Constructing polar ionic channels via amino network bridged aromatic rings systems for efficient sodium-ion migration

The development of solid-state sodium-ion batteries (SSSIBs) is hindered by sluggish Na⁺ migration in electrolytes and poor stability at electrolyte/electrode interfaces. To enhance Na⁺ transport performance and improve electrolyte/electrode interface stability, this study proposes an engineering strategy to construct a quasi-solid-state electrolyte (QEES) based on an amino network (-HN-C-NH-) connected with conjugated aromatic ring systems. This strategy leverages the π-electron cloud stacking effect of the conjugated aromatic rings to build highly continuous and strongly polar Na⁺ transport channels. The strong polar sites of the amino groups can effectively anchor anionic groups, promoting sodium salt dissociation and thereby increasing the concentration of free Na⁺ in the electrolyte. Meanwhile, the N atoms in the framework possess lone-pair electrons, which can form weak coordination with Na⁺, facilitating Na⁺ migration along the polar channels. The results show that the electrolyte exhibits a Na⁺ conductivity of 1.70 × 10^-4 S cm^-1 at room temperature and a Na⁺ transference number of 0.73, along with a wide electrochemical stability window compatible with various cathodes. The assembled solid-state sodium-ion batteries retain over 90% capacity after 1000 cycles at a 2C rate. This strategy of constructing polar channels via an amino-network-bridged conjugated aromatic ring system offers a new avenue for designing QSSEs with superior ion-transport properties.