Preparation And Energy Storage Performances Of 3D Porous Graphene Networks-Based Composites

Supercapacitors and Lithium-Ion Batteries(LIBs),as classes of state-of-the-art energy storage devices,have been attracting intensive research interest recently because of their wide range of applications in electrical vehicles,digital devices,etc.Various carbon materials especially graphene is currently pursued as electrodes materials due to their high electrical conductivity,large specific surface area,and good capacitive performance.It is reported that the key to achieving high power in porous carbon electrodes is to reduce the ion transport time.Herein we reported a simple and pervasive way to obtain a 3D graphene with hierarchical porous structure(3D-HPG).Sodium chloride is used to support glucose growing on with the catalysis of ferric nitrate and potassium hydroxide are added to produce microspores during the pyrolytic process.The thickness of the carbon nanosheets are scalable along with the content of sodium chloride that can adjust the material into different applications.By this approach,a balance between large surface area,good conductivity and stability can be reached and when applied as electrode material for ECs,it performed high specific capacitance,high rate capability and long cycle life.When utilized as a supercapacitor,this 3D architecture exhibited excellent capacitive performance,namely,high rate capacitance retention(215 A g-1 at 0.5 A g-1,193 A g-1 at 10 A g-1,and 168 F g-1 at 50 A g-1),and good specific capacitance retention ability(after 5000 cycles,the capacitance retention still remains at 83.7%).Tin and cobalt are also added into the precursor to fabricate metal nano-particles coved 3D-HPG,and catalyzing in-situ growing of CNTs on the structure.The content ratio of tin and cobalt can influence the morphology and structure of the composite and has a further impact on the electrochemical performance.When used as LIBs anode,this composite exhibited high capacity.642 mAh g-1 at the current density of 0.2 A g-1,and achieved good rate performance.535,466,407,368,245 and 194 mAh g-1 were obtained at 0.2 C,0.5 C,1 C,2 C,5 C,and 10 C,respectively.