Achieving High-Mass Loading Polyanionic Cathodes in Sodium-Ion Batteries Through Accessible Laboratory-Scale Dry-Processing Strategies.

Sodium-ion batteries require high-mass-loading electrodes to achieve competitive cell-level energy density for large-scale energy storage. However, conventional wet processing often induces structural heterogeneity and mechanical instability in thick electrodes. In this work, we demonstrate a versatile and accessible laboratory-scale dry-processing strategy requiring conventional ball-milling and thermal pressing. The degree of PTFE fibrillation can be regulated through controlled ball-milling to construct a stable and continuous electrode architecture. The optimized dry-processed sodium vanadium manganese phosphate (NVMP) cathode, with active material loading exceeding 40 mg cm-2, exhibits reduced polarization, stable interface evolution, and boosted ion diffusion, which meets the requirements of lab-scale testing and research for thick electrodes with high capacity. Hard-carbon||NVMP full cells further demonstrate reliable rate capability and prolonged cycling stability. This work demonstrates a versatile and accessible laboratory-scale strategy to construct stable thick-electrode architectures by regulating PTFE fibrillation. The methodology provides a convenient route for laboratory research on dry-processed electrodes and high-capacity sodium-ion batteries.