Synthesis And Study On Electrochemical Properties Of CoTe Electrode Materials

With the continuous development of human society,the problem of global warming is becoming more and more serious as the fossil fuels were over-exploited.Many ways can contribute to solving this problem,but one of the most direct and effective means is the improvement of renewable energy.Therefore,it is extremely urgent how to research and use the new energy storage devices.As a new type of energy storage device,supercapacitor has attracted extensive attention due to their advantages of high power density,long cycle life,low maintenance costs,et al.And the preparation of supercapacitor’s electrode materials has been becoming one of the key research directions.Cobaltous telluride（CoTe）has great potential as electrode materials owe to its excellent morphology and size,high specific surface area and good conductivity.However,little research has been done on CoTe electrode materials.So this paper focuses on the application of CoTe materials and their composites with manganese dioxide（CoTe@Mn O₂）in the field of supercapacitor.The main contents include:（1）CoTe nanowire materials are prepared by one-step hydrothermal method.By adjusting the temperature and time of reaction,the process route for making synthetic products with better performance is explored.And then the electrochemical properties of the obtained products are tested.In the three-electrode system,the specific capacitance of CoTe electrode is 609.02 F/g at a current density of 1 A/g.After forming the asymmetric supercapacitor,the specific capacitance of the capacitor is87.53 F/g at a current density of 1 A/g.Its maximum energy density is 31.12 Wh/kg and its maximum power density is 3999.1 W/kg respectively.After 2000 cycles,the specific capacitance retention rate is 92.73%with an excellent cycle stability.（2）In order to improve conductivity of CoTe electrodes prepared in（1）,CoTe nanowires are synthesized on nickel foam used as a substrate by one-step hydrothermal method.Through the analysis of the effect of reactant’s content on the final products,a synthetic product with better performance is obtained.After 2000cycles,the charge transfer resistance(R_ct)and internal resistance（R_s）of CoTe electrodes with nickel foam substrate each decreased by about 85%and 35%compared with non-nickel foam substrate under the same condition.That indicates an improvement in conductivity with the introduction of nickel foam.（3）The electrode performance is further improved by modifying the CoTe materials.The sea urchin-like Mn O₂materials are successfully synthesized on CoTe nanowires by a two-step hydrothermal method,and CoTe@Mn O₂composite materials grown on nickel foam are formed.After that,by adjusting the mass ratio of Mn O₂to CoTe,the test electrode with best performance is finally obtained.In the three-electrode system,its specific capacitance is as high as 1568.3 F/g at a current density of 1 A/g.At the same time,the maximum energy density and power density of the composed asymmetric supercapacitor are 84.45 Wh/kg and 4250.31 W/kg respectively.Compared with CoTe nanowires alone or CoTe nanowires grown on nickel foam,the results of these tests lead to the conclusion that CoTe@Mn O₂composite materials have a better performance for its specific capacitance and energy density of asymmetric supercapacitor.