With the rapid development of the new energy vehicle and energy storage battery industries, the recycling of spent lithium-ion batteries has become a core issue in resource circulation and environmental management. Pyrolysis, as a critical step in the recycling process, directly determines recycling efficiency, safety, and operational costs. However, the hidden risk of thermite reaction is often overlooked, which can lead to severe production accidents once triggered. This article provides an in-depth analysis of the hazards of thermite reactions, the limitations of traditional pyrolysis equipment, and recommends electromagnetic induction pyrolysis furnaces as a more suitable solution for industry needs, offering reference for battery recycling companies in their equipment selection.

Thermite Reaction: A “Critical Hidden Danger” in Pyrolysis of Spent Lithium-Ion Batteries

After crushing, spent lithium-ion batteries undergo pyrolysis to remove organic components such as electrolyte solvents, separators, and binders. This process requires precise temperature control within the range of 500–600°C. However, since the crushed materials contain aluminum foil, its surface passivation film can decompose under high temperatures (500–600°C) and in a hydrogen fluoride atmosphere. If the pyrolysis equipment lacks precise temperature control and exceeds 600°C, aluminum may undergo a vigorous thermite reaction with nickel-cobalt-manganese oxides (in NMC batteries) or iron oxides (in LFP batteries).

This reaction releases heat equivalent to five times that of electrolyte combustion, causing the temperature of reaction products to soar above 3000°C. This not only damages equipment and interrupts production but may also trigger fires, explosions, and other major safety incidents, leading to significant economic losses and safety risks for enterprises. Therefore, precise temperature control and excellent sealing performance are core prerequisites for selecting pyrolysis equipment.

Challenges of Traditional Pyrolysis Equipment

Poor Temperature Control Accuracy: Temperature in rotary kilns fluctuates easily, making it difficult to precisely control temperatures in different zones, which can easily trigger thermite reactions.

Inadequate Sealing: The rotating structure of the kiln results in inherently weak sealing, leading to gas leakage and potential safety hazards.

Low Thermal Efficiency: Thermal efficiency is only about 50%, resulting in high energy consumption costs. For example, a 10,000 tons/year production line may incur pyrolysis energy costs exceeding RMB 3.2 million annually.

Slow Startup: Preheating and startup take up to 3 hours, affecting production continuity and reducing operational efficiency.

Electromagnetic Induction Pyrolysis Furnace: Solving Safety and Energy Efficiency Challenges

The electromagnetic induction pyrolysis furnace adopts a multi-section furnace body with independent heating control for each zone, allowing precise regulation of temperatures in different areas and strictly maintaining the pyrolysis temperature within the safe range of 500–600°C. Leveraging the skin effect and instant electric-thermal conversion characteristics of electromagnetic induction heating, it offers rapid temperature response and high control accuracy, fundamentally avoiding thermite reactions caused by excessive temperatures and ensuring safe and stable production.

By abandoning the rotating structure of traditional rotary kilns and adopting a fixed-furnace design, the equipment completely resolves the sealing issues associated with rotation. The excellent overall sealing effectively prevents the leakage of harmful gases during pyrolysis, protecting operator health and ensuring compliance with environmental emission standards.

Compared to natural gas or resistance heating, electromagnetic induction heating offers higher heat transfer efficiency, increasing thermal efficiency from about 50% in traditional rotary kilns to over 90%. For a 10,000 tons/year lithium-ion battery recycling production line, pyrolysis energy costs can be reduced from over RMB 3.2 million to below RMB 1.6 million annually, saving more than RMB 1.6 million per year and substantially enhancing corporate profitability.

The preheating and startup time is reduced from 3 hours for traditional rotary kilns to within 1 hour, enabling quick response to production demands, reducing non-productive time, and enhancing the continuous operational efficiency of the production line, thereby further lowering operational costs.

Selection suggestions

Primarily evaluate the equipment’s temperature control accuracy and sealing performance, prioritizing devices with multi-zone independent temperature control and robust sealing structures to fundamentally avoid thermite reactions and gas leakage risks.

Pay attention to the equipment’s thermal efficiency and energy consumption levels, opting for energy-efficient models to reduce long-term operational costs.

Consider the equipment’s startup speed, stability, and maintenance costs to ensure efficient and continuous operation of the production line.

Prefer suppliers with strong R&D capabilities who can provide customized solutions to ensure the equipment’s compatibility with the production line.