Fe₃O₄-carbon Nanomaterials Compounds Preparation And Their Properties As Cathode For Lithium Air Battery

Lithium-ion battery is one of the most widely used energy storage equipment,but the energy density of lithium-ion battery is far less than the need of future power battery.Thus,the study of high energy density battery is focus of current research.Lithium-air battery has attracted lots of attentions owing to its high energy density and environmental-friendly property,whereas its disadvantages are obvious,such as the cathode failure caused by deposition of discharge product,corruption of lithium metal and inefficiency of cathode.While the improvement of cathode play essential part to solve the problems of lithium-air battery.Hence,this paper introduced a serials of composition of Fe₃O₄ and carbon nanomaterials as cathode for lithium-air battery.In this paper,Fe₃O₄/CNT composition was fabricated through a facile reflux method,and the factors of it were explored.According to the physical characterization,the composition interconnecting with each other forms network structure.The Fe₃O₄/CNT composition performed a specific capacity about 7200 mAh/g as the cathode for lithium-air battery using a current density of 0.5 A/g.The analysis by SEM of the cathode after discharge shows the discharge products grow along with the network structure,which prevent from blocking the transfer of oxygen and improve the performance of cathode.In this paper,Carbon nanotubes?CNTs?reinforced three-dimensional?3D?graphene foams with large specific surface areas and splendid flexibility were developed through a facile coating and template chemical vapor deposition?CVD?method,which denoted as 3D rebar graphene foams.During the procedure of CVD,the nickel foams served as both templates and catalysts.Meanwhile,the CNTs which were spin-coated on nickel foams worked as reinforcing bars and generated covalent bonding with the graphene substrates,resulting in a strong conjunction to alleviate the collapse when the nickel substrate were removed.After removing the Ni foams templates,the composite foams show many excellent features,such as long-range elasticity and high conductivity.Here we carried out an in-situ tensile test upon 3D rebar graphene foams through a scanning electron microscope which has a built-in micromechanical device.After stretching a serial 3D rebar graphene with graded addition of CNTs,the mechanical enhancement of 3D rebar graphene foams can be illustrated.And the Raman spectrum characters proved that the 3D graphene foams do comprised of few layers,and a certain amount of defects.Moreover,the 3D rebar graphene foams perform a specific capacity over 1,2000 mAh/g at the first discharge at a current density of 500 mAg^-1 on lithium-oxygen battery with DME electrolyte,and 7200 mAh/g with TEGDME electrolyte.Thus it can work as a promising electrode material for the energy storage devices requiring large specific surface areas and flexible conductive 3D structure.In this paper,N-doped 3D rivet graphene was prepared using the 3D rebar graphene as above.After coating and carbonizing,an array uniformly distributed on the surface of graphene.A series of characterization were carried out to demonstrate the excellent properties of Fe-N-C structure of it.The lithium-air battery with a N-doped 3D rivet graphene cycle 30 times with slight decay at a current density of 0.5 A/g and a fixed specific capacity of 1000 mAh/g.