Robust Succinonitrile Plastic Crystal-Based Ionogel for All-Solid-State Li-Ion and Dual-Ion Batteries

We have synthesized highly conducting and electrochemically stable solidlike ionogels based on poly(vinylidene fluoride-co-hexafluoropropylene) P(VdF–HFP) copolymer matrix, succinonitrile (SN) plastic crystal plasticizer, lithium trifluromethanesulfonate (LiOTf) salt, and 1-butyl-1-methylpyrrolidinium trifluromethanesulfonate (BMPyrrOTf) ionic liquid. It is observed that the presence of SN in the ionogels enhances their ionic conductivity. The composition SN/BMPyrrOTf/P(VdF–HFP) with a ratio 40:40:20 (w/w/w) containing 0.5 M LiOTf (ionogel-3) exhibits the highest ionic conductivity (∼12.18 mS cm–1) and Li+-ion transference number (∼31%). Ionogel-3 has shown long-term stability performance in lithium plating and stripping experiments at several current densities and improved electrochemical compatibility with electrodes at 30 °C. The Li-ion battery fabricated with ionogel-3 has delivered high specific discharge capacities of 86, 120, 139, 144, and 150 mAh g–1 at current densities of C/3, C/5, C/8, C/10, and C/12, respectively, at 30 °C. The fabricated Li–graphite dual-ion battery has also delivered high specific discharge capacities of 126, 89, and 51 mAh g–1 at 100, 300, and 500 mA g–1 current densities, respectively, maintaining a high average discharge voltage of ≥4.5 V.