PE PP separator

When sourcing PE (Polyethylene) or PP (Polypropylene) separators, you must prioritize porosity (typically 35%-50%), thickness (ranging from 9μm to 25μm), and pore size uniformity. For high-performance lithium batteries, ensure the material has a low thermal shrinkage rate (<5% at 105°C) and high puncture strength (≥300gf) to prevent internal short circuits. Additionally, verify the electrolyte wettability to ensure efficient ion transport.

The choice depends on your application. Wet-process separators (PE) offer higher tensile strength and smaller, more uniform pore sizes, making them ideal for high-energy-density batteries like those in electric vehicles. Dry-process separators (PP or PP/PE/PP multilayer) are more cost-effective and have better thermal stability, making them suitable for large-scale energy storage systems (ESS) and power tools where safety and cost are prioritized over extreme thinness.

Suppliers must provide RoHS and REACH certifications to ensure the absence of hazardous substances. For automotive-grade applications, look for manufacturers compliant with IATF 16949 quality management systems. Additionally, ensure the products meet UL1642 safety standards for lithium batteries and have passed UN38.3 testing if they are integrated into battery packs during shipping.

Request a Certificate of Analysis (COA) for each batch and ask for SEM (Scanning Electron Microscope) images to inspect the pore structure. It is highly recommended to order a sample roll for compatibility testing with your specific electrolyte. On Made-in-China.com, you can prioritize Audited Suppliers who have undergone third-party on-site inspections to verify their production capacity and QC processes.

The main risks are moisture absorption and physical deformation. Separators are highly sensitive to environmental conditions. Ensure the supplier uses vacuum-sealed aluminum foil packaging with desiccant. Specify that rolls must be shipped in reinforced wooden crates to prevent edge damage or core crushing during sea freight, as even minor edge defects can cause film breakage during high-speed battery winding.

Pricing for separators is heavily influenced by raw material resin costs and coating requirements (e.g., ceramic coating). For bulk orders, negotiate a tiered pricing structure based on annual volume. If you are a startup, look for suppliers on Made-in-China.com that offer flexible MOQs (e.g., 500-1000 sqm) for trial runs, but be prepared for a 10-20% price premium compared to container-load orders.

Always use Secured Payment services provided by the platform to ensure your funds are only released after you confirm receipt of the goods. For large industrial orders, consider using a Letter of Credit (L/C) or a 30% deposit / 70% balance against Bill of Lading (B/L). Avoid transferring funds to private bank accounts; always ensure the account name matches the registered company name on Made-in-China.com.

When shipping to the US or EU, be aware of Anti-Dumping Duties (ADD) that may apply to certain plastic film products. Work with a freight forwarder experienced in Class 9 hazardous goods if the separators are pre-assembled in cells. For the most cost-effective route from China, Sea Freight (FCL) is recommended for bulk rolls, while Air Freight should only be used for urgent R&D samples due to high volume-to-weight ratios.