1. & 2. Electrode Formulation: The Foundation

• Cathode: Cobalt oxide (LiCoO₂), lithium iron phosphate (LiFePO₄), or similar active materials, mixed with conductive additives (e.g., acetylene black), binders (PVDF), and coated onto an aluminum foil current collector.

• Anode: Primarily graphite, blended with conductive additives (acetylene black), binders (PVDF), and coated onto a copper foil current collector.

3. Current Collector & Coating Design: Current Pathways

Metal foils carry active material coatings with specific parameters:

4. Anode Excess Design: Buffer for Safety

During initial charging, the Solid-Electrolyte Interphase (SEI) layer forms on the anode, permanently consuming lithium ions. Thus, the anode’s design capacity must exceed the cathode’s to ensure sufficient lithium for cycling.

5. Capacity Design: Targets & Assurance

• Rated Capacity: Required energy output (Operating Current × Operating Time).

• Design Capacity: Typically 10%~20% higher than rated capacity to ensure reliability and lifespan. Calculated as:
  Design Capacity (Ah) = Coating Areal Density × Active Material Ratio × Active Material Specific Capacity (mAh/g) × Coated Electrode Area

• Design Margin: Accounts for manufacturing variations, ensuring batch capacity meets specifications.

6. & 7. Electrolyte: The Ion Highway

• Type Selection: Tailored to application needs:
  High-Temperature, Standard, Low-Cost, High-Voltage, Low-Temperature, High-Rate.

• Electrolyte Components:

  • Lithium Salt (e.g., LiPF₆): Provides lithium ions.

  • Solvent (e.g., EC/DMC blend): Dissolves salt and transports ions.

  • Additives: Enhance performance (e.g., SEI formation, flame retardancy, conductivity).

• Key Parameters: Ionic conductivity, thermal/chemical stability, operating temperature range.

8. Separator: The Critical Barrier

Prevents short circuits while enabling ion flow between electrodes:

• Materials: Microporous membranes—single-layer PE (polyethylene), double-layer PP/PE (polypropylene/polyethylene), or triple-layer PP/PE/PP.

• Thickness: Common options: 25μm, 35μm, 40μm (balances safety and ion conductivity).

9. Encapsulation: Aluminum Laminate

Protects pouch cells:

• Thickness: 88μm, 113μm, 122μm, or 153μm.

• Structure: Three primary layers bonded by adhesive:
  Outer: Nylon (barrier protection)
  Middle: Aluminum foil (moisture/oxygen barrier)
  Inner: CPP (cast polypropylene; heat-sealable layer).

Conclusion: Designing a lithium-ion cell is a symphony of precision—from electrode formulation and current collector engineering to capacity margins, electrolyte optimization, separator selection, and final encapsulation. Each step critically impacts performance, safety, and longevity. Mastering these principles unlocks the potential for efficient, reliable energy storage.

Design Flow:
Electrode Formulation → Current Collector/Coating Design → Anode Excess → Capacity Design → Electrolyte Selection → Separator Selection → Laminate Encapsulation