Research On The Performance Of Carbon Composite Manganese Oxide Lithium-ion Hybrid Supercapacitors

Advanced energy storage systerms are urgently needed with the rapaid developement of electric vehicles and portable electronic devices.Hybrid lithium-ion supercapacitors combine the both advantages of supercapacitors and lithium-ion batteries,making them very attractive for high power and high enrgy applicaions and thus they are being intensively investigated recently.However,battery-type electrodes shows mismatched issues with the supercapacitor electrode owing to the low rate performance and cycling stability of battery-type electrode materials,which hinders their pratical applications.Here,the lithium-ion storage performance of manganese oxide-based electroactive materials are investigated.Carbon-based materials were used to composite with the manganese oxides,which can reduce the agglomeration,buffer the volume change of manganese oxide during charging and discharging process,improve the reaction kinetics and stability of manganese oxide,and thus solve the mismatch issue of manganese oxide with the capacitive materials.The main research contents are as follows:?1?The rGO has been used to prevent the MnO from agglomeration and improve its conductivity,resuling the electrode material achieves higher specific capacity,rate performance and cycle life.Ammonia and NaOH were used as precipitants to prepare uniformly composite MnO nanoparticles on the graphene surface.Two composite materials,MnO/rGO_-NH3·H2O and MnO/rGO_-NaOH,were synthesized.The surface dispersion of graphene and the granular distribution of MnO prevent the agglomeration of MnO and buffer the volume change during charge and discharge,so that the composite electrode material exhibits good lithium ion energy storage performance.Both MnO/rGO_-NH3·H2O and MnO/rGO_-NaOH show higher specific capacity,rate performance and cycle life than pure MnO samples.Compared with MnO/rGO_-NH3·H2O,MnO/rGO_-NaOHNaOH samples show better energy storage performance due to the more uniform spatial distribution and smaller size of MnO particles.?2?Manganese-containing metal–organic framework?MOF?has been sued as the precursor to prepare MnO/C composite electrode materials,which shows improved cycling stability and rate performances.The manganese-containing MOF was prepared by using trimellitic acid as the organic ligand,and the resulting MOF was transformed into MnO/C composite electrode material by annealing at high temperature.MnO/C composite has a porous hollow spherical structure with protrusions on the surface,which can provide a larger specific surface area.The carbon matrix buffers the volume change of MnO during charging and discharging to improve its cycle stability,which can also reduce the charge transport resistance of MnO and thus improve its rate performance.?3?The lithium ion energy storage properties of different manganese oxide composite electrode materials were studied.Mn₃O₄/rGO composite was synthesized by reducing KMnO₄ in the presence of graphene oxide.Mn₃O₄ was grown into nanoparticles and they are anchored on rGO nanoclusters.The rGO effectively prevents the agglomeration of Mn3O4 and improves its conductivity.The Mn3O4/r GO composite electrode shows a higher lithium ion storage capacity and cycle stability than MnO/rGO and pure Mn₃O₄ electrodes.The Mn₃O₄/rGO has been used as the negative electrode material to assemble lithium ion hybrid supercapacitor with activated carbon,and the device exhibits excellent cycle stability.