Study On Preparation Of Directional Porous Materials And Its Performance For Supercapacitor

Energy crisis and environmental problems have always restricted the development of human civilization,so it is urgent to make full use of clean and renewable energy and develop new energy storage devices.Supercapacitors have become a hot research object in the field of energy storage because of their ultra-high power density and long-term cycle stability.However,the low energy density limits its further development.Therefore,it is necessary to find new electrode materials and reasonably design the structure of electrode materials in order to improve the energy storage performance of supercapacitors.The ice template method is a method to obtain porous materials by uniformly mixing raw materials with water and additives and making use of the"liquid-solid-gas"phase transformation of water.It has the advantages of simple operation and green environmental protection.At the same time,the materials prepared by ice template method can obtain directional pores and hierarchical structures on different layers.This directional porous structure is conducive to the transport of electrons and ions,so it can be used to prepare high-performance supercapacitor electrode materials.Therefore,based on the ice template method,the positive and negative materials of supercapacitors were prepared respectively as follows.For the positive materials,Polyaniline/TiO₂/three-dimensional graphene composites with directional structure were obtained by ice template and in-situ polymerization.The longest structure of Polyaniline array grown by TiO₂can reach more than 800nm.In addition,the oriented three-dimensional graphene and the Polyaniline nanowire array grow on it to form a unique double-oriented structure,this highly customized structure can improve the electrochemical performance of the material,and the specific capacitance of the whole material reaches 460 F/g at the current density of 2 A/g.After 10000 charge-discharge cycles,the capacity retention is 82%.For the negative materials,MXene/three-dimensional graphene composites with directional arrangement were prepared by ice template method.Because the pseudo-capacitance provided by a large number of active sites of MXene and the unique directional skeleton structure of three-dimensional graphene provide a fast transport path between ions and electrons,the composites can obtain better electrochemical performance.Under the current density of 1 A/g,the specific capacitance of the composite can reach 341 F/g,and the capacity retention is 96%after 10000 charge-discharge cycles.Finally,the above positive and negative materials are assembled into asymmetric supercapacitors,and a 1.6 V voltage window is obtained.When the power density is 942 W/kg,the energy density can reach 27 Wh/kg.After 5000 cycle tests,the specific capacitance retention of the capacitor can still reach 86.2%.