Lithium-rich nickel–manganese–cobalt oxide, Li1.2Ni0.18Mn0.59Co0.03O2, prepared by spray-dry process, exhibits rapid capacity fade and poor rate capability. The surface of Li1.2Ni0.18Mn0.59Co0.03O2 can be modified with LiCoPO4 through co-precipitation method in order to improve its electrochemical properties. The resultant LiCoPO4 particles are in nano-scale and accumulate on the surface of the Li1.2Ni0.18Mn0.59Co0.03O2 particles. The surface modification by LiCoPO4 is shown to significantly improve both the cyclic performance and the rate capability of Li1.2Ni0.18Mn0.59Co0.03O2. 相似文献
Alien atom was used to obtain a series of LiFe1-xLaxPO4/C (x=0, 0.002, 0.005, 0.01, 0.015) cathode materials with the aim of investigating the influence of participation of La on the electrochemical behavior of LiFePO4/C. Combination of X-ray diffractometer, scanning electron microscope equipped with energy dispersive spectrometer and high resolution transmission electron microscope was applied. The results show that all the La-doped LiFePO4/C samples are olivine type crystals, La ion is sufficiently introduced into the network, and every element is well homogeneously distributed. There are many pore spaces on the surface of particles. The content of carbon in the prepared cathode materials remains 13.6% calculated by TGA/DTA curves, and the particles are wrapped by a uniformly and continuous carbon layer with the thickness of about 2 nm. Similarly, the content of Fe2P also keeps the same basically in all the cathode materials as a result of the similar ratio (2.35) of peak intensity at 36.5o and 37.1o from XRD. The increasing trend is most pronounced at doped 0.005 which presents the highest initial discharge capacity of 163 mA×h/g, lowest charge transfer resistance of 5.52 W, superior diffuse ability of lithium ion (10-11 cm2/s) and the best capacity retention current rate of about 93% after 50 cycles at 0.1 C. 相似文献
Summary: This paper introduces a new inorganic poly(phosphazene disulfide) material. With unique element composition and molecular structure, the polymer has noncombustible safety and preferable conductivity. When used as cathode material for rechargeable lithium batteries, the polymer's first discharge capacity is as high as 467.9 mAh · g?1, which can be retained at 409.9 mAh · g?1 after 60 repeated cycles. Therefore, it has a great application potential in the field of lithium batteries.
Replacement of the Cl atoms by S? S groups by refluxing Na2S2 and linear poly(dichloro‐phosphazene). 相似文献
Relatively low capacity is a technological bottleneck of the development of sodium ion batteries. Herein, we present a series of hybrid layered cathode materials NaxLi1.5-xNi0.167Co0.167Mn0.67O2 (x?=?0.5, 0.6, 0.7, 0.8, 0.9, 1) with composite crystalline structures, which are prepared by co-precipitation method. The combined analysis of XRD, SEM and TEM reveals that the materials are composed of P2 structure, α-NaFeO2 structure and small amount of Li2MnO3. Among the as-prepared materials, Na0.6Li0.9Ni0.167Co0.167Mn0.67O2 delivers an initial reversible capacity of 222?mA?h?g?1 at 20?mA?g?1. Even at 100?mA?g?1, it shows a remarkable discharge capacity of 125?mA?h?g?1 in the first cycle and remains 60?mA?h?g?1 after 300 cycles. Such high capacity is achieved by the specific composite structure and sodium ions are proved to be able to intercalate/deintercalate in Li1.5Ni0.167Co0.167Mn0.67O2 with α-NaFeO2 structure. The Ex-situ XRD results of Na0.6Li0.9Ni0.167Co0.167Mn0.67O2 in the first cycle show that the P2 structure is well maintained along with irreversible phase transition of α-NaFeO2 structure, which is responsible for the long-term capacity fading. Owing to the high discharge capacity, the novel hybrid layered oxides NaxLi1.5-xNi0.167Co0.167Mn0.67O2 with composite structures can be considered as promising cathode materials to promote progress toward sodium-ion batteries. 相似文献
