Rheo-impedance as a predictive framework linking slurry-state properties to electrode performance in lithium-ion batteries

Abstract Lithium-ion battery (LIB) performance is determined by the structural and electrochemical properties of the electrodes, which are influenced by the parameters of slurry-dispersion and coating processes. Current evaluation methods are ex situ and provide limited guidance for manufacturing. Herein, we introduce rheo-impedance spectroscopy, which couples controlled shear with electrochemical impedance, as a real-time tool for slurry microstructure assessment under coating-relevant conditions. For lithium iron phosphate (LFP) slurries, interfacial resistance (Rgb) depends on non-monotonic shear-rate, reflecting transitions of carbon-black state from aggregated through well-dispersed to over-dispersed. Rgb is inversely correlated with coated-electrode resistance (Rc), enabling slurry-level prediction of electrochemical performance. Electrodes fabricated under optimal shear conditions exhibit reduced Rc, improved rate capability, and enhanced cycle lifetimes. By directly linking slurry dispersion with battery performance, rheo-impedance provides a predictive and resource-efficient framework for electrode quality control, enabling accelerated process optimization and reduced development costs, and facilitating scalable production of high-performance LIBs.