In the manufacturing process of new energy batteries, what important role can permanent magnetic iron removers play?

On the road of pursuing higher energy density, longer cycle life and absolute safety for new energy batteries, a tiny but deadly enemy is often overlooked - ferromagnetic impurities. They lurk like "ghosts" in raw materials and production processes, and permanent magnetic iron removers are the key line of defense against these invisible threats. Industry standards such as the newly issued "Lithium Iron Phosphate for Power Batteries" group standard in 2025 have tightened the upper limit of magnetic foreign matter from 10 ppm to below 3 ppm, and have almost stringent requirements on iron content. This means that the production line must have "microscope-level" iron removal capabilities.

First of all, ferromagnetic impurities are the "invisible killer" of battery performance and safety, mainly manifested as:

Micron-level destructive power: Even tiny iron filings and wear metal particles (such as stainless steel powder) that are invisible to the naked eye, once mixed into the electrode material.

Piercing the diaphragm and causing internal short circuit: Sharp impurities may pierce the thin battery diaphragm during the charging and discharging process, directly connecting the positive and negative electrodes, causing internal short circuits, which may cause battery failure and aggravated self-discharge, or even cause thermal runaway, leading to serious consequences of fire and explosion.

Catalyze side reactions and accelerate decay: Iron ions (Fe²⁺/Fe³⁺) are powerful redox catalysts. They will aggravate the decomposition of the electrolyte and consume active lithium ions, resulting in rapid decay of battery capacity, increased internal resistance, and greatly shortened cycle life. Especially for advanced material systems such as high nickel and silicon-based, the impact is more significant.

Destroy the uniformity of electrode coating: Impurity particles affect the uniformity and consistency of slurry coating, reducing the battery yield.

Secondly, the permanent magnetic iron remover uses the strong constant magnetic field generated by high-performance rare earth permanent magnetic materials (such as neodymium iron boron) to non-contact, efficiently and continuously absorb and remove ferromagnetic impurities in the material flow. It plays an indispensable role in multiple links of battery manufacturing:

1. "Gatekeeper" of raw material purification:

Key positive electrode materials (such as lithium iron phosphate, ternary materials, lithium cobalt oxide, etc.): Permanent magnetic iron remover is a necessary pretreatment equipment before the materials are put into batching. Remove the iron filings from the mines, crushing and grinding equipment wear that may exist in the raw material powder to ensure the purity of the source.

Negative electrode materials (graphite, silicon-based, etc.): It also needs to be strictly iron-removed to avoid impurities affecting the performance of the negative electrode.

Conductive agent (carbon black, etc.), binder: These auxiliary materials also need to be iron-removed.

2. "Scavenger" in the production process:

Slurry preparation link: During the mixing, dispersion and transportation of positive and negative electrode slurries, equipment friction (stirring paddles, pipelines, pumps and valves) will produce trace metal wear particles. The online installed pipeline permanent magnetic iron remover can capture these new impurities in real time to prevent them from mixing into the final coating slurry.

After electrode coating/before rolling: Some processes will set iron removal points after the wet coating is dried and before entering the roller press to remove impurities that may be introduced during the drying process.

Pole slitting process: The wear of the cutting tool will produce metal shavings. Setting an iron remover after slitting and before winding/stacking can effectively remove these new metal contaminants.

3. "Purifier" for recycling material processing: In the battery recycling process, when dealing with complex waste battery crushing materials, the permanent magnetic iron remover is a key equipment for separating iron shells, screws and other ferromagnetic metal impurities, laying the foundation for the subsequent recycling of high-value positive and negative electrode materials.

In short, in the production process, the manufacturing of new energy batteries is a multi-form mixed battlefield of powders, slurries, and finished products. Therefore, permanent magnetic iron removers have also evolved into a "three-level ladder":

As new energy batteries move towards the TWh era and performance and safety standards continue to improve, the requirements for material purity have reached an unprecedented level. Although permanent magnetic iron removers are not a direct component of battery production, they are the behind-the-scenes heroes that ensure the core quality of batteries - high safety, long life, and consistency. It quietly intercepts tiny ferromagnetic "killers" at various key nodes and is an indispensable and powerful magnetic defense line in the battery manufacturing process. Therefore, we call permanent magnetic iron removers the "invisible guardian" in new energy battery manufacturing.