Lithium battery manufacturing 30 process decryption: from the coating accuracy to the activation of the formation of process control points

🔥 Front-end pole piece fabrication: the battleground for 75% of defect sources

✅ Golden parameter matrix for slurry preparation

Material system	Viscosity range	solid	Particle Size Requirements	degree of vacuum
NCM Positive	3500±500mPa·s	78±2%	D50≤8μm	≤-0.085MPa
Graphite Anode	2500±300mPa·s	52±1%	D50≤20μm	≤-0.09MPa

Fatal Trap: Anode slurry temperature ＞30℃ will lead to PVDF molecular chain breakage, bonding force decreased by 40%.

⚙️ Battery coating process life and death line

Speed and precision game:

High-speed coating (45m/min) need to match the double-sided simultaneous thickness measurement system (accuracy ± 0.5μm)

Transfer roller speed ratio 1.15-1.25, gap thinning 20-30μm anti-tail dragging

Drying zone control:

Positive: 105℃(Zone1)→115℃(Zone2)→95℃(Zone3) Moisture≤1500ppm

Negative: 90℃(Zone1)→100℃(Zone2)→85℃(Zone3) Moisture≤2500ppm

NDT Battery Case: Moisture exceeds 300ppm → Black spot rate soared 8 times after 200 cycles4

🛡️ roll pressing/slitting explosion-proof program

Hot pressing process: positive compaction density 3.4-3.8g/cm³ (cold pressing rebound rate ↑300%)

Slitting burr control: Y-direction burr ≤ 1/2 diaphragm thickness (measured >12μm direct scrap)

Recommended equipment: Pilot Intelligent G16 Slitter (burr control ±3μm)

⚙️ Middle core synthesis: 0.01mm alignment error = thermal runaway

⚡ Winding vs. stacking ultimate showdown

parameters	Winding process (cylindrical/square)	Laminating process (soft cover)
efficiency	12PPM (BYD Blade Battery)	0.5s/piece (Honeycomb Energy Flying Stack 2.0)
Alignment accuracy	±0.3mm	±0.15mm
Tension control	0.08-0.15MPa	0.05-0.1MPa

Lesson learned: negative electrode coating less than 0.5mm → charging lithium precipitation → needle puncture through the diaphragm

🧪 The devil’s details of the injection process

Electrolyte infiltration equation:

Liquid injection volume (ml) = core pore volume × 1.15 + diaphragm absorption

Moisture stranding program:

Glove box dew point ≤ -45°C (GREE G-HBOX Pro measured value)

Helium leakage detection rate ≤ 2 × 10-⁷ Pa-m³/s (Precision Measurement Electronics HEL-800)

NDT Warning: Moisture >50ppm will trigger CMC dissociation → graphite layer stripping black slag

🔋 Back-end formation testing: SEI films make the difference between life and death

⚡ Chemistry Process Core Code

SEI Membrane Growth Control:

Optimal Current: 0.02C

Temperature Window: 45±1°C

Voltage Slope: dV/dt ≤ 5mV/min

Fatal Error: >0.05C current causes SEI membrane to cleave → 38% capacity degradation over 500 cycles

📊 Intelligent Strategies for Compartmentalization and Sorting

Filtering dimensions	threshold	Exclusion criteria	Equipment program
pressure drop	ΔV＞10mV/24h	Microshort circuit risk	High temperature aging room + AI monitoring
internal resistance	Deviation from the mean >5%	thermal runaway hazard	HIOKI 3560 Tester
capacity	<95% of nominal value	Breach of batch consistency	Ranch Electronic Separation Cabinet