Study On Lithium Storage Of Mn-Co-based Metal Organic Framework Derireved Materials

Lithium ion batteries(LIBs)has improved for many times,they have been closely related to the modern life.The increasing demand of better performance for the new generation of lithium ion batteries,such as higher battery life and much more safety.It is certain that electrode materials can influence the performance of lithium-ion battery.My research focus on anode material of lithium ion battery via metal organic frameworks(MOFs)materials,and the design of various shapes.With the composite material of MOFs was prepared,followed by carbonation,the oxidation of cobalt and manganese and MOFs-derived carbon composite nanomaterials were obtained.Thanks to the unique characteristics and structures,these materials shown excellent performance when they as anodes for lithium-ion batteries.The research can be divided into three parts,as it shown below:(1)Firstly,ZIF-67 grew on the surface of Mn O₂ nanorods.Then,ZIF-67 was transformed into NC/Co carbon layer and cobalt nanoparticles which distributed in the carbon after carbonation.At the same time,the carbon layer covers Mn O nanorods,such a structure can effectively alleviate volume expansion.The synergy is maximized by setting the molar ratio of cobalt and manganese.Cobalt nanoparticles played a role in regulating the solid electrolyte interface(SEI).This electrode showed a capacity of 1277.8 m Ah g^-1 when it cycled 300 times at200 m A g^-1.(2)By using hydrothermal method and functionalized with polyvinylpyrrolidone,the rod-shaped Mn-BTC(manganese as metal and trimesic acid as organic ligand)was prepared.Then,ZIF-67 grew with Mn-BTC attached to its surface.After carbonation,a cobalt oxide dodecahedron coated with a carbon layer derived from Mn-BTC was obtained.Compared with carbonized Mn-BTC,the former showed better morphology and electrical properties.Due to the support of the regular dodecahedron structure,Mn O-NC/Co showed a capacity of 1045.6 m Ah g^-1 after 100 cycles at 200 m A g^-1.(3)A bimetallic organic framework material(Co-Mn-BTC)containing cobalt and manganese was synthesized using cobalt acetate,manganese acetate and trimellitic acid.Followed by carbonation,hollow carbon spheres which contain cobalt and manganese oxides ware obtained.In addition,by adjusting the ratio of cobalt and manganese,the relationship between its electrical properties and particle size was concluded and analyzed.The optimal ratio of electrode material illustrated a capacity of 1088.5 m Ah g^-1at 1000 m A g^-1 after 600 cycles.