The VO2 powders were prepared by hydrothermal synthesis.The effects of heat treatment conditions and Y-doping on the structure and phase transition temperature of VO2 were studied.The XRD,SEM and TEM results show that...The VO2 powders were prepared by hydrothermal synthesis.The effects of heat treatment conditions and Y-doping on the structure and phase transition temperature of VO2 were studied.The XRD,SEM and TEM results show that the heat treatment temperature has a significant effect on the crystal transformation of VO2 precursor.Increasing temperature is conducive to the transformation of precursor VO2(B)to ultrafine VO2(M).The Y-doping affects the structure of VO2.Y^3+can occupy the lattice position of V4+to form YVO4 solid solution,which can increase the cell parameters of VO2.Due to the lattice deformation caused by Y-doping,the aggregation of particles is prevented,and the grain is refined obviously.DSC curves show that Y-doping can reduce the phase transition temperature of VO2(M).After adding 9 at.%Y,the phase transition temperature can be reduced from 68.3 to 61.3℃.展开更多
Disordered single-crystalline LiNi_(0.5)Mn_(1.5)O_(4)(LNMO)cathode materials with different Mn^(3+)contents were prepared by a simple temperature control strategy of a solid-state reaction.The effects of the mutual mo...Disordered single-crystalline LiNi_(0.5)Mn_(1.5)O_(4)(LNMO)cathode materials with different Mn^(3+)contents were prepared by a simple temperature control strategy of a solid-state reaction.The effects of the mutual modulation of the Mn^(3+) content and the bulk microstructure on the crystal structure and electrochemical properties of LNMO were systematically investigated.Results showed that a suitable Mn^(3+) content can enhance the structural stability and alleviate structural degradation and capacity fading.The excellent performance originates from the simultane-ous inhibition of microcrack formation and side reaction with electrolytes,ensuring the rapid diffusion of Li+during extraction and insertion.Consequently,the LNMO-800 sample delivers an excellent cycling stability with a capacity retention of 98.37%after 200 cycles,remarkable rate capacity of 115 mAh·g^(-1) at 10.0C,and rapid Li+diffusion coefficient of 4.43×10^(-9)cm^(2)·s^(-1).This work will allow for a deeper understanding of the coupling effect between Mn^(3+)content and bulk microstructure,especially in the design and development of Mn-based cathode materials.展开更多
基金Projects(51404183,51504177)supported by the National Natural Science Foundation of China。
文摘The VO2 powders were prepared by hydrothermal synthesis.The effects of heat treatment conditions and Y-doping on the structure and phase transition temperature of VO2 were studied.The XRD,SEM and TEM results show that the heat treatment temperature has a significant effect on the crystal transformation of VO2 precursor.Increasing temperature is conducive to the transformation of precursor VO2(B)to ultrafine VO2(M).The Y-doping affects the structure of VO2.Y^3+can occupy the lattice position of V4+to form YVO4 solid solution,which can increase the cell parameters of VO2.Due to the lattice deformation caused by Y-doping,the aggregation of particles is prevented,and the grain is refined obviously.DSC curves show that Y-doping can reduce the phase transition temperature of VO2(M).After adding 9 at.%Y,the phase transition temperature can be reduced from 68.3 to 61.3℃.
基金financially supported by the National Natural Science Foundation of China (Nos. 52034011 and 51974219)the Natural Science Basic Research Plan in Shaanxi Province (No. 2018JM5135)
文摘Disordered single-crystalline LiNi_(0.5)Mn_(1.5)O_(4)(LNMO)cathode materials with different Mn^(3+)contents were prepared by a simple temperature control strategy of a solid-state reaction.The effects of the mutual modulation of the Mn^(3+) content and the bulk microstructure on the crystal structure and electrochemical properties of LNMO were systematically investigated.Results showed that a suitable Mn^(3+) content can enhance the structural stability and alleviate structural degradation and capacity fading.The excellent performance originates from the simultane-ous inhibition of microcrack formation and side reaction with electrolytes,ensuring the rapid diffusion of Li+during extraction and insertion.Consequently,the LNMO-800 sample delivers an excellent cycling stability with a capacity retention of 98.37%after 200 cycles,remarkable rate capacity of 115 mAh·g^(-1) at 10.0C,and rapid Li+diffusion coefficient of 4.43×10^(-9)cm^(2)·s^(-1).This work will allow for a deeper understanding of the coupling effect between Mn^(3+)content and bulk microstructure,especially in the design and development of Mn-based cathode materials.
