A lithium iron phosphate battery is a type of lithium ion battery that uses lithium iron phosphate (LiFePO₄) as the positive electrode material and carbon (usually graphite) as the negative electrode material. The following is a detailed introduction to the lithium iron phosphate battery:
I. Definition and structure
Definition: Lithium iron phosphate battery is an inorganic substance, the chemical formula is LiFePO4, where Li+ represents metal lithium ion, Fe represents iron, PO4²⁻ represents phosphate ion.
Structure. To the left of the battery is the positive pole of the LiFePO₄ material in olivine structure. It is connected to the positive pole of the battery by aluminum foil. On the right is the negative electrode of the battery composed of carbon (graphite), which is connected to the negative electrode of the battery by copper foil. In the middle is a polymer diaphragm, which separates the positive and negative electrodes, through which lithium ions can pass but electrons cannot. The battery is filled with electrolytes and enclosed in a metal enclosure.
Second, the working principle
The charge and discharge reaction of the lithium iron phosphate battery is performed between the LiFePO₄ and FePO₄ phases.
During the charging process, part of the lithium ions in the lithium iron phosphate are removed, transferred to the negative electrode through the electrolyte, and embedded in the negative carbon material; At the same time, electrons are released from the positive electrode and reach the negative electrode from the external circuit to maintain the balance of the chemical reaction.
During the discharge process, the lithium ion self-electrode exits and reaches the positive electrode through the electrolyte, while the negative electrode releases electrons and reaches the positive electrode from the external circuit to provide energy for the outside world.
3. Characteristics and advantages
Energy density: lithium iron phosphate battery has a high energy density, the rated voltage of the single is
3.2V Lifepo4 Battery, and the charging cut-off voltage is 3.6V~3.65V. In recent years, with the progress of technology, its energy density continues to increase, and some excellent battery manufacturers have been able to achieve 175-180Wh/kg, or even higher.
Safety performance: The cathode material of lithium iron phosphate battery has stable electrochemical performance, a stable charging and discharging platform, and the structure of the battery will not change during the charging and discharging process, so the safety performance is good. High safety can be maintained even under special conditions such as short circuit, overcharge, extrusion, and needling.
Cycle life: The cycle life of lithium iron phosphate batteries is long, and the 1C cycle life is generally 2,000 times, or even more than 3,500 times. For the energy storage market, it is required to reach more than 4000-5000 times and ensure a service life of 8-10 years.
Other advantages: moderate operating voltage, large power capacity per unit weight, high discharge power, fast charging, wide operating temperature range (including good low temperature discharge performance and high temperature stability).
4. Application field
Because of its excellent performance, lithium iron phosphate batteries are widely used in many fields, especially in the field of new energy vehicles, such as electric vehicles, electric bicycles, power tools and so on. In addition, it is also widely used in energy storage systems,
Portable Power Station supplies and other fields.
5. Synthesis process
The synthesis process of lithium iron phosphate lithium battery has been basically improved, which is mainly divided into solid phase method and liquid phase method. Among them, the high temperature solid phase reaction method is the most commonly used, and there are researchers who combine the microwave synthesis method in the solid phase method with the hydrothermal synthesis method in the liquid phase method, that is, the microwave hydrothermal method. In addition, it also includes bionic method, cooling drying method, emulsion drying method, pulse laser deposition method and so on. By choosing the appropriate synthesis method, the product with small particle size and good dispersion performance can be synthesized, so as to effectively improve the performance of the battery.
In summary, lithium iron phosphate battery is a kind of lithium-ion battery with excellent performance and wide application. With the continuous progress of technology and the continuous expansion of the market, its future development prospects are very broad.
