| The application of lithium ion batteries in the emerging power and energy industry requires the specific energy density ofcathode material to meet900Wh/kg, but the cathode materials have been reported can hardly make the grade. Therefore, it is the hightime to explore electrode materials with considerable specific energy densities. This work carried out the exploration of synthesismethods and preparation process for the LiNiVO4-LiNi1/3Co1/3Mn1/3O2composites based on simulate computation with theLiNi1/3Co1/3Mn1/3O2, which possesses high reversible capacity performance and LiNiVO4, which has been named as5V cathodematerial as reactants, and the physical and chemical properties of the composites were further studied. In addition, anode materialMoS2achieved system characterization and deep analyz ation at atomic level for the high energy density and good safety performance.The main contents and conclusions are as follows:1. LiNiVO4and LiNi1/3Co1/3Mn1/3O2are synthesized via different methods and various preparation situations. Results show thatthe particle sizes of both LiNiVO4, prepared by solid state method at600℃with the Zirconia ball as milling ball, nickel carbonate asthe source of nickel and LiNi1/3Co1/3Mn1/3O2, obtained by coprecipitation method are around300nm and evenly distributed. Withthem as the reactants, LiNiVO4-LiNi1/3Co1/3Mn1/3O2samples are prepared by solid state method and hydrothermal method. Resultsshow that the physical property is more excellent, voltage plateau lies above4.5V and the first charge specific capacity reaches202mAh/g of the hydrothermal product, whose physical and chemical features well consistent with the composite. In addition, thestructure of hydrothermal product maintains stable when the lithiation/delithiation occurs; ICP analysis rules out the possibility that thecharge specific capacity at voltage above4.5V is obtained entirely from the electrolyte decomposition; and the comparison betweenball milled LiNiVO4-LiNi1/3Co1/3Mn1/3O2mixtures and hydrothermal products demonstrate convincingly that we have developed anew composite as electrode material.2. LiNiVO4-LiNi1/3Co1/3Mn1/3O2composites are prepared by hydrothermal mathode on various experimental conditions. Resultsshow that washing water quantities and washing methods, rather than the filling degree and the reactants mixed methods, are the key todetermine the V element content in the products. Centrifugal washing method can prevent the loss of V element more efficiently, theinitial charge capacity of the composite is found to be200mAh/g when the washing water dosage is250mL; but for the filteredwashing method the product can hardly exhibit voltage platform above4.5V when the washing water quantity is more than100mL.Based on these experiments, we have the the molar ratios of the reactants changed, it is found that the structures of the product areessentially the same, but the morphology and charge/discharge performance will favour that of the reactant with the increaement; havethe amount of lithium source added changed, it is found that the products cannot be reckoned as composite when nLi/nNCMis equal to4,and with the amount of lithium source added increased, the composite characteristics more obviously, when nLi/nNCMis equal to35,composite samples owned excellent electrochemical performances can be obtained.3. The physical properties and electrochemical performances of commercial MoS2are systematical studied. Results show thatthe sheet-liked MoS2takes on a considerably uniform distribution around the particle size of891nm with the specific surface area of8.8m2/g. In spite of the sub-micron size, it presents an initial discharge capacity of937mAh/g in the voltage range of0.01~3.0V, andshows capacitor characteristics during the first charging process, exhibits a calculated capacitance of574F/g, comparable to graphenewith exceptionally high specific surface area up to2675m2/g. In additation, the lithiated MoS2transits from the2H to1T form whenthe inserted Li content reaches more than56%. |
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