Lithium iron phosphate battery refers to a lithium ion battery using lithium iron phosphate as a positive electrode material. The cathode materials of lithium-ion batteries mainly include lithium cobalt oxide, lithium manganate, lithium nickel oxide, ternary materials, lithium iron phosphate, etc.
When the lithium iron phosphate battery is charged, the lithium ions Li+ in the positive electrode migrate to the negative electrode through the polymer separator; during the discharge process, the lithium ions Li+ in the negative electrode migrate to the positive electrode through the separator. Lithium-ion batteries are named after lithium ions migrate back and forth during charging and discharging.
When the lithium iron phosphate battery is charged, Li+ migrates from the 010 surface of the lithium iron phosphate crystal to the crystal surface. Under the action of the electric field force, it enters the electrolyte, passes through the separator, and then migrates to the surface of graphene through electrolysis, and then embedded in the graphene. In the lattice, at the same time, electrons flow to the aluminum foil electrode of the positive electrode through the conductor, and flow to the copper foil current collector of the negative electrode through the tab, battery pole, external circuit, negative pole, and negative ear, and then to the graphite negative electrode through the conductor. , is that the charge of the negative electrode reaches a balance, and after lithium ions are deintercalated from lithium iron phosphate, lithium iron phosphate is converted into iron phosphate.
When the lithium iron phosphate battery is discharged, Li+ is deintercalated from the graphite crystal, enters the electrolyte, passes through the separator, migrates to the surface of the lithium iron phosphate crystal through the electrolyte, and then re-embeds into the lattice of lithium iron phosphate through the 010 surface. Inside. At the same time, the battery flows to the copper foil collector of the negative electrode through the conductor, and flows to the copper foil collector of the positive electrode through the tab, battery negative pole, external circuit, positive pole and positive ear, and then to the lithium iron phosphate positive electrode through the conductor, so that the The charge of the positive electrode reaches an equilibrium state.
Chemical reaction equation of lithium iron phosphate battery
The positive electrode of the lithium-ion battery is a compound containing metallic lithium, generally lithium iron phosphate (such as lithium iron phosphate LiFePO4, lithium cobalt phosphate LiCoO2, etc.), and the negative electrode is graphite or carbon (generally, graphite is used), and organic compounds are used between the positive and negative electrodes. Solvent acts as electrolyte. When the battery is charged, the positive electrode is decomposed to generate lithium ions, and the lithium ions enter the negative electrode of the battery through the electrolyte and are embedded in the micropores of the carbon layer of the negative electrode. During the use of the battery (equivalent to discharge), the lithium ions embedded in the micropores of the negative electrode move back to the positive electrode. The more lithium ions that return to the positive electrode, the higher the discharge capacity. The battery capacity we usually refer to is the discharge capacity. In this way, during the charging and discharging process of the battery, lithium ions continuously run back and forth between the positive and negative electrodes, so the lithium ion battery is also called a rocking chair battery.
The electrochemical reaction equation of the lithium iron phosphate battery is shown below:
Positive reaction: LiFePO4?Li1-xFePO4+xLi++xe-;
Negative reaction: xLi++xe-+6C?LixC6;
The overall reaction formula: LiFePO4+6xC?Li1-xFePO4+LixC6.
Post time: May-13-2022