Understand the porous structure of your battery materials

Design electrode materials and separators with the right porosity to maximize the power, energy, safety, and lifetime of your batteries

 

Porosity in battery electrode materials and separators is a critical design parameter, as it directly influences the movement of ions and electrons within the battery. This, in turn, affects key performance metrics such as capacity, power output, lifetime, and safety. Porosity plays a vital role in governing electrolyte accessibility, ionic transport, reaction kinetics, and the structural stability of electrodes.

The challenge in battery design lies not only in achieving porosity, but in engineering the optimal pore type, size distribution, volume, and connectivity tailored to the specific application. To address this, we offer two advanced solutions for measuring pore size in battery electrode materials, coated electrodes, and separators: AutoPore and AccuPore.

 

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Pore size analysis in battery separators using AccuPore and AutoPore

Large through-pores can compromise mechanical integrity, reduce resistance to dendrite formation or particle intrusion, and pose serious safety risks—including cell failure or thermal runaway. By combining AccuPore with AutoPore, you can measure pore sizes down to 0.04 µm, detect critical flaws, and confidently quantify pore distribution and permeability.

 

 

Why porosity is important?

Trade-off between energy and power: The pores provide pathways for the liquid electrolyte to penetrate the electrode for efficient ion transport. At the same time, they reduce the active material tap density. Too little porosity leads to poor ionic flow and low-rate capacity (slow charge-discharge rate). Too much porosity, on the other hand, means low active material per volume, leading to reduced energy density (mileage per charge). Designing the “right” porosity is about balancing energy vs. power requirements.

Mechanical stability: Controlled porosity prevents electrode cracking and accommodates the volume changes that occur during cycling (e.g., in Si anodes or high-Ni cathodes). Excessive or poorly controlled porosity can make electrodes mechanically weak, leading to particle detachment, separator damage, or dendrite growth.

Typical Porosity Ranges in LIB Electrodes

  • Cathodes (NMC, LFP, etc.): ~25–35% porosity
  • Graphite Anodes: ~35–45% porosity
  • Silicon-rich Anodes: Higher porosity (~40–60%) to buffer volume expansion
  • Solid-State Batteries: Much lower porosity is preferred to ensure good particle–particle contact

Explore our solutions

AutoPore V
AutoPore

Mercury Intrusion Porosimetry (MIP)

Mercury porosimetry is based on the intrusion of mercury into a porous structure under strictly controlled pressures. AutoPore delivers this technique into a high-precision, class-leading operational safety instrument to analyse mesopores and macropores in battery separators, electrode materials, and coatings.

  • Wide range of measurable pore sizes: from 3 nm to 1100 µm.
  • High-resolution analysis for macropores and mesopores in both intrusion and extrusion analyses.
  • Equipped with triple failsafe safety features.
  • Complies with the ASTM Methods D4284, D4404, and D6761, as well as ISO 15901-1 and USP <267>
AccuPore
AccuPore

Capillary Flow Porometry (CFP)

Capillary flow porometry measures pore size distribution by displacing a wetting liquid with gas flow. AccuPore is a precision porometer that characterizes the size and relative abundance of through-pores in battery separators with accuracy and efficiency, offering vital insights into pore size distribution, flow, and permeability—supporting innovation and quality in separator research and production.

  • Wide range of measurable throughpores: from 0.013 to 500 µm.
  • Key measurements: Largest pore diameter (bubble point), mean pore diameter, smallest pore diameter, pore size distribution

Additional resources

 
Powering Up Battery Characterisation with Mastersizer 3000+
Whitepaper

Using Mercury Intrusion Porosimetry In Battery Research

This article is designed to be a technical guide with practical strategies to use mercury intrusion porosimetry for the characterization and subsequent optimization of battery and fuel cell materials.

Download this whitepaper

Download this whitepaper
 
Introducing Mastersizer 3000+ The smarter way to measure particle size
Application note

Characterizing Li-Ion Battery Separators – Pore Structure Determination

This application note will describe a test methodology using the AutoPore V, and its MicroActive software, to characterize the pore structure of a Li-ion battery separator.

Download this application note

Download this application note
 
Webinar - The importance of particle size analysis
Webinar

Lithium-ion Battery Separator: Pore Structure Determination Using Mercury Intrusion Porosimetry

Tune in to see an analysis of lithium-ion battery separator material, and what insights mercury intrusion porosimetry on the Micromeritics Autopore V can provide.

Watch the webinar

Watch the webinar »
 
Webinar - The importance of particle size analysis
Webinar

Unified Approach to Understanding Porous Materials

This webinar presents a generalized approach to modeling the pore size distribution which has been developed to determine the complete distribution of macro-, meso-, and micro-pores.

Watch the webinar

Watch the webinar