Influence of electrode porosity on physical properties and performance of dry processed LiFePO4-based electrodes

Dry battery electrode (DBE) processing potentially offers a more sustainable and cheaper, solvent-free alternative to conventional wet electrode paste manufacturing in battery cell production. However, optimal electrochemical performance of DBEs requires balanced mechanical integrity, electronic conductivity and ionic transport. In this study, the impact of porosity on microstructure, mechanical properties, and electrochemical performance of LiFePO 4 based DBEs was systematically investigated via post -calendering. The results demonstrate that decreasing the theoretical electrode porosity from 50% to 30% drastically increased adhesion strength and through-plane electronic conductivity, indicating improved particle contact and conductive network formation. Simultaneously, impedance-based analysis revealed increasing transport limitations which decreasing porosity, reflected by higher tortuosity values. Among the investigated electrodes, a theoretical porosity of 40% provided the most favourable balance between electronic and ionic transport properties, delivering the highest specific discharge capacity, superior rate capability and the best long-term cycling stability. These findings identify an optimal porosity window for the investigated dry-processed electrode formulation and highlight that maximizing electrode densification does not necessarily maximize electrochemical performance. Instead, electrode performance is governed by the interplay between conductive network formation and preservation of effective ionic transport pathways.