The Research On Micro-supercapacitor Based On Pesudocapacitive Material

With the popularization of the portable electronic devices,the miniaturization and integration of various technologies have received increasing attention of researchers.However,the development the energy storage,which is the essential part of the electronic devices,has lagged behind the advance of the other parts.Moreover,there is a great demand for the miniature energy storage in environmental protection,medical and biological applications.Micro-supercapacitor stands out among a variety of miniature energy storages,due to its high power density,long cycle life and environmental-friendly nature.It should be mentioned that the practical application not only requires excellent charge-discharge rate,but also the high energy density of miniature energy storages,to support long hours operation of electronic devices.Therefore,the research based on how to increase capacitance and energy density of micro-supercapacitors is of practical significance and commercial value.There are many ways to increase the capacitance of micro-supercapacitors,among which selecting the right electrode materials is more effective and concerned.The pesudocapacitors store charge through highly reversible electrochemical adsorption/desorption and oxidation-reduction reactions which occur on the surface or inside the pesudocapacitive electrode materials.These faradaic processes would let pesudocapacitors attain 10 to 100 times the capacitance compared to EDLCs.According to the discussion above,Mn O₂and Ni Co₂O₄are selected to be electrode materials which are formed on the interdigital current collector by electrodeposition.The main results are as follows:（1）The Mn O₂nanoflakes is grown at a current of 0.04 m A for 200s and electrochmical measure is performed under three-electrode system.According the CV and GCD curve,the mass and area specific capacitance of Mn O₂micro-supercapacitor,which operates at the voltage range of-0.3～0.3V,are calculated to be 488F/g and 0.46F/cm².（2）The active material Ni Co₂O₄is grown at a current of-0.04 m A for 200s and electrochmical measure is performed under three-electrode system.According the CV and GCD curve,the mass and area specific capacitance of Ni Co₂O₄micro-supercapacitor,which operates at the voltage range of 0.1～0.6V,are calculated to be 1002F/g and 3.48F/cm².For increasing the energy density,not only can we select the right electrode material,we can couple two different kinds of active material to make a asymmetric micro-supercapacitor,which would gain a wider operation voltage range.Before that we should match the capacitance between positive and negative electrode material,and it will ensure the stable cycling of the asymmetric device.At the end of paper,the calculation of capacitance matching is done for better preparation of asymmetric micro-supercapacitor based on Mn O₂and Ni Co₂O₄,and it’s used to be theoretical basis for future research.