Multi-Dimensional Optimized Interfaces with Rich Hydrogen-Bond Networks in Composite Solid Electrolytes for Interface-Dominated Li^<b>+</b> Transport.

Abstract

Rapid Li⁺ transport channels in composite solid electrolytes (CSEs) are often attributed to organic-inorganic interfaces. However, slow Li⁺ transport through polymer chains is still dominant due to inefficient interface construction and weak interface interactions. In this study, interface-dominated Li⁺ transport was achieved in ultracompatible CSEs by modifying sub-1 nm inorganic cluster chains (ICCs) with polyether amine (PEA). The abundant amino groups in PEA made ICCs monodisperse in the PVDF-HFP matrix and form hydrogen bonds with polymer chains. The distribution of organic-inorganic interfaces and interfacial hydrogen bonds was amplified by the multidimensional optimized interfaces. Moreover, the direction of -CF₂- groups was regulated by the hydrogen bonds to provide rich and continuous interface interaction sites and local charge accumulation regions for more free Li⁺ and more Li⁺ transport pathways, thereby making the Li⁺ interface transport dominant (52%) for the overall Li⁺ transport in CSEs. Consequently, the as-obtained composite solid electrolyte exhibits exceptional room temperature ionic conductivity (0.53 mS cm^-1), a substantial Li⁺ transference number (0.65), and a stable cycling performance (95% capacity retention of NCM/Li batteries after 500 cycles at 0.5 C). This work introduces key concepts for the practical application of ICCs and outlines core design principles for composite solid electrolytes.