What Role Does A High-Temperature Box Furnace Play In The Secondary Sintering And Structural Repair Of Recycled Ncm?

The high-temperature box furnace serves as the primary reaction vessel for regenerating the electrochemical performance of recycled Nickel-Cobalt-Manganese (NCM) battery materials. By maintaining a constant thermal environment, typically at 600 °C, it facilitates the physical infiltration of lithium additives and drives chemical reactions that repair the material's atomic structure.

Core Takeaway The box furnace acts as a restorative chamber where thermal energy enables molten lithium to penetrate and heal crystal defects caused by battery usage. Simultaneously, it synthesizes a protective, high-conductivity coating on the particle surface, effectively reversing degradation and preparing the material for reuse.

The Mechanism of Structural Repair

Thermal Activation and Infiltration

The primary function of the furnace is to provide a stable temperature of 600 °C. This specific thermal energy is required to melt lithium hydroxide (LiOH) additives introduced during the recycling process.

Once in a molten state, the lithium hydroxide becomes highly mobile. The furnace's sustained heat facilitates the infiltration of this molten lithium into the defects of the NCM crystal lattice.

Reversing Cation Mixing

Batteries degrade when lithium ions are lost, leading to structural collapses known as "cation mixing." The furnace environment allows the infiltrated lithium to occupy these vacancies, effectively correcting the atomic disorder.

Restoring Phase Stability

Loss of lithium often causes the NCM material to shift toward an undesirable spinel phase. The re-lithiation process within the furnace reverts these formations, restoring the material to its original, high-performance layered structure.

Surface Engineering and Protection

Driving Solid-Phase Reactions

Beyond internal repair, the furnace powers a critical reaction on the surface of the material. The thermal energy drives a solid-phase reaction between residual lithium hydroxide and added aluminum hydroxide.

In-Situ Coating Generation

This reaction results in the formation of a layered lithium aluminate (LiAlO2) coating. Because this coating is generated "in-situ" (during the heating process), it adheres perfectly to the repaired NCM particles.

Enhancing Conductivity

The LiAlO2 coating is not merely a physical barrier; it possesses high lithium-ion conductivity. This ensures that the recycled material retains excellent ion transport properties while being protected from future degradation.

Understanding the Trade-offs

Atmosphere Control Limitations

While box furnaces are excellent for bulk processing and maintaining constant temperatures, they typically offer less precise atmospheric control than tube furnaces. If a specific reducing or oxidizing environment (e.g., hydrogen or argon flow) is strictly required to control metal ion valence, a box furnace may be less effective than a tube furnace.

Temperature Uniformity Risks

In secondary sintering, the repair relies on the melting kinetics of lithium. If the box furnace has cold spots or uneven heating zones, the lithium infiltration may be incomplete in some batches, leading to inconsistent structural repair.

Making the Right Choice for Your Goal

To maximize the quality of recycled NCM materials, align your furnace parameters with your specific regeneration targets:

If your primary focus is deep structural repair: Ensure the furnace can maintain 600 °C consistently to guarantee the complete melting and infiltration of lithium hydroxide into lattice defects.
If your primary focus is surface stability: Prioritize the precise ratio of aluminum precursors, as the furnace heat will convert these reactants directly into the protective LiAlO2 conductive layer.

The high-temperature box furnace is the bridge that transforms degraded battery scrap into high-value, active cathode material.

Summary Table:

Process Stage	Function of Box Furnace	Resulting Benefit
Lithium Infiltration	Melts LiOH at 600°C to penetrate crystal defects	Heals atomic disorder and lattice vacancies
Phase Restoration	Reverses cation mixing via thermal activation	Reverts spinel phases to high-performance layered structures
Surface Engineering	Drives solid-phase reaction of Al and Li precursors	Forms protective, high-conductivity LiAlO2 coatings
Mass Production	Facilitates bulk regeneration of cathode scrap	Transforms battery waste into high-value active materials

Revolutionize Your Battery Recycling with KINTEK

High-performance NCM regeneration requires absolute thermal precision. KINTEK provides industry-leading Muffle, Tube, Rotary, Vacuum, and CVD systems designed to meet the rigorous demands of secondary sintering and structural repair.

Backed by expert R&D and manufacturing, our furnaces are fully customizable to ensure uniform heating and stable thermal environments, preventing cold spots and ensuring consistent lithium infiltration. Whether you are scaling up bulk processing or require precise atmospheric control for specialized cathode chemistry, our equipment delivers the reliability your lab needs.

Ready to optimize your material recovery? Contact us today to discuss your custom furnace solution!

Visual Guide

References

Yu Wang, Chris Yuan. Direct upcycling of degraded NCM <i>via</i> low-temperature surface engineering for high performance lithium-ion batteries. DOI: 10.1039/d5eb00018a

This article is also based on technical information from Kintek Furnace Knowledge Base .