Pore characterization in battery separators: Unlocking safer, more efficient batteries

Lithium-ion batteries power devices, vehicles, and energy systems – and at their core lies a critical yet often overlooked component: the separator. More than just a thin membrane, it prevents internal short circuits, allows ion transport, and directly influences battery safety and efficiency.

Why separators matter
A reliable separator must balance several roles:

• Enable ionic flow through an interconnected network of through-pores
• Prevent shorts from particles or dendrites
• Shut down near thermal runaway to enhance safety
• Maintain chemical, electrochemical, and mechanical stability

Since pore structure drives performance, safety, and lifetime, precise pore analysis is essential.

The science of pore characterization
Two complementary techniques reveal how separators function:

• Capillary Flow Porometry (CFP) measures through-pores that enable Li-ion transport. While necessary for conductivity, oversized throughpores threaten mechanical integrity and safety.
• Mercury Intrusion Porosimetry (MIP) captures both through- and blind-pores, providing insight into total porosity and tortuosity.

Case study: Celgard separators
Using Micromeritics’ AccuPore (CFP) and AutoPore (MIP), Celgard 2500 Monolayer and H2512 Trilayer separators were compared:

• Trilayer showed smaller maximum and mean through-pore sizes than the Monolayer, indicating a tighter, more uniform structure.
• MIP confirmed a narrower pore size distribution in the Trilayer, supporting improved consistency and performance.

These findings highlight how combining CFP and MIP delivers a full picture of separator reliability—critical for demanding applications like EVs.

To learn more about this, join our upcoming webinar on November 12: “Optimizing Battery Separator Performance with Advanced Pore Characterization“.

Learn how pore size distribution, porosity, and connectivity influence battery safety and performance.

Topics include:

• Through vs. blind pores and why connectivity matters.
• CFP vs. MIP: strengths and insights.
• Real-world Celgard separator case study.
• Implications for design and manufacturing.

Who should attend: Battery separator manufacturers, battery scientists, materials scientists, and R&D professionals advancing energy storage.

Speaker: Julian Hungerford, PhD in chemical engineering (Georgia Tech), specialist in porous materials and pore characterization at Micromeritics.