以辉钼矿(MoS_(2))、褐铁矿和无烟煤为原料,通过碳热还原法制备了MoS_(x)@ZVI复合材料。研究了MoS_(2)用量、焙烧温度、无烟煤用量和焙烧时间对MoS_(x)@ZVI去除酸性橙G(OG)的影响,并确定了制备MoS_(x)@ZVI的较优制备条件为焙烧温度1000...以辉钼矿(MoS_(2))、褐铁矿和无烟煤为原料,通过碳热还原法制备了MoS_(x)@ZVI复合材料。研究了MoS_(2)用量、焙烧温度、无烟煤用量和焙烧时间对MoS_(x)@ZVI去除酸性橙G(OG)的影响,并确定了制备MoS_(x)@ZVI的较优制备条件为焙烧温度1000℃、MoS_(2)用量6%、焙烧时间60 min和无烟煤用量25%。通过X射线衍射、扫描电子显微镜和能谱仪对较优条件制备的MoS_(x)@ZVI进行表征,结果表明,材料中生成了大量核壳结构的硫化零价铁,内核为Fe-Mo-C合金,外壳可能由硫化钼、FeS、C、钼氧化物和铁氧化物组成。降解实验结果表明,将较优条件制备的MoS_(x)@ZVI碎磨至粒径<0.1 mm,用0.6 g MoS_(x)@ZVI处理400 mL 200 mg/L OG模拟废水,在初始pH=3.0~10.0范围处理150 min,OG的去除率均在90%以上。展开更多
Potassium-ions batteries(PIBs)are attracting increasing attention as up-and-coming youngster in largescale grid-level energy storage benefiting from its low-cost and high energy density.Nevertheless,enough researches ...Potassium-ions batteries(PIBs)are attracting increasing attention as up-and-coming youngster in largescale grid-level energy storage benefiting from its low-cost and high energy density.Nevertheless,enough researches regarding indispensable cathode materials for PIBs are badly absent.Herein,we synthesize K-deficient layered manganese-based oxides(P2-K_(0.21)MnO_(2) and P3-K_(0.23)MnO_(2))and investigate them as cathode of PIBs for the first time.As the newcomer of potassium-containing layered manganese-based oxides(K_(x)MnO_(2))group,P2-K_(0.21)MnO_(2) delivers high discharge capacity of 99.3 mAh g^(-1) and P3-K_(0.23)MnO_(2) exhibits remarkable capacity retention rate of 75.5%.Besides,in-situ XRD and ex-situ XRD measurements reveal the reversible phase transition of P2-K_(0.21)MnO_(2) and P3-K_(0.23)MnO_(2) with the potassium-ions extraction and reinsertion,respectively.This work contributes to a better understanding for the potassium storage in K-deficient layered K_(x)MnO_(2)(x≤0.23),possessing an important basic scientific significance for the exploitation and application of layered K_(x)MnO_(2) in PIBs.展开更多
The understanding of reaction mechanisms of electrode materials is of significant importance for the development of advanced batteries.The LiMn2O4 cathode has a voltage plateau around 2.8 V(vs.Li^+/Li),which can provi...The understanding of reaction mechanisms of electrode materials is of significant importance for the development of advanced batteries.The LiMn2O4 cathode has a voltage plateau around 2.8 V(vs.Li^+/Li),which can provide an additional capacity for Li storage,but it suffers from a severe capacity degradation.In this study,operando X-ray diffraction is carried out to investigate the structural evolutions and degradation mechanisms of LiMn2O4 in different voltage ranges.In the range of 3.0-4.3 V(vs.Li^+/Li),the LiMn2O4 cathode exhibits a low capacity but good cycling stability with cycles up to 100 cycles and the charge/discharge processes are associated with the reversible extraction/insertion of Li^+from/into LixMn2O4(0≤x≤1).In the range of 1.4-4.4 V(vs.Li^+/Li),a capacity higher than 200 mAh/g is achieved,but it rapidly decays during the cycling.The voltage plateau around 2.8 V(vs.Li^+/Li)is related to the transformation of the cubic LiMn2O4 phase to the tetragonal Li2Mn2O4 phase,which leads to the formation of cracks as well as the performance degradation.展开更多
The design of anode materials with a high specific capacity,high cyclic stability,and superior rate performance is required for the practical applications of sodium-ion batteries(SIBs).In this regard,we introduce in t...The design of anode materials with a high specific capacity,high cyclic stability,and superior rate performance is required for the practical applications of sodium-ion batteries(SIBs).In this regard,we introduce in this work a facile,low-cost and scalable method for the synthesis of nanocomposites of amorphous molybdenum sulfide(a-MoS_(x))and hierarchical porous carbon and have systematically investigated their performance for sodium ion storage.In the synthesis,ammonium molybdate tetrahydrate and thioacetamide are used as molybdenum and sulfur sources,respectively,with abundant corn starch as the carbon source and KOH as an activation agent.A simple pyrolysis of their mixtures leads to the formation of nanocomposites with a-MoS_(x)embedded within a hierarchical porous carbon(MoS_(x)@HPC),which are featured with a high surface area of up to 518.4 m^(2) g^(-1)and hierarchical pores ranging from micropores to macropores.It has also been shown that the annealing of MoS_(x)@HPC results in the formation of crystalline MoS_(2)nanosheets anchored in the hierarchical porous carbon matrix(MoS_(2)@HPC).The as-prepared nanocomposite MoS_(x)@HPC1 at an optimum carbon content of 32 wt%delivers a high specific sodium storage capacity of 599 mAh g^(-1)at 0.2 A g^(-1)and a high-rate performa nce with a retained capacity of 289 mAh g^(-1)at 5 A g^(-1).A comparison of the electrochemical performances of MoS_(x)@HPC and MoS_(2)@HPC demonstrates the superior specific capacity,rate performance,and charge transfer kinetics of the former,highlighting the unique advantageous role of amorphous MoS_(x)relative to crystalline MoS_(2).展开更多
The hierarchical structure of the composite cathodes brings in significant chemical complexity related to the interfaces,such as cathode electrolyte interphase.These interfaces account for only a small fraction of the...The hierarchical structure of the composite cathodes brings in significant chemical complexity related to the interfaces,such as cathode electrolyte interphase.These interfaces account for only a small fraction of the volume and mass,they could,however,have profound impacts on the cell-level electrochemistry.As the investigation of these interfaces becomes a crucial topic in the battery research,there is a need to properly study the surface chemistry,particularly to eliminate the biased,incomplete characterization provided by techniques that assume the homogeneous surface chemistry.Herein,we utilize nano-resolution spatially-resolved x-ray spectroscopic tools to probe the heterogeneity of the surface chemistry on LiNi0.8Mn0.1Co0.1O2 layered cathode secondary particles.Informed by the nano-resolution mapping of the Ni valance state,which serves as a measurement of the local surface chemistry,we construct a conceptual model to elucidate the electrochemical consequence of the inhomogeneous local impedance over the particle surface.Going beyond the implication in battery science,our work highlights a balance between the high-resolution probing the local chemistry and the statistical representativeness,which is particularly vital in the study of the highly complex material systems.展开更多
文摘以辉钼矿(MoS_(2))、褐铁矿和无烟煤为原料,通过碳热还原法制备了MoS_(x)@ZVI复合材料。研究了MoS_(2)用量、焙烧温度、无烟煤用量和焙烧时间对MoS_(x)@ZVI去除酸性橙G(OG)的影响,并确定了制备MoS_(x)@ZVI的较优制备条件为焙烧温度1000℃、MoS_(2)用量6%、焙烧时间60 min和无烟煤用量25%。通过X射线衍射、扫描电子显微镜和能谱仪对较优条件制备的MoS_(x)@ZVI进行表征,结果表明,材料中生成了大量核壳结构的硫化零价铁,内核为Fe-Mo-C合金,外壳可能由硫化钼、FeS、C、钼氧化物和铁氧化物组成。降解实验结果表明,将较优条件制备的MoS_(x)@ZVI碎磨至粒径<0.1 mm,用0.6 g MoS_(x)@ZVI处理400 mL 200 mg/L OG模拟废水,在初始pH=3.0~10.0范围处理150 min,OG的去除率均在90%以上。
基金support from the Key Project of Guangdong Province Nature Science Foundation (No. 2017B030311013)the Scientific and Technological Plan of Guangdong Province, Guangzhou and Qingyuan City, China (Nos. 2019B090905005, 2019B090911004, 2017B020227009, 2019DZX008, 2019A004)+2 种基金the financial support from the National Key R&D Program of China (2018YFB1502600)the National Natural Science Foundation of China (No. 51922042 and 51872098)the Sino-Singapore International Joint Research Institute (SSIJRI), Guangzhou 510700, China.
文摘Potassium-ions batteries(PIBs)are attracting increasing attention as up-and-coming youngster in largescale grid-level energy storage benefiting from its low-cost and high energy density.Nevertheless,enough researches regarding indispensable cathode materials for PIBs are badly absent.Herein,we synthesize K-deficient layered manganese-based oxides(P2-K_(0.21)MnO_(2) and P3-K_(0.23)MnO_(2))and investigate them as cathode of PIBs for the first time.As the newcomer of potassium-containing layered manganese-based oxides(K_(x)MnO_(2))group,P2-K_(0.21)MnO_(2) delivers high discharge capacity of 99.3 mAh g^(-1) and P3-K_(0.23)MnO_(2) exhibits remarkable capacity retention rate of 75.5%.Besides,in-situ XRD and ex-situ XRD measurements reveal the reversible phase transition of P2-K_(0.21)MnO_(2) and P3-K_(0.23)MnO_(2) with the potassium-ions extraction and reinsertion,respectively.This work contributes to a better understanding for the potassium storage in K-deficient layered K_(x)MnO_(2)(x≤0.23),possessing an important basic scientific significance for the exploitation and application of layered K_(x)MnO_(2) in PIBs.
基金the financial support by the National Natural Science Foundation of China (51871133, 51671115)support by the Department of Science and Technology of the Shandong Province for the Young Tip-Top Talent Support Project.
文摘The understanding of reaction mechanisms of electrode materials is of significant importance for the development of advanced batteries.The LiMn2O4 cathode has a voltage plateau around 2.8 V(vs.Li^+/Li),which can provide an additional capacity for Li storage,but it suffers from a severe capacity degradation.In this study,operando X-ray diffraction is carried out to investigate the structural evolutions and degradation mechanisms of LiMn2O4 in different voltage ranges.In the range of 3.0-4.3 V(vs.Li^+/Li),the LiMn2O4 cathode exhibits a low capacity but good cycling stability with cycles up to 100 cycles and the charge/discharge processes are associated with the reversible extraction/insertion of Li^+from/into LixMn2O4(0≤x≤1).In the range of 1.4-4.4 V(vs.Li^+/Li),a capacity higher than 200 mAh/g is achieved,but it rapidly decays during the cycling.The voltage plateau around 2.8 V(vs.Li^+/Li)is related to the transformation of the cubic LiMn2O4 phase to the tetragonal Li2Mn2O4 phase,which leads to the formation of cracks as well as the performance degradation.
基金financially supported by grants from the Natural Science and Engineering Research Council of Canada(Grant#RGPIN-2020-05546)。
文摘The design of anode materials with a high specific capacity,high cyclic stability,and superior rate performance is required for the practical applications of sodium-ion batteries(SIBs).In this regard,we introduce in this work a facile,low-cost and scalable method for the synthesis of nanocomposites of amorphous molybdenum sulfide(a-MoS_(x))and hierarchical porous carbon and have systematically investigated their performance for sodium ion storage.In the synthesis,ammonium molybdate tetrahydrate and thioacetamide are used as molybdenum and sulfur sources,respectively,with abundant corn starch as the carbon source and KOH as an activation agent.A simple pyrolysis of their mixtures leads to the formation of nanocomposites with a-MoS_(x)embedded within a hierarchical porous carbon(MoS_(x)@HPC),which are featured with a high surface area of up to 518.4 m^(2) g^(-1)and hierarchical pores ranging from micropores to macropores.It has also been shown that the annealing of MoS_(x)@HPC results in the formation of crystalline MoS_(2)nanosheets anchored in the hierarchical porous carbon matrix(MoS_(2)@HPC).The as-prepared nanocomposite MoS_(x)@HPC1 at an optimum carbon content of 32 wt%delivers a high specific sodium storage capacity of 599 mAh g^(-1)at 0.2 A g^(-1)and a high-rate performa nce with a retained capacity of 289 mAh g^(-1)at 5 A g^(-1).A comparison of the electrochemical performances of MoS_(x)@HPC and MoS_(2)@HPC demonstrates the superior specific capacity,rate performance,and charge transfer kinetics of the former,highlighting the unique advantageous role of amorphous MoS_(x)relative to crystalline MoS_(2).
基金Project supported by U.S.Department of Energy,Office of Science,Office of Basic Energy Sciences under Contract No.DE-AC02-76SF00515National Science Foundation under Grant No.DMR-1832613.
文摘The hierarchical structure of the composite cathodes brings in significant chemical complexity related to the interfaces,such as cathode electrolyte interphase.These interfaces account for only a small fraction of the volume and mass,they could,however,have profound impacts on the cell-level electrochemistry.As the investigation of these interfaces becomes a crucial topic in the battery research,there is a need to properly study the surface chemistry,particularly to eliminate the biased,incomplete characterization provided by techniques that assume the homogeneous surface chemistry.Herein,we utilize nano-resolution spatially-resolved x-ray spectroscopic tools to probe the heterogeneity of the surface chemistry on LiNi0.8Mn0.1Co0.1O2 layered cathode secondary particles.Informed by the nano-resolution mapping of the Ni valance state,which serves as a measurement of the local surface chemistry,we construct a conceptual model to elucidate the electrochemical consequence of the inhomogeneous local impedance over the particle surface.Going beyond the implication in battery science,our work highlights a balance between the high-resolution probing the local chemistry and the statistical representativeness,which is particularly vital in the study of the highly complex material systems.
