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Particle Characterization Solutions for New Energy and Energy Storage Materials: From R&D to Production, Precise Particle Size & Shape Control Empowers Battery Performance Breakthroughs

Driven by the dual forces of global carbon neutrality goals and the electrification megatrend, the energy density, cycle life, and safety of energy storage devices such as lithium-ion and sodium-ion batteries are continuously setting new industry benchmarks. However, the "key" that determines these performance metrics often lies hidden within the micro-nano particle world beyond the reach of the naked eye — the particle size distribution, morphology, and contaminant particle content of cathode and anode materials directly dictate electrode packing density, ion transport efficiency, coating uniformity, and battery safety margins. How to select the most appropriate testing methods at different process stages, and how to achieve end-to-end precise control from R&D to production, have become core challenges for new energy enterprises seeking to improve quality and reduce costs.

With over a decade of deep expertise in particle characterization technologies, Mipu Technology offers a comprehensive portfolio encompassing static image analysis (particle size & shape analyzers), laser diffraction (laser particle size analyzers), online laser particle size monitoring systems, and microflow imaging analyzers. In addition, we have innovatively developed the "Sandwich Transmission Imaging Method" and "Fiber Classification Testing Method" tailored for frontier directions such as solid-state electrolytes and dry electrode processes. We not only provide high-precision instruments but also customize the most suitable testing solutions based on material type and application scenario (R&D vs. production), ensuring data accuracy and optimal efficiency, and helping enterprises control product quality from the source.

Why Do R&D and Production Require Different Testing Methods?

During the development and manufacturing of new energy materials, the requirements for particle characterization differ fundamentally between the R&D and production stages. Based on years of industry experience, Mipu Technology has summarized the following methodology selection principles:

Mipu Technology offers both technology pathways and further optimizes dispersion and testing conditions based on material characteristics (dry powder/slurry, moisture sensitivity, size range, agglomeration tendency) to ensure data truly reflects the intrinsic properties of the material.

Lithium-Ion Battery Materials: Image Analysis for R&D, Laser/Online Monitoring for Production

The particle characteristics of lithium-ion battery cathode materials (ternary materials, LFP, LCO, LMO), anode materials (artificial graphite, natural graphite, silicon-carbon, hard carbon, LTO), and separator coating materials (alumina, boehmite, PVDF) serve as the cornerstone of battery energy density, rate capability, and safety.

2.1 Cathode Materials

R&D: Static Image Analysis Particle Size & Shape Analyzer

Why is it suitable?
The sphericity and particle size grading of cathode materials directly impact tap density and coating uniformity. For example, if lithium iron phosphate (LFP) particles exhibit irregular plate-like shapes, they tend to cause orientation non-uniformity during coating, leading to electrode cracks. In contrast, LFP with high sphericity can achieve higher tap densities (≥2.2 g/cm³). Image analysis can statistically evaluate the sphericity distribution, aspect ratio, and convexity of thousands of particles, helping R&D personnel determine whether milling/spheroidization processes meet targets and identify the presence of acicular particles or hard agglomerates.

Typical Testing Workflow: A small amount of cathode dry powder is uniformly dispersed on a glass slide (or using a vibrating feeder). Static image analysis captures 5,000–10,000 particles, outputting D10, D50, D90, mean sphericity, and distribution histograms.

Case Study: A ternary material manufacturer discovered through image analysis that particles with sphericity <0.8 accounted for 25% of their product, corresponding to a tap density of only 2.1 g/cm³. After adjusting the ball-milling process, the proportion of particles with sphericity >0.85 increased to 85%, tap density rose to 2.35 g/cm³, and battery volumetric energy density improved by 8%.

Production: Laser Particle Size Analyzer (Offline) or Online Laser Monitoring

Why is it suitable?
Production lines require rapid (<2 minutes) acquisition of D10, D50, D90, and Span values to adjust milling pressure or classifier rotor speed. Laser diffraction offers high repeatability, complies with ISO 13320, and enables testing of dozens of samples per batch, ensuring consistent particle size across every production lot.

Online Solution: An online laser particle size analyzer is installed at the outlet pipe of a jet mill, employing an isokinetic sampling probe with compressed air dispersion, outputting particle size distributions every 30–60 seconds. The system links via PLC with milling pressure and classifier speed: when D50 is too high, milling pressure is automatically increased; when D50 is too low, pressure is reduced. Field data shows that this closed-loop control maintains D50 fluctuation within ±3%, reducing batch rejections due to particle size non-conformance by over 50%, with annual cost savings of several million RMB per production line.

2.2 Anode Materials

R&D: Static Image Analysis Particle Size & Shape Analyzer

Why is it suitable?
The layered structure of graphite anodes introduces anisotropy. High-sphericity artificial graphite reduces "edge orientation," improving the first-cycle coulombic efficiency (ICE). Image analysis can precisely quantify sphericity (target >0.9) and aspect ratio (<1.5), preventing excessive flake-like graphite that leads to non-uniform lithium deposition or even lithium plating. For silicon-carbon anodes, image analysis enables observation of nano-silicon dispersion uniformity on the carbon matrix and identification of large agglomerates.

Testing Method: Dry dispersion followed by static image acquisition, with particular focus on the proportion of particles with aspect ratio >2 and particles with sphericity below 0.85.

Production: Laser Particle Size Analyzer (Offline) or Online Monitoring

Why is it suitable?
Graphite anode production requires strict control of particle size distribution (typically D50 10–20 μm, Span 0.8–1.2). Laser particle size analyzers efficiently complete testing of each batch of raw materials, intermediates, and finished products. For micron-sized carbon matrices in silicon-carbon anodes, laser diffraction is equally applicable.

2.3 Separator Coating Materials (Alumina, Boehmite, PVDF)

Applicable Method: Laser Particle Size Analyzer or Nanoparticle Size Analyzer (Image analysis is not applicable, as particle sizes range 0.1–1.5 μm, below the resolution limit of optical microscopy).

Unified R&D and Production Approach: Wet dispersion (sodium hexametaphosphate + ultrasonication) is used to measure D50, D90, and distribution width. Particles that are too coarse (D90 >2 μm) lead to rough coating surfaces and reduced air permeability; particles that are too fine tend to agglomerate, clogging separator pores. Precise particle size control via laser diffraction ensures optimal separator air permeability and ionic conductivity.

2.4 Online Laser Particle Size Testing Technology – Detailed Overview

Principle: Online laser particle size analyzers are based on Fraunhofer diffraction and Mie scattering theory. A specially designed sampling probe is directly integrated into the pneumatic conveying pipeline, using compressed air to disperse dry powder to an appropriate concentration — eliminating the need for sampling and dilution, enabling in-situ real-time monitoring.

Core Advantages: Compared to offline testing (sampling every 2–4 hours with significant lag), online systems provide second-level feedback, truly enabling closed-loop process control.

Applicable Scenarios: Pulverization, classification, and blending processes for cathode and anode dry powder materials. For slurry-type materials, Mipu Technology offers specialized dilution modules (with constant dilution ratio to prevent agglomeration) for online slurry particle size monitoring.

Sodium-Ion Battery Materials: Tailored Solutions for Hydrolysis Sensitivity

As an important complement to lithium-ion batteries, sodium-ion batteries are rapidly being deployed in energy storage stations, low-speed electric vehicles, and other applications due to their abundant sodium resources, low cost, and excellent low-temperature performance. However, their cathode materials (Prussian blue, layered oxides, polyanionic compounds) and anode materials (hard carbon, soft carbon) are generally susceptible to hydrolysis — exposure to air for just a few minutes can cause lattice degradation, leading to distorted test data.

R&D: Static Image Analysis + Inert Gas Protection

Why is it suitable?
Image analysis enables sample spreading and imaging within a nitrogen-filled glove box, allowing intuitive assessment of whether the material has been moisture-damaged (indicated by surface cracks, color changes, or particle adhesion). Simultaneously, particle size and morphological parameters are obtained to assist in optimizing synthesis and drying processes.

Testing Workflow: Samples are transferred under inert atmosphere to a sealed sample cell, followed by static image acquisition, maintaining moisture content <10 ppm throughout the process.

Production: Laser Particle Size Analyzer + Dry Nitrogen Dispersion

Why is it suitable?
The laser particle size analyzer employs dry dispersion, replacing conventional compressed air with high-purity nitrogen while maintaining a sealed dispersion and testing circuit to prevent sample contact with airborne moisture.

Data Validation: For the same hard carbon sample, D50 repeatability RSD is <2% under protected conditions, compared to >15% under unprotected conditions with D50 drift exceeding 20%. The Mipu solution accurately reflects true material particle size, providing reliable data for production.

Core Innovative Testing Technologies (Mipu Exclusive)

4.1 Sandwich Transmission Imaging Method for Solid-State Electrolytes – Designed for Submicron Moisture-Sensitive Particles

Solid-state electrolytes (oxide-type LLZO, sulfide-type LGPS, etc.) are critical materials for next-generation high-safety solid-state batteries. However, they are extremely sensitive to moisture and oxygen, with particle sizes typically ranging from submicron to several microns. Traditional testing faces two major challenges: ① laser diffraction can only output equivalent spherical diameter without providing morphological information; ② dispersion and loading operations within glove boxes are cumbersome, introducing hydrolysis and human errors.

Applicable Method: Static Image Analysis Transmission Imaging Technology (not laser diffraction).

Innovative Solution: The solid-state electrolyte sample is sealed between two transparent polymer films, forming a "film–sample–film" sandwich structure, placed directly under a high-resolution transmission microscope for imaging. The films are <50 μm thick, transparent to visible/near-infrared light, enabling true morphology and particle size analysis for particles as small as 0.2 μm.

Technical Advantages:

• Complete isolation from environmental moisture and oxygen; the sample remains under inert protection throughout testing.

• Direct acquisition of true particle morphology (sphericity, aspect ratio, convexity, agglomeration state), distinguishing primary particles from agglomerates.

• Extremely simple operation: no complex dispersion within a glove box required; sample loading and testing can be completed in 5 minutes.

Data Comparison: For the same sulfide electrolyte, three repeated D50 measurements using the conventional glove box + laser method yielded an RSD of 5.6%, while the Sandwich Transmission Imaging Method achieved an RSD of 1.8%, with the added capability of outputting sphericity distributions to assist R&D personnel in optimizing synthesis processes.

4.2 Dry Electrode Fiber Classification Testing Method – Static Image Analysis + AI Recognition

Dry electrode technology (solvent-free, low energy consumption, environmentally friendly) is emerging as a new industry direction. Its core is the fibrillation of PTFE binders via high-speed airflow to form a three-dimensional network structure that binds active materials. The length, diameter, and spatial distribution uniformity of fibers directly determine electrode tensile strength, conductivity, and cycle stability. However, conventional testing methods cannot quantify the degree of fibrillation.

Applicable Method: Static Image Analysis (not dynamic methods).

Innovative Solution: A small amount of dry electrode mixed powder is uniformly spread on a glass slide. A high-resolution microscope camera captures static images across multiple fields of view at 30–50 frames per second. Mipu's proprietary AI algorithms, based on morphological features (aspect ratio >5, circularity <0.3, convex hull defect rate), automatically classify three particle types:

• Fibers (PTFE): Aspect ratio >5, width 0.1–1 μm

• Active Materials (e.g., NMC, graphite): Equant-shaped, particle size 1–20 μm

• Conductive Additives (carbon black): Submicron agglomerates

Output Parameters: Mean fiber length, length distribution, diameter distribution, fiber/active material contact frequency, and mixing uniformity index.

Technical Advantages: Static method precisely measures true fiber dimensions (eliminating motion blur inherent in dynamic methods) and quantifies both "insufficient fibrillation" and "excessive fibrillation."

Experimental Data: A dry electrode manufacturer's trials showed that with insufficient fibrillation time, mean fiber length was <50 μm, resulting in a 40% reduction in electrode tensile strength. Excessive fibrillation formed large agglomerates (>50 μm), increasing electrical resistance by 30%. Through the Mipu method, the optimal fibrillation time window (60–90 seconds) was identified, yielding significant electrode performance improvements.

Testing Solutions for Other Energy Storage Materials

Mipu Technology's particle characterization solutions can also be extended to the following areas:

Full-Process One-Stop Service: From Method Selection to Process Optimization

Mipu Technology provides not only instruments but also comprehensive methodological consulting and full-process services based on material characteristics and process stage:

1. Early R&D: Static Image Analysis Particle Size & Shape Analyzer is recommended to establish a "morphology–size–performance" database, guiding formulation and process design.

2. Pilot Scale-Up: Laser particle size analyzer performs high-frequency particle size fluctuation testing (dozens to hundreds of samples per day), supplemented by image analysis for morphology spot checks to ensure process robustness.

3. Mass Production: Online laser particle size monitoring systems enable real-time closed-loop control, significantly reducing defect rates; offline laser particle size analyzers serve as QC and verification tools.

4. Special Materials (Solid-State Electrolytes, Dry Electrodes): Sandwich Transmission Imaging and Fiber Classification Testing methods address industry pain points.

Our services include:

• Free sample pre-testing and solution recommendations

• On-site installation, training, and SOP development

• Data interpretation and process optimization guidance (e.g., how to adjust ball-milling time based on sphericity, how to modify classification parameters based on particle size fluctuations)

• Test reports compliant with GB/T 19077, ISO 13320, GB/T 30835, GB/T 24533, and other standards, with full data traceability

Conclusion: Choose the Right Method, Achieve Precise Measurement and Control

There is no "one-size-fits-all" method for particle characterization of new energy battery materials. The R&D stage requires the "eyes" of imaging to reveal morphological details and establish structure–property relationships; the production stage requires the "speed" and "online" capabilities of laser diffraction to ensure batch-to-batch consistency. Leveraging static image analysis, laser diffraction, online monitoring systems, and exclusive innovative technologies including Sandwich Transmission Imaging and Fiber Classification Testing, Mipu Technology delivers optimal particle characterization solutions from the laboratory to the production line — tailored to your specific needs.

Let every particle's size and morphology — at the right time, with the right method, be measured with precision.

Contact Mipu Technology today to obtain your customized particle characterization solution, and join us in driving the new energy industry toward higher quality, greater safety, and enhanced consistency.