Horizontal continuous graphitization technology for negative electrode materials

　　I. Overview

　　Under the dual carbon control policy, investment in new energy in the fields of electric vehicles and wind-solar-storage energy is accelerating, leading to strong demand for new energy lithium batteries.

　　The anode is one of the main materials of the battery. Its shipment volume has rapidly increased from 146,000 tons in 2017 to 720,000 tons in 2021, with a CAGR (compound annual growth rate) of 49%. The year-on-year growth in 2021 reached 97.3%. In 2022, the shipment volume of anode materials reached 1.37 million tons, a year-on-year increase of 90.3%, with a slight slowdown in growth rate. The track is crowded, overcapacity exists, and industry competition is fierce. New directions and technologies are needed to break through!

　　Anode materials are roughly divided into carbon-based materials and non-carbon-based materials:

　　Carbon-based materials: including graphite, graphene, and disordered carbon.

　　Non-carbon-based materials: including silicon-based materials, tin-based materials, titanium-based materials, nitrides, etc.

　　Currently, the most mainstream anode material is carbon-based graphite anode material, which can be further divided into natural graphite and artificial graphite. Artificial graphite is superior in quality to natural graphite and accounts for the absolute majority of production.

　　II. Background of Anode Materials

　　Graphite is the most important process in the production of graphite anode materials, directly affecting the final output and quality of the anode, and having a significant impact on the market and enterprises. Graphite is a high-energy-consuming production process, accounting for a very high proportion of the total cost of anode materials, approximately 50%. Its high energy consumption also leads to the impact of "dual control" on graphite production, resulting in insufficient capacity utilization and difficulties in obtaining approval for new capacity. Therefore, under the premise of energy saving and emission reduction and improved efficiency, new technologies and directions are needed.

　　Graphite processes can be divided into batch and continuous production methods:

　　Batch production is a process where materials are loaded into the furnace without moving, undergoing processes such as heating, high-temperature graphitization, and cooling, before power is cut off, cooling, and unloading. This method has relatively high energy consumption.

　　Secondly, continuous graphitization is a production process without power interruption. The graphitized materials need to move through a series of temperature zones to achieve continuous graphitization, which has lower energy consumption.

　　Therefore, the continuous production method for graphite anode materials has become an effective breakthrough direction for the industry.

　　After years of demonstration and practice of continuous graphitization of carbonizing agents, we have made progress. Under the dual carbon control policy, the continuous graphitization of anode materials and carbon materials has milestone significance for energy saving and emission reduction. It has the advantages of small investment, good quality, and high output.

　　III. Status of Graphitization Technology

　　Graphitization refers to the transformation of carbon atoms from a disordered and irregular arrangement to a regular hexagonal planar network structure at high temperatures, resulting in stable high conductivity, high thermal conductivity, corrosion resistance, and friction resistance of the material.

　　From a production perspective, the process of anode materials is relatively long (more than 10 small processes). The graphitization process of artificial graphite anode materials has high technical barriers, and the technical differences between various players mainly lie in this aspect. Graphitization processing accounts for approximately 50% of the production cost of artificial graphite anode materials and is also an important process for quality.

　　As mentioned earlier, there are several graphitization methods: the crucible method, the box method, and the continuous method. The first two methods use Acheson furnaces and internal heating series furnaces, while the continuous method uses continuous graphitization furnaces. The crucible method and the box method are both batch productions, while the continuous furnace is continuous production.

　　Currently, the graphitization of anode materials usually uses the crucible and box methods, using graphitization furnaces for producing graphite electrodes in the carbon industry for graphitization processing.

　　1. Crucible method:

　　High investment, high energy consumption, poor environmental protection, and high operating costs.

　　Batch production, one furnace in and one furnace out.

　　2. Box method:

　　High investment, high energy consumption, poor environmental protection, and high operating costs.

　　Batch production, one furnace in and one furnace out.

　　3. Continuous graphitization method:

　　Continuous graphitization is continuous production, with advantages in cost, efficiency, and environmental protection. It has become an important new direction for in-depth industrial exploration and is currently at the forefront of competition among industry leaders.

　　Advantages of continuous graphitization:

　　1. Higher thermal energy utilization rate

　　2. Saves production auxiliary materials. The continuous method consumes almost no auxiliary materials, while the Acheson method consumes approximately 4 tons of auxiliary materials per ton of product.

　　3. The continuous production process is closed, and waste gas is centrally treated, which is environmentally friendly. Specialized equipment collects and processes waste gas, while the Acheson method is an open production environment and cannot effectively collect waste gas.

　　4. Very low carbon emissions, only 25% of the Acheson method's carbon emission equivalent.

　　5. Continuous production organization, intermediate products are not "grounded", saving a lot of labor and transportation costs.

　　Bottlenecks of horizontal continuous graphitization technology

　　Continuous graphitization of anode materials is difficult and has high technical content.

　　Through years of practice and research, Sanhe Carbon has designed a continuous graphitization furnace. To adapt to the fine powder of anode materials, based on the vertical continuous furnace, we have designed and developed a horizontal continuous graphitization furnace, hoping to provide a revolutionary solution for China's energy saving and emission reduction and dual carbon control.

　　As shown below, the advantages of continuous graphitization technology are:

　　The investment is 1/4 of the crucible method, the operating cost is 1/6, the floor area is 1/5, and the construction period is 1/3. It is environmentally friendly, low-cost, high-quality, and has good product consistency.

　　Energy consumption is only 1/4-1/5 of the crucible method, saving energy and reducing emissions, in line with the national major strategy, and is very important for the development of high-end technology in the industry in China and the world.

　　IV. Horizontal Continuous Graphitization Furnace for Carbon and Anode Materials

　　The horizontal continuous graphitization furnace for carbon and anode materials that we have developed and designed has a horizontal cylindrical structure, including a base, support, feeding system, discharge cooling system, special transformer, core heating components, circuit short network, electrical control system, and safety production control system.

　　The furnace body is divided into preheating, heating, and cooling zones. The central area is the high-temperature zone. The furnace body is equipped with a heat insulation zone, insulation zone, structural layer, insulation layer, and outer body. It ensures the thermal performance of the furnace body, the structural stability of the furnace body at high temperatures, the normal operation of the electrical system, and the qualified and consistent quality of the product.

　　Safety production,

　　Ensuring product quality,

　　Equipment design includes:

　　1. Charging position control

　　2. Central temperature control

　　3. Feed rate control

　　4. Explosion pressure control

　　5. Water pressure control

　　6. Water shortage control

　　7. Discharge temperature control

　　8. Purification control

　　9. Furnace thermal stability control

　　10. Hydraulic pressure control

　　11. Frequency control

　　12. Central tube control

　　13. Leakage prevention control

　　Advantages:

　　1. Low investment and short construction period.

　　2. No auxiliary materials, no crucible, low operating cost.

　　3. Significantly reduces heat loss, resulting in noticeable energy saving and emission reduction.

　　4. Good exhaust performance.

　　5. Good purification performance.

　　6. High temperature.

　　7. Good product consistency.

　　8. Good safety.