In-situ polymerization formed self-healing quasi-solid electrolyte for high-loading lithium batteries

Abstract

High-energy-density lithium batteries face critical challenges including mechanical damage and poor electrode/electrolyte contact, which leads to discontinuous interfacial charge transfer and high interfacial resistance. To address these issues, a novel self-healing quasi-solid electrolyte (SHQSE) was synthesized through in-situ polymerization. The design employs hydroxyethyl acrylate as a molecular bridge to combine acrylates and polyurethanes with disulfide and complementary hydrogen bonds. These multiple dynamic bonds enable rapid Li⁺ transport (7.2 × 10^–4 S cm^-1) and enhanced self-healing capability. Furthermore, the excellent solid electrolyte/electrode interfacial contact is achieved during cycling through in-situ polymerization, and interfacial defects caused by polymer chain exchange and reorganization are effectively repaired. Consequently, capacity retention of 62.6 % in high-loading (>10 mg cm^-2) LiFePO₄ cells and 75.5 % in LiNi_0.8Mn_0.1Co_0.1O₂ cells after 500 cycles were obtained. Additionally, the self-healing polymer (SHP) functions as ion conductive agent, and continuous Li⁺ transport paths formed within silicon carbon (Si/C) electrodes enable electrode integrity, achieving 74.5 % capacity retention over 200 cycles at 0.33 C. Moreover, the 2 Ah NCM811|Si/C@SHP soft pack battery with SHQSE exhibits an ultra-long cycle life and safety. This innovatively in-situ formed SHQSE offers an effective way for the development of high-performance solid-state batteries.