Synthesis Of Vanadium-based Compounds And Its Electrochemical Properties

Actually, the energy issue has risen to a high degree of national security stategywith the continued growth of global energy consumption, as well as oil and coal andother fossil resources are depleting. In order to sustain development of21st century,energy conservation has become the consensus of the international community, soresearch and development of clean, cheap, environmental, friendly and green energyhas become an important issue. Lithium-ion batteries are excellent renewableresources for their high voltage, high energy density, high specific power and so on,which can provide an effective way for solving energy problem. However,commercial lithium-ion batteries are still having some problems, such as the poorperformance at a large current density, the low capacity and the problem ofenvironmental pollution. Thus, research and development of new lithium ionelectrode materials is of great theoretical and practical significance.The main contents and results are as following:(1) LiZnVO4was successfully prepared via a solid-state reaction route usingZnO, Li2CO3, V2O5as raw materials, and used as the anode materials in rechargeablelithium-ion battery. Furthermore, the relationship between structure andelectrochemical propeties was also studied. The result indicates that the LiZnVO4elcctrode exhibits excellent cycling stability even at a high current density. A largeinitial discharge capacity of824mAhg-1at a current density of1Ag-1was obtainedand and can remain314mAhg-1even afer70cycles. The electrode has111mAhg-1of discharge capacity at current density of8Ag-1, and has330mAhg-1of dischargecapacity back to1Ag-1after60cycles. This result indicates that the electrodecomposed of LiZnVO4exhibited a high rate performance. The structure ofLiZnVO4after charged and discharged proccess was also researched by usingtransmission electron microscopy (TEM), high resolution transmission electronmicroscopy (HRTEM) and X-ray diffraction (XRD) to learn the electrochemicalreaction mechanism of the electrode.(2) Co2V2O7-CTAB composite nanobelts were successfully synthesized using a simple hydrothermal route starting from CoCl2·6H2O, NH4VO3and CTAB. It wasfound that the synthesized nanobelts are highly crystalline. Furthermore, a possiblemechanism for the formation of Co2V2O7-CTAB composite nanobelts was proposed.When using the as-prepared Co2V2O7-CTAB composite nanobelts as an anodematerial in rechargeable lithium ion battery, it exhibits an initial discharge capacity of1287mAhg-1and can be remained400mAhg-1afer20cycles. This result indicatesthat the Co2V2O7-CTAB composite nanobelts have a potential application in lithiumbatteries.(3) CaV2O6and Ca2V2O7were successfully prepared via a hydrothermal routeunder different pH values using CoCl2·6H2O and NH4VO3as raw materials. Usingthe as-prepared pruducts as the anode materials in a rechargeable lithium ion battery,the electrode made of CaV2O6exhibits an initial discharge capatity of705mAhg-1,and374mAhg-1of capacity can be retained after20cycles. On the other hand,Ca2V2O7electrode fades faster than CaV2O6one for its sepecial crystal strutrue.