ti0.01O2(Ni23Mn65)matrix and is reported to exhibit high initial discharge capacity,cyclability and rate capability.The density functional theory(DFT)calculation and experimental data prove the enhancement of the Mn3+/Mn4+redox process to improve the specific discharge capacity and the P2/O3biphasic structure to optimize the anion kinetics.The synthesized oxide Ni33Mn60 delivers a high initial discharge specific capacity of 140.21 mAh g-1,a crucial discharge capacity of 76.07 mAh g-1at 10C,a preferable capacity retention rate of 78.97%after 200 cycles at 5C and cycle stability at high voltages above 4.3V.In situ X-ray diffraction(XRD)and galvanostatic intermittent titration technique(GITT)tests show that Ni33Mn60 has reversible structure evolution and fast Na+diffusion kinetics due to the ion effect and unique P2/O3 biphasic structure,respectively.This work provides a new thought about adjusting matrix ratio for the preparation of P2/O3 biphasic cathode materials for advanced SIBs.
摘要The problem of water and sulfur poisoning in flue gas atmosphere remains a significant obstacle for low-temperature deNOx catalysts.This study investigated the sulfation mechanism of the CoMn2O4/CeTiOx(CMCT)catalyst during the selective catalytic reduction of NOx with NH3 under conditions containing H2O and SO2 at 150℃.Employing a comprehensive suite of time-resolved analysis and characterization techniques,the evolution of sulfate species was systematically categorized into three stages:initial rapid surface sulfate accumulation,the transformation of surface sulfates to bulk metal sulfates,and partial sulfates decomposition after the removal of H2O and SO2.These findings indicate that bulk metal sulfates irreversibly deactivate the catalyst by distorting active component lattices and consuming oxygen vacancies,whereas surface sulfates(including ammonium sulfates and surface-coordinated metal sulfates)cause reversible performance loss through decomposition.Furthermore,the competitive adsorption of H2O and SO2 significantly influences the catalytic efficiency,with H2O suppressing SO2 adsorption while simultaneously enhancing the formation of Brönsted acid sites.This research underscores the critical role of sulfate dynamics on catalyst performance,revealing the enhanced SO2 resistance of the Eley-Rideal mechanism facilitated by the Ce-Ti support relative to the Langmuir-Hinshelwood pathway.Collectively,the study unravels the complex interplay of sulfate dynamics influencing catalyst performance and provides potential approaches to mitigate deactivation in demanding atmospheric conditions.