Self-Healing Poly(Ionic Liquid) Ionogel Polymer Electrolyte Enabled by Ion-Dipole Interaction for Flexible Lithium Metal Batteries

ABSTRCT Ionic liquids (ILs) gel polymer electrolytes (IGPEs) for lithium ion batteries has attracted great attention due to its high ionic conductivity and good mechanical strength. However, the poor compatibility of ILs with neutral polymer matrix leads to the uneven distribution of ILs in IGPEs, which seriously affects the electrochemical performance and makes the electrolyte membrane easy to damage. In this work, we prepare a poly(ionic liquid) (PIL) based IGPE (PEPIL). PIL matrix (PVE) and IL have good compatibility, and the ion-dipole interaction between the imidazolium cations and the alkoxy dipole not only further increases the compatibility of PVE and IL, but also endows PEPIL with excellent self-healing ability. As a consequence, PEPIL exhibits high ionic conductivity (1.32 × 10-4 S cm-1) and wide electrochemical stability window (5.2 V). In addition, the electrostatic attraction increases the lithium ion transference number (0.61). Moreover, excellent thermal stability (340 °C) is also achieved. Thus, LiFePO4/PEPIL/Li cell delivers discharge capacity of 140.0 mA h g-1 with capacity retention of 86% at 0.2 C after 160 cycles under ambient temperature. More importantly, the healed PEPIL can completely restore its electrochemical properties, showing great application potential in flexible electronic devices.