Detailed Explanation of The Charging And Discharging Principles And Battery Characteristics of Lithium Iron Phosphate Batteries

Lithium iron phosphate battery Lithium iron phosphate battery refers to a lithium-ion battery using lithium iron phosphate as the cathode material. The negative electrode is also graphite. The electrolyte is also mainly lithium hexafluorophosphate. No matter what state the battery is in, it can be charged and used at any time. There is no need to discharge it before charging. It is currently the safest lithium battery.

Charging and discharging principle of lithium iron phosphate battery

 The charge and discharge reaction of lithium iron phosphate battery is carried out between the two phases of LiFePO4 and FePO4. During the charging process, LiFePO4 gradually breaks away from lithium ions to form FePO4. During the discharge process, lithium ions are embedded in FePO4 to form LiFePO4.

When the battery is charging, lithium ions migrate from the lithium iron phosphate crystal to the crystal surface. Under the action of the electric field force, they enter the electrolyte, then pass through the separator, and then migrate to the surface of the graphite crystal through the electrolyte, and then are embedded in the graphite lattice.

At the same time, electrons flow to the aluminum foil collector of the positive electrode through the conductor, flow to the copper foil collector of the negative electrode of the battery through the tab, battery positive post, external circuit, negative post, and negative tab, and then flow to the graphite negative electrode through the conductor. , so that the charge on the negative electrode reaches balance. After the lithium ions are deintercalated from the lithium iron phosphate, the lithium iron phosphate is converted into iron phosphate.

When the battery is discharged, lithium ions are deintercalated from the graphite crystal, enter the electrolyte, then pass through the separator, migrate to the surface of the lithium iron phosphate crystal through the electrolyte, and then re-embedded into the lithium iron phosphate lattice.

At the same time, electrons flow to the copper foil collector of the negative electrode through the conductor, flow to the aluminum foil collector of the positive electrode of the battery through the tab, negative pole of the battery, external circuit, positive pole, and tab, and then flow to the iron phosphate through the conductor. Lithium positive electrode balances the charge of the positive electrode. After lithium ions are embedded in the iron phosphate crystal, the iron phosphate is converted into lithium iron phosphate.

Characteristics of lithium iron phosphate battery

High energy density: According to reports, the energy density of square aluminum-shell lithium iron phosphate batteries mass-produced in 2018 was around 160Wh/kg. In 2019, some excellent battery manufacturers can probably achieve the level of 175-180Wh/kg. Some individuals Powerful manufacturers use lamination technology to make the capacity larger, or can achieve 185Wh/kg.

Good safety performance: The electrochemical performance of the cathode material of lithium iron phosphate battery is relatively stable, which determines that it has a stable charging and discharging platform. Therefore, the structure of the battery will not change during the charging and discharging process, and it will not burn or explode, and even if It is still very safe under special conditions such as short circuit, overcharge, extrusion, and acupuncture.

Long cycle life: The 1C cycle life of lithium iron phosphate batteries generally reaches 2,000 times, or even more than 3,500 times. The energy storage market requires more than 4,000-5,000 times, ensuring a service life of 8-10 years, which is higher than 1,000 times for ternary batteries. The cycle life of long-life lead-acid batteries is about 300 times.

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