Unveiling the Relationship between the Surface Chemistry of Nanoparticles and Ion Transport Properties of the Resulting Composite Electrolytes

Fundamental understanding of the transport properties within nanoparticle composite electrolytes is necessary for the development of next-generation electrochemical devices. Herein, the effect of surface-modified silica nanoparticles with aminophenyl, amide, and sulfonate functional groups (AP-SiO₂, AM-SiO₂, and SU-SiO₂) on the ion transport properties of composite electrolytes is systematically investigated. The competition between surface repulsive and attractive interactions of nanoparticles is reflected in the nature of the morphology and particle network in electrolytes, further affecting the ionic conductivity of electrolytes and diffusion coefficient of ions. The obvious decrease is observed in the AP-SiO₂-based system because of the severe agglomeration of nanoparticles. By contrast, the AM-SiO₂ and SU-SiO₂ form the regular particle network structure and accelerate the salt dissociation in electrolytes, thereby providing an effective ion transport pathway and more mobile ions for conduction, respectively. Consequently, the composite systems with AM-SiO₂ and SU-SiO₂ deliver remarkable enhancement in the ion transport properties.