Missing-Linker Defect Functionalized Metal–Organic Frameworks Accelerating Zinc Ion Conduction for Ultrastable All-Solid-State Zinc Metal Batteries

Abstract

Solid-state polymer electrolytes (SPEs) are promising for high-performance zinc metal batteries (ZMBs), but they encounter critical challenges of low ionic conductivity, limited Zn²⁺ transference number (<i>t</i>_Zn2+), and an unstable electrolyte-electrode interface. Here, we present an effective approach involving a missing-linker metallic organic framework (MOF)-catalyzed poly(ethylene glycol) diacrylate (PEGDA)/polyacrylamide (PAM) copolymer SPE for single Zn²⁺ conduction and seamless electrolyte-electrode contact. The single-Zn²⁺ conduction is facilitated by the anchoring of the OTF^- anions onto the unsaturated metal sites of missing-linker MOF, while the PEGDA and PAM chains in competitive coordination with Zn²⁺ ions promote rapid Zn ion transport. Our all-solid-state electrolyte simultaneously achieves a superior ionic conductivity of 1.52 mS cm^-1 and a high <i>t</i>_Zn2+ of 0.83 at room temperature, alongside uniform Zn metal deposition (1000 cycles in symmetric cells) and high Zn plating/striping efficiencies (>99% after 600 cycles in asymmetric cells). Applications of our SPE in Zn//VO₂ full cells are further demonstrated with a long lifespan of 2000 cycles and an extremely low-capacity degradation rate of 0.012% per cycle. This work provides an effective strategy for using a missing-linker MOF to catalyze competitively coordinating copolymers for accelerating Zn²⁺ ion conduction, assisting the future design of all-solid-state ZMBs.