Monodispersed Sub-1 nm Inorganic Cluster Chains in Polymers for Solid Electrolytes with Enhanced Li-Ion Transport

The organic-inorganic interfaces can enhance Li⁺ transport in composite solid-state electrolytes (CSEs) due to the strong interface interactions. However, Li⁺ non-conductive areas in CSEs with inert fillers will hinder the construction of efficient Li⁺ transport channels. Herein, CSEs with fully active Li⁺ conductive networks are proposed to improve Li⁺ transport by composing sub-1 nm inorganic cluster chains and organic polymer chains. The inorganic cluster chains are monodispersed in polymer matrix by a brief mixed-solvent strategy, their sub-1 nm diameter and ultrafine dispersion state eliminate Li⁺ non-conductive areas in the interior of inert fillers and filler-agglomeration, respectively, providing rich surface areas for interface interactions. Therefore, the 3D networks connected by the monodispersed cluster chains finally construct homogeneous, large-scale, continuous Li⁺ fast transport channels. Furthermore, a conjecture about 1D oriented distribution of organic polymer chains along the inorganic cluster chains is proposed to optimize Li⁺ pathways. Consequently, the as-obtained CSEs possess high ionic conductivity at room temperature (0.52 mS cm^-1 ), high Li⁺ transference number (0.62), and more mobile Li⁺ (50.7%). The assembled LiFePO₄ /Li cell delivers excellent stability of 1000 cycles at 0.5 C and 700 cycles at 1 C. This research provides a new strategy for enhancing Li⁺ transport by efficient interfaces.