Lithium batteries often explode, why not use (cheap, heavy, safe) lead-acid batteries? Isn't safety the most important thing?

Compared with lead-acid batteries, lithium-ion batteries seem to have frequent accidents, but they are more popular with car companies than lead-acid batteries. Why? The specific reasons are analyzed as follows:

1. Long service life and low comprehensive use cost

Although lead-acid batteries are cheaper and more expensive to recycle compared to lithium-ion batteries, the deadliest reason for their loss to lithium-ion batteries is that the service life of lead-acid batteries is too short.

At present, the more popular lithium-ion batteries are ternary lithium batteries and lithium iron phosphate batteries. Under normal circumstances, the number of cycles of ternary lithium batteries is more than 1,000 times, the number of cycles of lithium iron phosphate batteries is more than 2,000 times, and the number of cycles of lead-acid batteries is only 300 to 350 times. In contrast, the service life of lithium batteries is about 3-6 times that of lead-acid batteries.

2. Light weight

At present, the density of lithium-ion batteries is generally 200~260wh/g, while the density of lead-acid batteries is generally 50~70wh/g. In contrast, the capacity density of lithium batteries is 3 to 5 times that of lead-acid batteries, which means that under the same capacity, the weight of lead-acid batteries is 3 to 5 times that of lithium batteries. , Lithium batteries occupy an absolute advantage.

3. Large battery capacity

Compared with lead-acid batteries, lithium-ion batteries have a higher average voltage and higher energy density, in other words, lithium-ion batteries have a larger capacity for the same size battery.

4. High depth of discharge

Depth of discharge, as the name suggests, refers to the total capacity used before charging the battery. (PS: If you use a quarter of the battery capacity, the depth of discharge will be 25%.)

Usually the battery is not fully discharged when in use. Generally, the lead-acid battery can only run to 50% of the depth of discharge. If this limit is exceeded, it will have a negative impact on its life. But in contrast, lithium-ion batteries can handle more than 80% deep discharge, which means that lithium-ion batteries have higher usable capacity.

5. Long warranty period

The warranty period of lead-acid batteries is generally 1 year, while the warranty period of lithium batteries can be longer. According to national regulations, the main parts of the car must be guaranteed for at least 2 years or more than 50,000 kilometers. According to this requirement, lead-acid batteries cannot meet the requirements of regulations at all.

In addition, lithium-ion batteries also have the advantages of stronger adaptability to high and low temperature and less affected by temperature factors, so in addition to price, lithium batteries are hanging lead-acid batteries in all aspects.

Is safety the most important thing for batteries?

It is true that safety must be a major concern for everyone. Compared with lithium-ion batteries, lead-acid batteries are more stable, but their electrolyte is sulfuric acid. During normal use, sulfur dioxide gas will also be released, and excessive inhalation It will also harm the human body.

Neither of those two batteries is absolutely safe. Why do many people think that lithium-ion batteries are extremely dangerous?

Mainly because of the lithium-ion battery, if nothing happens, it's amazing. Do you still remember the video that blasted major online platforms 2 months ago? An owner of a community in Chengdu pushed a battery car into the elevator and suddenly smoked and spontaneously ignited. Many people were burned, including a baby.

Why are lithium-ion batteries easy to catch fire? The main reason is due to cost compression or irregular use.

Take the accident of an electric car that caught fire not long ago in Hangzhou. During the later investigation process, the family members of the parties stated that they had spent 500 yuan to replace the battery in 2020.

It is understood that the battery used in general electric bicycles is 48V20Ah, and the energy is 960Wh, which is nearly 1 kWh. The cost of a lithium-ion battery photocell in a formal enterprise requires 500 yuan. If the battery management system, casing, wires and sales expenses are added, the cost can be controlled at 1,000 yuan, which is very low. How did the 500 yuan lithium battery come from? Everyone can imagine it.

Summarize

At present, after years of development, lithium-ion batteries have undergone multiple tests and verifications from material design to device design, from laboratory to production line, and the safety factor has been greatly improved. Therefore, as long as everyone purchases products through formal channels, the standard Use, you don't have to worry too much about its safety.