Preparation Of Multi-doped LiFePO₄/C Cathode Materials By Phosphating Slag

With the development of my country’s economy and the improvement of industrialization,most of the machinery manufacturing industry and steel enterprises in my country generally require metal anticorrosion coating,and the anticorrosion coating is usually completed by pickling and phosphating process.The metal surface treatment process usually uses a phosphating process.The white solid waste generated in the metal phosphating process is called phosphating slag.There are many ways to classify phosphating slag.According to the difference of phosphating solution,it can be divided into iron-based and manganese-based phosphating slag.The main components of iron-based and manganese-based phosphating slag are iron phosphate,manganese phosphate and zinc phosphate,and also contain a small amount of transition metal ions.At present,phosphating slag is classified as hazardous solid waste in China,and the treatment method of phosphating slag is mainly to be directly discharged.The direct discharge of hazardous solid waste phosphating slag in the environment will inevitably cause environmental pollution.For the resource utilization of phosphating slag,if manganese phosphate or iron phosphate can be extracted from the phosphating slag and used as the main raw material for preparing lithium iron phosphate and lithium manganese phosphate cathode materials,the The resource utilization of the main components can also solve the problem of high production cost of lithium iron phosphate cathode materials.In this paper,phosphating slag is a phosphate slag produced by a Zhejiang company as raw material,and ferric phosphate is prepared by hydrothermal purification.And study the ratio of different phosphoric acid and phosphating slag to purify and prepare iron phosphate.The conclusion is that the ratio of phosphoric acid: phosphating slag is 1:3,and the purity of iron phosphate obtained at a constant temperature of 150°C for 12 hours is the highest,and the electrochemical performance of the lithium iron phosphate cathode material is better.Lithium iron phosphate has the advantages of high theoretical specific capacity and good safety performance.Therefore,lithium iron phosphate batteries can be used in energy storage equipment,military fields,and so on.In addition,lithium iron phosphate has good cycle reversibility and lightness,and lithium iron phosphate batteries can be used in the fields of electronic products and new energy vehicles.Lithium iron phosphate as a cathode material hinders its application and development in power batteries due to its low electronic conductivity and small ion diffusion coefficient.The reason is that its poor rate performance is caused by defects such as low electronic conductivity and small lithium ion diffusion coefficient.The poor rate performance of lithium iron phosphate severely restricts the development and application of this material in power-type lithium-ion batteries.In order to solve the problems of low electronic conductivity and small lithium ion diffusion coefficient,most researchers currently use three general methods to improve its rate performance:reducing particle size,carbon coating,and metal element doping.Among these three general methods,metal element doping can significantly improve the rate performance of lithium iron phosphate cathode materials.Firstly,the phosphating slag is purified to prepare iron phosphate,and then the purified iron phosphate and chemical iron phosphate are respectively made into lithium iron phosphate button batteries,and then the electrochemical performance of the button battery is measured,and then the electrochemical performance is compared.In order to study the effect of metal ion doping on purified iron phosphate to prepare lithium iron phosphate battery cathode materials,manganese ions were first doped into the lithium iron phosphate battery material made of purified iron phosphate,and then the electrochemical performance of manganese ion doping was studied.Impact.The doping of different ions into purified iron phosphate was further studied,and then the mixture was used to make lithium iron phosphate button batteries,and the difference of lithium iron phosphate battery materials before and after doping was compared.This article first uses hydrothermal pickling method to purify solid waste phosphating slag to obtain purified iron phosphate,and the purified iron phosphate is mixed with carbon source,lithium source,etc.in a certain proportion,and the mixture is passed through a tube furnace at high temperature.The calcination method prepares the lithium iron phosphate/carbon composite material.Firstly,study the influence of manganese on lithium iron phosphate batteries,and secondly,the influence of manganese ion doping on the electrochemical performance of lithium iron phosphate battery materials made of purified iron phosphate.