Decoupling the effects of surface morphology and interfacial chemistry on localized electrochemical kinetics in LiCoO2 cathodes.

Spatial heterogeneity at electrode/electrolyte interfaces critically influences the electrochemical performance and degradation of lithium-ion batteries, yet the respective contributions of surface morphology and interfacial chemistry to localized electrochemical kinetics remain difficult to distinguish experimentally. Existing characterization techniques reveal either material structural transformation or chemical reconstruction but cannot quantitatively decouple their individual effects on local electrochemical behaviour. Herein, we establish a correlative multimodal strategy by integrating scanning electrochemical cell microscopy (SECCM), atomic force microscopy (AFM), Raman spectroscopy, and finite-element modelling to investigate the spatiotemporal evolution of LiCoO2 thin films during environmental exposure. Spatially resolved SECCM measurements reveal distinct microdomain-dependent electrochemical heterogeneity despite the initially homogeneous structure of the films. Correlative structural and chemical analyses, together with quantitative simulations, demonstrate that surface morphology and interfacial chemistry govern distinct aspects of the electrochemical response. By independently introducing the roughness factor and the effective lithium-ion diffusion coefficient into the multiphysics model, these two contributions can be quantitatively decoupled, with morphology predominantly determining the current response amplitude and interfacial chemistry governing kinetic limitations. This work provides a distinct strategy for correlating local interfacial evolution with electrochemical function and offers new insights into heterogeneous electrochemical interfaces in advanced energy-storage materials.