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About Lithium Iron Phosphate(LiFePO4) Batteries, those things you have to know

Nov 12,2021 | Power Station Battery

 

About Lithium Iron Phosphate(LiFePO4) Batteries, those things you have to know

Lithium iron phosphate battery, the full name of lithium iron phosphate lithium-ion battery, refers to the lithium-ion battery that uses lithium iron phosphate as the positive electrode material. Here are the battery naming rules in the industry. At present, we usually use the positive electrode material to name the battery. The negative electrode generally uses graphite as the negative electrode, and lithium iron phosphate refers to the lithium iron phosphate material used in the positive electrode.

The positive electrode of lithium-ion battery is lithium iron phosphate material, which has great advantages in safety performance and cycle life. These are also some of the most important technical indicators of power batteries. The 1C charging and discharging cycle life can reach 2000 times, and it is not easy to burn and explode when overcharged. Large-capacity lithium-ion batteries made from lithium iron phosphate cathode material are easier to use in series. Why lithium iron phosphate batteries can defeat other batteries and set off a lithium battery storm?

 

 

 

 

The main advantages of lithium iron phosphate batteries:

High safety performance

The P-O bond in lithium iron phosphate crystals is stable and difficult to decompose. Even at high temperatures or overcharge, it will not collapse and generate heat like lithium cobalt oxide or form strong oxidizing substances. The decomposition temperature of lithium iron phosphate is about 600 ℃, so it has good security. Although there have been burning and explosions in the case of overcharging, the safety of overcharging has been greatly improved compared with ordinary liquid electrolyte lithium cobalt oxide batteries and ternary batteries.

Long life

The cycle life of lead-acid batteries is about 300 times, up to about 500 times, while the cycle life of lithium iron phosphate power batteries is more than 2000 times, and the standard charge (0.2C, 5 hours) use can reach 2000 times. Lead-acid batteries have a maximum life span of 1-1.5 years, while lithium iron phosphate batteries have a theoretical life span of 7-8 years under the same conditions. Considering comprehensively, the performance-price ratio is theoretically more than 4 times that of lead-acid batteries. With a dedicated charger, the lithium iron phosphate batteries can be fully charged within 40 minutes at 1.5C . The starting current can reach 2C, but lead-acid batteries have no such performance.

Good high-temperature performance

The peak value of lithium iron phosphate electric heating can reach 350℃-500℃ , while lithium manganate and lithium cobaltate are only around 200℃. With high-temperature resistance, lithium iron phosphate electric heating peak can reach 350℃-500℃, while lithium manganate and lithium cobaltate are only around 200℃.

Large capacity

It has a larger capacity than ordinary batteries (lead-acid, etc.). It can be known from the capacity density of the battery that the energy density of lead-acid batteries is about 40WH/kg. The mainstream lithium iron phosphate batteries on the market have an energy density of more than 90WH/kg.

No memory effect

Rechargeable batteries can quickly fall below their rated capacity when they are constantly charged to the full, a phenomenon known as the memory effect. NiMH and NiCd batteries have memory, while lithium iron phosphate batteries do not have this phenomenon (lithium-ion batteries generally do not have memory effect). No matter what state the battery is in, it can be used while charging, without first placing.

Lightweight

A lithium iron phosphate battery with the same capacity is 2/3 the volume and 1/3 the weight of a lead-acid battery, but its energy density is several times that of a lead-acid battery.

Environmentally friendly

Lithium iron phosphate battery is generally considered to be free of any heavy metals and rare metals (the nickel-hydrogen battery requires rare metals), non-toxic (SGS certified), non-polluting, in line with European RoHS regulations, and a green battery.

 

 

Having said that, what is the structure and principle of lithium iron phosphate batteries?

The positive electrode of the LiFePO4 battery is lithium iron phosphate with an olivine structure. The aluminum foil is connected to the positive electrode of the battery. In the middle is a polymer membrane, which separates the positive electrode from the negative electrode, but the lithium-ion Li+ can pass through and the electron E - cannot. On the right is the negative electrode of the battery, which is made of carbon (graphite), and is connected to the negative electrode of the battery by the copper foil. Between the upper and lower ends of the battery is the electrolyte of the battery, which is sealed in a metal case.

When the LiFePO4 battery is charged, the lithium-ion Li+ in the positive electrode migrates to the negative electrode through the polymer membrane. During the discharge, Li+, the lithium-ion in the negative electrode, migrates through the membrane to the positive electrode. Lithium-ion batteries are named because lithium ions migrate back and forth during charge and discharge. Generally speaking, the nominal voltage of the LiFePO4 battery is 3.2V, the termination charging voltage is 3.6V, and the termination discharging voltage is 2.0V.

There are big differences in the capacity of lithium iron phosphate power batteries, which can be divided into three categories: small-scale from a few tenths to a few milliamperes, medium-scale tens of milliamp-hours, and large-scale hundreds of milliamp-hours. Similar parameters of different types of batteries also have some differences. Because lithium iron phosphate power batteries have the above characteristics, they have been widely used.

Well, lithium iron phosphate battery is so powerful, where are they mainly used?

 

 

 

 

In recent years, under the concept of sustainable development, to achieve the goal of energy-saving and emission reduction, lithium batteries have achieved certain development results under the current technical background. In the future, with the increase of investment in technology research and development, it is bound to usher in brand new development. If you are interested in lithium batteries and want to purchase related products, don't hesitate to contact us as soon as possible!

 

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