Synthesis Research Of Biomimetic Graphene Composite And Its Electrical Properties

With the expanding of nuclear usage,the continuous proliferation of nuclear pollution,clean nuclear fusion energy is facing technical problems in the short term making it difficult to achieve a breakthrough.As oil,natural gas and other natural non-renewable resources are being depleted,people are beginning to think about how to develop new power supply technology,and are seeking new energy development imminently in practical applications,such as lithium batteries,super capacitors and so on.In the current research areas,with the high power density,long cycle life,low cost,environmental-friendly and other advantages,the super capacitor has become the most promising energy storage device.According to its special energy storage principle,the super capacitor was mainly divided into two kinds:（1）Double-layer capacitance（EDLC）;（2）Pseudo-capacitance.In order to make the prepared supercapacitor electrode material having high specific capacitance and good cycle life and other characteristics,and achieving the low cost and environmental-friendly,the experiment used biological template method to prepare a graphitized better and low cost of graphene.Graphene as the representative of the most advanced carbon materials,due to its high electrical conductivity,large surface area and superior flexibility.However,EDLC is still not sufficient for most energy storage devices.To address this problem,we chose the pseudo-capacitor electrode materials such as metal oxides（NiO,Co₃O₄,etc.）which were introduced and loaded onto the surface of graphene as the second-phase to integrate with their advantages through the complementary effect.The cycling stability of the graphene electric double layer capacitor and the high energy density of the pseudo-capacitance electrode material will result in a composite material having excellent electrochemical performance.The experiment of this paper is mainly divided into three parts.In order to obtain high specific capacitance,good cycle life super capacitor materials,the first part was the preparation and verification of electrochemical properties of Co-Ce@graphene: the graphene materials were prepared by high temperature calcination method,and the composite materials with Co₃O₄ and CeO2 were prepared by hydrothermal method.The second and third parts were preparation of Ni-Ce@graphene and Co-Ni@graphene,respectively.The results show that the maximum specific surface area of Ce-Co-Graphene is 364 m2/ g and the particle size is about 20 nm.The results of Electrochemical test show that: in the solution of 1 mol·L-1 Na2SO4,1 A/g of the current density,the material nano-particle loading of 80%,the resulting of composite has the highest specific capacitance of 220 F·g-1.Meanwhile,after 1000 cycles of charge and discharge tests,composites still have high electrochemical performance,and always maintained at 90%.Additionally,the maximum specific surface area of Ni-Ce@graphene was 262 m2/ g,and the particle size is about 40 nm.The results of Electrochemical test show that: in the solution of 1 mol·L-1 Na2SO4,1A/g of the current density,the material nano-particle loading of 80%,the capacitance was 180 F/g.And after 1000 cycles of charge and discharge test,the total capacitance remained at only 78%.Last but not least,the maximum specific surface area of Ni-Co@graphene as the load reached 312 m2/ g,and the particle size is about 10 nm.The results of Electrochemical test show that: in the solution of 1 mol·L-1 Na2SO4,0.5 A/g of the current density,the material nano-particle loading of 80%,the capacitance was 320 F/g,after 1000 cycles of charge and discharge tests,composites still show high electrochemical performance,maintaining at about 92%.Finally,results show that cannabis stalks template graphitized can successfully be used to prepare graphene material.The performance of Dual load material is also much better than a single load.It can be inferred,there is still a lot of room for development in the regulation of the type and proportion of metal oxide loads.According to the experiment,it is possible to find better metal oxides and even to achieve a composite loading of three different metal materials to improve the electrochemical performance or catalytic performance.