LITHIUM IRON PHOSPHATE BATTERIES

What is a Lithium Iron Phosphate Battery?

LiFePo4 batteries are reliable power sources with high performance and high performance. They actively displace not only old lead acid but also modern Li-ion batteries. Today, battery data is found not only in industrial equipment, but also in household appliances – from smartphones to electric bicycles.

LFP batteries were developed by the Massachusetts University of Technology in 2003. Their basis is an advanced Li-ion technology with a changing chemical composition: lithium ferrophosphate is used for the anode instead of lithium cobaltate. The battery is widely distributed thanks to companies like Motorola and Qualcomm.

How are LiFePO4 Batteries Manufactured?

The main components for the production of LiFePo4 batteries are supplied to the factory in the form of a dark gray powder with a metallic sheen. The production scheme of anodes and cathodes is the same, but due to the inadmissibility of mixing components, all technological processes are carried out in different workshops. The entire production is divided into several stages.
First step: Creation of electrodes. To do this, the finished chemical composition is covered on both sides with a metal foil (usually aluminum for the cathode and copper for the anode). The foil is pre-treated with a suspension so that it can function as a current acceptor and a conductive element. The finished elements are cut into thin strips and folded several times, forming square cells.
Second step: Direct battery assembly. The cell-shaped cathodes and anodes are placed on both sides of the separator of the porous material and firmly fixed. The resulting block is placed in a plastic container, filled with electrolyte and sealed.
Last step: Battery charge/discharge test. Charging causes a gradual increase in voltage so that there is no explosion or ignition due to the release of a large amount of heat. To discharge the battery, the battery is connected to a powerful consumer. Finished products are shipped to the customer before deviations are detected.

Working Principle of LiFePO4 Batteries

LFP batteries consist of electrodes tightly pressed against a porous separator on both sides. To power the devices, both the cathode and anode are connected to existing collectors. All components are placed in a plastic case filled with electrolyte. A controller is built into the case that regulates the current supply during charging. The principle of operation of LiFePo4 batteries is based on the interaction of lithium ferrophosphate and carbon. The reaction itself proceeds according to the following formula: LiFePO4 + 6C → Li1-xFEPO4 + LiC6 The charge carrier of the battery is a positively charged lithium ion. It has the ability to penetrate the crystal lattice of other materials through the formation of chemical bonds.

Characteristics of LiFePO4 Batteries

Regardless of the manufacturer, all LFP cells have the same characteristics:

• peak voltage – 3.65 V;
• voltage at midpoint– 3,3 V;
• voltage in a fully discharged state– 2,0 V;
• nominal operating voltage– 3,0-3,3 V;
• minimum voltage under load – 2,8 V;
• durability – 2 to 7 thousand charge/discharge cycles;
• About self-loading at a temperature of 15-18 C – up to 5% per year.

The specifications presented are particularly relevant for LiFePo4 cells. Depending on how many of them are combined into one battery, the parameters of the batteries will vary.
Domestic production samples have the following characteristics:

• capacity – up to 2000 Ah;
• voltaik – 12 v, 24 v, 36 v ve 48 v;
• at various operating temperatures – from -30 to about +60 C;
• with charging current – from 4 to 30A.

All batteries do not lose quality during storage for 15 years, have a stable voltage and are characterized by low toxicity.

Advantages and Disadvantages of LiFePO4 Batteries

LFP batteries are based on Li-ion technology, which allows them to combine all the advantages of these power sources and at the same time get rid of their drawbacks. Among their main advantages:

• Durability – up to 7,000 cycles.
• High charging current which reduces the time for energy boost.
• Constant operating voltage that does not drop until the charge is completely depleted.
• High peak voltage – 3.65 Volts.
• High nominal capacity.
• Lightweight – up to several kilograms
• Low environmental pollution during disposal.
• Frost resistance – work can be carried out at temperatures from -30 to +60C.

But batteries also have disadvantages. The first of these is the high cost. The price of one element for 20 Ah can reach 35 thousand rubles. The second and last drawback is the difficulty of making a battery yourself, unlike lithium-ion cells. Other obvious minuses in these power supplies have not yet been identified.

How to Charge LiFePO4 Batteries?

Chargers for LiFePo4 batteries are practically no different from conventional inverters. In particular, it is possible to save a large current strength at the output, up to 30A, which is used to quickly charge the cells.
When buying a ready-made battery pack, difficulties with their charging should not arise. In their design, electronic control is integrated, which protects all cells from complete discharge and oversaturation of electricity. Expensive systems use a balancing board that evenly distributes energy between all cells of the device.
When recharging, it is important not to exceed the recommended amperage if you are using third-party chargers. This will reduce battery life several times on a single charge. If the battery heats up or swells, the amperage exceeds the permissible values.

Where are LiFePo4 batteries used?

LFP batteries are very important for the industry. They are used to maintain the operability of devices in meteorological stations and hospitals. They are also applied as a buffer in wind farms and used to accumulate energy from solar panels. Instead of the usual lead-acid elements, 12 v batteries began to be used in modern cars. LiFePo4 designs are installed as the main power source for electric bicycles and ATVs, motor boats. Widespread importance in everyday life. They are built into phones, tablets and even screwdrivers. However, such devices differ significantly in price from their less technological counterparts. Therefore, it is still difficult to meet them on the market.

We can count the usage areas of LiFePO4 batteries as follows;

• Radio batteries
• Base stations
• Electric bicycles
• Solar systems
• Wind turbines
• Electrical hand and household appliances
• Space technologies
• Camera systems
• Golf vehicles
• Boats
• It is used in many areas such as disabled vehicles.