What Is LiFePO4 Battery? Why It Is a Good Choice

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Part 1. What is an LFP battery?

The cathode materials of lithium-ion batteries mainly include lithium cobalt oxide, lithium manganate, lithium nickel oxide, ternary materials, lithium iron phosphate, etc. LiFePO4 battery is a lithium-ion battery that uses lithium iron phosphate as the cathode material. LFP battery is a rechargeable battery, mainly used as a power battery. It has great advantages over NI-MH and Ni-Cd batteries.

Part 2. Why it is a good choice

Although lithium cobalt oxide is now the cathode material used in most lithium-ion batteries, the positive material of lithium-ion batteries is lithium iron phosphate, which has great advantages in safety performance and cycle life.
Lithium iron phosphate batteries have higher charging and discharging efficiency. The charge and discharge efficiency can reach over 90% under rate discharge, while lead-acid batteries are about 80%. The 1C charge-discharge cycle life can reach 2,000 times; it will not explode when punctured or burn or explode easily when overcharged. Large-capacity lithium-ion batteries made of lithium iron phosphate cathode materials are easier to connect in parallel and series. These are also some of the most important technical indicators of power batteries.

Part 3. How LiFePO4 Battery Works

The internal junction of the LiFePO4 battery is LiFePO4, with an olivine structure as the positive electrode of the battery. The aluminum foil is connected to the battery’s positive electrode, and there is a polymer separator in the middle, separating the positive electrode from the negative electrode. Lithium ions Li+ can pass through, but electrons e- cannot. On the right is the battery negative electrode, composed of carbon (graphite). Connected to the negative terminal of the battery by copper foil. Between the upper and lower ends of the battery is the electrolyte, and the battery is sealed by a metal casing.
When the LiFePO4 battery is charged, the lithium ions Li+ in the positive electrode migrate to the negative electrode through the polymer separator. During the discharge process, lithium ions Li+ in the negative electrode migrate to the positive electrode through the separator. Lithium-ion batteries are named because lithium ions migrate back and forth during charging and discharging.

Part 4. LiFePO4 battery features

High-efficiency output: standard discharge is 2~5C. Continuous high current discharge can reach 10C. Instantaneous pulse discharge (10S) can reach 20C;
Good performance at high temperatures: For example, when the external temperature of Ufine’s LiFePO4 battery is 65°C, the internal temperature of the battery is as high as 95°C. The battery’s temperature can reach 160°C at the end of discharge. However, the structure of the LiFePO4 battery can still ensure safety and integrity.

Safety: Even if the LiFePO4 battery is damaged internally or externally, the battery will not burn or explode, making it safer;
Excellent cycle life: after 500 cycles, the discharge capacity of the LiFePO4 battery is still greater than 95%;
Can be charged quickly;
Environmentally friendly.

Part 5. Li-Ion Vs. LiFePO4 batteries advantages and disadvantages

Advantages of LiFePO4 Batteries

1. Safety

The P-O bond in the lithium iron phosphate crystal is stable and difficult to decompose. Even at high temperatures or overcharges, the structure will not collapse, generate heat, or form strong oxidizing substances like lithium cobalt oxide. Therefore, the LiFePO4 battery is safe.

There are reports that in actual operation, a few LiFePO4 battery samples were found to be burning during acupuncture or short-circuit experiments, but there was no explosion incident. In the overcharge experiment, high-voltage charging that was several times higher than its discharge voltage was found. There are still explosions. Even so, its overcharge safety has improved greatly compared to ordinary liquid electrolyte lithium cobalt oxide batteries.

2. Longer lifespan

The cycle life of long-life lead-acid batteries is about 300 times, and the maximum is 500 times. The LiFePO4 battery has a cycle life of more than 2,000 times and can reach 2,000 times when used with standard charging. Most lead-acid batteries of the same quality have a service life of 1 to 1.5 years. In comparison, the LiFePO4 battery has a theoretical life of 7 to 8 years when used under the same conditions.

3. Good high-temperature performance

The electric heating peak of lithium iron phosphate can reach 350℃~500℃, while the peak temperature of lithium manganate and lithium cobalt oxide is only about 200℃. LiFePO4 battery has a wide operating temperature range (-20℃-~+75℃).

4. Large capacity

LiFePO4 batteries have a larger capacity than ordinary batteries (lead-acid, etc.). The monomer capacity is 5AH-1000AH.

5. No memory effect

When a rechargeable battery is constantly working under the condition of being fully charged and not fully discharged, the capacity will quickly fall below the rated capacity value. This phenomenon is called the memory effect. Like nickel metal hydride and nickel-cadmium batteries, there is a memory effect. Still, lithium iron phosphate batteries do not have this phenomenon. No matter what state the LiFePO4 battery is in, it can be charged and used at any time. There is no need to discharge it first and then recharge it.

6. Lightweight

Compared with lead-acid batteries, the volume of lithium iron phosphate batteries with the same specification and capacity is 2/3 of the volume of lead-acid batteries, and the weight is 1/3 of lead-acid batteries.

7. Environmentally friendly

Although lithium batteries belong to the new energy industry, they cannot avoid the problem of heavy metal pollution. Lead, arsenic, cadmium, mercury, chromium, etc., may be released into dust and water during the processing of metal materials. In addition, the battery itself is a chemical substance, so it is possible to produce two types of pollution: process waste pollution during the production of lithium batteries, and battery pollution after the battery is scrapped.
But LiFePO4 battery is generally considered to not contain any heavy metals and rare metals. No pollution, compliant with European RoHS regulations.

Part 6. Lithium iron phosphate battery disadvantages

LiFePO4 battery also has shortcomings, such as poor low-temperature performance, low tap density, and compaction density. The volume of lithium iron phosphate batteries of the same capacity is larger than that of lithium-ion batteries such as lithium cobalt oxide. Therefore, the LiFePO4 battery does not have an advantage over micro batteries.

When lithium iron phosphate is used in power batteries, like other batteries, it needs to face battery consistency issues.

Part 7. LiFePO4 battery applications

  1. Due to the above characteristics of lithium iron phosphate batteries, batteries of various capacities can be widely used quickly. Its main application areas are:
  2. Large electric vehicles: buses, electric cars, tourist buses, hybrid vehicles, etc.;
  3. Light electric vehicles: electric bicycles, golf carts, small flat battery vehicles, forklifts, cleaning vehicles, electric wheelchairs, etc.;
  4. Power tools: electric drills, chainsaws, lawnmowers, etc.;
  5. Remote control cars, boats, airplanes, and other toys;
  6. Energy storage equipment for solar and wind power generation;
  7. UPS and emergency lights, warning lights, and miner’s lamps;
  8. Replaces 3V disposable lithium batteries and 9V nickel-cadmium or nickel-metal hydride rechargeable batteries in cameras;
  9. Small medical equipment and portable instruments, etc.;

Part 8. FAQs

  • Do LiFePO4 batteries last longer?

    Yes, LiFePO4 batteries often have a longer lifespan compared to other battery types due to their inherent stability, making them a reliable choice for applications requiring longevity.
  • What is the lifespan of a LiFePO4 battery?

    The lifespan of a LiFePO4 battery can range from 2000 to 5000 cycles, depending on factors like depth of discharge, charging methods, and operating conditions.
  • Do LiFePO4 batteries degrade if not used?

    LiFePO4 batteries have a low self-discharge rate, resulting in minimal degradation when not in use for extended periods.
  • How Long Does a LiFePO4 Battery Last?

    The lifespan of a LiFePO4 battery depends on factors like usage patterns, depth of discharge, charging methods, and operating conditions, but it can typically last for several years.
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Gerald

Electronic Engineering Writer

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