Preparation And Electrochemical Properties Of Micro/nanostructured MoO3-based Compounds As Positive Electrode Aterials

The rapid development of the global economy now heavily dependent on fossil fuels,causing environmental pollition.For the future of the economy we need to change our minds to seek sustainability and green energy.The supercapacitors can not only meet the requirements of high power,long period,high energy storage and high power density,but also reduce the pollution of global ecosystem.Therefore,supercapacitors have attracted much attention,and electrode materials have an important influence on the electrochemical properties of supercapacitors.Among transition metal oxides,MoO₃ has a unique layered structure,with a large interlayer spacing can be uesd intercalation/deintercalation metal ions.Different metal ions can be embedded in MoO₃ to exert the synergistic effect of multiple metals,thus improving the electrochemical properties of MoO₃-based elecrode materials.In this paper,the preparation and elecrochemical properties of MoO₃-based electrode materials are studied in three aspects:?1?We made four different electrode materials of Li_xMoO₃?the mole ratio of Li and Mo of 1:2,1:4,1:6,1:8?by ball milling and solid phase method,according to the ICP test,the specific X values were Li_0.31MoO₃,Li_0.55MoO₃,Li_0.63MoO₃,Li_0.97MoO₃respectively.Electrochemical tests were carried out for four electrode materials in a the elecrolyte of 0.5 M Li₂SO₄.The results showed that the molar ratio of Li to Mo was 1:4 that is Li_0.55MoO₃ exhibited the best electrochemical performance.And there were two pairs of obvious redox peaks in the cyclic voltammograms and the maximum specific capacitance of Li_0.55MoO₃ was 108.5 F g^-1under the scanning rate of 1 mv s^-1.?2?We synthesied the compound of NiO@CaMoO₄ by hydrothermal method which Ni was embedded in CaMoO₄.The four elements of Ni,O Ca and Mo in NiO@CaMoO₄ were determined by XRD,EDS and XPS.And the four elements in NiO@CaMoO₄ valence states were Ni²⁺,O^2-,Ni²⁺,Mo⁶⁺respectively.The TEM diagram of this materials showed that it is a needle-like structure with BET value of84.93 m²g^-1.The electrochemical testing of NiO@CaMoO₄ electrode materials in the three kinds of electrolyte of 2 M KOH,NaOH and LiOH.The test results showed that NiO@CaMoO₄ in 2 M KOH electrolyte in the current density of 1 A g^-1,the capacitance can reach 583 F g^-1.One of the reasons is that the conductivity of Li⁺,Na⁺,K⁺are different and the conductivity of K⁺is the highest;The second is that K⁺hydrinium is the smallest of the three,so it has the highest electrical conductivity.?3?We made five kinds of electrode materials of Mn_xNi_yMo₄O₁₉?the mole ratio of Mn and Mo of 0:1,1:1,1:2,1:3 and 1:0?by hydrothermal method,and their electrochemical tests were carried out in 1 M KOH electrolyte.The test results showed that Mn and Mo in the 1:1 that is Mn_2.4Ni_2.6Mo₄O₁₉9 in current density of 1 A g^-11 specific capacitance is up to 503 F g^-1,which showed that a large number of small holes in the material,and after 700 cycles the capacitance remains at 91%,it showed Mn_2.4Ni_2.6Mo₄O₁₉9 has a good cycle performance.