1. LiFePO4 Battery Structure

Lithium iron phosphate battery is called LiFePO4 battery for short. LiFePO4 with olivine structure is used as the cathode of the battery, and the positive electrode of the battery is connected by aluminum foil.

In the middle is a polymer separator, which separates the cathode from the anode. Lithium ions can pass through, but electrons cannot.

On the right is the anode of the battery composed of graphite, which is connected to the negative electrode of the battery by copper foil.

The electrolyte is between the upper and lower ends of the battery, and the battery is hermetically sealed by a metal case, as shown in Figure 1. When the battery is charging, the lithium ions in the cathode migrate to the anode through the polymer separator; during the discharge process, the lithium ions in the anode migrate to the cathode through the separator. Lithium-ion batteries are named after lithium ions migrate back and forth during charging and discharging.

Figure 1 Structural diagram of lithium iron phosphate battery

2. Charging Process of LiFePO4 Battery

When charging, under the action of the electric field force, lithium ions enter the electrolyte from the surface of the lithium iron phosphate crystal, pass through the diaphragm, migrate to the surface of the graphite crystal, and then embed in the graphite lattice.

After lithium ions are deintercalated from lithium iron phosphate, lithium iron phosphate is converted into iron phosphate. The process is shown in Figure 2:

Figure 2 Charging Process of LiFePO4 Battery

3.Discharging Process of LiFePO4 Battery

During discharge, lithium ions are deintercalated from the graphite crystal, enter the electrolyte, pass through the diaphragm, migrate to the surface of the lithium iron phosphate crystal, and then re-intercalate into the lattice of the lithium iron phosphate. The process is shown in Figure 3:

Figure 3 Discharging Process of LiFePO4 Battery

The nominal voltage of a lithium iron phosphate battery cell is 3.2V, the charging voltage of a single cell is 3.7V, and the end-of-discharge voltage is 2.5V. The battery module consists of a battery cell and a battery management system (BMS), usually consisting of 15 or 16 The cells are connected in series to form a 48V or 51.2V battery module.

About quarelex

Established in 2017, Enerri Energy Group(parent company of quarelex), is one of the pioneering companies in applying the lithium-ion battery technology into low-speed motive power batteries and also battery energy storage systems(BESS). Our key solutions include:

1. Lithium-ion(LiFePO4) power batteries for material handling equipment: Forklifts, Narrow Aisle Trucks, Walkie Pallet Jacks, AGVs, etc.

2. Lithium-ion(LiFePO4) power batteries for low-speed vehicles: Golf Carts, E-Bikes, etc.

3. Lithium-ion(LiFePO4) storage batteries for hybrid/off-grid solar system: Residential low&high voltage battery, Commercial battery energy storage systems(BESS).

4. Solar inverters: hybrid, off-grid solar inverters for residential solar systems.

5. Lithium-ion battery charger: 24V-96V, 10A-300A.

6. Cloud-based Energy Management System(EMS).