Using Colloid Electrostatic Self-assembly Process To Fabricate Mn₃O₄/Graphene Composite For Energy Storage

In this research, a facile and novel route was successfully developed to prepareelectrode composite material for supercapacitor and lithium ion battery.Thecomposite was synthesized via a colloidal electrostatic coassembly process driven bythe electrostatic force between the positive metallic oxide colloidal particles andnegative GO sheets, followed aftertreatment. The metallic oxide nanoparticlescooperating with graphene were found well-dispersed on graphene sheets, thusimprove the performance of composite. The modified graphene nanocomposite whichhas more excellent performance and mixed effect could be applied in many fieldssuch as supercapacitors, lithium-ion batteries, catalysts, solar cells,etc.The reactionoccurred in aqueous solution, so it was low cost, energy saving, simple technologyand easy to industrial production.Firstly，the Mn3O4/rGO nanocomposite was prepared via a colloid electrostaticself-assembly process following heat treatment. The similar combination occurreddriven by the positively charged Mn3O4colloidal particles and negatively chargedgraphene oxide (GO) sheets. Mn3O4/rGO composite (MGC) was obtained afterreduction of GO at500℃for5h under N2. It was found that Mn3O4nanoparticleswith small size dispersed uniformly onto the surface of reduced graphene oxide (rGO)sheets. The MGC composite exhibited a specific capacitance of134F/g in1MNa2SO4aqueous electrolyte and a good rate property. The results showed that theMGC prepared via this method could be used as electrode material for highperformance supercapacitors.On the basis of above, we wrapped composite with carbon to improve itsperformance. Using sucrose as the resource of carbon to wrap precursor not onlyimproved the conductivity of composite effectively, but also controlled the particlesize of composite. The preparation of the Mn3O4/GO composite occurred driven bythe positively charged Mn3O4colloidal particles and negatively charged grapheneoxide (GO) sheets via a colloid electrostatic self-assembly process. Then sucrose of different mass were added. The mixture was putted into ultrasonic bath for5h. Afterthat，the precipitate was centrifuged，dried and grinded. The C/Mn3O4/rGO wasobtained after heating to500℃for5h under N2.We assessed the electrochemicalperformance of composite when it was used as electrode for supercapacitor andlithium ion battery. The composite exhibited a specific capacitance of233F/g forsupercapacitor. Its first charge/discharge can reach983.5mAhg-1while366mAhg-1when stable and it have a good cycle stability.