Autonomous disulfide-crosslinked PEGDA solid polymer electrolyte for self-healing lithium-ion batteries under urban EV conditions

The accelerating demand for lithium-ion batteries (LIBs) in urban electric vehicles (EVs) has intensified exposure to harsh operational environments characterized by repetitive cycling, mechanical stress, and temperature fluctuations. These conditions critically accelerate electrolyte degradation, compromising both safety and electrochemical performance. Conventional electrolytes—whether liquid, gel, or solid-state—are prone to irreversible damage under such stresses. Although polymer-based self-healing electrolytes with dynamic bonding chemistries have emerged, most require external stimuli (heat or pressure) for activation and often exhibit limited ionic conductivity, restricting their practical adoption. This study introduces a disulfide-crosslinked poly(ethylene glycol) diacrylate (PEGDA) solid-state polymer electrolyte capable of autonomous self-healing under ambient conditions, without external intervention. The dynamic covalent disulfide bonds facilitate spontaneous bond exchange reactions, restoring both ionic transport pathways and mechanical integrity after damage. The electrolyte was fabricated via UV-induced photopolymerization and integrated into a LiFePO₄/Li full-cell configuration. Bond kinetics and stress evolution were modeled in MATLAB R2023a, while electrochemical performance was experimentally validated using a Gamry Interface 1010E and NEWARE CT-4008 battery cycler. The proposed electrolyte achieved an ionic conductivity of 1.20 × 10⁻³ S cm⁻¹, self-healing efficiency of 98%, and retained 85% capacity after 750 cycles at 1C, representing a 15–20% improvement in lifespan and cycling stability over conventional systems. Remarkably, electrochemical functionality was restored within 60 min of ambient healing. These findings establish a robust, stimuli-free self-healing mechanism for next-generation LIBs, offering a promising pathway toward resilient, maintenance-free, and sustainable energy storage systems for electric mobility.