The coating preparation of lithium-ion battery cells is the core link of electrode manufacturing, which directly affects the energy density, cycle life, rate performance and safety of the battery cells. The electrode coating (the positive electrode is coated on aluminum foil, and the negative electrode is coated on copper foil) is composed of active materials, conductive agents, binders, etc. Its uniformity, density, adhesion and other characteristics are crucial to the performance of the battery cells.
The core purpose of coating preparation
The core function of electrode coating is to realize the embedding/de-embedding (energy storage and release) of lithium ions through uniformly distributed active materials, and at the same time, to build an electronic conduction network through conductive agents and binders to ensure the adhesion and structural stability of coating and current collector. Therefore, coating preparation needs to achieve:
● Uniform mixing of various components (active materials, conductive agents, binders);
● Uniform coating thickness/surface density (mass per unit area);
● Strong adhesion to current collector, no cracking or shedding;
● Reasonable porosity (taking into account both lithium ion diffusion and structural stability).
There are various ways to prepare lithium-ion battery cell coatings, and different methods are suitable for different material systems, coating thicknesses and production requirements. Ultrasonic spraying, as a high-precision spraying technology, has unique advantages in specific scenarios. Ultrasonic spraying is a type of non-contact spray coating. Its core principle is to atomize the solution into fine droplets through ultrasonic vibration, and then deposit the droplets on the substrate in a directional manner through drainage and air conduction to form a uniform coating.
Advantages of ultrasonic spraying:
● High coating uniformity
● High material utilization
● Suitable for ultra-thin coatings and complex structures
● Protect flexible diaphragms and improve yield
Ultrasonic spraying is an important method for preparing lithium-ion battery cell coatings with high precision and low damage. It is especially suitable for ultra-thin coatings, surface coatings and complex structural scenes, but its efficiency and cost limit its large-scale mass production application. In the future, in the field of solid-state batteries and high-end customized batteries, ultrasonic spraying will expand its application scope through technology upgrades to multi-nozzle and roll-to-roll, becoming an important supplement to traditional coating methods.
