Safety issues of iron-lithium batteries

Iron-lithium batteries are not as safe as some friends on the Internet say. There is also the danger of an explosion. Technology requires truthfulness and rigor.

The lithium iron phosphate battery 26650-3AH was overcharged by 3C10V, and the battery exploded. Repeat the test and the results are similar.

(Note that the experiment is an experiment on an unformed product, and the person cannot provide a photo)

When the lithium battery is charged and discharged at a large current, the inside of the battery continues to heat up, and the gas generated during the activation process expands, the internal pressure of the battery increases, and the pressure reaches a certain level. If the outer casing has a flaw, it will rupture, causing liquid leakage, fire, and even explosion. Therefore, when you use it, you must pay attention to safety.

However, during normal use, the battery management system is generally used to protect the power lithium battery, so there is almost no explosion. However, for mobile phone batteries, because the protection measures are not in place, it is more likely to explode.

The advantages of lithium iron phosphate batteries are:

The lithium iron phosphate battery has a long life and a cycle life of more than 2,000 times. Under the same conditions, lithium iron phosphate batteries can be used for 7 to 8 years.

Be safe to use. Lithium iron phosphate batteries undergo rigorous safety testing and will not explode even in traffic accidents.

Charging is fast. With a dedicated charger, the battery can be fully charged by charging at 1.5C for 40 minutes.

The lithium iron phosphate battery is resistant to high temperatures, and the lithium iron phosphate battery can reach a hot air value of 350 to 500 degrees Celsius.

The lithium iron phosphate battery has a large capacity.

Lithium iron phosphate batteries have no memory effect.

The lithium iron phosphate battery is environmentally friendly, non-toxic, non-polluting, with a wide range of raw materials and low prices.

The disadvantages of lithium iron phosphate batteries are:

The lithium iron phosphate battery has a low tap density and a density of generally 0.8 to 1.3.

The conductivity is poor, the lithium ion diffusion rate is slow, and the actual specific capacity is low when the charge and discharge are high.

The lithium iron phosphate battery has poor low temperature performance.

Lithium iron phosphate battery has a long life of about 2,000 times, but the life of lithium iron phosphate battery pack is short, generally about 500 times.

LiFePO4 as a lithium ion battery cathode material has the advantages of low price, non-toxicity, good environmental compatibility, high specific capacity (170mAh/g), high working voltage, long cycle life, high temperature performance and good safety performance.

Main problems: low electronic conductivity, poor discharge at large rates

The main advantages and disadvantages of lithium-ion batteries

Advantage

Sealed battery; no maintenance required

Long cycle life

More than 1000 times (Lithium iron phosphate battery cycle life is more than 2000 times, 1C charge and discharge 100% DOD)

Wide operating temperature range

Charging at -20~60°C, discharge at -40~65°C (The lithium iron phosphate battery has excellent high temperature performance, which is very suitable for solar energy products. It needs to use the battery of cylindrical 18650 or 26650 steel shell, and the flexible packaging is in high temperature environment. It is easy to precipitate gas, resulting in a sudden drop in battery life)

Long storage life

Low self-discharge rate: 2~8%/month (year self-discharge is around 15%)

Fast charging capability (capacity type batteries can be charged at 1-2C charging current, which is much more efficient than lead-acid batteries with 0.1-0.2C charging, and has many advantages in power and energy storage applications)

High discharge rate and high power discharge capacity (the battery has no significant drop in discharge capacity at 1C-3C rate discharge, compared with acid battery series and nickel battery)

High capacity and energy efficiency

High quality specific energy and high volume specific energy

About 159W·h/kg, about 400W·h/L

No memory effect

Disadvantage

Moderate initial price

Attenuation at high temperatures

Need to protect the circuit

Battery performance is attenuated when discharged below 2V

Loss of capacity or possible thermal runaway during over-discharge

Battery overheating occurs when overcharging

When the battery crashes, it will vent and may be out of control

The cylindrical battery structure generally has a lower output power than the cadmium/nickel or metal hydride/nickel battery

If you take a lithium iron phosphate battery and a ternary lithium ion battery, compare the power and energy storage and lighting. Let's take the cylindrical 26650 model as an example. The first is the ability to adapt to high and low temperatures. Lithium iron phosphate has excellent high temperature performance, especially in summer. In low latitudes, the temperature at noon will be relatively high. In outdoor use, iron and lithium batteries are undoubtedly dominant; however, there are few products can be eaten at high and low temperatures, and the low temperature performance of the iron-lithium battery needs to be improved. The low-temperature performance of the ternary lithium-ion battery is much better than that of the iron-lithium battery. Look at the picture.

Then look at the cycle life of the battery, with Hite's iron lithium 26650 model 3200mah battery and ternary 26650 model 4500mah battery under laboratory conditions, 1C charge and discharge, 100% DOD, iron lithium battery life > 2000 times, ternary The battery is more than 1000 times. Of course, if the battery is 80% DOD, 60% DOD, 40% DOD, the life expectancy will increase exponentially attachment.

Other features, such as security, stability, price, combination, and ease of access, require consulting with a dedicated manufacturer who will provide appropriate advice.

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