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 arbon anodes, coated electrodes, and separator, is a critical design parameter because it directly affects how ions move inside the battery, which in turn influences capacity, power, cycle life, and safety. Porosity is essential as it governs the electrolyte access, ionic transport and storage, reaction kinetics, and structural stability of electrodes. The challenge in battery design is not just having porosity, but having the right type, size distribution, volume, and connectivity of pores for the target application. We offer three highly advanced solutions to measure pore size and volume in battery electrode materials, coated electrodes, and battery separators – Gas adsorption (TriStar/3Flex), Mercury Intrusion (AutoPore) and Capillary Flow (AccuPore).

 

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Pore size analysis in battery separators using AccuPore and AutoPore
Application note

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.

Download this application note

Download this application note
 
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Characterization of microporous carbon anodes using N₂ and CO₂ adsorption isotherms on TriStar II Plus 3030

The rapid evolution of silicon-carbon (Si-C) composite anodes and sodium-ion batteries has placed a spotlight on the importance of microporous carbons. In Si-C anodes, high microporosity provides a robust scaffold for silicon deposition, maximizing specific surface area and capacity. For sodium-ion batteries, hard carbon remains the leading candidate for efficient ion intercalation.

 

 

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

Tristar / 3Flex
TriStar/3Flex – Gas Adsorption pore analysis

Mercury Intrusion Porosimetry (MIP)

Pore analysis via gas adsorption measures how a degassed sample adsorbs gas (e.g., nitrogen at 77 K) over a range of pressures. The isotherm reveals surface area (BET) and pore size distribution (BJH/DFT), distinguishing micropores and mesopores by their pressure-dependent filling behavior. TriStar II Plus is a widely used surface area and pore size analyzer

  • Measurement capability: Surface area (BET), pore size distribution, and total pore volume Pore size range: ~0.35 nm to 300+ nm (micro to mesoporous range, depending on method) Analysis method: Gas adsorption (typically N₂ at 77 K; optional other gases like Kr, CO₂) Number of analysis stations: 3 simultaneous measurement ports

3Flex has even higher precision for the analysis of micropores.

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+
Application note

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.

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Download this application note
 
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

Characterizing Li-ion Battery Separators: Pore Structure Determination

Lithium-ion (Li-ion) batteries are an advanced technology that will play a key role in the trend toward renewable and sustainable industrial electrification solutions.

Watch the webinar

Watch the webinar »
 
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.

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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