Preparation method of ferrous lithium phosphate cathode composite material

Abstract

The invention relates to a preparation method of a ferrous lithium phosphate cathode composite material. The method comprises the following steps: stocking a ferric iron-source compound, a lithium-source compound, phosphate, doped tantalum compounds and carbon black according to a certain proportion; firstly adding the ferric iron-source compound into an ultrafine ball mill so as to have the grain diameter of 100 nm to 500 nm by ball milling; then, adding other raw materials and using acetone as a dispersant for ball milling and mixing, drying in vacuum and sintering at a low temperature in an inert protective atmosphere oven to deacidize ferric iron; afterwards, adding a certain amount of conductive agent material to obtain ferrous lithium phosphate, ball milling, mixing and drying and sintering at a high temperature in the inert protective atmosphere oven; and finally, shattering, crushing and elutriating to obtain the ferrous lithium phosphate cathode composite material. The invention has the advantages that the materials ensure the tap density and can achieve favorable capacity and magnification performance, and secondary sintering enables the carbon coating to be more even and the granular magnification to be better.

Description

Technical field [0001] The invention relates to a method for preparing a lithium iron phosphate positive electrode composite material. Background technique [0002] Since the advent of lithium ion secondary batteries in the 1990s, they have developed rapidly due to their irreplaceable advantages. Cathode material is the main component of lithium ion secondary battery, the material currently mainly includes LiCoO 2 , LiMn 2 O 4 And LiFePO, which is currently a research hotspot 4 material. LiCoO 2 Due to its insufficient high-temperature safety performance and the scarcity of metal cobalt, it is restricted in the application of high-power and large-capacity power batteries; LiMn 2 O 4 Due to its poor high-temperature cycle performance and safety performance, it is also insufficient in application; LiFePO 4 (Lithium iron phosphate) has become one of the most promising cathode materials due to its advantages such as good cycle performance, moderate voltage platform, stable discharge,...

AI Technical Summary

Problems solved by technology

In the production of lithium ferrous phosphate, ferrous iron and ferric iron are mostly used as iron sources. Lithium ferrous phosphate made from ferrous iron sources has good electrochemical performance, but the tap density is low, and ferrous iron sources such as oxalate The iron content of iron, ferrous acetate, etc. is low, and the cost of raw materials is high; the discharge capacity of lithium ferrous phosphate made from ferric iron source is low, mainly because the mass of iron ions is large and difficult to diffuse, so that the surface and internal iron of the particles The concentration difference of ferrous salt is large, which affects its capacity, but the advantage is that the tap density is higher, and the material cost is about half lower than that of ferrous salt.