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GB/T28535 - 2018 Separators for Lead - Acid Batteries
- By: JinHan
- Nov 24,2025
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Scope: This Standard specifies the classification, designation, marking, requirements, test methods, inspection rules, labeling, packaging, transportation, storage and other aspects of separators for lead - acid batteries. It applies to ultra - fine glass fiber separators, microporous polyethylene separators and sintered polyvinyl chloride separators for lead - acid batteries.
General Requirements: It covers performance indicators such as the resistance of the separator (≤0.00050d Ω·dm²), maximum pore size (≤22μm), and wet pressure retention capacity (≥75%). Among them, microporous polyethylene separators also have requirements for oil content, with the oil content of the type for automotive batteries ranging from 12.0% to 18.0%. Meanwhile, it is stipulated that when 20 layers of separators are stacked and subjected to a pressure of 100N, the service life of PE/PVC separators is 1 year, and that of glass fiber separators is 3 months.
Technical Requirements
Physical Properties: The average pore size is generally required to be 1 - 5μm, the porosity is 50 - 70%, and the thickness is usually 0.8 - 2.5mm with a tolerance of ≤±5%. The longitudinal/transverse tensile strength shall be ≥3MPa, the elongation at break shall be ≥200%, and the surface resistance shall be ≤0.003Ω·cm².
Chemical Properties: When immersed in a 40% sulfuric acid solution (at 50℃) for 72 hours, the mass loss rate shall be less than 5%, the dimensional change rate shall be ≤3%, and the content of impurity elements such as Fe and Cl shall be less than 0.01%.
Safety and Environmental Adaptability: The separators shall meet the UL94 V - 0 flame retardant standard. No cracks shall occur during the bending test at - 30℃, and the structure of the separators shall remain intact after 100 simulated charge - discharge cycles of the battery.
Test Methods
Pore Size Distribution and Porosity: To be determined by the mercury intrusion porosimetry or gas adsorption method.
Thickness Uniformity: To be detected at multiple points using a laser thickness gauge.
Tensile Strength and Elongation at Break: To be tested by a universal testing machine.
Resistivity: To be measured in a standard acid solution.
Acid Corrosion Resistance: Immerse the separator in a 40% sulfuric acid solution (at 50℃) for 72 hours, then detect the mass loss rate and dimensional change rate.
Microporous Structure: Observe by Scanning Electron Microscope (SEM), detect the content of impurity elements with the assistance of Energy Dispersive Spectrometer (EDS), and verify the active reaction interface through specific surface area testing (BET method).
Auto - Ignition Temperature: Determine the thermal decomposition characteristics of the separator.
Low - Temperature Brittleness: Conduct a bending test at - 30℃.
Cycle Durability: Evaluate the structural integrity of the separator after 100 simulated charge - discharge cycles of the battery.
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