Study On Prepartion Of Lithium Ferrite With Waste Lithium Iron Phosphate Batteries

The21st century is named the era of energy, while the depletion of resource is a serious problem facedby all the human beings living in this world. Accompanied with the increasingly acute problem of energy,meanwhile, environmental degradation can not be neglected. In order to relieve the pressure of energy andthe environmental problem, no one in the world does not need to promote high-efficient clean electricvehicles. With the development of the electric vehicles, lithium iron phosphate as a cathode material ofpower battery has been widely used, leading to the increasing number of waste lithium iron phosphatebattery year by year. Taking full advantages and reusing of these waste batteries can not only reduceenvironmental pollution but also promote the development of new industries which can bring considerableeconomic profits. While the study of recycling and reusing of lithium iron phosphate battery still lack sofar.Recycling of spent lithium-ion battery research has focused on the recycling of the battery cathodeactive material. In this paper, systematic researches on recycling and reusing of spent lithium-ion batterywhich used LiFePO4as cathode material are made. In the first place, make research on the separation ofcathode active material and aluminum foil, next in use hydrochloric acid as solvent to dissolve cathodeactive material, finally use the method of Sol-Gel to make high value-added lithium ferrite materials.Doping Mn and Zn to improve the property of the product are put forward into these foundation. Inaddition, XRD、IR、SEM、TG-DSC and VSM techniques are used to characterize in the experimentalprocess.Past research has shown that by calcining under nitrogen protection about2h at400℃,the cathode of spent LiFePO4lithium-ion battery can perfectly remove the adhesive—PVDF. The optimal conditionsof using hydrochloric acid as solvent to dissolve the cathode active materials: the concentration ofhydrochloric acid is Vol（HCl）: Vol（H2O）=1:5, solid-liquid ratio is100g/L, the temperature is60℃andthe reaction time is30min. The optimal conditions of synthesizing lithium ferrite use sol-gel method: themolar ratio of citric acid to the total metal ions is1:1, the pH value of the solution is6, the calcinedtemperature is800℃, the calcined time is3h. The magnetic parameters of lithium ferrite made by thismethod are as follows: saturation magnetization (Ms) is53.372emu/g, coercive force (Hc) is101.07G,remanent magnetization (Mr) is13.387emu/g.The dopant of Mn2+、Zn2+not only do not change the spinelstructure of the lithium ferrite, but also increase the magnetic properties of the lithium ferrite. Theimprovement of its magnetic properties is most obvious when Zn2+was doped.In this paper, the innovation is: the lithium ferrite with spinel structure were synthesised by sol-gelmethod with the waste lithium iron phosphate batteries, and the best prepareing conditions were studied．In this study, we put forward a new development direction for the recycling and reusing of spentLiFePO4, it will make a certain guiding significance in this field. Our study can also provide some usefulbasic information for the industrial application, which not only has high theoretical significance and goodapplication prospect, but also can make huge contribution to taking full advantage of resources andenvironmental protection.