Lithium iron phosphate battery lithium iron phosphate battery refers to lithium iron phosphate as the cathode material of lithium ion battery. The negative electrode is also graphite. The main electrolyte is lithium hexafluorophosphate. No matter what state the battery is in, it can be charged and used with no need to recharge it first. It is the safest lithium battery at present.
Charge and discharge principle of lithium iron phosphate battery
The charge and discharge reaction of lithium iron phosphate battery is carried out between LiFePO4 and FePO4 phases. During the charging process, LiFePO4 is gradually separated from lithium ions to form FePO4. During the discharge process, lithium ions are embedded into FePO4 to form LiFePO4.
When the battery is charged, the lithium ions migrate from the lithium iron phosphate crystal to the crystal surface, enter the electrolyte under the action of an electric field force, then pass through the membrane, then migrate through the electrolyte to the surface of the graphite crystal, and then embedded in the graphite lattice.
At the same time, the electrons flow through the conductive body to the aluminum foil collector of the positive electrode, through the electrode lug, battery positive pole, external circuit, negative pole and negative pole lug flow to the copper foil collector of the battery negative electrode, and then through the conductive body flow to the graphite negative electrode, so that the charge of the negative electrode reaches balance. After the lithium ion is removed from the lithium iron phosphate, the lithium iron phosphate is converted to iron phosphate.
When the battery discharges, the lithium ions detach from the graphite crystal and enter the electrolyte, where they pass through the membrane, migrate to the surface of the lithium iron phosphate crystal through the electrolyte, and then reembed into the crystal lattice of the lithium iron phosphate.
At the same time, electrons flow through the conductive body to the copper foil collector of the negative electrode, through the electrode lug, battery negative pole, external circuit, positive pole, positive pole lug flow to the aluminum foil collector of the battery positive electrode, and then through the conductive body flow to the positive electrode of lithium iron phosphate, so that the charge of the positive electrode reaches balance. Iron phosphate is converted to lithium iron phosphate after lithium ions are embedded in iron phosphate crystals.
Characteristics of lithium iron phosphate batteries
High energy density: It is reported that the energy density of the square aluminum shell lithium iron phosphate battery produced in mass production in 2018 is about 160Wh/kg. In 2019, some excellent battery manufacturers can achieve 175-180Wh/kg level, while some powerful manufacturers adopt the lamination process and make the capacity larger, or can achieve 185Wh/kg.
Good safety performance: the electrochemical performance of lithium iron phosphate battery cathode material is stable, which determines it has stable charge and discharge platform, therefore, in the process of charging and discharging the battery structure will not change, not combustion, explosion and even in the short circuit, over charge, extrusion, under special conditions, such as acupuncture, is still very safe.
Long cycle life: lithium iron phosphate battery 1C cycle life is generally up to 2000 times, and even more than 3500 times, and for the energy storage market requirements of more than 4000-5000 times, to ensure 8-10 years of service life, higher than the three-way battery cycle life of more than 1000 times, and long life lead-acid battery cycle life in about 300 times.
