Lithium iron phosphate (LiFePO4) is a novel lithium-ion battery electrode material. It is mainly used in power lithium-ion batteries as a positive electrode active material and is commonly referred to as lithium iron phosphate.
Characteristics and performance of lithium iron phosphate
1. High energy density: Its theoretical specific capacity is 170 mAh/g, and the actual specific capacity of the product exceeds 150 mAh/g (0.2C, 25°C);
2. Safety: It is currently the safest cathode material for lithium-ion batteries; and it does not contain any heavy metal elements that are harmful to the human body.
3. Long lifespan: Under 100% DOD conditions, it can be charged and discharged more than 2000 times. This is because lithium iron phosphate has good lattice stability, and the insertion and extraction of lithium ions have little impact on the lattice, thus exhibiting good reversibility. The drawback is its poor electron-ion conductivity, making it unsuitable for high-current charging and discharging. To apply it to electric vehicles and power tools, conductive materials (mainly carbon) are coated onto the surface of the material, and other metal oxides are doped to replace some of the Fe lattice positions, which has increased the conductivity of lithium iron phosphate by more than 1 million times. Currently, lithium-ion batteries made from this material can undergo high-current discharge and charging at 10-20C or even 30C, and exhibit excellent discharge performance.
4. No memory effect;
5. Electrical performance: Lithium batteries with lithium iron phosphate cathode materials can be charged at high rates, and can now be fully charged in as little as 30 minutes.
Specific physical parameters: (1) Loose packing density: 0.8 g/cm³, (2) Tapered density: 1.1-1.4 g/cm³, (3) Median particle size: 2.0-5.0 μm, (4) Specific surface area <15 m²/g, (5) Coating parameters: LiFePo₄:C:PVDF=90:3:7, (6) Electrode compaction density: 2.1-2.4 g/cm³
Electrochemical performance: Specific capacity >150mAh/g, test conditions: half cell: 0.2C, 4--2.0V, greater than 154mAh; discharge according to actual battery 0.2C, discharge voltage: 3.65V--2.5V, temperature 25℃, discharge capacity greater than 150mAh.
6. Number of cycles: 2000
The performance of lithium-ion batteries primarily depends on the positive and negative electrode materials. Lithium iron phosphate (LFP) has only emerged as a positive electrode material in recent years, with China developing a large-capacity LFP battery in July 2005. Its safety performance and cycle life are unmatched by other materials, which are also the most important technical indicators for power batteries. A 1CDOD charge-discharge cycle life reaches 2000 cycles. A single cell will not burn under an overcharge voltage of 30V and will not explode upon puncture.
Lithium iron phosphate cathode material can be made into larger capacity lithium-ion batteries and is easier to use in series to meet the needs of frequent charging and discharging of electric vehicles. It has the advantages of being non-toxic, non-polluting, safe, widely available, inexpensive, and long-lasting, making it an ideal cathode material for the next generation of lithium-ion batteries.
