Crystal Transformation Strategy in Hydrogen-Bonded Organic Framework Solid-State Electrolyte for Stable Zinc-Ion Batteries

Solid-state zinc ion batteries (ZIBs) hold great potential for sustainable and high-safety reserves. However, the advancement of solid-state ZIBs is constrained by the shortage of reasonable solid-state electrolytes (SSE) with abundant hopping sites, effective hydrogen evolution reaction (HER) inhibition, and favorable interfacial compatibility. Herein, the hydrogen-bonded organic framework (HOF) CAM-Ag with Zn²⁺ hopping sites is developed as SSE for ZIBs. Taking advantage of the short-distance Zn²⁺ conduction pathways by crystal transformation through incorporating the Ag−N coordinate bonds, CAM-Ag SSE achieves a significant ionic conductivity of 1.14 × 10⁻⁴ S cm⁻¹ at room temperature and superior Zn²⁺ transference number of 0.72. An abundant hydrogen bonds network effectively inhibits the initiation of HER and the subsequent generation of by-products. Moreover, the rapid Zn²⁺ conduction kinetics facilitated the inhibition of dendrite growth, promoting the uniform Zn²⁺ distribution. CAM-Ag SSE displays an extensive electrochemical stability range of 0–2.66 V and remarkable electrochemical compatibility, enabling stable Zn²⁺ plating/stripping for ≈1000 h at 1 mA cm⁻². Consequently, CAM-Ag SSE-based solid-state ZIBs achieve a specific capacity of 315 mAh g⁻¹ with only 1.5% decrease in capacitance after 24 h. The proposed HOF-based SSE displays a potential pathway for advancing stable and high-performance solid-state ZIBs.