Lithium iron phosphate battery introduction

Long life, rate discharge, high temperature resistance and other advantages, is considered to be a new generation of lithium batteries. Juda Lithium Battery can

provide customers with battery cell, BMS (power management system), and integrated battery customization solutions to meet customers’ personalized power

needs.

1, lithium iron phosphate battery characteristics

Good safety performance, puncture does not explode, overcharge does not burn does not explode;

Good cycle life, lithium iron phosphate battery cycle life can reach more than 2000 times;

High temperature performance is good, working temperature range -20℃ to 70℃;

High vibration density, higher capacity under the same conditions;

It can realize 1C-5C fast charging capability and greatly shorten the charging time.

2. Application field

Power storage, special equipment, robots, AGV, rail transit, medical equipment, emergency backup, power communication, etc.

Lithium iron phosphate battery advantages

1, good safety performance

Safety comes from the stability of the positive electrode material and reliable safety design, lithium iron phosphate battery pack has undergone rigorous safety

testing, even in a violent collision will not produce explosion.

2, long cycle life

The 1C cycle life of lithium iron phosphate batteries generally reaches 2,000 times, or even more than 3,500 times, and the energy storage market requires more

than 4000-5000 times, which is higher than other types of lithium batteries.

3, good high temperature performance

Lithium iron phosphate battery thermal peak can reach 350~500℃, the operating temperature range is wide (-20~+75℃), high temperature (60℃) can still

release 100% capacity.

4. Fast charging

Using a dedicated charger, the 1.5C charge can be fully charged in 40 minutes.

5, green environmental protection

Lithium iron phosphate battery green environmental protection, non-toxic, pollution-free, wide source of raw materials, cheap.

Lithium iron phosphate battery voltage and capacity

1, lithium iron phosphate battery voltage

The nominal voltage of the single lithium iron phosphate battery is 3.2V, the charging voltage is 3.6V, and the discharge cut-off voltage is 2.0V. The lithium iron

phosphate battery pack reaches the voltage required by the equipment through the series combination of the battery cell, and the battery voltage =N* the number

of series. Commonly used lithium iron phosphate battery pack voltages are as follows:

12V lithium iron phosphate battery

24V lithium iron phosphate battery

36V lithium iron phosphate battery

48V lithium iron phosphate battery

2, lithium iron phosphate battery capacity

The capacity of the lithium iron phosphate battery pack is determined according to the capacity and number of cells connected in parallel, generally according to

the specific requirements of the electrical equipment to determine, the more lithium iron phosphate cells in parallel, the greater the capacity. Common lithium iron

phosphate battery capacity has 10 ah, ah, ah, 40, 50, ah, ah, 100 200 ah, ah 400, etc.

Structure and working principle of lithium iron phosphate battery

1, lithium iron phosphate battery structure

As shown in the figure, on the left is the olivine structure of LiFePO4 as the positive electrode of the battery, which is connected with the positive electrode of the

battery by aluminum foil; in the middle is the polymer diaphragm, which separates the positive electrode from the negative electrode, but lithium ion Li+ can pass

through and electron e- cannot pass through; on the right is the negative electrode of the battery composed of carbon (graphite), which is connected with the

negative electrode of the battery by copper foil.

2, the working principle of lithium iron phosphate battery

When the LiFePO4 battery is charged, the lithium ion Li+ in the positive electrode migrates to the negative electrode through the polymer diaphragm; During the

discharge process, lithium ion Li+ in the negative electrode migrates to the positive electrode through the diaphragm. Lithium-ion batteries are named because

lithium ions migrate back and forth as they are charged and discharged.

Lithium iron phosphate battery charger

1.LiFePO4 Battery Charging

The charge of lithium iron phosphate battery pack is recommended to use CCCV charging mode, that is, constant current before constant voltage. Constant current

0.3C is recommended. Constant pressure Recommendation 3.65.

2. Is the lithium iron phosphate battery the same as the lithium-ion battery charger

Both batteries are charged by constant current and then constant voltage (CCCV), but the constant voltage point is not the same.

The nominal voltage of the lithium iron phosphate battery is 3.2V, and the charging cut-off voltage is 3.6V.

The nominal voltage of the ordinary lithium battery is 3.6V, and the charging cut-off voltage is 4.2V.

3, use solar energy to charge lithium iron phosphate batteries

Solar panels can not be directly charged to the lithium iron phosphate battery, because the voltage of the solar panel is unstable, can not be directly charged to the

lithium iron phosphate battery, the need for a voltage regulator circuit, but also supporting the corresponding lithium iron phosphate battery charging circuit to

charge.

4, use the generator to charge the lithium iron phosphate battery

The generator cannot directly charge the lithium iron phosphate battery, because the electricity emitted by the generator is alternating current or pulse direct

current, and the lithium iron phosphate battery must be charged for regulated direct current.

Lithium iron phosphate battery and ternary lithium battery

Affected by the structure, lithium iron phosphate and ternary have their own advantages and disadvantages in performance, ternary has advantages in energy

density and fast charging speed, and lithium iron phosphate has advantages in cycle life, safety and economy.

1. Material comparison

The negative electrode, electrolyte and diaphragm of the two batteries are similar, and the biggest difference is the positive electrode material, which is named

after it.

2. Energy density

From the cell level, the ternary battery has a higher energy density. The rated voltage and theoretical specific capacity (mAh/g) of the lithium iron phosphate

anode material are lower than that of the ternary battery, and its energy density has been developed to the “ceiling”.

3. Charging efficiency

Ternary lithium batteries have great advantages over lithium iron phosphate batteries in terms of charging efficiency. When the ternary lithium battery and the

lithium iron phosphate battery are charged below 10C, there is no significant difference in the constant current ratio, and when the rate is charged above 10C, the

constant current ratio of the lithium iron phosphate battery is rapidly reduced, and the charging efficiency is rapidly reduced.

4. Cycle life

In theory, lithium iron phosphate has an advantage in terms of longevity. Its olivine crystal structure is more stable, the expansion is lower, the electrochemical

reaction is more stable.

5. Security

Lithium iron phosphate batteries have incomparable advantages in terms of safety. Its positive electrode is low, there is no thermal chain reaction similar to

ternary oxygen release, and the thermal stability temperature can reach more than 300 ° C, while the ternary battery is about 150-200 ° C.

6. Economy

In terms of price, the current lithium iron phosphate LiFePO4 has obvious advantages, the relative price of raw materials is cheap, and the domestic industrial

chain is relatively mature. If you want to reduce the price of ternary NCM batteries, cobalt is the key. Cobalt is mainly associated ore, production is small and

unevenly distributed, and the price has continued to rise in recent years.

Cycle life and influencing factors of lithium iron phosphate battery

1. Lithium iron phosphate battery is used at room temperature

Small current charge and discharge

In this field, if the lithium iron phosphate battery is used normally, the cycle life is basically more than 2000 times; Small lithium battery manufacturers, slightly

inferior quality also has more than 1000 cycle life;

High rate stable charge and discharge use

Most of the applications of high rate discharge are power lithium batteries, most of which are used in the application of providing power to the motor. Because

most lithium iron phosphate batteries operate under high load conditions, the battery material decay time is accelerated, and the cycle life is also about 800 times.

High rate unstable charge and discharge use

The lithium iron phosphate battery used in this case will have a shorter life, only about 300 times.

2, lithium iron phosphate battery used in high temperature environment

The high temperature performance of lithium iron phosphate batteries is not very mature at present, the operating temperature is -20℃ to 125℃, this temperature

range is the theoretical value, and the practical application temperature range is smaller.

Small current charge and discharge

If the lithium iron phosphate battery is used normally in this field, if the battery brand manufacturers are strong and the quality is good, the cycle life is basically

more than 1000 times; Small lithium battery manufacturers, slightly inferior quality also has more than 500 cycle life; Because it is used at high temperature, the

damage to the battery is relatively large.

High rate stable charge and discharge use

Because most lithium iron phosphate batteries operate under high load conditions, accelerating the attenuation time of battery materials, the cycle life is sharply

decreased, and the poor quality cell may be about 300 cycles; The strong battery brand manufacturers will be better in equipment technology and material

application, and the cell quality will be better, but the cycle life will be about 500 times.

High rate unstable charge and discharge use

High temperature plus discharge rate unstable operation, greater damage to the battery, cycle life is relatively low, several battery manufacturers do tests found

that 250 to 300 times, the battery can not be used.

3. Lithium iron phosphate battery is used in low temperature environment

The low temperature environment has a greater impact on the performance of lithium iron phosphate batteries than high, according to the current market

situation, lithium iron phosphate batteries work below -20 ° C to -40 ° C, and the life is significantly reduced, and the cycle life is about 300 times.

4, lithium iron phosphate battery cycle life factors

Charge and discharge

When choosing a charger, it is best to use a charger with a correct termination charging device cut off, so as not to shorten the service life of the lithium iron

phosphate battery due to overcharging. Generally speaking, slow charging can extend the service life of the battery more than fast charging.

Discharge depth

The depth of discharge is the main factor affecting the life of lithium iron phosphate battery, the higher the depth of discharge, the shorter the life of lithium iron

phosphate battery. In other words, as long as the depth of discharge is reduced, the service life of lithium iron phosphate batteries can be greatly extended.

Therefore, we should avoid putting the lithium battery UPS too low a voltage.

Working environment

If the lithium iron phosphate battery is used at high temperatures for a long time, its electrode activity will decay and shorten its service life, so keeping it at the

appropriate operating temperature as far as possible is a good way to extend the life of the lithium iron phosphate battery.