Metal organic frameworks enabled rational design of multifunctional PEO-based solid polymer electrolytes

Electrochemical performance, mechanical properties as well as fire safety are crucial factors to evaluate solid polymer electrolytes (SPEs). In this article, we purposely choose metal-organic frameworks (HKUST-1 MOFs) as the multifunctional additive to modify the PEO-based SPEs. The PEO-LiTFSI-10HKUST-1 MOFs electrolyte (PL10HM) has shown enhanced ionic conductivity, which reaches 2.4 × 10⁻³ S cm⁻¹ at 80 °C. With the HKUST-1 MOFs, the electrochemical stability window and lithium-ion transfer number were largely enhanced as compared to the PEO-LiTFSI electrolyte (PL). The crystal structure, morphology, thermal stability, micro and macro mechanical properties were characterized systematically. The reduction in peak heat release rate (pHRR) of 42% was realized, which means the PL10HM possesses higher fire safety. The as-fabricated Li/PL10HM/LiFePO₄ battery exhibited a simultaneous good rate capability up to 1C and highly stable cyclability for over 100 cycles. These results demonstrate the unique characteristics of such a novel electrolyte membrane, potentially enabling the high performance, safe use in the practical solid-state batteries.