A Free-Standing Ion-Conductive Membrane Based on Quasi-Dissociated LiPF6

As a carrier of ion conduction function, electrolyte is an indispensable part of any electrochemical energy storage system. A salt can only become an ion conductor electrolyte when dissolved in a solvent or at a state in a molten/quasi-molten situation, that is, a traditional electrolyte solution or fast ion conductor. Here, we reported an alternative quasi-dissociated state of a salt at room temperature. A LiPF6 can be dissociated to a certain extent by ZIF-8 and EC; thus a solid quasi-dissociated salt, a “puffed” like LiPF6 with longer bond length and more disordered atomic arrangements, has been achieved with an intrinsic ionic conductivity of 7.20 × 10–6 S cm–1 at 25 °C. Then, PEO was employed as the base material for casting, and by further dissociating the solid quasi-dissociated LiPF6 (SQDL), a free-standing ion-conductive membrane (ICM) has been obtained with good flexibility and excellent interfacial compatibility. The ICM possesses a high ionic conductivity of 1.07 × 10–3 S cm–1 and exhibits excellent battery performance in a lithium iron phosphate (LFP) solid battery with a discharge specific capacity of 139.9 mAh g–1 at 0.5 C.