Micro-nanostructural Stibino-based Oxides: Synthesis And Electrochemical Properties

The main contents of the present work are as follows: a series ofmicro-nanostructural stibino-based oxides: antimonite manganese, antimonite zinc,antimoniate copper, antimoniate zinc and antimoniate manganese were synthesized by thesolvothermal method or solid state reaction. The obtained products were characterized byX-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electronmicroscope (TEM) measurements. Based on the SEM and TEM experimental results, thepossible mechanisms for the formation of the products were discussed. Furthermore,these micro-nanostructural ternary oxides were used as the cathode materials for Li-ionbatteries (LIB) and the electrochemical mechanism were also investigated.(i) MnSb2O4green crystal and microspheres were successfully synthesized usingSbCl3, MnCl24H2O and N2H4H2O as precursors in the absence of templates. Theobtained products were characterized by XRD、SEM and TEM, respectively. It was foundthat the synthesized MnSb2O4are stick-like green crystal and the MnSb2O4microspheresare composed of nanosheets with a thickness of20-30nm. The size of mrcrospheres is ca.10-15μm and the nanosheets are highly crystalline. Based on a series of experimentalresults, the possible mechanisms for the formation of the micro-nanostructured productswere discussed. Furthermore, these products were used as the cathode materials for Li-ionbatteries (LIB), and their electrochemical properties were also investigated. Theelectrochemical performance of MnSb2O4microspheres is better than that of MnSb2O4green crystal. It delivers a high initial discharge capacity of2197.9mAh/g, correspondingto the formation of Li3Sb. At the same time, it trends to loose electrochemical active withincreasing cycles, and only168.3mAh/g of capacity can be retained after50cycles. Thisresult can be attributed to the fact that the electrical conductivity of MnSb2O4is poor. Onthe other hand, it caused by volumetric variations during the Li ionintercalation/deintercalation into/out of anode. Thus, it is still to be enhanced for theelectrochemical performnces of MnSb2O4.(ii) ZnSb2O4light-yellow crystals were successfully synthesized starting from SbCl3,ZnCl2and N2H4H2O as precursors by using a simple synthetic in the absence oftemplates. The obtained products were characterized by XRD and SEM. It was found thatthese products are highly crystalline and their size is found to be ca.10um. Furthermore, it was used as the cathode materials for Li-ion batteries (LIB), theelectrochemical mechanism was investigated as well. The initial discharge capacity ofZnSb2O4is as high as1444.3mAh/g, corresponding to the formation of LixSb(1≦x≦3)alloy, LiyZn(y≦1) alloy and Li2O. The initail reversible charge is found to be ca.515.5mAh/g, and only45mAh/g was retained after50cycles.(iii) MSb2O6(M=Cu,Mn,Zn) were synthesized using the solid state reaction at a hightemperature. It was found that these MSb2O6products are highly crystalline because theywere obtained at a high temperature. Furthermore, these materials have been used as theelectrode materials for Li-ion batteries and their electrochemical performances were alsoinvestigated in detail. It was found that that the cell made of CuSb2O6exhibited a bettercycling stability, which is better than that of cells composed of ZnSb2O6and MnSb2O6.The initial discharge capacity of CuSb2O6is as high as1982.1mAh/g, corresponding tothe formation of Li3Sb. However, the capacity decreased significantly with increasingcycling and only140mAh/g was retained after50cycles. These results might beattributed to the intrinsic of MSb2O6including electrical conductivity and volumetricvariations. Obviously, the electrochemical performances are needed to be improved in thefuture.