Research On Preparation Of Cathode Materials For Magnesium Ion Batteries With Forsterite

Forsterite contains elements such as Mg,Si and Fe.It is of great significance to comprehensively utilize forsterite to convert it into products with high added value.Magnesium-ion batteries have the advantages of high safety,large capacity,and abundant magnesium resources,which have attracted widespread attention.Synthesis of magnesium ion battery cathode material with forsterite as raw material has broad application prospects.The forsterite sand was pretreated by acid dissolution method,the dissolution effects of hydrochloric acid,nitric acid and sulfuric acid on forsterite sand were comparatively studied.The phase structure of the dissolved solid residue was characterized by SEM,EDS and XRD.It was shown that nitric acid has the best effect to dissolve forsterite.The mother solution obtained by dissolving forsterite in nitric acid was used to prepare the precursor synthesized by the sol-gel method,which was calcined to prepare the cathode material for magnesium ion batteries.The influences of calcination temperature and iron-manganese ratio on the phase structure,surface morphology and electrochemical properties of the materials were discussed.The results show that spherical Mg-Fe-Mn composite oxides were obtained from precursors calcined at 500℃～600℃.The higher the calcination temperature,the better the crystallinity,but the degree of agglomeration became greater.The cyclic voltammetry characteristics,capacity-voltage relationship,rate impedance performance of the obtained materials were comprehensively analyzed to determine that 550℃was the optimal calcination temperature.The change of the iron-manganese ratio in the composite oxide had no effect on the morphology,but will change the unit cell structure of the material.Comparing the electrochemical properties of the cathode materials for magnesium ion batteries synthesized with different iron-manganese ratios,the material obtained with iron-manganese ratio of 3:17 had the best electrochemical performance,which had 77.83%of the capacity retention rate after 1000cycles.The aqueous magnesium ion hybrid battery was assembled using the obtained material.At the current density of 0.5 A·g^-1,the specific capacity of the battery was up to62.5 m Ah·g^-1,and the capacity retention rate after 1000 cycles was 65.79%,which showed good battery performance.Based on the above research,a new technology for comprehensive utilization of forsterite was proposed to convert waste forsterite into a high value-added magnesium ion battery cathode material,and a preliminary exploration of the process was carried out,which provided new ideas for subsequent process development.Figure 48;Table 3;Reference 94...