The production process of artificial graphite mainly includes the following steps:
Raw material preparation: Select high-quality petroleum coke, needle coke, etc. as raw materials, and crush and screen them to ensure uniform particle size of the raw materials. At the same time, mix the raw materials with additives such as binders and conductive agents to improve the conductivity and structural strength of the negative electrode materials.
Molding: The mixed materials are molded or extruded to form negative electrode sheets of a certain shape and size.
Pre-carbonization: Pre-carbonize the negative electrode sheets at a lower temperature to give them a preliminary graphitized structure.
High-temperature carbonization: Deeply carbonize the negative electrode materials under high temperature to achieve the ideal graphitization degree. This process is usually carried out in a non-oxidizing atmosphere of 2500-3000℃ to convert the amorphous chaotic layer structure of carbon into an ordered graphite crystalline structure.
Cooling and crushing: After carbonization is completed, the negative electrode material is cooled and then crushed into particles suitable for screening.
Screening and grading: The negative electrode material is divided into different particle size grades through screening equipment to meet the needs of different products.
Surface treatment: The surface of the negative electrode material is treated to improve its wettability with the electrolyte and cycle stability.
Packaging: The treated negative electrode material is packaged to ensure the safety and cleanliness of the product during transportation and storage.
Selection of raw materials and binders for artificial graphite: The aggregates of artificial graphite are divided into three categories: coal system, petroleum system and coal and petroleum mixed system. The high specific capacity negative electrode uses needle coke as the raw material, and the ordinary specific capacity negative electrode uses cheaper petroleum coke as the raw material. Asphalt is used as a binder.
Application areas of artificial graphite: Artificial graphite is mainly used as the negative electrode material of lithium batteries, affecting the initial efficiency and cycle performance of lithium batteries. Negative electrode materials account for 6% to 10% of the cost of lithium batteries.