Preparation Of Iron Molybdate Hollow Microspheres And Its Application In Sodium Ion Batteries

High-efficiency storage technologies and equipment have received widespread attention due to their growing demand.Sodium-related energy storage systems?such as sodium ion batteries?SIB?and sodium ion capacitors?SIC??are considered to be future candidates for large-scale energy storage technologies and equipment because of their rich sources and low cost.In the past decades,in order to promote the development of sodium-related energy storage systems,researchers have made many efforts,including optimization of structure and composition,modification of effective materials,and design and exploration of new materials.O4)3 is a superconductor of Na⁺,and its structure has an ideal Na⁺transmission channel.Compared with olivine and layered materials?such as Na Fe,?,it is more suitable as a cathode material for sodium ion batteries.However,due to the poor electronic conductivity and long ion transmission channels of this material,its electrochemical power and electrochemical performance have great limitations and are limited in applications.Hollow microspheres with core-shell structure are widely used in electrode materials,and show excellent electrochemical performance and unique structural advantages.In this paper,firstly,ammonium molybdate and ferric chloride were used as raw materials to prepare and synthesize ferric molybdate materials by co-precipitation-high temperature calcination.The effects of raw material ratio and calcination temperature on the synthesis of ferric molybdate were studied.The comprehensive thermal analysis established Burning system.The best Mo/Fe is 1.5:1,the best firing system is:calcination temperature500?,heating rate 5?/min,holding time 30min,high purity iron molybdate with particle size of tens of nanometers Particles.Taking the raw material ratio and synthesis conditions prepared by ferric molybdate as reference,O4)3 hollow microspheres were prepared by carbon sphere order template method and self-assembly method.First,using glucose as a carbon source to synthesize carbon microspheres with a particle size ranging from 300 to 500 nm through hydrothermal reaction;then using carbon microspheres as a hard template to adsorb Mo O4^2-and Fe³⁺chelated by citric acid;Iron molybdate hollow microspheres.The best raw material ratio is Mo/Fe=1.7,the best firing system is:calcination temperature 450?,heating rate 1?/min,holding time 30min,single-shell and multi-shellO4)3 can be obtained.The experiment microspheres.It was found that with the extension of the adsorption time,the specific surface area of the sample increased from 9.30m²·g^-1 to 20.1856m²·g^-1,and the sample increased the number of pore,which pore size is from 10 to 100nm.And the pore size distribution of the sample is also improved.UsingO4)3 hollow microspheres as the positive electrode material for sodium ion batteries,due to its hollow internal free volume and large specific surface area,it can make the electrolyte contact with the electrode material more fully and provide more redox.The active site shortens the ion and electron transmission channels and eases the volume expansion caused by the insertion and extraction of Na⁺during the charging and discharging process.Therefore,O4)3 hollow microspheres have better electrochemical performance.When the adsorption time is 10h,the first charge specific capacity ofO4)3 hollow microspheres is 373.2m Ah·g^-1,the discharge specific capacity is418.5m Ah·g^-1,and the cycle stability is good(After 120 cycles,while the current density is0.1A·g^-1,the specific capacity remains at 214.2m Ah·g^-1);the rate performance has been greatly improved,and it still has a higher charge-discharge specific capacity at a high rate,and the discharge specific capacity is greatly attenuated Reduced(at 0.8A·g^-1 current density,the attenuation is reduced from 77%to 27.07%);In addition,the unique core-shell hollow structure reduces the charge transfer resistance and ion transmission resistance,making the overall AC impedance of the battery It becomes smaller,which improves the electrochemical performance of iron molybdate material well.