Preparation Of Graphene-based Manganese Oxides And Their Application On Lithium/Sodium-ion Batteries

The commercial lithium ion batteries which used graphite as anode can not meet the new demands of electronic industry because of the low theoretical capacity of 372 mAh g-1 for graphite,so it is urgent to explore other high performance materials to replace graphite.In recent years,due to the earth-rich and cheap sodium resourer,sodium-ion batteries have attracted great deal of attention.Among all the anode materials,owing to its high theoretical specific capacity,rich abundance and friendliness,manganese-based oxides have attracted special attention in lithium/sodium-ion batteries.In this work,a series of graphene-based/manganese oxides composites with different morphology and structure have been prepared by hydrothermal method and so on.When used as anode materials for lithium/sodium-ion batteries,these composites deliver outstanding cycling and rate performance.The main contents of this study are presented as follows:1.MnO nanowires/graphene(MnO/GR)composite is successful prepared using MnO2 as precursor though a simple two-step hydrothermal and calcination process.The MnO/GR composite exhibits better lithium storage performance:after 100 cycles,the composite still delivers a discharge capacity of 1006 mAh g-1 at the current density of 100 mA g-1.It also shows good sodium storage performance:after 100 cycles,the composite delivers a discharge capacity of 191 mAh g-1 at the current density of 50 mA g-1.2.Mn3O4/porous graphene(Mn3O4/pGR)composite is successful synthesized using MnO2 as precursor,glucose as carbon precursor,sodium chloride and silicon dioxide(SiO2)as templates.The Mn3O4/pGR anode delivers excellent lithium storage performance:the discharge capacity of the composite keep at 790 mAh g-1 after 100 charge/discharge cycles at the current density of 100 mA g-1,this value is 1.9 and 3.4 times higher than the discharge capacity of Mn3O4 nanowires and pGR.When used as an anode in sodium-ion batteries,Mn3O4/pGR exhibits a specific capacities of 229 and 232 mAh g-1 after 50 cycles,at the current density of 50 mA g-1,which 2.5 times higher than the discharge capacity of Mn3O4 nanowires(93 mAh g-1).3.Flexible CoMn2O4/graphene/CNTs(CoMn2O4/GR/CNTs)and Co3O4/graphene/CNTs(Co3O4/GR/CNTs)films are successfully prepared through a facile filtration strategy and a subsequent thermally treated process.When used as anodes for lithium batteries,these films can be pressed onto nickel foam without other conductive additive and binder which simplifying the manufacturing process.When using as anode in lithium ion battery,CoMn2O4/GR/CNTs film and Co3O4/GR/CNTs films exhibit perfect discharge capacities of 881 mAh g-1 and 863 mAh g-1,respectively(after 55 cycles,at the current density of 100 mA g-1).These value are-2 times higher than the discharge capacity of CoMn2O4 and Co3O4.