Mixed-linker MOFs-derived cross-linked copolymer electrolyte enables high lithium mobility for dendrite-free all-solid-state batteries

Abstract

Metal-organic framework (MOF) materials have received extensive attentions as emerging fillers for solid electrolytes. However, MOF particles are served separately as fillers in solid electrolytes that bring limited ion-conduction improvement and interfacial problems between electrolytes and electrodes, which cannot fully exploit the advantages of MOFs. Herein, we propose a novel mixed-linker metal–organic framework to immobilize anions and chemically bond with the loosely coordinated copolymer backbone to form a cross-linked copolymer hybrid solid electrolyte, thus providing continuous ion-conductive paths for lithium ions transport and enhancing the lithium-ion transference number. This novel unique vinyl-functionalized MOF (Vinyl-ZIF-8) only allows tiny lithium ions to pass through its internal nanopores and restricts the movement of anions through electrostatic interaction, and its high specific surface area of 992.62 m2/g further enhances the adsorption of anions on the MOF particles surface, along with the loosely coordinated Li+ sites, showing synergistic effect and resulting in a high lithium-ion transference number reaching up to 0.73. The Li symmetrical battery assembled with this MOF-based solid electrolytes has cycled for 2000 h at 0.1 mA cm−2 with a stable polarization voltage, indicating good dendrite-suppression of lithium metal electrode and good interfacial compatibility between electrolytes and electrodes. Furthermore, the solid-state batteries assembled with MOF-based hybrid electrolytes and LiFePO4 or modified LiCoO2 electrodes also exhibit excellent cycling performance and rate performance at 25 ℃.