Self-Healing Electrolyte Material Based on Quadruple Hydrogen Bond

As a lightweight energy system, lithium ion batteries are used in different industries and fields. The electrolyte acts as a channel for ion transmission in the battery. Polymer materials are applied as electrolyte since they have the advantages of high safety, high thermal stability and high mechanical strength. However, polymer will crack in certain external environments. Thus, some researchers proposed to prepare self-healing materials and applied them to electrolyte in lithium ion battery. This work is dedicated to solve the problem that the polymer electrolyte is susceptible to mechanical damage. The preparation method of 2-ureido-4-1H-pyrimidinone (Upy) unit which contains the quadruple hydrogen bonds was proposed. And grafted Upy on the polyvinyl alcohol (PVA) polymer matrix was performed to prepare a self-healing electrolyte material. The chemical structure, thermal stability, self-healing ability and electrochemical performance of PVA-Upy membrane were studied. The results showed that PVA-Upy material was successfully prepared by this method and proved by FT-IR and ¹H-NMR measurement. PVA-Upy material showed good thermal stability and mechanical strength, and had a self-healing efficiency of 90.20% in tensile strength at 70 ℃. As for electrolyte, it had an electrochemical window of 5 V and its highest ion conductivity was 2.06×10⁻³ S/cm. Being assembled as LiFePO₄/PVA-Upy/Li cell, it showed good cycle stability which suggested the application prospect in lithium ion batteries.