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Thanks to years of hard work and hard work, China has made remarkable achievements in many cutting-edge fields of science and technology in recent years. Chinese people are also becoming more and more accustomed to Xi it will not be long before they will see the news of breakthroughs in domestic technology.
With the support of such technological breakthroughs, the advantages of mainland products in terms of commodity quality and manufacturing costs have become more and more prominent. Lithium battery technology, which is the core technology of many electronic products and new energy vehicles, is an example.
Today, China's lithium battery industry has occupied more than 70% of the world's lithium battery shipment market, replacing Japan as the world's largest producer of lithium battery market.
However, behind this success, there are still hidden concerns. As a crucial battery separator material processing technology in the structure of lithium batteries, it is still firmly in the hands of other countries.
Could it be that the mainland's lithium battery leadership is an illusion of seeming prosperity?
The development of lithium batteries in China
Once upon a time, the most popular country in the world's lithium battery market was Japan. Due to the first-mover advantage in technology, Japan once accounted for more than 90% of the world's lithium battery shipments.
When the world enters the era of electric energy, grasping the leading position in the production and research of lithium batteries means that in the future development of new electronic technologies, we can lead and formulate the development direction of the electronic field at the first time.
In the same way, if other countries want to develop their own electronic science and technology path, then lithium battery, as the best way to store electricity at that time, is an unavoidable research breakthrough direction.
Ironically, the mainland, as the world's largest graphite exporter, has not been able to make enough profits from graphite exports. Foreign companies that control the core technology usually import graphite from the mainland, process it and then sell it to the mainland.
When importing, it is bought according to the price of raw material graphite, and when it is exported, it is sold according to the price of lithium battery raw materials.
knew that it was a loss-making business, but because of the lack of the mainland's own lithium battery raw material processing technology, the mainland enterprises at that time could only reluctantly accept it. Such an unfair trade method continued until the rise of mainland battery companies.
BYD was originally just a little-known domestic car brand, but due to a large investment in new energy vehicles, the company has become a leader in the field of domestic electric vehicles in just a few years.
In addition to technical research on electric vehicles, BYD also focuses on on-board lithium batteries. Not only BYD, but also the development of the new energy vehicle industry has also given birth to the glory of the "CATL era".
Today, CATL's battery products have covered many fields, including electric vehicles, and have gained a leading position in the world.
However, there are also voices that China's lithium battery has not achieved a real lead, after all, as an important separator material and material processing technology inside the lithium battery, it is still impossible for the mainland to produce independently.
Since we can't make a breakthrough in all aspects, it means that we haven't gotten rid of the situation of restricted development, so is this statement objective? What is the battery separator?
What is a lithium battery separator
In most lithium batteries, the positive and negative electrodes of the battery, the battery separator and the organic electrolyte exist as the most important structure of a battery. In the past, researchers usually focused on cathode and anode materials.
The 2019 Nobel Prize in Chemistry was awarded to three scholars from the United States, the United Kingdom and Japan, who provided new ideas for the future development of lithium batteries through the exploration of lithium battery cathode and anode materials, and can lead the development of future lithium battery technology.
However, just like the staff living behind the halo of stars, although the battery separator as a whole never occupies the most important position, its existence is indeed the part that determines the lower limit of the operation of a lithium battery.
So how to judge the quality of the separator? The general criteria are divided into insulation, chemical stability and pore passability. To put it simply, the battery separator should be able to "separate" and "pass".
The so-called "separation" is that it is necessary to be able to separate the positive and negative poles of the battery to avoid short circuits, so insulation is very important. And "passing" means that ions can pass through smoothly and flow freely between the poles.
After many iterations, the material of the battery separator has also evolved. From the earliest woven film to the later non-woven film and composite film, until today's more mainstream polyolefin material microporous membrane material has changed many times.
Compared with traditional materials, polyolefin materials have the advantages of low material cost, strong plasticity, and a wide range of material sources. Because of this, most of the current battery separator materials use microporous membranes made of this material.
However, polyolefin materials are derived from petroleum by-products, so they are not the best choice in terms of environmental protection, and their replacement by newer materials will be an inevitable trend in the future.
In addition to polyolefin materials, polyvinylidene fluoride and polyimide, which are not so widely used, have also become common application materials for lithium battery separators. The latter is often used for the exterior coating of polyolefin materials.
However, the above traditional chemical materials have common defects: firstly, these materials have poor affinity for the electrolyte, and cannot completely absorb the electrolyte, which will affect the chemical properties inside the battery;
In addition, this material has poor environmental adaptability to thermochemical reactions, and it is easy to deform at high temperatures when the reaction produces heat energy. The deformed separator structure will affect the efficiency of the battery at least and may cause safety problems at worst.
Especially in the design of batteries in some high-tech fields, due to the harsh environment its working state can not be guaranteed, so the characteristics of the above traditional materials determine that they are not considered in high-end fields such as aviation.
In order to solve this problem, most of the current foreign research directions focus on how to improve the material to make it more suitable for the strict battery use environment. But this direction is not necessarily suitable for the mainland.
Since it is impossible to break through in the production and processing of battery separator materials in a short period of time, the mainland might as well open up its own road, after all, we are no strangers to the operation of "corner overtaking", and "last mover first come" is also what we have been doing.
So how can the mainland start from a new perspective, avoid the restrictions of foreign diaphragm technology, and find a way of our own?
Research on new materials for diaphragms
From an objective point of view, there is still a big gap between the mainland's current technology accumulation in battery separators and foreign countries. Although the polyolefin wet process and the coating separator technique have been mastered, they are still concentrated at the low-end level.
Following others means that you can only imitate forever and cannot surpass. In view of the fact that today's lithium batteries have paid more and more attention to the indicators of "three highs, one long and one low", we need to plan the future research direction from a higher perspective.
The so-called "one long and one low" refers to "long battery life" and "low cost".
This also requires that the material selection of battery separators needs to follow the principles of high efficiency, light and thin, low cost and safety. The first thing that mainland battery separator manufacturers should do is naturally to improve their existing products and stabilize the low-end market;
At the same time, in the research of new materials such as meta-aramid and cellulose, it is also necessary to adopt a more forward-looking vision while developing, and design separator materials and separator spinning technologies that are more suitable for the future market.
So far, whether it is relatively environmentally friendly meta-aramid and cellulose, or isotopically chemically synthesized PET, PAN and other materials. All of them have defects such as poor heat resistance or high material cost, and it will take time for these new materials to become mainstream.
In fact, we can change the way of thinking and start from the aspect of battery characteristics. After all, the development direction of batteries will also change in the future, and the new development direction of lithium batteries will inevitably lead to corresponding changes in separator technology.
For example, the more efficient "high-nickel ternary lithium battery" will cause a large amount of nickel ions in the electrolyte when an internal chemical reaction occurs. If too many nickel ions are concentrated on the negative electrode of the battery, it will affect the battery efficiency.
At this time, the battery separator is required to selectively allow nickel ions to pass through, and when the number of nickel ions passing through is lower than the standard level, it will not only increase the stability of the cathode, but also ensure the safety of the battery itself.
It is advisable to change the spinning structure in the separator manufacturing process to ensure that the number of nickel ions passing through is within a controllable range. For the characteristics of this kind of battery, "more" is not necessarily good, but "less is more".
It can also be used as one of the special alternative solutions for high-nickel lithium batteries by using mainstream basic materials and nano-resin coating the surface. It can be seen that in different lithium battery fields, we can dig deep into the space is not small.
Because the progress of science and technology cannot be solved by closing the door alone, we still need to seek cooperation with other enterprises at home and abroad in the development of new diaphragm technology, but the mastery of common patents can also help mainland enterprises get rid of the current predicament.
epilogue
Holding the world's largest lithium battery application market, it is one of the biggest cards of mainland enterprises. In addition to supporting a large number of low-end battery companies, the huge market also provides valuable opportunities for the research and development of lithium-ion battery-related materials in mainland China.
Resources
1. "Discussion on the Development Status and Trend of Lithium-ion Power Battery Separator Materials"
2 Research Progress on New Lithium Battery Separator Materials
3 Preparation and Research Progress of Lithium-ion Battery Separator Materials
4 "Research Progress on Lithium Battery Separators, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences"
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