Material Design And Electrochemical Performance Study Of Graphene/Manganate Composite Anode

ZnMn2O4 is a kind of functional material that is widely used in various fields,such as catalyst,sensor,electrical ceramic and in Biomedical Science.Because of the characteristic of wealthy sources,low-cost,high theoretical specific capacity,environmental friendly and non-toxic,ZnMn2O4 is recently recognized as a potential alternative material for lithium ion battery anode.However,with in-depth research going on,the disadvantages of ZnMn2O4 such as low conductivity and high volume effect during lithiation also emerge.These properties adversely affect its cycle life and rate capability that restrict its development.Aiming to improve the conductivity and volume effect of ZnMn2O4,studies have been done as follows.1.Prepared GO by improved Hummers method,and utilized simplified one-step hydrothermal method to compound single phase ZMO,then got five samples ZMO/RGO composites by adding varied volume of GO(0.5-5 ml)to investigate its effect and obtain the best additive amount.As a result,the grain size and aggregation phenomenon of ZnMn2O4 were reduced by adding GO,the specific capacity,cycle and rate capability were also improved in different levels.The sample with 1.5 ml GO showed the best electrochemical performance which had a first discharge specific capacity of 1415 mAh·g-1,and 85.8%conservation rate after 50 cycles.2.Prepared mesoporous ZnMn2O4 by coprecipitation and high-temperature calcination method.The first discharge specific capacity was 1423 mAh·g-1 when the calcination temperature was 600℃.To further improve,achieved synthesis of Ag/GO by salt balance method with Nano-Ag sol,then got ZMO/Ag,ZMO/Ag/RGO by coprecipitation.In consequence,the conductivity and rate capability of ZnMn2O4 were improved by adding the Nano-Ag particles,furthermore,the specific capacity was significantly increase with Ag/GO.The first discharge specific capacity of the synthesis of ZMO/Ag/RGO reached 1637 mAh·g-1 and the average discharge specific capacity was 710 mAh·g-1 at 1000 mA·g-1.3.By changing the solvent and precipitant in high-temperature calcination and solvent combined method,prepared three kinds of ZnMn2O4 with different appearance.According to the experiment results,ZMO showed the best performance with H2O and C2H5OH as solvent,and NH4HCO3 as precipitant.In that situation,the first discharge specific capacity was 1167 mAh·g-1.Based on this solvent method,prepared two kinds of synthesis of ZnMn2O4/Fe2O3 through in-situ growth and coherent growth methods,respectively.The results showed that the samples prepared by coherent growth methods had the best properties,which obtained a first discharge specific capacity of 1852 mAh·g-1 and a high conservation rate of 93%after 50 cycles.It resulted from the addition of Fe2O3 that strengthen the structure stability.