Preparation And Propreties Of Transition-Metal Oxides On Three-Dimensional Ordered Macroporous Cu Current Collectors As Anode Materials

Three-dimensional ordered macroporous?3DOM?materials owns many advantages such as large aperture,thin hole wall,highly ordered on three-dimensional space and structural stability.At the same time,it possesses the features of large specific surface area and the internal connection of the channel structure,which makes it to be an ideal substrate to frabicate high stability and high-energy lithium-ion battery.Transition metal oxides such as Fe₃O₄(928m Ah g^-1),CuO(640m Ah g^-1)and SnO₂(1494mAh g^-1)are widely used in the anode materials of Lithium-ion batteries,due to their numerous advantages for instance high reversible capacities,simple preparation process,natural abundance and non-toxicity.However,the poor electronic conductivity,and large volume change during cycling have seriously limited the cycle stability and rate performance of Lithium-ion batteries.In this paper,we proposed to construct a novel 3DOM Cu structure on the surface of Cu current collector and composited with transition metal oxides,in which way can strengthen the comprehensive performance of anode materials.The PMMA microspheres with uniform particle size were obtained by emulsifier free emulsion polymerization to fabricate colloidal crystal templates.Afterwards,we prepared3 DOM Cu/Fe₃O₄,SnO₂,CuO composite anode materials by using electrodeposition and immersion method.The phase and morphology characterization of the prepared samples were analyzed.And the electrochemical performance of samples were tested under conditions.In chapter 3,a highly ordered colloidal crystal template was prepared on Cu plate by electrophoresis.Then,the colloidal crystal was used as the template to let copper nucleat in the gap of PMMA microspheres by electrodeposition,afterward 3DOM Cu structure is successfully prepared on the copper surface.Through lots of experiments,the choice of additive during electrophoresis process,the current density and the time of electrodeposition,and the removal method of the template,all will have impact on the 3DOM Cu structure.The optimal condition for the preparation of 3DOM Cu structure is: adding PEG200 to increase the wettability of PMMA microspheres,the optimal deposition condition?current density of 6mA/cm2 for 5min?,and dissolving the PMMA microspheres by acetone,and then a well-structured 3DOM Cu surface can be obtained.In chapter 4,the 3DOM Cu/Fe₃O₄ composite anode material was prepared by electrodepositing on the copper current collector covered with 3DOM Cu structure.The influence of the presence of 3DOM Cu structure on the electrochemical performance of Fe₃O₄ anode material was also discussed.It was found that the composite material of 3DOM Cu/Fe₃O₄ showed excellent electrochemical performance,it delivers a stable capacity of 700 mAh g^-1 for up to 400 cyclies at density of 500 mA g^-1 and 466.7 mAh g^-1 at high rate of 4A g^-1.Which is significantly better than the pure Fe₃O₄ anode material.In chapter 5,3D porous Cu/CuO composite anode material was prepared by soaking oxidation method on the copper current collector coated with 3DOM Cu structure.However,the 3D porous Cu/CuO composite film showed no electrochemical performance improvement,but the pure CuO film electrode exhibited better capacity,cycle and rate performance because of its small and thin nanosheets that well contact with the collector.And the 3DOM Cu/SnO₂ composite anode material was fabricated by electrodeposition method.The results show that the electrochemical performance of 3DOM Cu/SnO₂ composite film is not improved compared with that of pure SnO₂ film without 3DOM Cu structure.But the surface porous structure of 3DOM Cu increases the electrical conductivity of SnO₂,so the rate performance is improved slightly.