Common Cutting Defects in Lithium Battery Manufacturing and How to Prevent Them

Precision slitting and cutting are used across the entire lithium battery production process, from copper/aluminium foil processing and electrode slitting to separator converting and nickel strip production. Cut edge quality directly affects cell consistency, assembly yield, and battery safety.

Uncontrolled cutting defects push up material scrap rates and production costs and bring potential safety risks like internal short circuits. Below we look at the most common cutting defects in battery production, their causes, and practical fixes.

Most Common Cutting Defects in Li-ion Battery Production

1. Edge Burrs & Metal Whiskers

Burrs and fine metal whiskers are one of the most common quality risks in foil and electrode slitting. Too much burr on copper & aluminium foil or electrode edges will pierce the separator, which causes internal short circuits and speeds up self-discharge. For nickel strip processing, uneven burrs also reduce welding reliability during pack assembly.

2. Cutting Dust & Particle Contamination

Tiny metal dust and coating particles from slitting will easily contaminate electrode surfaces and separators. These particles raise the risk of micro-shorts in finished cells, shorten cycle life, and cause performance degradation over long-term use.

3. Edge Waviness & Dimensional Deviation

Wavy cut edges and strip width out of tolerance directly affect alignment accuracy during winding and stacking. Poor dimensional consistency causes uneven electrode layers, less uniform cell capacity, and higher rejection rates in later assembly steps.

4. Material Delamination & Coating Peel-off

For coated electrodes and composite copper foils, too much cutting force or a dull edge will cause coating peel-off or interlayer delamination. This defect damages the structural integrity of electrodes and causes fast capacity fade in finished cells.

5. Built-up Edge & Adhesive Wear

Ductile materials like nickel strips and high-nickel cathodes tend to form built-up edges (BUE) on the cutting tip. Adhesive wear gradually blunts the blade, makes cutting quality worse over production runs, and shortens the effective service life of the knife.

Root Causes & Targeted Prevention Measures

Cutting defects rarely come from a single cause. They usually result from a mix of blade condition, material properties, process settings, and machine condition.

For burrs and whiskers

Main causes

• Dull cutting edges, incorrect knife clearance, low wear resistance of the blade

How to prevent

• Use slitting knives with precision-ground edge geometry.
• Set clearance to match your material thickness.
• Choose wear-resistant carbide substrates to keep edges sharp for longer.

For dust and particle generation

Main causes

• Rough edge surfaces, too much material deformation during shearing, unstable cutting force

How to prevent

• Use mirror-finish cutting edges for clean, smooth shearing.
• Optimise the edge angle to reduce material tearing.
• Keep cutting speed and web tension consistent.

For edge waviness and dimensional error

Main causes

• Blade runout, unstable material tension, uneven knife pressure along the axis

How to prevent

• Use high-precision knives with tight runout control.
• Calibrate slitter holders and shaft alignment.
• Keep unwinding and rewinding tension systems stable.

For delamination and coating peel-off

Main causes

• Blunt edges, too much cutting impact force and edge angle are incompatible with multi-layer materials

How to prevent

• Keep blades sharp all the times.
• Optimise edge geometry for multi-layer composite structures.
•  Avoid too much overhang, which increases cutting impact.

For built-up edge and adhesive wear

Main causes

• High ductility of the workpiece material, high surface roughness on the cutting edge, low surface hardness

How to prevent

• Polish cutting edges to ultra-low surface roughness.
• Choose suitable blade materials and optional surface coatings to reduce adhesion. Adjust cutting speed to match your material properties.

How Shen Gong Carbide Knives Help Reduce Cutting Defects

With full in-house production from carbide powder to finished knives, Shen Gong offers a full line of lithium battery cutting knives for foil slitting, electrode processing, separator converting, and nickel strip production.

Ultra-fine grain carbide substrate

Our standard battery-grade knives use Shen Gong’s in-house developed ultra-fine grain carbide grades. Every material batch goes through full performance testing and is kept on file for 3 years, with official test reports available on request. This ensures consistent quality across batches and full traceability through the entire production process. Our carbide substrates offer excellent wear resistance and edge toughness, effectively preventing chipping and early dulling.

Micro-precision edge grinding

Our proprietary grinding technology creates mirror-finish, defect-free cutting edges. This minimises material adhesion, reduces dust, and keeps burr height under 2 μm under proper operating conditions.

Application-optimised geometries

Each blade is designed with targeted edge angles and profiles for specific materials. This ensures clean shearing with minimal deformation.

Optional high-performance coatings

For harsh high-speed, high-abrasion conditions, we offer PVD, DLC, and ETaC-3 coating options to extend knife life further and reduce adhesive wear.

Full-process knife portfolio

From circular slitting knives and cross-cut guillotine knives to separator blades and nickel strip shear knives, Shen Gong provides matched knife solutions for most stages of battery production.

Final Notes

Systematically preventing cutting defects requires coordinated improvements to cutting knives, process settings, and equipment maintenance. Upgrading to high-precision carbide cutting knives is the most direct and effective way to keep cut quality consistent, reduce scrap rates, and lower overall production costs.

As an experienced industrial carbide knife manufacturer with over 28 years of expertise, Shen Gong provides reliable slitting solutions and custom engineering services for battery makers and material suppliers worldwide.