Design, Preparation And Lithium Storage Performance Of Transition Metal Oxide Anode Materials

Rechargeable lithium ion batteries?LIBs?with super electrochemical properties have been extensively applied in ubiquitous portable power source,such as electric cars,mobile phones and other convenient electronic products.However,due to the low theoretical capacity,the commercial graphite as anode material cannot meet the demand of high endurance and high capacity.Thus,it is urgent to seek the alternative anode materials with high capacities.Transition metal oxides,because of their high specific capacity,abundant reserves,environmental friendliness and ease of preparation,have become a research central issue in the field of electrochemical energy storage and are considered as the most promising electrode materials for lithium-ion batteries?LIBs?.Typically,cobalt-based transition metal oxide due to excellent theoretical discharge specific capacity,large tap density,low cost and wide spread availability,has attracted widespread attention as potential alternative anode materials in the fields of LIBs research.However,it can't be widely used because of its serious volume expansion during charging and discharging and low conductivity.Therefore,improving the conductivity and cyclic stability of TMOs materials are the key point to change the chemical properties.In order to obtain LIBs with excellent electrochemical performance,the composite materials with a certain structure can be produced by mixing transition metal oxides with porous carbon materials and multi-component transition metal oxides.It is of great significance to promote the application of LIBs in new energy vehicles and other fields.In this paper,the multi-component transition metal oxide composite materials and the transition metal oxides with certain structure and porous carbon composites are made by dealloying method and template method.As anode materials for lithium-ion batteries,their electrochemical properties have been studied.The main results are as follows:?1?NiCo₂O₄ dendritic nanporous structure are successfully synthesized by dealloying and high temperature annealing as anode material for LIBs to study its electrochemical properties.Bimetallic oxides NiCo₂O₄ can be prepared by dealloying Co₁₀Ni₂₀Al₇₀?at.%?alloys in aqueous NaOH solution in the presence of H₂O₂ and high-temperature annealing.The material is assembled into a dendritic nanporous structure with a nanoscale structure as the basic unit.Compared with the different reaction conditions,it is found that after the treatment of H₂O₂ and the reaction time of 64 h,the material has excellent cycling performances and outstanding rate capability.The anode showed the best rate capability and its average discharge capacities were1195.2,1067.5,940.4 and 691 mAh/g at current densities of 100,200,500,and 1000 mA/g,respectively.The higher discharge capacity of 1181 mAh/g could be delivered,when the current density reduced back to 100 mA/g.Under the current density of 100 mA/g,the specific capacity of 1016.9 mAh/g after 100 cycles.Therefore,Ni Co₂O₄ dendritic nanporous structure made by dealloying and high temperature annealing show excellent electrochemical properties.?2?OMC@Co₃O₄@G composite materials are made by using hard and soft template method and calcining at high temperature in inert atmosphere.As anode material of lithium-ion battery,its electrochemical properties are studied.The Co₃O₄ nanoparticles are uniformly embedded in the surface and the channels of one-dimensional mesoporous carbon,and then assembled in the two-dimensional layered structure of graphene.At the current density of 100mA/g,the first discharge specific capacity of OMC@Co₃O₄@G electrode is 1277.4 mAh/g,and the specific capacity of 100 cycles is 741.6 mAh/g.When the charge-discharge current density changes at 100,200,500,1000 and 2000 mA/g,the discharge specific capacity of OMC@Co₃O₄@G composite electrode is 785.2,740.4,619.1,489 and 331.3 mAh/g,respectively.Especially under the high current density of 2000 mA/g,its reversible capacity can reach 331.3 mAh/g,which is superior to other cobalt-based oxide loaded carbon materials.When the current density returns to 100 mA/g,its reversible capacity is 795.7 mAh/g.Therefore,the OMC@Co₃O₄@G composite material,shows excellent cycling performance and high-rate capability.