Thick Electrode Design Enabled by a Carbon–Binder Domain–Resolved Dual - Pore Transmission Line Modelfor Lithium - Ion Batteries

Abstract

Thick electrodes are essential for achieving high-energy-density lithium-ion batteries, yet their performance is often constrainedby transport limitations. A central factor is the carbon-binder domain (CBD), which plays a dual role in electrode. It provideselectronic pathways but simultaneously impedes ionic transport. The coexistence of pores between active materials and nanoscalepores 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 pathwaysthrough 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 ortransmission 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 electronicand 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 thickelectrodes and delivers quantitative insight into how electronic and ionic transport are balanced within multiscale pore networks.