Production process of lithium iron phosphate cathode material and three major raw materials: lithium carbonate, phosphoric acid, and iron

Lithium iron phosphate cathode material is a type of cathode material used for lithium-ion batteries.

 It is composed of lithium iron phosphate, conductive agents, adhesives, etc.

 Lithium iron phosphate cathode material has the advantages of high energy density, long cycle life, and high safety, 

and is widely used in fields such as electric vehicles and energy storage systems. 

In the production process of lithium batteries, the positive electrode material is one of the key factors affecting battery performance. 

Among them, lithium carbonate, phosphoric acid, and iron are the three important raw materials for preparing LEP positive electrode materials. 

This article will start with the performance of lithium iron phosphate and the production process of three raw materials, introducing their roles and importance in the preparation of LEP cathode materials.

1、 Lithium iron phosphate

Lithium iron phosphate has an ordered olivine structure. 

The chemical formula of lithium iron phosphate is LiMPO4, where lithium is monovalent and the central metal iron is divalent; 

Phosphate ions are negative trivalent and are commonly used as positive electrode materials for lithium batteries.

 The application fields of lithium iron phosphate batteries include energy storage devices, power tools, light electric vehicles, large electric vehicles, small equipment, and mobile power sources.

2、 Lithium iron phosphate as a positive electrode material for lithium batteries

Compared with other lithium-ion battery cathode materials, olivine structured lithium iron phosphate has the advantages of safety, environmental protection, low cost, long cycle life, 

and good high-temperature performance, making it one of the most promising lithium-ion battery cathode materials.

①High safety performance: Lithium iron phosphate crystals have stable P-O bonds that are difficult to decompose. 

They will not collapse or generate strong oxides during overcharging and high temperatures, making overcharging safer.

Long cycle life

The cycle life of lead-acid batteries is about 300 times, and the service life is between 1-1.5 years.  

And lithium iron phosphate batteries can have a cycle count of over 2000, with a theoretical lifespan of 7-8 years.

②Good high-temperature performance: Lithium iron phosphate has an electric heating peak of 350 ℃ -500 ℃, 

while lithium manganese oxide and lithium cobalt oxide only have around 200 ℃.

③ Environmental Protection: Lithium iron phosphate batteries are generally considered to be free of heavy metals and rare metals, non-toxic, pollution-free, 

and are absolutely green and environmentally friendly batteries.

The charging and discharging mechanism of lithium iron phosphate as a positive electrode material is different from other traditional materials.

 Its charging and discharging reactions involve the two phases of lithium iron phosphate and iron phosphate in the electrochemical reaction. 

The charging and discharging reactions are as follows:

Charging response:

LiFePO4 -xLi+ -xe-→xFePO4 +(1-x)LiFePO4

Discharge reaction:

FePO4+xLi+ +xe-→xLiFePO4+(1-x)FePO4

During charging, Li+dissociates from LiFePO4, and Fe2+loses one electron to become Fe3+; 

During discharge, Li+is embedded in iron phosphate to form LiFePO4. 

The change of Li+occurs at the LiFePO4/FePO4 interface, so its charge discharge curve is very flat and the potential is relatively stable, making it suitable as an electrode material.

3、 The production process of lithium carbonate

Lithium carbonate is one of the important raw materials for preparing lithium iron phosphate cathode materials. 

The production process of lithium carbonate mainly includes steps such as ore beneficiation, leaching and extraction, carbonate precipitation, and lithium carbonate purification.

 Firstly, lithium salt is extracted from lithium ore, then converted into lithium carbonate through chemical reactions, and finally purified to obtain high-purity lithium carbonate. 

The purity and crystallinity of lithium carbonate have a significant impact on the performance of positive electrode materials. 

Therefore, strict control of various process parameters is required during the production process to ensure that the quality of lithium carbonate meets the requirements.

Phosphoric acid is another important raw material for preparing lithium iron phosphate cathode materials. 

The production process of phosphoric acid mainly includes steps such as ore beneficiation, leaching and extraction, phosphate precipitation, and phosphate purification of phosphate ore. 

Firstly, phosphate salts are extracted from phosphate rock, then converted into phosphoric acid through chemical reactions, and finally purified to obtain high-purity phosphoric acid. 

The purity and crystallinity of phosphoric acid also have a significant impact on the performance of positive electrode materials. 

Therefore, strict control of various process parameters is necessary during the production process to ensure that the quality of phosphoric acid meets the requirements.

Iron is the third important raw material for preparing lithium iron phosphate cathode materials. 

The production process of iron mainly includes steps such as ore beneficiation, leaching and extraction, oxidation-reduction, and iron powder preparation.

 Firstly, iron salts are extracted from iron ore, then converted into iron powder through redox reactions, and finally refined to obtain high-purity iron powder. 

The purity and particle size of iron powder also have a significant impact on the performance of positive electrode materials. 

Therefore, strict control of various process parameters is necessary during the production process to ensure that the quality of iron powder meets the requirements.

In summary, lithium carbonate, phosphoric acid, and iron are the three important raw materials for preparing LEP cathode materials, 

and their production processes directly affect the performance and quality of the cathode materials. 

In actual production, it is necessary to strictly control various process parameters to ensure that the quality of raw materials meets the requirements,

 thereby ensuring the performance and stability of the final positive electrode material. 

At the same time, continuously optimizing the production process of raw materials, improving the purity and crystallinity of raw materials, 

will help improve the performance of positive electrode materials and reduce costs, promoting the development and progress of the lithium battery industry.