The reason why dry separators are less used in the ternary power battery market is thickness, because thinner separators can reserve more space for the battery to accommodate active materials, thereby increasing energy density. After the dry-process separator is made thin, if the strength is reduced, it will lead to potential safety hazards in the lithium battery.
However, with the improvement of technical process, the dry-processed diaphragm is gradually transitioning to the trend of thinning. The dry separator used in power batteries was 32 μm at first, and then gradually evolved into 25 μm, 24 μm, and 22 μm. The mainstream model at this stage is 20 μm.
The unanimous view of the industry is that the trend of dry process separators in 2019 will be dominated by products below 20μm. (The cost is half of the wet separator), which is sufficiently attractive for power battery companies.
However, the use of thin diaphragms not only tests the technical strength and mass production capacity of diaphragm enterprises, but also tests the technical R&D and engineering strength of power battery enterprises.Also read:catl lifepo4 cells
A senior executive of a diaphragm company said that the dry diaphragm is composed of a crystalline region and an amorphous region, and is fibrous. This fibrous material will reduce the stress in the electrolyte, and the stress reduction will eventually cause the diaphragm to wrinkle. This problem is not obvious when the diaphragm is thicker than 20μm, but it will show up soon after it is made thinner.
"Previously, no power battery company has used a 16μm single-layer dry-process separator. Some hidden problems will start to enlarge after the separator becomes thinner, and the wrinkling of the separator has also become the most troublesome problem for battery companies using a 16μm single-layer film." The above high level said.
At present, a small number of domestic diaphragm enterprises have large-scale mass production capacity on 16μm diaphragm products, and have entered the verification system of first-line power battery enterprises with R&D strength.
"Pushing the flames" of cost reduction and high pressure
In the traditional impression, dry-process separators are suitable for lithium iron phosphate batteries, and wet-process separators are suitable for ternary batteries, but in fact there is no strict technical route distinction between the two, such as BAK Battery, Funeng Technology and other ternary battery companies Dry-process separators have always been used; BYD, Guoxuan Hi-Tech and other lithium iron phosphate batteries use wet-process separators.
"The technical process of each power battery company is different, and the material system used is also different, which is mainly related to the company's technical system and usage habits. Since the new energy vehicle industry belongs to the policy market, subsidies have changed from decline to exit, and the cost of batteries has increased. Under the reduced requirements, it is not impossible for battery companies to change their material systems." A chief engineer of a power battery company explained.Also read:lithium ion battery 300ah
In the face of the sharp decline in the subsidy policy, car companies have switched from the blind pursuit of energy density to the idea of obtaining subsidies, and started a comprehensive market orientation. Based on the comprehensive consideration of cost and performance, power battery companies are also actively cooperating with car companies. .
In addition to converting some wet diaphragms to dry diaphragms to reduce costs, localization replacement has also become an important idea for power battery companies to reduce costs.
Gaogong Lithium Battery noticed that the dry-process diaphragms used by domestic ternary power battery companies are mainly imported. In order to meet the cost reduction demand of domestic new energy vehicles, the dry-process diaphragms of power batteries are gradually turning to domestic products.
On January 28, Funeng Technology and Xingyuan Materials signed a cooperation agreement. The two parties agreed that the supply demand for lithium battery separator products in 2019 will be no less than 40 million square meters, and the total annual purchase is allowed to be adjusted within 20%. If the guaranteed supply of the agreement is fully implemented, the estimated contract value is about 102 million yuan.
In addition, the increase in market demand for dry-process diaphragms this year also comes from the heating up of the energy storage market. At the same time, the demand for lithium iron phosphate batteries in sub-sectors such as A00-class models, electric logistics vehicles, 48V micro-hybrid systems, electric online car-hailing vehicles, and electric forklifts has increased significantly, which has also driven the increase in dry-process separators.
Wang Xiangdong, CTO of Zhongke Technology, said that thanks to the company's early roots and cultivation of the energy storage market, the heating up of the domestic and foreign energy storage markets this year has brought considerable incremental benefits to the company's dry-fabricated double-pull diaphragm. The collection and account period are better than those in the power field.Also read:lithium battery 200ah
It is worth noting that while the domestic dry process diaphragm faucets are adding new wet process production capacity, they still maintain the expansion rhythm of dry process production capacity. The capacity expansion of dry-process diaphragm faucets and large-scale manufacturing will inevitably lead to further reductions in product costs.
In 2018, Xingyuan Materials plans to build 8 new-generation lithium-ion battery dry-process separator production lines by using the technical experience accumulated for many years in the field of lithium-ion battery dry-process separators. After the project is put into production, it will form an annual production capacity of 400 million square meters of dry-process separators for lithium-ion batteries. According to data from the Lithium Battery Research Institute (GGII), China's lithium battery separator shipments reached 2.02 billion square meters in 2018, a year-on-year increase of 39.7%. Among them, the shipment volume of wet process diaphragms was 1.31 billion square meters, an increase of 66.4% year-on-year; the shipment volume of dry process diaphragms was 706 million square meters, an increase of 7.8% year-on-year, and the growth rate was much lower than that of wet process.
In 2019, the new subsidy policy was launched, the "half-cut" decline and the increased emphasis on product safety performance forced the new energy vehicle and power battery industry chain to return to market-oriented thinking. As a result, dry-process separators with low cost, excellent performance and thinning are also expected to usher in a "counter-attack" in the market.
Gaogong Lithium Battery has learned that the current dry single-pull separator used in power batteries on a large scale is 20 μm, and 18 μm and 16 μm are already on the road of large-scale application. In 2018, the price of dry-process single-pull films dropped by more than 40% year-on-year. This year, the average price of some low-end dry-process single-pull base films has fallen below 1 yuan/square meter (wet process diaphragms are at 1.8-2 yuan/square meter).
"Currently, the mainstream of ternary power batteries uses wet coating separators with a thickness of 12+4 (12μm base film + 4μm coating), and the trend of dry single pulling this year is less than 20μm. The use of 16μm products." The above-mentioned person said that once the 16μm products are used on a large scale, under the blessing of cost advantages, the dry single-pull diaphragm will erode the wet diaphragm market to a certain extent.