Granutools Introduces the Conductivity Unit for GranuPack

Introduction: Understanding Electrical Conductivity in Powders

Electrical conductivity is a fundamental property in many industrial processes, particularly in battery materials, conductive formulations, and advanced powders.

However, unlike bulk solids, powder electrical conductivity cannot be directly inferred from the intrinsic conductivity of the material. Instead, it strongly depends on:

• Particle-to-particle contacts
• Packing structure and porosity
• Surface chemistry and oxidation
• Formulation parameters (e.g., binder or conductive additives)

As a result, conductivity evolves dynamically as the powder becomes more compact. When particles rearrange during densification, the number and quality of electrical pathways increase, directly impacting conductivity.

This makes direct measurement of electrical conductivity in powder form essential to obtain meaningful, process-relevant data.

Exploring the Conductivity Unit for GranuPack: A New Measurement Approach

The Conductivity Unit for GranuPack introduces a novel methodology to couple conductivity measurement with tapped density analysis.

Integrated directly into the GranuPack system, the unit replaces the standard measurement cell with a dedicated conductivity cell. During a standard tapped density protocol:

• The powder is subjected to controlled tapping
• Its packing fraction progressively increases
• Bulk density is continuously measured
• Electrical conductivity is measured simultaneously

This approach provides a direct and reproducible way to monitor conductivity as a function of densification, enabling a deeper understanding of powder behavior under conditions close to industrial processes.

Key Measurement Principle: Conductivity vs Packing Fraction

The uniqueness of the Conductivity Unit lies in its ability to measure conductivity across different packing states.

In powders:

• At low packing fractions → limited particle contacts → low conductivity
• At higher packing fractions → increased contacts → improved conductive paths

This relationship is particularly critical because conductivity does not vary linearly with densification and is difficult to model or predict.

At the same time, the tapped density measurement reflects how particles rearrange under mechanical tapping, reducing voids and increasing solid fraction.

By combining both measurements, the device provides:

• A conductivity vs packing curve
• Insight into percolation thresholds and contact efficiency
• A quantitative basis for comparing materials and formulations

Key Features of the Conductivity Unit

Simultaneous Measurement of Conductivity and Density

The system records electrical conductivity and tapped density in a single experiment, enabling direct correlation between structure and electrical response.

Measurement Under Controlled Densification

Conductivity is measured during progressive compaction, reproducing realistic process conditions.

High Reproducibility and Automation

Fully controlled by the GranuPack software, the method ensures operator-independent results with high repeatability.

Seamless Integration

The Conductivity Unit is designed as a plug-and-play add-on compatible with existing GranuPack systems.

Applications: From Battery Materials to Advanced Powders

The Conductivity Unit is particularly relevant for battery and electrode manufacturing, where powder properties directly influence performance:

• Electrical conductivity governs electron transport in electrodes
• Densification processes (e.g., calendering) modify conductivity
• Powder formulation determines final electrochemical performance

Measuring conductivity as a function of packing provides valuable insight for:

• Material screening
• Optimization of conductive additives
• Blend comparison and formulation development

Beyond batteries, the unit supports applications in:

• Conductive polymer composites
• Additive manufacturing powders
• Metallurgy and advanced ceramics
• Any process where electrical properties of powders matter

Towards Better Process Understanding

By linking electrical conductivity to powder packing behavior, the Conductivity Unit enables a more comprehensive understanding of powder performance.

It allows users to answer key questions such as:

• How does densification impact conductivity?
• Which formulation provides the best conductive network?
• At which packing level does a conductive pathway form?
• How sensitive is conductivity to batch variations?

This information is critical to anticipate process behavior and optimize material selection before manufacturing steps.

Conclusion: Extending Powder Characterization to Electrical Properties

The Conductivity Unit for GranuPack represents a significant step forward in powder characterization.

By combining electrical and mechanical measurements in a single automated test, it provides a unique and process-relevant perspective on powder behavior.

This new approach enables:

• More informed material selection
• Improved formulation strategies
• Better control of industrial processes

The Conductivity Unit continues Granutools’ mission to deliver physically meaningful, reproducible, and application-oriented powder measurements.

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