SP³ Diamond Coating × IF-WS₂ Superlubrication: Reduce Friction in Li-ion Electrode Slitting & Winding

SP³ Diamond Coating × IF-WS₂ Superlubrication: Reducing Friction in Li-ion Electrode Slitting & Winding to Solve High-Throughput Production Bottlenecks

Technical Overview

In precision manufacturing for energy devices, surface friction on tooling and winding cores critically impacts yield and throughput. In Li-ion battery production, electrode slitting and winding are sensitive processes: cutters suffer fatigue cracking, adhesive wear and abrasive wear; winding cores may experience tail-pull failures or core damage due to high friction with separator papers, especially with ceramic or aramid separators.

Power Micro's combined SP³ diamond coating (ultra-hard carbon layer) and IF-WS₂ (fullerene-like WS₂) superlubricant coating delivers both extreme hardness and exceptional lubrication on tungsten carbide cutters and winding pins—reducing friction coefficients, extending tool/core life, and resolving high-throughput production bottlenecks for high-energy NMC cell manufacturing。

◆ Problem Statement: Failure Modes

Fatigue failure：repeated lateral/shear loads cause micro-cracks and progressive chipping of the cutter edge.
Adhesive wear：electrode materials (e.g., aluminum foil) cold-weld or adhere to cutter surfaces, causing plastic adhesion and edge failure.
Abrasive wear：embedded hard particles in electrode coatings abrade and score cutter surfaces.
Tail-pull / winding pull-out：excessive friction between winding pins and separator/paper leads to pull-out failures or internal core damage due to stress concentration.

◆ Solution Concept

Combine two surface engineering technologies：

SP³ diamond coating：creates a high sp³ fraction ultra-hard carbon layer (diamond-like), hardness near Hv≈6500, improving wear resistance and chipping resistance.
IF-WS₂ (fullerene-like WS₂) superlubricant coating：deposited atop or in combination with the hard film to provide self-lubrication, low surface energy, and sustained low friction (μ < 0.03) under high temperature/pressure.

Paired, SP³ protects edges while IF-WS₂ reduces friction and adhesion—together extending cutter and winding pin life. Coatings can be regenerated or re-applied to enable multiple service cycles.

◆ Mechanism Details

1. SP³ Diamond Coating

◎Composition & structure：high sp³ bonded carbon network, diamond-like, delivering extreme indentation hardness and scratch resistance.
◎Process highlights：film uniformity, residual stress management, and interfacial adhesion (bonding layers) are critical; deposition must be tuned to avoid embrittlement of the tungsten carbide substrate.

2. Superlubricant IF-WS₂

◎Structural traits：fullerene-like spherical WS₂ nanoparticles with layered slip mechanisms and low shear strength.
◎Function：forms a thin interfacial film to lower surface energy, prevent cold welding between metal and electrode materials, and supply long-lasting solid lubrication.

Applications & Case Studies

◆Case A：Electrode Slitting

Problem：Aluminum foil adhesion leads to adhesive wear and chipping.
Process：Apply SP³ coating for edge reinforcement, then deposit IF-WS₂ on cutting edge or as a conformal layer.
Result：Friction coefficient (lab test) reduced from ~0.18 to ~0.025; tool life increased 2.5–4×; edge chipping dramatically reduced.

◆Case B：Winding Core / Pin

Problem：High friction between ceramic/aramid separators and winding pin causes tail-pull failures; solid release agents are temporary and introduce contamination.
Process：Composite SP³ + IF-WS₂ treatment on winding pins; surface micro-texturing may enhance coating anchorage.
Result：Tail-pull success nearly 100%; pin reuse cycles >10; production downtime events reduced by ~70%.

Note：The above data are based on typical field and laboratory test results; actual values may vary depending on materials and process conditions.

◆Advantages & limitations

Advantages

Substantial reduction in friction and adhesion; extended cutter/pin life.

Reduced downtime and maintenance, improved yield.

Cuts dependence on solid/liquid release agents—lower contamination risk。

Compatible with existing tool substrates and other surface treatments (PVD/nitriding).

Limitations

Higher upfront coating cost and equipment investment vs. release agent application.

Large or irregular parts may require zone processingn.

Process must be tuned per electrode material, speed, and tension profiles.

◆Key metrics & comparison (example data for web display)

Metric	Untreated	SP³ only	SP³ + IF-WS₂
Friction μ (Al on WC, dynamic)	0.15-0.20	0.08-0.12	0.02-0.03
Tool life (cycles)	baseline 1×	1.8-2.5×	2.5-4×
Tail-pull success	85%	92%	≈99-100%黏
Residual material (μg/cm²)	10-50	3-10	<1-3

Note：The test conditions were based on quantitative friction experiments and production line observations conducted at room temperature, under standard pressure and operating speed. Specific projects should be validated and calibrated according to actual materials, line speed, and tension profiles.

Q&A

Q1：What is the difference between SP³ coating and conventional DLC ?

SP³ emphasizes high sp³ bonding (diamond-like), delivering greater hardness and edge protection compared to conventional DLC—DLC offers lower cost and friction but less chipping resistance.

Q2：How durable is IF-WS₂ under high humidity or temperature conditions？

IF-WS₂ is an inorganic solid lubricant with good thermal stability (system-dependent up to several hundred °C); humidity has limited effect on lubrication, but mechanical anchorage must be ensured.

Q3：Can the coating be repaired or regenerated on-site？

IF-WS₂ can be locally reapplied for short-term restoration; full SP³ recoating typically requires specialized off-line deposition processes.

Q4：What is the typical ROI (Return on Investment) after implementation？

ROI depends on cutter costs, downtime savings, and throughput; typical projects recover investment in 6–24 months.

Implementation Recommendations

Pilot small-scale trials under representative materials and line speeds.
Combine micro-texturing for improved coating anchorage; design interlayer adhesion if paired with PVD.
Define maintenance SOPs and coating inspection metrics (friction, surface energy, visual crack check).
Instrument the line to monitor friction/tail-pull success rates and tune tension profiles.

Conclusion & Contact

SP³ diamond + IF-WS₂ superlubricant treatment addresses the root mechanisms of electrode cutter and winding core failures—reducing friction, extending tool life, improving tail-pull success, and lowering downtime. For project evaluation, pilot tests, and ROI analysis, contact Power Micro International Company to arrange trials and obtain technical reports.

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