A series of La-Cu-Zn-O mixed oxide catalysts were synthesized by a co-precipitation method and calcined under different temperatures. The XRD, BET, TPR, N2 O-adsorption, XPS, SEM and TPD techniques were carried out to...A series of La-Cu-Zn-O mixed oxide catalysts were synthesized by a co-precipitation method and calcined under different temperatures. The XRD, BET, TPR, N2 O-adsorption, XPS, SEM and TPD techniques were carried out to measure the aimed catalysts. The results indicated that the chemical environment of lanthanum element changes with the increase of calcination temperature. The La2 CuO4 perovskite structure is obtained at the temperature higher than 823 K and the special copper species appear in the perovskites due to the special structure property. The catalysts with La2 CuO4 perovskite structure show higher methanol selectivity compared with the mixed copper catalyst. For the perovskite catalysts, the conversion of CO2 changes with the same tendency of the copper species ratio（（Cu^（α＋）＋Cu^0）/（Cu（Total））%）, which implied both Cu^（α＋） and Cu^0 are important active sites in the perovskite catalyst for the reaction.展开更多
La<sub>2</sub>CuO<sub>4</sub>, the parent compound of the La system high-temperaturesuperconductors, can be rendered superconducting at～40 K by substituting A<sup>2+</sup>（A=Ca, S...La<sub>2</sub>CuO<sub>4</sub>, the parent compound of the La system high-temperaturesuperconductors, can be rendered superconducting at～40 K by substituting A<sup>2+</sup>（A=Ca, Sr, Ba） at La<sup>3+</sup> sites or introducing excess oxygen to compound by annealingunder high oxygen pressures as well as other treatments. It is a hard Moot insulatorof which crystal cells contain Cu-O sheet, and 3D antiferromagnetic property展开更多
The structural transformations,oxygen releasing and side reactions with electrolytes on the surface are considered as the main causes of the performance degradation of Li-rich layered oxides(LROs)cathodes in Li-ion ba...The structural transformations,oxygen releasing and side reactions with electrolytes on the surface are considered as the main causes of the performance degradation of Li-rich layered oxides(LROs)cathodes in Li-ion batteries.Thus,stabilizing the surfaces of LROs is the key to realize their practical application in high energy density Li-ion batteries.Surface coating is regarded as one of the most effective strategies for high voltage cathodes.The ideal coating materials should prevent cathodes from electrolyte corrosion and possess both electronic and Li-ionic conductivities simultaneously.However,commonly reported coating materials are unable to balance these functions well.Herein,a new type of coating material,La_(2)CuO_(4)was introduced to mitigate the surface issues of LROs for the first time,due to its superb electronic conductivity(26-35 mS·cm^(-1))and lithium-ionic diffusion coefficient(10^(-12)-10^(-13)cm^(2)·s^(-1)).After coating with the La_(2)CuO_(4),the capacity retention of Li_(1.2)Ni_(0.54)Co_(0.13)Mn_(0.13)O_(2)cathode was increased to 85.9%(compared to 79.3%of uncoated cathode)after 150 cycles in the voltage range of 2.0-4.8 V.In addition,only negligible degradations on the deliverable capacity and rate capability were observed.展开更多
基金Project supported by the Natural Science Foundation of Ningxia Province(NZ16003)
文摘A series of La-Cu-Zn-O mixed oxide catalysts were synthesized by a co-precipitation method and calcined under different temperatures. The XRD, BET, TPR, N2 O-adsorption, XPS, SEM and TPD techniques were carried out to measure the aimed catalysts. The results indicated that the chemical environment of lanthanum element changes with the increase of calcination temperature. The La2 CuO4 perovskite structure is obtained at the temperature higher than 823 K and the special copper species appear in the perovskites due to the special structure property. The catalysts with La2 CuO4 perovskite structure show higher methanol selectivity compared with the mixed copper catalyst. For the perovskite catalysts, the conversion of CO2 changes with the same tendency of the copper species ratio（（Cu^（α＋）＋Cu^0）/（Cu（Total））%）, which implied both Cu^（α＋） and Cu^0 are important active sites in the perovskite catalyst for the reaction.
文摘La<sub>2</sub>CuO<sub>4</sub>, the parent compound of the La system high-temperaturesuperconductors, can be rendered superconducting at～40 K by substituting A<sup>2+</sup>（A=Ca, Sr, Ba） at La<sup>3+</sup> sites or introducing excess oxygen to compound by annealingunder high oxygen pressures as well as other treatments. It is a hard Moot insulatorof which crystal cells contain Cu-O sheet, and 3D antiferromagnetic property
基金Project supported by the National Key Research and Development Program of China(Grant No.2019YFE0100200)the National Natural Science Foundation of China(Grant No.U1964205)the Beijing Municipal Science and Technology Commission(Grant No.Z191100004719001)。
文摘The structural transformations,oxygen releasing and side reactions with electrolytes on the surface are considered as the main causes of the performance degradation of Li-rich layered oxides(LROs)cathodes in Li-ion batteries.Thus,stabilizing the surfaces of LROs is the key to realize their practical application in high energy density Li-ion batteries.Surface coating is regarded as one of the most effective strategies for high voltage cathodes.The ideal coating materials should prevent cathodes from electrolyte corrosion and possess both electronic and Li-ionic conductivities simultaneously.However,commonly reported coating materials are unable to balance these functions well.Herein,a new type of coating material,La_(2)CuO_(4)was introduced to mitigate the surface issues of LROs for the first time,due to its superb electronic conductivity(26-35 mS·cm^(-1))and lithium-ionic diffusion coefficient(10^(-12)-10^(-13)cm^(2)·s^(-1)).After coating with the La_(2)CuO_(4),the capacity retention of Li_(1.2)Ni_(0.54)Co_(0.13)Mn_(0.13)O_(2)cathode was increased to 85.9%(compared to 79.3%of uncoated cathode)after 150 cycles in the voltage range of 2.0-4.8 V.In addition,only negligible degradations on the deliverable capacity and rate capability were observed.
