There have always been controversies on the topic that lead-acid batteries will be replaced by lithium batteries. For now, there are reasons why lead-acid batteries dominate the field of starting power sources and not replaced by lithium-ion batteries.
Today, Ansheng Intelligent Brain will take you to analyze:

01 demand
At present, lithium-ion batteries are mainly used in the field of 3C electronic products such as mobile phones and tablet computers. They have the highest energy density among commercially available batteries, but they still cannot meet people's needs. Why?
In a word, a larger battery cell cannot be inserted in a limited space. Although lithium-ion batteries have made continuous progress in manufacturing processes and research and development of new materials since Sony’s commercialization in 1990, their reaction mechanisms and commercial positive and negative materials (graphite and lithium cobalt oxide) have basically not undergone essential changes. Therefore, compared with the upgrade speed of electronic products complying with Moore's Law, it is obviously not able to keep up, but people have strict requirements on the volume and weight of 3C products, so the space that can be provided for batteries is limited, so it can only be done in terms of battery life. Concession
But the car is different. It can provide a large enough battery storage space. Although the lithium-ion battery has a higher energy density, in order to save that little space, the complete power supply and electricity system is changed. As Liang Ruizhi said, This is obviously a laborious and labor intensive task, requiring a series of electric parts to cooperate; it is not cost-effective in terms of cost. In terms of space cost and the change cost of related supporting components, auto manufacturers are more willing to choose the former. Relative to the entire car, space is not a big deal.
So in terms of demand, manufacturers are not very willing to replace the starting power supply with lithium-ion batteries.

02 performance
Although everyone agrees that lithium-ion batteries have a tendency to dominate the world, they are weaker than lead-acid batteries in at least two respects, and these two points are even more fatal in car starting power: low-temperature performance and high-current performance.
Let’s talk about low-temperature performance first. The discharge performance of lead-acid batteries at low temperatures is actually very good. When discharged at a temperature of -10°C at a rate of 10C, the voltage holding time above 10V can be longer than 90s, which is sufficient for most of China The harsh environment in the region; and the low-temperature performance of lithium-ion batteries is much worse, especially for the most popular LiFePO4 (lithium iron phosphate) material, its discharge performance at low temperatures will decline sharply, and it is difficult to achieve practical results in the Northeast and Northwest regions. Application, or that there is still a long way to go from actual application.
The second is the high current characteristics. The instantaneous current when the car starts is mostly above 200A, and the luxury car may be even higher. As far as the current lithium-ion battery anode and cathode materials, graphite and lithium cobalt oxide are concerned, both are not high-power anode materials, and their performance drops sharply at high rates; while the current research is relatively mature high-power anode material Li4Ti5O12 (Lithium titanate) and the cathode material LiFePO4, they have a lot of injuries. The former is flatulence, and the latter is batch and poor low-temperature performance. Both will cause rapid degradation of battery performance, and may cause Come safety hazards.

03 security

The starting power used in cars is mostly fixed in the engine compartment and has high airtightness. Therefore, safety is very important to the car. The heat and potential dangers caused by the instantaneous release of several hundred amperes of current it goes without saying.
The safety of lead-acid batteries belongs to a very high level in the current battery system. First, the excellent high-current performance means that the battery is not prone to accidents; secondly, even if an accident occurs, the positive and negative materials are all lead compounds, and electrolysis Liquid or sulfuric acid solution, the three are not flammable, can only cause the surrounding parts to burn.
The negative electrode material of lithium-ion batteries is graphite, a kind of carbon material, so the flammability does not need to be said. The electrolyte is an ester solvent and a lithium salt. The ester solvent is not only flammable but also extremely volatile (most of the aromatic smell brought by the laboratory switch glove box is due to it). Once a large amount of heat is released or in the car It is easy to burn or even explode during a collision, pushing the accident to a higher level, with disastrous consequences. At the same time, there is an important factor that cannot be ignored. Li-ion batteries are prone to form lithium dendrites on the negative electrode when they are discharged at high currents, piercing the diaphragm and causing internal short-circuits and explosions. This is a consensus in the lithium battery industry. In fact, there are many other problems. For example, the stability of electrode materials caused by long-term high state of charge (SOC) of the battery is also a big problem. There is not much research on it at present, and many mechanisms are still unclear. Wait, there are too many safety issues for lithium-ion batteries, so I won’t explain them all here.

04 Cost

In terms of cost, the cost of lead-acid batteries is undoubtedly the lowest, whether it is electrode materials, electrolyte, or assembly environment requirements, are far lower than lithium-ion batteries.
As far as electrode materials are concerned, most of the electrode materials for lithium-ion batteries require complicated process preparation and a high-temperature heat treatment process (graphitization temperature is greater than 2000 degrees, and most of the cathode materials also require seven or eight hundred degrees), and the cost is mostly 15-20w/ For more than a ton, graphite may be lower; lead oxide and lead sulfate used in lead-acid batteries are relatively cheaper. As for the electrolyte, the price of lithium ion batteries using multiple ester solvents is higher, and there are strict requirements for water content, mostly within tens of ppm. The electrolyte salt lithium hexafluorophosphate is not only expensive but also easy to decompose, causing danger and one of the decomposition products. It is the horrible HF, Baidu can know its harm in one click! The lead-acid battery is a sulfuric acid solution, so there is no need to say more about it.


05 Environment
At present, most of the voices in the society say that lead-acid batteries pollute the environment and lithium-ion batteries are environmentally friendly. In fact, this is a big misunderstanding. Before, there were too many small lead-acid battery factories in southern China that did not pay attention to environmental protection and discharged them. The country wants to reduce the scale of lead-acid batteries and vigorously develop new energy sources. Therefore, the media's arguments are also highly targeted, which is not the case.
The best part of lead-acid batteries compared to lithium-ion batteries is the recycling mechanism. Now lead-acid batteries are mainly used in the fields of electric bicycles and starting power supplies. Both of these fields have strong pertinence. That is, when users change batteries, they all return to special stores to replace them. Why? You can convert old batteries into money to buy new ones! According to my observations, the majority of electric bicycle owners in counties, cities, and towns basically have this awareness, not to mention cars. These used batteries will basically be returned to a special lead plate recycling plant for secondary treatment and re-preparation of electrode materials.
Have you ever seen a special organization for recycling lithium-ion batteries to prepare electrode materials? Sorry, I haven't seen it. The reasons are as follows: First, the application field of lithium-ion batteries is too wide, which determines the difficulty of its recycling; second, most of the lithium-ion batteries are small, and most people usually throw away or sell their mobile phones or mp3s if they are not used. In the end, these batteries basically lie in the trash can. Although the lithium-ion battery contains less heavy metals and only the positive electrode material contains cobalt metal, it can’t support such a large user volume in the world. In the long run, this is still a However, there is no organization that pays much attention to this issue. The country should pay more and more attention to this issue.
Therefore, in general, there is no problem with lead-acid batteries as long as they pay attention to relevant environmental protection measures during the manufacturing process, because they are sealed and maintenance-free during use, and there will be a corresponding recycling mechanism in the end.

in conclusion:
In fact, the lead-acid battery is definitely an evergreen tree in the chemical power industry. It has been more than a hundred years since its birth. In recent years, although it has been said that it will be replaced by lithium-ion batteries, I think it cannot be replaced in some fields temporarily. of. Everyone should look at the problem with a developmental perspective. The research on lead-acid batteries has been progressing. Li-ion batteries still have a long way to go. They are still young (25 years old), haha, I hope there will be more high-end batteries in the future!