Preparation And Capacitance Energy Storage Performance Of Manganese Oxide Aerogel Complex

As a new energy storage device,supercapacitor has the characteristics of safety,environmental protection,high power density and long service life.As a transition metal oxide,manganese oxides have received extensive attention due to high specific capacitance,rich valence state,abundant raw materials,and environmental friendliness.However,the application of manganese oxides electrode materials is severely restricted by the low electric conductivity and sluggish redox reaction rate.The nanostructured design of the manganese oxides has been employed to increase the redox reaction rate.Manganese oxides aerogel has attracted extensive attention due to their interconnected 3D porous skeleton.Benefiting from the special structural characteristics,manganese oxides aerogel exhibits abundant exposed active sites shortening the ion diffusion paths,which facilitate the electrochemical kinetics and achieve high capacitance and fast energy storage.In order to improve the low conductivity of manganese oxides,compositing nanometer-sized manganese oxides with conductive carbon materials is an effective method.Bamboo grows rapidly,and the bamboo charcoal is a promising material in supercapacitors due to its porous structure,good conductivity,abundant raw materials,and environmental friendliness.Nevertheless,the tightly and uniformly anchor of manganese oxide nanoparticles on carbon substrates remains a challenge because of the poor interfacial compatibility between the polar manganese oxides and the non-polar carbon materials.Herein,the polyaniline layer is designed as a coupling bridge to improve the interfacial compatibility of the carbon/manganese oxide composite material,and a ternary composite with stable structure is prepared.The polyaniline layer contains s and good conductivity,which is beneficial to the uniform anchoring of manganese oxide nanoparticles on the porous carbon substrate.The polyaniline layer with crosslinked networks not only possesses good electrical conductivity,polar amino groups and non-polar benzene ring,but also enables high interface compatibility for anchoring Mn3O4 nanoparticles.The prepared electrode material with excellent performance is assembled into an asymmetric supercapacitor,thereby obtaining an energy storage device with high energy density.The activated carbon(AC)was prepared by chemical activation of the natural bamboo using potassium hydroxide.Using manganese nitrate aqueous solution as manganese source,citric acid as template agent,1,2-propylene oxide as gelling agent,and the AC as composite component for the preparation of activated carbon/manganese oxide aerogel complex(AC/Mn3O4).The effects on the morphology and electrochemical properties of AC/Mn3O4 was studied by SEM,TEM,XPS,XRD,GCD,CV and EIS.The results show that AC/Mn3O4 achieves a high specific capacitance of 325 F g-1 at 0.5 A g-1,188 F g-1 at 20 A g-1,and the specific capacitance is reduced by 15.1%after 10,000 cycles at 5 A g-1.The activated carbon/polyaniline composite(AC/polyaniline)was synthesized by a dynamic interfacial polymerization of aniline using ammonium persulfate as oxidizing agent.With different content of AC/polyaniline as the composite component for the preparation of activated carbon/polyaniline/manganese oxide aerogel complex(AC/polyaniline/Mn3O4).The mechanism of the effect of polyaniline layer on the morphology,electrochemical performance of AC/polyaniline/Mn3O4 was studied by SEM,TEM,XPS,XRD,GCD,CV and EIS.The results showed that the crystal structure of manganese oxide aerogel is Mn3O4 and the manganese element were+2 valence and+3 valence.The AC/polyaniline/Mn3O4 with 2%AC/polyaniline content has the most excellent electrochemical performance,it achieves a high specific capacitance of 352 F g-1 at 0.5 A g-1,remarkable rate performance of 248 F g-1 at 20 A g-1,and good cycle stability with 90.1%capacitance retention after 10,000 cycles at 5 A g-1.The polyaniline-mediated strategy shows great potential for improving the interfacial compatibility and preparing high performance electrode materials.An asymmetric supercapacitor is assembled by using AC as a negative electrode and AC/polyaniline/Mn3O4 as a positive electrode.The electrochemical performance of this energy storage devices was studied by CV,EIS,GCD and so on.The energy density of this asymmetric supercapacitor can reach 25.8 Wh kg-1 and maintains 16.8 Wh kg-1 at a high power density of 8.7 kW kg-1 in an operating potential range of 0-1.5 V.And,the specific capacitance decreases to 65%of the original value and the coulombic efficiency remains 100%after 8000 cycles at 5 A g-1.Compared to most manganese oxide-based supercapacitors,this device has better electrochemical performance.The study suggests that the low-cost and high-performance activated carbon/polyaniline/Mn3O4 has broad application prospects in electrochemical energy storage fields.