Synthesis, Structure And Properities Of Sulfate Polyanion Group Cathode Materials For Sodium-ion Batteries

The uses of renewable energy (URE) attract much attention due to increased energy demand and environment issues. While the key for URE is the development of large-scale electrochemical energy storage devices. In the past two decades, the Li-ion batteries (LIBs) have been developed very well and used extensively for electronics, hybrid vehicles and grid-power storage. But with the increase of LIBs demand, the limited lithium resources become a new big problem. Development of sodium storage materials has become an important research project.Traditional sodium-ion batteries cathode material is in the form of the transition metal oxide, in recent years polyanion cathode materials become a hot research area on lithium-ion and sodium-ion battery electrode materials, compared to other cathode materials, polyanion cathodes have higher voltage and higher thermal stability, because of the inductive effect. According to the anionic species, we can divided cathode materials to phosphate type, silicate type, borate type and sulfate type cathode material.Anion groups can have the function to support and stabilize the compound crystal structure, anion with oxygen atoms formed covalent bond so that improves lattice stability, simultaneously increasing the safety of the material. Sulfate materials is my topic main research direction, compared with phosphates, they exhibit higher electrode potential because of the higher electronegativity and more ionic S-O band.We synthesized an new sulfate polyanion group Cathode material which have three-dimensional network structure by solid state reaction,the crystals can be obtained by cooling the melt of samples. Stoichiometric amount of reagents (Na2SO4: MnSO4-H2O=1:3 in mole ratio) were mixed homogeneously annealing at 500? for 9hours,a light pink Na2Mn3(SO4)4 polycrystalline powder was obtained.XRD and FTIR were used to characterize the physical properties of the prepared products. Furthermore, electrochemical performance of the sample materials were investigated, such as EIS and magnetic properties, and calculated the open circuit voltage. Based on the above investigation results, we changed the ratio of metal ions, Stoichiometric amount of reagents (Na2SO4: MnSO4·H2O=1:1 in mole ratio) were mixed homogeneously annealing at 700? for 6hours,a light yellow Na2Mn(SO4)2 polycrystalline powder was obtained.XRD and FTIR were used to characterize the physical properties of the prepared products. Furthermore, electrochemical performance of the sample materials were investigated.