The development of efficient photocatalysts is of paramount importance for the photocatalytic degradation of organic compounds.An effective approach is to construct heterojunctions with tight interface structures in o...The development of efficient photocatalysts is of paramount importance for the photocatalytic degradation of organic compounds.An effective approach is to construct heterojunctions with tight interface structures in order to enhance interfacial charge transfer and achieve high photocatalytic activity.A magnetically recyclable photocatalytic composite,comprising Ag_(3)PO_(4)/CoFe_(1.95)Dy_(0.05)O_(4)(AP/CFDO)S-scheme heterojunction,was synthesized using a simple hydrothermal method.The composition,microstructure and photoelectrochemical properties of the nanocomposites were comprehensively characterized by various advanced characterization methods.The photocatalytic activity of the AP/CFDO nanocomposites was investigated by subjecting methylene blue(MB)to degradation.The results demonstrated that AP/CFDO exhibited high degradation efficiency in the catalytic degradation of MB,with a degradation efficiency of 99.8%achieved within 30 min under visible light irradiation.Furthermore,after five repeated experiments,the degradation efficiency of MB under visible light irradiation remained at 90%.Furthermore,the degradation process followed the first-order kinetic reaction model,with a rate constant of 0.14042 min^(-1),which was 2.47 and 10.77 times that of Ag_(3)PO_(4)(AP,0.05678 min^(-1))and CFDO(0.01304 min^(-1)).This phenomenon can be attributed to the S-scheme heterojunction constructed between AP and CFDO,which enables the effective spatial separation and transfer of photogenerated carriers.Finally,the reaction mechanism of photocatalytic degradation of MB was studied by adding different free radical scavengers.The results of capture experiments showed that superoxide radicals and hydroxyl radicals were the main active substances in the process of photocatalytic degradation.展开更多
Nickel-rich cathode materials have received widespread attention due to their high energy density.However,the poor rate capability and inferior cycle stability seriously hinder their large-scale application.The tradit...Nickel-rich cathode materials have received widespread attention due to their high energy density.However,the poor rate capability and inferior cycle stability seriously hinder their large-scale application.The traditional co-precipitation method for preparing them has a long process and easily arises agglomeration leading to inhomogeneous element distribution.Here,a novel precursor containing Li element was prepared by ultrafast spray pyrolysis(SP)in 3–5 s.Then the precursor was used to synthesize pristine LiNi_(0.9)Co_(0.05)Mn_(0.05)O_(2)(NCM90)and 1%Mg modified LiNi_(0.9)Co_(0.05)Mn_(0.05)O_(2)(NCM90-Mg1).This method gets rid of mixing Li/Mg source and the precursor prepared by common co-precipitation,thus could achieve homogeneous lithiation and Mg2+doping.The cell parameter c is expanded,and the cation disorder is reduced after Mg2+doping.Furthermore,the harmful H2-H3 phase transition in NCM90-Mg1 is also well suppressed.As a result,the obtained NCM90-Mg1 shows better electrochemical performance than NCM90.Within 2.8–4.3 V(25℃),the specific discharge capacity of NCM90-Mg1 at 5 C is as high as 169.1m Ah/g,and an outstanding capacity retention of 70.0%(10.0%higher than NCM90)can be obtained after400 cycles at 0.5 C.At 45℃,a capacity retention of 81.9%after 100 cycles at 1 C is recorded for NCM90-Mg1.Moreover,the NCM90-Mg1 also exhibits superior cycle stability when cycled at high cut-off voltage(4.5 V,25℃),possessing the capacity retention of 79.2%after 200 cycles at 1 C.Therefore,SP can be proposed as a powerful method for the preparation of multi-element materials for next-generation high energy density LIBs.展开更多
The ultra-high nickel cathode material has important application prospect in power lithium-ion batteries.However,the poor structural stability and serious surface/interfacial side reactions during long cycles severely...The ultra-high nickel cathode material has important application prospect in power lithium-ion batteries.However,the poor structural stability and serious surface/interfacial side reactions during long cycles severely hinder the material's practical application.In this paper,Cs^(+)doping and polymethyl methacrylate(PMMA)coating are used to synergistically modify the NCM955 material.The results show that the corresponding discharge specific capacity of NCMCs-2@P-2 material reaches 152.02 m Ah/g at 1 C(1 C=200 m A/g)and 125.66 m Ah/g at 5 C after 300 cycles,and the capacity retention is 78.11%and72.21%,respectively.In addition,it still maintains 156.36 m Ah/g discharge specific capacity at 10 C,and these rate and cycle properties exceed those reported on ultra-high nickel cathode material.Moreover,NCMCs-2@P-2 material has higher migration energy barrier of Ni^(2+)and lower migration energy barrier of Li+than that of NCM955 material.Therefore,NCMCs-2@P-2 material has excellent electrochemical properties,which has been proved by a series of structural characterization,theoretical calculation and performance test.The synergistic enhancement of Cs^(+)doping and PMMA coating accelerates lithium ion diffusion kinetics,stabilizes crystal structure,and inhabits surface/interface side reaction.展开更多
利用超细旋转盘式砂磨机细化颗粒固相烧结法,合成锂离子电池正极材料Li Ni0.80Co0.15Al0.05O2。原料经过砂磨后,混合均匀,粒径达到纳米级。根据塔曼定理,混合均匀的微小粒径可以在相同的烧结温度下,提高烧结的强度。SEM、XRD分别表征NC...利用超细旋转盘式砂磨机细化颗粒固相烧结法,合成锂离子电池正极材料Li Ni0.80Co0.15Al0.05O2。原料经过砂磨后,混合均匀,粒径达到纳米级。根据塔曼定理,混合均匀的微小粒径可以在相同的烧结温度下,提高烧结的强度。SEM、XRD分别表征NCA材料的颗粒形貌和晶形结构。结果显示,通过细化颗粒烧结后的样品具有良好的形貌和层状结构。CV法测试样品的氧化还原性能,电池测试系统测试样品的电化学性能。测试结果显示,经过细化颗粒,在720℃合成的NCA材料具有良好的层状结构,018/110峰分裂明显。样品的电化学性能优良,0.2C下,首次放电容量达到182 m Ah?g?1,30次循环后容量保持率99.9%。1C下,首次放电容量153 m Ah?g?1,100次循环后容量保持率92.6%。展开更多
基金Supported by 2023 Anhui Modern Coal Processing Technology Research Institute Open Fund Project(MTY202305)。
文摘The development of efficient photocatalysts is of paramount importance for the photocatalytic degradation of organic compounds.An effective approach is to construct heterojunctions with tight interface structures in order to enhance interfacial charge transfer and achieve high photocatalytic activity.A magnetically recyclable photocatalytic composite,comprising Ag_(3)PO_(4)/CoFe_(1.95)Dy_(0.05)O_(4)(AP/CFDO)S-scheme heterojunction,was synthesized using a simple hydrothermal method.The composition,microstructure and photoelectrochemical properties of the nanocomposites were comprehensively characterized by various advanced characterization methods.The photocatalytic activity of the AP/CFDO nanocomposites was investigated by subjecting methylene blue(MB)to degradation.The results demonstrated that AP/CFDO exhibited high degradation efficiency in the catalytic degradation of MB,with a degradation efficiency of 99.8%achieved within 30 min under visible light irradiation.Furthermore,after five repeated experiments,the degradation efficiency of MB under visible light irradiation remained at 90%.Furthermore,the degradation process followed the first-order kinetic reaction model,with a rate constant of 0.14042 min^(-1),which was 2.47 and 10.77 times that of Ag_(3)PO_(4)(AP,0.05678 min^(-1))and CFDO(0.01304 min^(-1)).This phenomenon can be attributed to the S-scheme heterojunction constructed between AP and CFDO,which enables the effective spatial separation and transfer of photogenerated carriers.Finally,the reaction mechanism of photocatalytic degradation of MB was studied by adding different free radical scavengers.The results of capture experiments showed that superoxide radicals and hydroxyl radicals were the main active substances in the process of photocatalytic degradation.
基金supported by the National Natural Science Foundation of China(No.52122407)the Science and Technology Innovation Program of Hunan Province(No.2022RC3048)。
文摘Nickel-rich cathode materials have received widespread attention due to their high energy density.However,the poor rate capability and inferior cycle stability seriously hinder their large-scale application.The traditional co-precipitation method for preparing them has a long process and easily arises agglomeration leading to inhomogeneous element distribution.Here,a novel precursor containing Li element was prepared by ultrafast spray pyrolysis(SP)in 3–5 s.Then the precursor was used to synthesize pristine LiNi_(0.9)Co_(0.05)Mn_(0.05)O_(2)(NCM90)and 1%Mg modified LiNi_(0.9)Co_(0.05)Mn_(0.05)O_(2)(NCM90-Mg1).This method gets rid of mixing Li/Mg source and the precursor prepared by common co-precipitation,thus could achieve homogeneous lithiation and Mg2+doping.The cell parameter c is expanded,and the cation disorder is reduced after Mg2+doping.Furthermore,the harmful H2-H3 phase transition in NCM90-Mg1 is also well suppressed.As a result,the obtained NCM90-Mg1 shows better electrochemical performance than NCM90.Within 2.8–4.3 V(25℃),the specific discharge capacity of NCM90-Mg1 at 5 C is as high as 169.1m Ah/g,and an outstanding capacity retention of 70.0%(10.0%higher than NCM90)can be obtained after400 cycles at 0.5 C.At 45℃,a capacity retention of 81.9%after 100 cycles at 1 C is recorded for NCM90-Mg1.Moreover,the NCM90-Mg1 also exhibits superior cycle stability when cycled at high cut-off voltage(4.5 V,25℃),possessing the capacity retention of 79.2%after 200 cycles at 1 C.Therefore,SP can be proposed as a powerful method for the preparation of multi-element materials for next-generation high energy density LIBs.
基金supported the National Science Foundation of China(Nos.22362011,22169007,51804199)the Science and Technology Major Project of Guangxi(No.AA19046001)+2 种基金the Open Research Fund of Guangxi Key Laboratory of Electrochemical and Magnetochemical Functional Materials(Nos.EMFM20201105,EMFM20181119)Shenzhen Medical Research Fund(No.20231211121324001)Shenzhen Science and Technology Program(No.KQTD20180412181422399)。
文摘The ultra-high nickel cathode material has important application prospect in power lithium-ion batteries.However,the poor structural stability and serious surface/interfacial side reactions during long cycles severely hinder the material's practical application.In this paper,Cs^(+)doping and polymethyl methacrylate(PMMA)coating are used to synergistically modify the NCM955 material.The results show that the corresponding discharge specific capacity of NCMCs-2@P-2 material reaches 152.02 m Ah/g at 1 C(1 C=200 m A/g)and 125.66 m Ah/g at 5 C after 300 cycles,and the capacity retention is 78.11%and72.21%,respectively.In addition,it still maintains 156.36 m Ah/g discharge specific capacity at 10 C,and these rate and cycle properties exceed those reported on ultra-high nickel cathode material.Moreover,NCMCs-2@P-2 material has higher migration energy barrier of Ni^(2+)and lower migration energy barrier of Li+than that of NCM955 material.Therefore,NCMCs-2@P-2 material has excellent electrochemical properties,which has been proved by a series of structural characterization,theoretical calculation and performance test.The synergistic enhancement of Cs^(+)doping and PMMA coating accelerates lithium ion diffusion kinetics,stabilizes crystal structure,and inhabits surface/interface side reaction.
文摘利用超细旋转盘式砂磨机细化颗粒固相烧结法,合成锂离子电池正极材料Li Ni0.80Co0.15Al0.05O2。原料经过砂磨后,混合均匀,粒径达到纳米级。根据塔曼定理,混合均匀的微小粒径可以在相同的烧结温度下,提高烧结的强度。SEM、XRD分别表征NCA材料的颗粒形貌和晶形结构。结果显示,通过细化颗粒烧结后的样品具有良好的形貌和层状结构。CV法测试样品的氧化还原性能,电池测试系统测试样品的电化学性能。测试结果显示,经过细化颗粒,在720℃合成的NCA材料具有良好的层状结构,018/110峰分裂明显。样品的电化学性能优良,0.2C下,首次放电容量达到182 m Ah?g?1,30次循环后容量保持率99.9%。1C下,首次放电容量153 m Ah?g?1,100次循环后容量保持率92.6%。
