Preparation And Electrochemical Performance Of Manganese Oxide Nanocomposites

Owing to high energy density,light in mass,cost-effective,environmental benignity and long cycle life,lithium-ion batteries have attracted widespread concerns in society,which become more and more important about environmental issues and energy problems.Electrode material is the key to lithium-ion batteries,which performance determines the main indicators of lithium-ion batteries.In this paper,when we used manganese oxide as the main research object,we adoped different methods to synthesis nanomaterial oxides with various morphologies.Then,a series of nanocomposites were simply prepared by compounding with graphene and carbon nanotubes.This method was not only costed lowly and operated simply,but also easily regulated the morphologies of the manganese oxide.While the nanocomposites with graphene and carbon nanotubes can effectively improved the conductivity of the manganese oxide and avoid the massive agglomeration of the two components.The main research results were as follows:1、Nanorod Mn₃O₄@GNS nanocomposites using graphene and MnSO₄·H₂O as precursors were synthesised by a simple,effective,extensive solvothermal method.Besides,we investigated the effects of different ratios on the nanorod Mn₃O₄@GNS nanocomposites.When the the content of graphene was 35%,it showed a maximum reversible specific capacity of 1155.2 mA h g^-1 at 100 mA g^-1,and the extraordinary cycling stability,with no decay in capacity for up to 100 cycles.After 40 cycles the nanorod Mn₃O₄@GNS-3 5 can exhibited a high reversible specific capacity of 431.9 mA h g^-1 at 800 mA g^-1,showed great rate performance。2、3D rGO/CNT/Mn₃O₄ nanocomposite was prepared by a very simple two step method.During this process,the rGO/CNT was prepared by chemical reduction,which could act as a conductive substrate.Subsequently,we adopted a very effective method to make nanoparticle Mn₃O₄ anchored on rGO/CNT conductive substrate.With the rGO/CNT conductive substrate added,the specific capacity gradually rised.After 100 cycles,the reversible specific capacity of 3D rGO/CNT/Mn₃O₄ nanocomposite was 1338.4 mA h g^-1 at current density of 100 mA g^-1.Furthermore,the specific capacity of 3D rGO/CNT/Mn₃O₄ nanocomposite increased from 1093.8 mA h g^-1 at 100 mA g^-1 to 607.8 mA h g^-1 at 2000 mA g^-1.When the current density rebacked to 100 mA g^-1,the reversible specific capacity of 3D rGO/CNT/Mn₃O₄ nanocomposite rebounded to 1080.5 mA h g^-1,it reveals good rate stability.3、Nanoflower manganese dioxide/graphene（MG）was prepared using MnSO₄·H₂O and KMnO₄ as the manganese sources,and graphene as carbon source through a simple hydrothermal method.The MG-2（the addition amount of MnSO₄·H₂O was 0.0704 g）reveals the high reversible specific capacity and excellent cycling stability.After 230 cycles,the reversible specific capcacity of MG-2 was 1198.7 mAh g^-1 at a current density of 100 mA g^-1.At the current density of 1600 mA g^-1,the specific capcacity of MG-2 was still retains 368.3 mA h g^-1.When the current density rebacks to 100 mA g^-1,the specific capacity rebounded to 725.5 mA h g^-1.it exhibits good rate performance and the excellent structure stability.