In the era of solid-state batteries, the future path of the "dry process and wet process" for Lithium Batteries separators
.jpg)
I. The Importance of the Separator The main function of the separator is to separate the positive and negative electrodes of the battery to prevent internal short circuits, while allowing lithium ions to migrate freely during the charging and discharging process. To meet the requirements of battery safety, efficiency, and long life, the separator needs to possess the following core technical requirements:
.jpg)
1. Porosity and pore size distribution: Directly affect ionic conductivity and battery energy density.
2. Mechanical strength and elasticity: It should have sufficient tensile strength and flexibility to cope with the thermal expansion and mechanical stress inside the battery.
3. Electrolyte permeability: Effectively control the penetration of the electrolyte to prevent excessive liquid intrusion from affecting the battery's stability and cycle life.
4. Thermal stability: In a high-temperature environment, the material should have good thermal stability to prevent the separator from rupturing or short-circuiting due to thermal expansion.
5. Safety: It can effectively prevent the penetration of lithium dendrites and avoid the phenomenon of battery thermal runaway.
II. Comparison of the Dry and Wet Separator Processes
Dry Separator
1. The production process includes steps such as raw material mixing, melt extrusion, stretching and forming, and heat setting. First, the polymer raw materials and additives are mixed to form a uniform melt, which is extruded under tensile stress to form a lamellar crystal structure. Slit-like micropores are formed through subsequent stretching, and finally, a microporous structure separator is obtained by final shaping.
2. Advantages: The production process does not use solvents or liquids, and the operation is relatively simple and environmentally friendly.
3. Disadvantages: In terms of porosity and pore size uniformity, it is slightly inferior to the wet separator.
Wet Separator
1. During the production process, the polymer is mixed with a pore-forming agent (such as a small molecule high-boiling solvent), heated and melted, cooled to form phase separation, and then microporous membranes with uniform pore size distribution and high porosity are formed through steps such as stretching and solvent extraction.
2. Advantages: The uniformity of coating thickness, porosity, and pore size can be precisely controlled by process parameters, with a higher degree of customization. It can provide higher porosity, more uniform pore size distribution, and stronger mechanical properties.
3. Disadvantages: The production process is relatively complex and may involve environmental issues such as solvent treatment.
III. The Current Situation and Development Trends of the Domestic Separator Market In recent years, driven by the new energy vehicle and energy storage industries, the shipment volume of domestic lithium battery separators has continued to grow. In 2023, the global shipment volume of lithium battery separators exceeded 21 billion square meters, among which the shipment volume of Chinese separator enterprises accounted for more than 83% of the global shipment volume, firmly occupying the dominant position in the global lithium battery separator market.
.jpg)
Specifically analyzing the shipment volume of different types of separators, the wet separator occupies a relatively large market share due to its advantages. In 2023, the shipment volume of lithium battery separators in China reached 17.69 billion square meters, with the wet separator accounting for as high as 73%.
.jpg)
With the emergence and rapid development of new battery technologies such as solid-state batteries, more stringent requirements have been placed on separator materials. Solid-state batteries have higher requirements in terms of interface stability, thermal stability, and mechanical strength, and the wet separator,with its unique advantages, is likely to become one of the key technologies indispensable in the commercialization process of solid-state batteries.
IV. Future Prospects In the era of the rise of solid-state batteries, both the dry and wet separators are facing new opportunities and challenges. The dry separator can continue to play its advantages of being environmentally friendly and easy to operate, and play a role in some application scenarios that are sensitive to cost or have relatively low requirements for specific performance. The wet separator should continuously improve its technical level to meet the requirements of high-demand application scenarios such as solid-state batteries.
.jpg)
Whether it is the dry or wet separator, both will continue to play an important role in the field of new energy batteries, and their development will also promote the progress of the entire new energy industry. In the future, we look forward to the continuous innovation of these two processes to make greater contributions to the realization of more efficient, safe, and sustainable energy storage and utilization.