Lithium Battery Electrode Preparation Process Flow

The preparation of lithium battery electrodes is a multi-step, precision-driven process that directly influences cell performance, including energy density, cycle life, and rate capability. This flow involves material preparation, slurry mixing, coating, drying, calendering, slitting, and electrode assembly, with strict quality control at each stage to ensure uniformity and reliability.

The process begins with raw material preparation: cathode active materials (e.g., NMC, LFP, or LCO) are mixed with conductive additives (carbon black, graphene) and binders (PVDF for cathodes, CMC/SBR for anodes) in a solvent (NMP for cathodes, water for anodes). This mixture is blended in high-shear mixers to form a homogeneous slurry with a viscosity of 1,000–5,000 cP, ensuring even distribution of conductive particles and proper adhesion to the current collector.

Next, the slurry is coated onto metal current collectors—aluminum foil (10–20 μm thick) for cathodes and copper foil (6–12 μm thick) for anodes—using slot-die or comma-bar coating techniques. The coating thickness is precisely controlled (50–200 μm dry) to achieve the desired areal capacity (2–5 mAh/cm²), with edge trimming to prevent short circuits.

After coating, the electrodes undergo drying in convection or infrared ovens at 80–130°C to remove solvents, with residual solvent content kept below 500 ppm to avoid electrochemical reactions. The dried electrodes are then calendered (compressed) using rollers to increase density (2.5–4.0 g/cm³ for cathodes, 1.5–2.0 g/cm³ for anodes), improving conductivity and reducing porosity while maintaining sufficient space for electrolyte infiltration.

Following calendering, the electrodes are slit into strips of specific widths (10–200 mm) using laser or mechanical cutters, with burrs removed to prevent internal short circuits. Finally, tabs (aluminum for cathodes, nickel for anodes) are welded to the current collectors using ultrasonic or resistance welding, ensuring low-contact resistance.

Each step requires rigorous testing: slurry viscosity, coating thickness uniformity, and electrode density are measured to maintain consistency. Any deviation can lead to capacity loss, increased internal resistance, or safety hazards, making electrode preparation a critical foundation of lithium battery manufacturing.

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