| Among these electrochemical energy storage technologies,Li-ion batteries stand out because of their high energy density,high power density and long cycle life.However,Li resources in the earth crust is relatively scarce.As a result,sodium gained more attention.For the first,it is rich in resources and is widely distributed in earth.Secondly,sodium and lithium belong to the same main group,they have similar physical and chemical properties.All in all,sodium ion batteries can be used as a novel low-cost electrochemical energy storage technology,which can substitute for lithium ion batteries in the future in large-scale energy storage field.In this thesis,two layered metal oxides used as cathodes for Na-ion batteries are studied as follows:?1?A new cathode material with pure anionic O redox couple was studied in-depth,include designation,syntheses and characterization.And we found P-type layered metal oxides have better performance on the anionic redox reaction.After introduce Zn in the structure,we designed a P2-Na0.68Zn0.28Mn0.72O2,which exhibits exceptionally high charge capacity.The material has high air stability and can be stored in air;There is a reversible capacity of about 150 mAh g-1 between 2.0-4.2 V,the charging platform is located at 4.1 V in the first cycle,which corresponds to the P2-OP4 phase transition process,and returns to the initial state after discharge.XPS test results show that it has a highly reversible anion redox reaction,and has good rate performance and cycle performance.?2?Deep research and study on cathode material of O3-NaFeO2 doped with transition mental of Cu and Mn was also carried out.A two-phase mixed cathode material NaCu0.1Fe0.1Mn0.8O2 was obtained,which shows a reversible capacity of 110mAh g-1 in the voltage range of 2.0-4.0 V.This provides a direction for the study of new cathode material. |
PDF Full Text Request