Particle size distribution (PSD) describes the range and proportion of particles of various sizes in a batch of granular or powdered material. In battery electrodes, the active materials and additives come as particles, and their size distribution can greatly affect processing and performance. For example, a cathode powder might have a median particle size or D50, of 10 micrometers, meaning half the particles are smaller than 10 µm. The powder will also have some distribution around that mean, perhaps ranging from 1 µm fines to 20 µm larger particles. A narrow PSD means most particles are similar in size, while a broad PSD means there’s a wide range of sizes. PSD can impact how well materials pack (tighter packing can increase energy density but might reduce electrolyte penetration), how they coat (very large particles might clog a slot-die coater or sediment out), and how they perform electrochemically (smaller particles usually give more surface area and better power but may cause more side reactions). Controlling PSD is also crucial for consistency; different batches of material might behave differently if their PSDs differ.
NOVONIX measures and optimizes particle size distribution as part of its material development. NOVONIX uses techniques like laser diffraction particle size analysis to characterize the PSD of new powders they create or receive. If a certain performance issue is noticed, say, an electrode has high resistance, NOVONIX might check if the PSD changed – maybe a supplier delivered material with more fines. When developing synthetic graphite, for example, NOVONIX targets a specific PSD that balances tap density (packing density) with rate performance. They also consider bimodal distributions (mixing large and small particles deliberately) to improve packing. On the manufacturing side, NOVONIX ensures that the particle sizes work with coating equipment (not settling out in slurry, etc.). By paying attention to PSD, NOVONIX ensures that battery materials can be processed uniformly and perform predictably, which is key for scaling up and for achieving high-performance cells.
