| Lithium-ion batteries(LIBs)have high energy density,large specific capacity,small mass,small volume and long cycle life,is considered as energy storage devices with broad application prospects.Manganese oxide anode materials have great research value and application prospects because of their high theoretical specific capacity,low cost and friendly environmental effects.In addition,manganese oxide,as the cathode material of the next generation of safe and green energy storage water-based zinc ion batteries(ZIBs),has the advantages of high working voltage and high energy density.However,whether it is applied to LIBs or ZIBs,several problems of manganese oxide still hinder its practical application,especially the poor cycle performance caused by large volume changes during ion insertion/removal,and the poor rate performance caused by low conductivity.In view of these problems,this paper improves its electrochemical performance by nano-sizing it and combining it with carbon nanotubes with high conductivity.The research results mainly include:Firstly,designing the structure of manganese oxide according to its defects.Composite CNT with good conductivity and Mn O2 using hydrothermal method to obtain Mn O2@CNT compound,and then explore and optimize its electrochemical characteristics through a series of experimental conditions.The specific capacity batteries gradually increases after 120 times constant current charge and discharge at0.25 A g-1 and stabilizes around 1157 m Ah g-1 as LIB.The discharge specific capacity of Mn O2 in the ZIB has been significantly improved after recombination with CNT.The discharge specific capacity of Mn O2@CNT is about 56 m Ah g-1 after 300 times constant current charge and discharge at 0.5 A g-1 as ZIB and the average capacity loss per lap is about 0.31%.This preparation method of combining active materials and carbon nanotubes can be widely used in lithium/zinc ion batteries,further expanding the research scope of lithium/zinc ion battery materials.Subsequently,dual carbon nanotube structure with porous flexible electrodes CMn2O3@CNT is obtained by Mn O2@CNT electrode prepared and calcined in an argon atmosphere at 350 ℃ and have excellent electrochemical properties.The penetrating CNT skeleton can improve the conductivity and mechanical strength of Mn2O3.The porous network structure can alleviate the volume expansion and contraction of Mn2O3 during the reaction process,improve the stability of the electrode structure,and reduce the dissolution of manganese.Meanwhile,the CNT skeleton can disperse Mn2O3 particles,reduce agglomeration and facilitate electrolyte infiltration,shorten ion transport distance,and accelerate ion reaction kinetics.The discharge specific capacity of Mn2O3@CNT-CNT is about 720 m Ah g-1 after 1800 times constant current charge and discharge at 1.2 A g-1 as LIB.Its discharge specific capacity is about 264 m Ah g-1after 300 times constant current charge and discharge at 0.5 A g-1,about 102 m Ah g-1after 900 times at 1 A g-1 as ZIB.about 50 m Ah g-1 after 1800 times at 3 A g-1 and the average capacity loss per turn is only 0.0056% as ZIB.This preparation method of bipolar CNT materials can be extended to various types of composite materials,realizing the innovation of manganese oxide electrode materials for lithium/zinc ion batteries and further broadening its research scope.In summary,this paper takes manganese oxide electrode materials for lithium/zinc ion batteries as the main research content,broadens the research scope of lithium/zinc ion battery materials,and provides a new exploring methods for the research of manganese oxide electrode materials in lithium/zinc ion batteries. |
PDF Full Text Request