Change lanes to overtake! The "new" technology of high-temperature calcination of lithium battery materials has been introduced

　　"I am not against the 'volume', not against the 'volume' at all, it is precisely because of the 'volume' that we can achieve the 'volume' of electric vehicles to the same price as fuel vehicles or even lower." At the 5th New Energy Vehicle and Power Battery (CIBF2024 Chongqing) International Exchange Conference, Dr. Wu Zhen, Founder/General Manager of Cigna Advanced Thermal Technology (Suzhou) Co., Ltd., said in his speech that "the low level of involution is also one of the reasons why the lithium battery industry has entered a 'cold winter'." ”

　　In the face of the "involution" and "cold winter" that the lithium battery industry is currently experiencing, Dr. Wu Zhen believes that in order to cross the "cold winter" and pass through the cycle, it is necessary to maximize the cost, and the high-level "involution" is to continuously reduce the comprehensive cost through the technological innovation of products, processes and equipment. On the basis of more than ten years of industrial kiln technology accumulation, its development team has devoted 4 years to develop a new technology of rollless electric side heating trolley kiln with completely independent intellectual property rights, which has the characteristics of high yield, low consumption, stable operation and good temperature uniformity, which will help lithium battery enterprises establish core differentiated advantages in the "cold winter" period.

　　According to Wu Zhen, the high-temperature calcination technology of rollless electric side heating trolley kiln developed by Cigna has been commercialized in 2023. The first continuous production line of pure oxygen atmosphere for ternary material customers has achieved the expected effect of doubling the production capacity of a single line and reducing the energy consumption per ton by about 20%; In terms of temperature uniformity, it also meets the needs of high-nickel and medium-nickel ternary products; The overall operation of the equipment is very stable and does not require rollers; At the same time, the operation and maintenance of the equipment is easier.

01

Evolution of high-temperature calcination technology for cathode materials

　　In the more than 20 years of development of the lithium battery industry, the cathode material kiln technology has undergone the technical iteration of shuttle kiln, push plate kiln and roller kiln, and the production has experienced from batch to continuous, and the single-line production capacity of the kiln has been continuously increased by increasing the number of saggers stacked in the furnace cavity. The driving force behind the continuous iteration of kiln technology and equipment is mainly the industry's continuous pursuit of capacity improvement and energy consumption reduction.

　　Wu Zhen said that the subversive changes in the high-temperature calcination technology of cathode materials are all in the bottleneck period of the development of the previous generation of mainstream equipment, and then give birth to a new generation of technology. At present, subject to the limitations of rollers and temperature uniformity, the development of roller kilns has reached a bottleneck period, which is a good time for equipment and material enterprises to change lanes and overtake.

　　"The roller kiln technology has developed from the initial two-row two-layer to the current six-row double-layer, and we think that it has basically reached the ceiling." In Wu Zhen's view, there are still the following pain points in the current roller kiln:

　　The first is the production capacity, the impact of the mechanical strength and length limitation of the roller on the production capacity and the stability of the production line operation;

　　the second is the temperature field, which continuously increases the number of sagger stacks to the roller kiln and has a great impact on the temperature uniformity;

　　The third is the air flow, especially for the ternary cathode, the bottom sagger air flow is not smooth, so many products must be calcined by the single-layer method;

　　Fourth, energy consumption, the space utilization rate in the roller kiln cavity is not high, resulting in large energy consumption.

02

The technological innovation point of the rollless electric side hot trolley kiln

　　In response to the above pain points, Wu Zhen shared with the participants the unique innovative technology of Cigna Advanced - the rollless electric side heating trolley kiln has carried out comprehensive innovation in terms of material transportation mechanism, kiln configuration, heating layout and intake and exhaust mechanism.

　　In terms of transportation institutions, according to Wu Zhen, the roller-free electric side hot trolley kiln has completely canceled the rollers, and the new transportation mechanism can carry more materials, thereby achieving a significant increase in production capacity. According to reports, the technology draws on the concept of tracks and trolleys in traditional tunnel kilns, replacing the rollers with trolleys, which have a very large load and can carry more materials; Wheel-rail transportation is more stable and controllable; In addition, there are basically no consumables or consumables, making it easier to maintain.

　　In terms of furnace configuration and heating layout, it has been redesigned to meet the requirements of temperature uniformity, atmosphere control and energy consumption reduction. Wu Zhen said that the rollless electric side heating trolley kiln changed the layout of the heater and sagger along the horizontal direction in the roller kiln, and changed to a vertical layout, and the sagger was stacked in two columns to a high place, and the heating layout changed accordingly, the heater was installed vertically, and the thin and tall furnace cavity (more compact structure) increased the space utilization rate by about 50%, and it is expected to be further improved in the future. While increasing production capacity, it is also conducive to reducing energy and gas consumption.

　　In terms of the intake and exhaust mechanism, the intake/exhaust mechanism is arranged on both sides of the kiln wall, so that the process gas can efficiently enter the bottom sagger. The original "bottom-up" airflow mode in the vertical direction of the middle bottom intake/top exhaust of the roller kiln has been changed to an innovative horizontal airflow, which is more conducive to the airflow into the sagger, and when the airflow is discharged from the other side of the sagger, the exhaust gas inside the sagger can also be effectively discharged.

　　On the one hand, the number of exhaust ports is not limited by the structural strength of the kiln, and a reasonable number of kiln bodies can be set in the corresponding temperature zone according to the needs of the process, and the exhaust ports are very close to the sagger, which is convenient for a large amount of exhaust gas to be discharged quickly.

　　On the other hand, the combination design of the intake/exhaust mechanism is very flexible, and different combinations can be adopted according to the different reactions of materials in different temperature ranges, such as the air intake and top exhaust on both sides, or the intake on one side and the exhaust on one side/top exhaust, which can form a variety of different combination types.

　　In terms of temperature uniformity, at present, the temperature uniformity is measured by the traditional temperature measuring block method in the sagger arrangement mode of two rows of ten layers by heating the silicon carbon rod, and the temperature uniformity has been measured within ± 6 °C (reaching the same level of six rows of double-layer roller kilns).

　　In terms of air tightness, due to the cancellation of rollers, there is no large number of roller perforations in the furnace body of the rollerless electric side hot trolley kiln, which is more conducive to improving the air tightness of the kiln body. Wu Zhen said that in the actual operation of the continuous production line of ternary materials, when the atmosphere is switched, the oxygen concentration in the furnace has basically exceeded 99% after the air is switched to pure oxygen for 2 hours. During the normal high-nickel ternary operation, the constant temperature section can basically be maintained at more than 99%, and the heating section can be maintained at more than 98% oxygen concentration.

　　In terms of production capacity improvement, from the perspective of the technology that has been implemented so far (for the first burning of lithium battery ternary cathode materials), the production capacity is twice that of the four-row double-layer, which is 50% higher than that of the six-row double-layer. Wu Zhen pointed out that in the future, with the iteration of technology, after the effective heating length is increased, two more layers of sagger can be stacked, and the production capacity is expected to increase by another 25%.

　　For example, if the length and width of a single sagger are increased by 7 cm, the material loading capacity of each sagger can be increased by more than 40% without increasing the material filling thickness, which is conducive to further improving the single-line production capacity of the kiln. "For lithium iron phosphate, the kiln body of about 70 meters can reach a production capacity of nearly 15,000 tons, which is more than double that of the six-row double-layer roller kiln," said Wu Zhen.

　　In terms of energy saving, taking the technology that has been implemented as an example, in the 6 consecutive months of operation, the average power consumption of lithium battery ternary cathode materials is 2100 kWh/ton, while the current roller kiln is almost 2500 kWh-2800°/ton, saving about 20% of electricity.

　　"At present, the high-temperature calcination technology of the rollless electric side heating trolley kiln is being promoted from the cathode material to more fields, such as sodium anode, solid electrolyte, oxide, etc., and the research and development of high-temperature calcination and CVD coating integrated equipment is also being carried out." Looking forward to the future, Dr. Wu Zhen said that this innovative technology platform has great scalability, and Cigna Pioneer expects to cooperate deeply with customers to build a highly customized high-temperature calcination production line, helping customers form a core competitiveness with unique process processing equipment and "rolling" at a higher level. In addition, Cigna Pioneer has also made an overseas layout of core patents, which can help domestic material companies go overseas to "roll".