In order to confirm the optimal Li content of Li-rich Mn-based cathode materials(a fixed mole ratio of Mn to Ni to Co is0.6:0.2:0.2),Li1+x(Mn0.6Ni0.2Co0.2)1-xO2(x=0,0.1,0.2,0.3)composites were obtained,which had a typ...In order to confirm the optimal Li content of Li-rich Mn-based cathode materials(a fixed mole ratio of Mn to Ni to Co is0.6:0.2:0.2),Li1+x(Mn0.6Ni0.2Co0.2)1-xO2(x=0,0.1,0.2,0.3)composites were obtained,which had a typical layered structure with R3m and C2/m space group observed from X-ray powder diffraction(XRD).Electron microscopy micrograph(SEM)reveals that the particle sizes in the range of0.4-1.1μm increase with an increase of x value.Li1.2(Mn0.6Ni0.2Co0.2)0.8O2sample delivers a larger initial discharge capacity of275.7mA·h/g at the current density of20mA/g in the potential range of2.0-4.8V,while Li1.1(Mn0.6Ni0.2Co0.2)0.9O2shows a better cycle performance with a capacity retention of93.8%at0.2C after50cycles,showing better reaction kinetics of lithium ion insertion and extraction.展开更多
P2-type Na_(2/3)Fe_(1/2)Mn_(1/2)O_(2) was synthesized by a facile sol−gel method,and the effect of calcination temperature on the structure,morphology and electrochemical performance of samples was investigated.The re...P2-type Na_(2/3)Fe_(1/2)Mn_(1/2)O_(2) was synthesized by a facile sol−gel method,and the effect of calcination temperature on the structure,morphology and electrochemical performance of samples was investigated.The results show that the sample obtained at 900℃ is pure P2-type Na_(2/3)Fe_(1/2)Mn_(1/2)O_(2) phase with good crystallization,which consists of hexagon plate-shaped particles with the size and thickness of 2−4μm and 200−400 nm,respectively.The sample exhibits an initial specific discharge capacity of 243 mA·h/g at a current density of 26 mA/g with good cycling stability.The high specific capacity indicates that P2-type Na_(2/3)Fe_(1/2)Mn_(1/2)O_(2) is a promising cathode material for sodiumion batteries.展开更多
In this paper,we study the systematics of the 2_(1)^(+)states in the N=82 even-even isotones with proton numbers between 52 and 72.We calculate the level energies of the 0_(1)^(+),2_(1)^(+)states and the electric quad...In this paper,we study the systematics of the 2_(1)^(+)states in the N=82 even-even isotones with proton numbers between 52 and 72.We calculate the level energies of the 0_(1)^(+),2_(1)^(+)states and the electric quadrupole reduced transition probabilities B(E2;2_(1)^(+)→0_(1)^(+)),in the framework of the nuclear shell model with a monopole-and multipole-optimized realistic interaction.Our calculations yield good agreement with the experimental data and show a 2.5 MeV gap at Z=64 subshell closure in^(146)Gd.We predict that the B(E2;2_(1)^(+)→0_(1)^(+))value for^(146)Gd is close to those for^(142)Nd and^(144)Sm,and the values increase rapidly from^(148)Dy to^(152)Yb.展开更多
Let TΩ be the singular integral operator with kernel Ω（x）/｜x｜n where is homogeneous of degree zero, integrable and has mean value zero on the unit sphere Sn-1. In this paper, by Fourier transform estimates, L...Let TΩ be the singular integral operator with kernel Ω（x）/｜x｜n where is homogeneous of degree zero, integrable and has mean value zero on the unit sphere Sn-1. In this paper, by Fourier transform estimates, Littlewood-Paley theory and approximation, the authors prove that if Ω∈（lnL）2 （Sn- 1）, then the commutator generated by TΩ and CMO（Rn） function, and the corresponding discrete maximal operator, are compact on LP（Rn, ｜s｜γp） for p∈ （1, ∞） and γp ∈ （-1, p-l）展开更多
基金Project(21473258) supported by the National Natural Science Foundation of ChinaProject(13JJ1004) supported by Distinguished Young Scientists of Hunan Province,ChinaProject(NCET-11-0513) supported by Program for the New Century Excellent Talents in University,China
文摘In order to confirm the optimal Li content of Li-rich Mn-based cathode materials(a fixed mole ratio of Mn to Ni to Co is0.6:0.2:0.2),Li1+x(Mn0.6Ni0.2Co0.2)1-xO2(x=0,0.1,0.2,0.3)composites were obtained,which had a typical layered structure with R3m and C2/m space group observed from X-ray powder diffraction(XRD).Electron microscopy micrograph(SEM)reveals that the particle sizes in the range of0.4-1.1μm increase with an increase of x value.Li1.2(Mn0.6Ni0.2Co0.2)0.8O2sample delivers a larger initial discharge capacity of275.7mA·h/g at the current density of20mA/g in the potential range of2.0-4.8V,while Li1.1(Mn0.6Ni0.2Co0.2)0.9O2shows a better cycle performance with a capacity retention of93.8%at0.2C after50cycles,showing better reaction kinetics of lithium ion insertion and extraction.
基金the financial supports from the Natural Science Foundation of Hunan Province,China(No.2020JJ5102)the Scientific Research Fund of Hunan Provincial Education Department,China(No.19A111).
文摘P2-type Na_(2/3)Fe_(1/2)Mn_(1/2)O_(2) was synthesized by a facile sol−gel method,and the effect of calcination temperature on the structure,morphology and electrochemical performance of samples was investigated.The results show that the sample obtained at 900℃ is pure P2-type Na_(2/3)Fe_(1/2)Mn_(1/2)O_(2) phase with good crystallization,which consists of hexagon plate-shaped particles with the size and thickness of 2−4μm and 200−400 nm,respectively.The sample exhibits an initial specific discharge capacity of 243 mA·h/g at a current density of 26 mA/g with good cycling stability.The high specific capacity indicates that P2-type Na_(2/3)Fe_(1/2)Mn_(1/2)O_(2) is a promising cathode material for sodiumion batteries.
基金National Key R&D Program of China(2018YFA0404403)National Natural Science Foundation of China(12075169,12035011,11605122)Fundamental Research Funds for the Central Universities(22120240207)。
文摘In this paper,we study the systematics of the 2_(1)^(+)states in the N=82 even-even isotones with proton numbers between 52 and 72.We calculate the level energies of the 0_(1)^(+),2_(1)^(+)states and the electric quadrupole reduced transition probabilities B(E2;2_(1)^(+)→0_(1)^(+)),in the framework of the nuclear shell model with a monopole-and multipole-optimized realistic interaction.Our calculations yield good agreement with the experimental data and show a 2.5 MeV gap at Z=64 subshell closure in^(146)Gd.We predict that the B(E2;2_(1)^(+)→0_(1)^(+))value for^(146)Gd is close to those for^(142)Nd and^(144)Sm,and the values increase rapidly from^(148)Dy to^(152)Yb.
基金supported by National Natural Science Foundation of China(Grant No.11371370)
文摘Let TΩ be the singular integral operator with kernel Ω（x）/｜x｜n where is homogeneous of degree zero, integrable and has mean value zero on the unit sphere Sn-1. In this paper, by Fourier transform estimates, Littlewood-Paley theory and approximation, the authors prove that if Ω∈（lnL）2 （Sn- 1）, then the commutator generated by TΩ and CMO（Rn） function, and the corresponding discrete maximal operator, are compact on LP（Rn, ｜s｜γp） for p∈ （1, ∞） and γp ∈ （-1, p-l）
