Covalently linked metal–organic framework (MOF)-polymer all-solid-state electrolyte membranes for room temperature high performance lithium batteries

Abstract

Extensive attention has been paid to metal–organic frameworks (MOFs) in the fields of gas storage/separation, sensors, catalysis, drug delivery and so on. However, the potential application of MOFs as electrolytes in lithium-ion batteries (LIBs) still needs to be further studied. In this study, showcased as the first example in the domain of all-solid-state electrolytes, a MOF covalently linked by flexible polymer chains toward a flexible stand-alone hybrid all-solid-state polymer electrolyte (HSPE) film is prepared by one-pot UV photopolymerization. Specifically, the precursors of the HSPE are composed of vinyl functionalized MOF (M-UiO-66-NH₂) nanoparticles, poly(ethylene glycol) diacrylate (PEGDA), a lithium salt and a photoinitiator. It is confirmed that HSPE-1-8 (m_M-UiO-66-NH2 : m_PEGDA = 1 : 8) possesses over 5 times higher ionic conductivity (4.31 × 10⁻⁵ S cm⁻¹ at 30 °C) and much better interfacial contact with Li electrodes than the SPE without incorporation of the vinyl functionalized MOF. Furthermore, at room temperature, the assembled cell of Li/HSPE-1-8/LiFePO₄ exhibits outstanding rate capacity (it can reach 140, 124 and 80 mA h g⁻¹ at 0.2, 0.5 and 1C, respectively) and excellent long cycle performance. Meanwhile, the solid cell can also be well run at 60 °C (the discharge capacity reaches 110 mA h g⁻¹ at 2C). Combined with the superior low/high temperature performance of the cell, it is believed that the MOF-based hybrid SPE can be one of the most promising high-safety and high performance electrolytes for LIBs.