A Metal–Organic Framework-Modified Single-Ion Conducting Solid Polymer Electrolyte for Lithium-Ion Batteries

The use of a single-ion conducting solid polymer electrolyte (SISPE) can effectively mitigate concentration polarization induced by cell operation, thereby inhibiting dendrite formation and enhancing the safety and longevity of lithium-ion batteries. However, the conductivity of a SISPE is typically limited by lithium-ion dissociation. To address this limitation, we prepared a SISPE with high ionic dissociation through reversible addition–fragmentation chain transfer (RAFT) polymerization by using lithium 4-styrenesulfonyl-(phenylsulfonyl)-imide (SSPSILi) and UIO-66-NH-Met as raw materials. Although the obtained SISPE did not exhibit stunning conductivity at room temperature (4.57 × 10–6 S cm–1, 25 °C), it exhibited stable thermodynamic properties and exceptional ionic conductivity (σ) at elevated temperatures (up to 10–4 S cm–1 at 60 °C). Moreover, it demonstrated a high Li-ion transference number (tLi+ ≥ 0.8) in the absence of any plasticizer and possessed a wide electrochemical stabilization window of 4.8 V at 25 °C. By chemically grafting metal–organic framework (MOF) fillers onto the polymer backbone, we established a robust ion transfer channel that effectively reduced interfacial potential barriers between each component. The open metal active centers interact with anions, inhibiting the shuttle of anions and promoting the dissociation of Li+, thereby improving ion conductivity. The SISPE was assembled into a battery. The capacity of the battery assembled with a SISPE hardly decayed after 300 cycles at 1 C, and the Coulombic efficiency was ultimately maintained above 98%. Li|SISPE membrane|Li batteries still exhibit stable lithium plating/stripping behavior after cycling for 2000 h at a current density of 0.2 mA cm–2, showing excellent rate capacity and cycling stability.