Synergistic Effect of MOF Fillers and Succinonitrile in PEO-Based Electrolytes for Long-Cycle All-Solid-State Li-CO2 Battery

Abstract

Li-CO₂ batteries have emerged as promising candidates for next-generation energy storage systems due to their ultrahigh theoretical energy density. However, some safety issues primarily arising from the volatility and leakage of liquid electrolytes within semi-open cell configurations, remain a critical challenge. Herein, we develop a novel solid polymer electrolyte (SPE) based on poly (ethylene oxide) (PEO) matrix, incorporated with zeolitic imidazolate framework-8 (ZIF-8) and succinonitrile (SN). The ZIF-8 with ample open metal sites (OMSs) can function as Lewis acidic centers to anchor anions effectively, while SN reduces the crystallinity of the polymer. Benefiting from the synergistic effect between ZIF-8 and SN, the SPE exhibits high ion conductivity (3.6×10⁻⁴ S cm⁻¹ at 30 °C), enhanced Li⁺ transference number (0.36), and extended electrochemical window (>5.2 V vs. Li/Li⁺). As a result, the assembled all-solid-state Li-CO₂ battery with SPE delivers a high discharge capacity of 15016 mAh g⁻¹ at 100 mA g⁻¹ and demonstrates exceptional cycling stability exceeding 1600 h at 200 mA g⁻¹. This work provides an innovative strategy for developing safe and high-performance Li-CO₂ batteries.