Morphologies Preparation And Electrochemical Properties Of Several Ternary Metal Oxides

Lithium ion batteries have many advantages,such as long cycle life,high working voltage,light weight,good energy density and friendly environment and so on.As an important energy storage and supply device,lithium ion batteries have been widely applied in portable electronic devices such as hybrid/electric vehicles and mobile communications.The performance of lithium ion batteries depends mainly on the selection of electrode materials and the structural design of the materials.The materials of unique structure have many advantages:high reactive activity,great transportation of charge and material,and structural stabilitiy to avoid collapse,which can effectively improve the performance of lithium ion batteries.Ternary metal oxides have become a kind of much promising electrode material because of its good electrochemical performance,environmental protection,low cost and so on.Therefore,the preparation and electrochemical properties of porous ZnMn₂O₄ rugby-balls,porous Co Mn₂O₄ microspheres and flower-like Zn Mn₂O₄ hollow nanotubes are studied in this paper.（1）Hierarchical porous ZnMn₂O₄ rugby-balls on Ni foam were first synthesized via a hydrothermal method and then an annealing process.The Zn Mn₂O₄ rugby-balls were composed of interconnected nanosheets of about 25 nm.The growth mechanism is also proposed.In addition,the unique structure of hierarchical porous ZnMn₂O₄ rugby-balls on Ni foam exhibited superior electrochemical performances including high specific capacity,long cyclic stability and good rate capability.At a constant current density of 100 m A g^-1,the initial discharge and charge capacities were 1584 m A h g^-1 and 1114 mA h g^-1 respectively,after 100cycles,the reversible capacity could remain 614 mA h g^-1.These results demonstrate great potential of hierarchical porous Zn Mn₂O₄ rugby-balls on Ni foam in advanced LIBs.Furthermore,this method may provide a novel route for the synthesis of a series of hierarchical porous ternary spinel oxides rugby-balls.（2）To deal with the large volume change for lithium-ion batteries（LIBs）,we illustrate the synthesis of CoMn₂O₄ microspheres with sub-nanoparticles by a hydrothermal method followed by thermal treatment.The size of microsphere is approximately 2.2μm,and the sub-nanoparticle is about 17 nm.There is sufficient void space between CoMn₂O₄microspheres with sub-nanoparticles for ensuring the well structural integrity.As advanced anode for lithium ion batteries,CoMn₂O₄ microspheres display stable specific capacity retention of 772 mA h g^-1 over 500 cycles at a current density of 100 m A g^-1.Such a kind of structure is beneficial for enhanced rate and cycling capabilities in LI Bs applications,which could increase contact area between electrolyte and active materials,short path for lithium ions and electrons,and accommodate the volume change with additional void space during cycling.It has a great application prospect to use as electrochemical energy storage because of the enhance performance.（3）The flower-like Zn Mn₂O₄ hollow nanotubes were firstly synthesized by a hydrothermal method and calcination treatment.The composition,morphology and structure were characterized and electrochemical performance was analyzed.The results showed that flower-like hollow nanotubes were obtained through calcination treatment,showing hollow structure about 8μm.The first charge and discharge capacity was measured at 2152/1263 mA h g^-1 when the current density at 400 mA g^-1.After 300 cycles,the capacity was up to 515 m A h g^-1 and corresponding to the coulombic efficiency of 99%,which exhibited preferable cycling performance.The stability of the structure was also shown by rate performance,which has been tested under different current density.The excellent electrochemical performance was shown resulting from its unique structure.