Preparation And Electrochemical Properties Of New CuCo₂O₄ Electrode Materials

With the increasing global warming and depletion of fossil energy,people’s demand for the energy is more urgent.Development and use of electric vehicles as the main means of transportation has become an inevitable trend.Supercapacitor,as a new energy storage device,behaves high power density,quick charge and discharge property,long cycle life and good security,becomes the next generation of the most promising energy storage device.As the different charge storage mechanism,supercapacitor can divide into double layer supercapacitor based on carbon electrode materials and pseudocapacitance capacitor composed by transition metals and conducting polymer materials.CuCo₂O₄ is an important transition metal oxides material,because it’s abundant resources,low cost,non-poisonous and excellent electrical conductivity has attracted researcher great interest.In this master’s paper,we prepare different morphology of the CuCo₂O₄ electrode material,and do a series characterization with the material;also we carried out detail study and discussion about the electrochemical performance of the electrode material.The main research contents of our paper as shown in following sentence:（1）We have prepared maguey-like CuCo₂O₄ nanowire material via a hydrothermal and annealing at 300 oC for 3 h.The result of the electrochemical test show a high areal capacitance of 3.27 F cm^-2 at the current density of 5 mA cm^-2 and the specific capacitance of 982 F g^-1 at the current density of 1.5 A g^-1.Compared to the previous hedgehog CuCo₂O₄ electrode material,the electrochemical performance has a big promotion.The charge-discharge resistance is 1.89 Ω,is lower than those other reported single CuCo₂O₄ electrode materials.At scan rate of 50 mV s^-1,our obtained materials behave a high specific capacitance retention of 100.9% for 3000 CV cycles.What’s more,at the current density of 30 mA cm^-2,our obtained materials exhibits a high capacitance retention of 100.6% for 4000 GCD cycles,which was consistent well with the CV results.Also we have studied the formation mechanism of the maguey-like CuCo₂O₄ nanowires.We can deduce that it formed a mass of nanosheet at the first,and then the nanosheet was transformed into nanowires slowly,finally it almost change into nanowires structure.In addition to this,we had assembled the symmetric capacitor device with the electrode materials and tested the electrochemical performance of the assembled device.At the current density of 1 A g^-1,the specific capacitance of our assembled capacitor was 118.0 F g^-1,what’s more,our assembled device exhibited a high energy density of 16.87 Wh kg-1 and a high power density of 8.20 KW kg-1.Even at the high power density of 8.20 KW kg-1,the energy density of our assembled device was 10.25 Wh kg-1.（2）We have prepared the hedgehog precursor of the CuCo₂O₄ material by a facile hydrothermal and chemical bath deposition,then annealing at 300 oC for 3 h to obtain the CuCo₂O₄ electrode materials.The result of the electrochemical test demonstrate that the specific capacitance of the hedgehog CuCo₂O₄ material exhibits a high areal capacitance of 0.907 F cm^-2 at current density of 5 mA cm^-2 and a high specific capacitance of 334.3 F g^-1 at 5 mV s^-1 of the cyclic voltammetry cycle.The conclusion of the electrochemical impedance spectrum（EIS）indicates that the equivalent series resistance is 0.39 Ω.After 800 GCD cycles,the capacitance retention is 90.5%,exhibit a high electrochemical stability.And we had study the influence of electrochemical performance at different testing temperature,the result demonstrate that the electrode material behave the best specific capacitance at 30 oC testing temperature.