Step-by-Step Coin Cell Preparation Workflow for Lithium-Ion Materials

Get a clear step-by-step workflow for preparing lithium-ion coin cells, from electrode mixing and coating to punching, drying, assembling, and sealing. This presentation helps researchers achieve consistent cell performance and reliable electrochemical testing results.

Transcript

1. Step-by-Step Coin Cell Preparation Workflow for Lithium-Ion Materials Submitted By: M-Kube Enterprise Pty Ltd
2. Importance of Standardized Coin Cell Preparation in Battery Research • Lithium-ion material evaluation relies on highly repeatable, contamination- free Coin Cell preparation. • Coin cells provide controlled geometry, consistent stack pressure, and minimal active material consumption. • Ensures accurate comparison between batches, chemistries, binders, conductive carbons, and electrolytes. • Serves as the foundational testing protocol before transitioning to pouch or cylindrical formats.
3. Breakdown of Coin Cell Components (CR20xx Families) Primary coin cell components: • Stainless steel top cap • Stainless steel bottom case • PP or PEEK sealing gasket • Stainless steel spacers (varied thickness) • Wave spring (predefined compression force) • Anode & cathode punched electrodes • Separator (PP/PE-based microporous films) • High-purity electrolyte (carbonate, ether, ionic liquid, or solid-state compatible) Note: R&D labs must source from a consistent coin cell case supplier to avoid variability in crimp sealing torque, indentation hardness, and electrolyte compatibility.
4. Coin Cell Preparation Equipment Required for High-Precision Workflows • Slurry mixer (planetary, dual-axis centrifugal) • Vacuum-grade doctor blade coater • Film calendaring press (precision thickness control) • Precision electrode punching system (±0.01 mm tolerance) • Vacuum drying chambers (100–150°C continuous stability) • Argon glovebox with <1 ppm H₂O and <1 ppm O₂ • Hydraulic crimping machine with adjustable die settings • Complete coin cell assembly kit consisting of cases, springs, spacers, and gaskets Advanced labs use automated or semi-automated mechanical arms to reduce operator-induced variability.
5. End-to-End Lithium-Ion Coin Cell Preparation Workflow Overview • Slurry Formulation • Electrode Coating • Controlled Drying • Calendaring • Precision Punching • Electrode Post-Drying & Storage • Full coin cell assembly under inert atmosphere • Crimping & Mechanical Integrity Verification • Electrochemical Formation & Conditioning • Powder Material Verification
6. Step 1: Material Verification & Pre- Processing • Characterize powder morphology (SEM), particle distribution (laser diffraction), and moisture content (Karl Fischer). • Pre-dry active materials at 120–150°C to eliminate absorbed water. • Verify binder integrity and carbon black dispersibility before slurry mixing. • This step ensures reproducibility in lithium-ion coin cell preparation, especially for moisture-sensitive linkages (e.g., NMC blends).
7. Step 2: High-Consistency Slurry Formulation • Active material : Carbon : Binder ratios optimized per chemistry. • Solvent handling: -NMP for PVDF-based cathodes -DI-water for CMC/SBR anodes • Use vacuum planetary mixing to eliminate micro-bubbles. • Adjust viscosity and rheology for uniform coating thickness and controlled drying kinetics. • Well-formulated slurry reduces scattering in final performance metrics.
8. Step 3: Electrode Coating Procedure • Apply slurry onto Al (cathode) or Cu (anode) foil using doctor blade with calibrated gap. • Maintain coating uniformity ±3 µm across width. • Control drying rate to prevent binder migration and cracking. • Evaluate film adhesion and microstructure post drying. • Integration of precise coating parameters improves balance with downstream coin cell parts in the stack.
9. Step 4: Thermal Drying & Solvent Removal • Gradual heating to avoid film defects: -Stage 1: 60–80°C (surface drying) -Stage 2: 110–130°C (solvent evaporation) • Vacuum bake removes residual moisture to prevent electrolyte decomposition. • Final foil moisture <50 ppm recommended.
10. Step 5: Calendaring for Controlled Porosity & Density • Achieve targeted porosity: -Cathodes: 30–40% -Anodes: 40–50% • Calendaring defines transport pathways for Li⁺ diffusion and electrolyte infiltration. • Surface roughness and mechanical modulus directly influence final SEI formation. • This step is critical before moving to coin cell assembly.
11. Step 6: Precision Punching of Electrodes • Use hardened steel punching dies for dimensional accuracy. • Maintain clean edges to avoid separator puncture risks. • Perform mass loading QC on every batch. • Store punched discs in sealed containers inside glovebox antechamber.
12. Step 7: Final Vacuum Drying & Controlled Transfer to Assembly Zone • Dry punched electrodes at 110°C for 4–12 hours. • Transfer to glove box through bake-out cycle to maintain low ppm moisture. • Prevent air exposure to avoid electrolyte decomposition and SEI disruption.
13. Step 8: Coin Cell Assembly Inside Glove Box Standard CR2032 example configuration: • Bottom case → anode placement • Separator alignment • Controlled electrolyte dosing (using precision micro-pipette) • Cathode placement • Application of spacer for uniform contact force • Placement of stainless steel spring • Alignment of top cap • Crimping using hydraulic press • Proper coin cell components stacking eliminates internal shorting and ensures reproducibility.
14. Step 9: Crimping & Mechanical Integrity Verification • Apply defined pressure to ensure gasket sealing and structural rigidity. • Inspect for: • Uniform crimping edge • No micro-leakage • No top-cap deformation • Poor sealing causes electrolyte evaporation and gas swelling. • Reliable crimping requires precision coin cell preparation equipment and high- quality metal cases.
15. Step 10: Electrochemical Formation, Wetting & Testing • Rest the assembled cell for electrolyte soaking (6–24 hours). • Perform formation cycles at low C-rates to stabilize SEI. • Subsequent testing includes: • Charge/discharge cycling • Rate capability • EIS impedance mapping • CV scans to analyze redox behavior • Data collected provides accurate material performance insights due to consistent Coin Cell preparation workflows.
16. Quality Assurance & Failure Mode Diagnostics Common issues and engineering countermeasures: • Electrolyte leakage → verify gasket fit and case hardness • Swelling → check moisture, ensure deeper vacuum baking • Shunted separator → examine punching precision, check for metal burrs • High impedance rise → verify calendaring pressure uniformity and electrolyte infiltration • Capacity fade mismatch → assess mass loading uniformity
17. Conclusion • Successful lithium-ion coin cell preparation depends on controlling slurry chemistry, electrode microstructure, drying conditions, and assembly accuracy. • High reproducibility across studies is only possible when using optimized coin cell preparation equipment, consistent coin cell components, and standardized assembly procedures. • A well-executed workflow ensures precise evaluation of emerging lithium-ion materials for next-generation energy storage systems.