The three key stages in the production of ternary cathode materials for lithium-ion batteries are mixing and grinding, high-temperature sintering, and crushing and decomposition. The control of each stage and the performance of the equipment will have a direct or indirect impact on the final product. Among these, grading, screening, and packaging are the final stages of ternary material production. Let's take a look at these stages.
●Classification
The particle size distribution of ternary lithium-ion battery materials affects the specific surface area, compaction density, electrode processing performance, and battery electrical performance. While pulverizing equipment can control particle size, it cannot control particle size distribution. To control particle size distribution, grading equipment is required. Grading of ternary materials typically involves adding an air classifier after an air jet mill to directly classify the pulverized product. Different air classifiers and grading processes can be selected based on the particle size distribution requirements of the ternary materials.
● Screening
To prevent the presence of foreign matter or large particles in the material, ternary lithium-ion battery materials need to be screened. The Dmax of ternary materials should be at least less than 50 μm, but sometimes it may exceed this limit. Vibrating screens offer high screening efficiency, typically 80%–95%; they can screen a wide range of raw material particle sizes, from greater than 250 mm to 0.1 mm or 0.01 mm; they have a high output per unit area; and they are easy to adjust with less screen clogging. However, these screens require specialized transmission equipment and consume power.
Regarding the overall operation of a vibrating screen, the most important components are the screen mesh, the motor, and the bearings. In the use of ternary cathode materials for lithium-ion batteries, the selection of the screen mesh is crucial. Because the manufacturing process of ternary materials must prevent the introduction of iron impurities or other metals, the screen mesh must be made of a non-metallic material and resistant to alkali corrosion.
●Packaging
Ternary lithium-ion battery materials are typically packaged using vacuum packaging or vacuuming followed by inert gas filling. There are many types of vacuum packaging machines, generally categorized as mechanical extrusion, tube insertion, chamber conveyor belt, rotary table, and thermoforming. The principle of mechanical extrusion vacuum packaging is as follows: after filling the bag, elastic materials such as sponges are used on both sides to expel the air from the bag before sealing it. This method is the simplest, but the vacuum level is low, making it suitable for applications where high vacuum requirements are not necessary.
One of the important quality indicators for ternary lithium-ion battery cathode materials is particle size and particle size distribution. Particle size and particle size distribution affect the specific surface area, tap density, compaction density, processing performance, and chemical properties of ternary materials. Therefore, the particle size and particle size distribution of ternary materials used in lithium-ion batteries must be strictly controlled.
Advantages of ternary cathode materials for lithium-ion batteries
1. The price of ternary cathode materials for lithium-ion batteries is not high, and the cost is low.
2. Better cycle performance than normal lithium cobalt oxide.
3. The specific capacity is slightly higher than that of lithium cobalt oxide.
4. It offers a good balance between capacity and security.
5. Good overfill resistance and easy to synthesize
6. Low polarization during high-current charging and discharging. The battery has high input/output capability, allowing for continuous 3C charging and 5C discharging.
Amid the booming trend of ternary lithium-ion batteries, many domestic cathode material companies face enormous foreign patent fees during their development. Domestic ternary material patent applications are relatively scattered, especially with leading companies having limited involvement, resulting in a weak overall research atmosphere. Domestic companies need to prioritize cathode material R&D and intellectual property protection. Secondly, there is significant room for improvement in the safety and cost aspects of ternary materials.
