Micron Size NaCrO₂ Particles Enable High‐loading Dry‐processed Electrode for Sodium Ion Batteries

Abstract Dry‐process fabrication using fibrillatable binder is emerging as a promising method to produce high‐loading electrodes for energy storage applications, favored by its cost‐efficiency and eco‐friendliness. While previous studies have demonstrated the advantages of dry process over the traditional slurry method, there remains a gap in understanding how the particle size of active materials influences the mechanical and electrochemical performance of dry electrodes. In this study, four different particle size NaCrO₂ materials (Average size, S‐NCO: 0.6 µm, M1‐NCO 1.5 µm, M2‐NCO: 4.4 µm, and L‐NCO: 9.9 µm) are synthesized to investigate the effect of particle size on dry‐processed high‐loading electrodes. The findings reveal that the larger micron‐sized (>4.4 µm) NCO dry films exhibit significantly improved tensile strength and electrochemical performance, primarily ascribed to the low film porosity, abundant inter‐particle connection by the binder, comprehensive carbon coverage, and efficient percolation of the conductive pathway. Notably, a full cell incorporated with a high loading (5.2 mAh cm⁻²) and high active material ratio (96.5 wt.%) L‐NCO film electrode demonstrates promising cycling stability and rate capability. These results provide valuable insights regarding the design and fabrication of dry‐processed electrodes for future energy storage applications.