Synthesis And Electrochemical Properties Of Metal Oxides As Anode Materials In Lithium-ion Battery

There are still problems existing during the preparation of metal oxides anode materials for lithium-ion battery,such as complicated processes,low productivity,high cost and waste et al.To solve these problems,we developed a method combining DC arc plasma evaporation and oxidation.This method had many advantages such as high productivity,low cost and waste et al.The most important advantage was its flexibility and general applicability which meant a lot of metal or alloy oxides could be prepared by this method.In this subject,we obtained the oxides of Fe,Co,Mn and Sn with this method.Then their structures,constituents,morphology and electrochemical properties were tested by XRD,SEM,TEM,Electrochemical Workstation and LAND Battery Test System.During the study of Fe based oxides anode materials,it was found that,to some extent,the average valence and initial specific capacity increased while the capacity stability decreased along with the increase of temperature.For example,the initial discharge specific capacity of iron based oxides obtained at 350^oC and 450^oC were about 951mAh/g and 1177mAh/g when cycled at a current density of 200mA/g,respectively.After 25 cycles,the specific capacity only remained about 308mAh/g for product obtained at350^oC while it was about 500mAh/g for the one obtained at 450^oC.The results showed that suitable degree of oxidation can improve the electrochemical properties of metal oxides products.For the study of cobalt oxides,the particle of products would be bigger and agglomerate more seriously when increased the temperature of oxidation.Although both of the products oxidized at 350^oC or 450^oC were Co₃O₄,the oxides obtained at 350^oC had a smaller particle and lighter aggregation.The products were used as electrode materials in the lithium-ion battery and they were cycled at a current density of 200mA/g.The initial specific capacities of Co₃O₄ obtained at 350^oC and 450^oC were about 1165mAh/g and 1156mAh/g,respectively.And the remained specific capacities after 100 cycles were about512mAh/g and 327mAh/g for the products obtained at 350^oC and 450^oC,respectively.Furthermore,the ohmic resistance and charge transfer resistance of Co₃O₄ oxidized at 350^oC were almost not change between the 1^st cycle and25^th cycle,while it grew noticeably for the Co₃O₄ obtained at 450^oC from the1^st cycle to the 25^th cycle.All of the result above illustrated that,to some extent,the Co₃O₄ oxidized at a lower temperature showed a better electrochemical performance.For Mn oxides,the products obtained at 450^oC showed a higher initial specific capacity,while their cycling stability performed worse than the products obtained at 350^oC.When it turned to Sn based oxides anode materials,the product obtained at 350^oC showed better performance than the pure Sn powder in the electrochemical tests.