Thick Electrode Design Enabled by a Carbon–Binder Domain–Resolved Dual‐Pore Transmission Line Model for Lithium‐Ion Batteries

ABSTRACT Thick electrodes are essential for achieving high‐energy‐density lithium‐ion batteries, yet their performance is often constrained by transport limitations. A central factor is the carbon‐binder domain (CBD), which plays a dual role in electrode. It provides electronic pathways but simultaneously impedes ionic transport. The coexistence of pores between active materials and nanoscale pores within the CBD has previously been recognized, but their individual contributions have not been quantitatively resolved. Here, we introduce the Dual‐Pore Transmission Line Model (DTLM), which separates ionic transport into two parallel pathways through interparticle and CBD pores. DTLM provides a physically grounded and domain‐resolved interpretation of porosity–tortuosity behavior, offering additional insight beyond what can be obtained from conventional Bruggeman relations or transmission line models. Guided by this framework, we design an optimized electrode formulation with 2 wt.% carbon black (CB), moderate milling, and a reduced binder‐to‐CB ratio. This formulation maintains CBD pore accessibility, reduces both electronic and ionic resistance, and substantially improves rate capability in high‐loading (10.0 mAh cm −2 ) and low‐porosity (20%) electrodes. Beyond this demonstration, DTLM offers a transferable framework for microstructure‐guided design of next‐generation thick electrodes and delivers quantitative insight into how electronic and ionic transport are balanced within multiscale pore networks.