A high-voltage tolerance gel polymer electrolyte functioned by surface dielectric layer enabling durable supercapacitors

Immense attention has been focused on developing supercapacitors in the field of energy storage by virtue of their exceptional power density, extended cycling stability and operational safety. However, traditional liquid electrolytes pose severe challenges in response to leakage, high volatility and low electrochemical stability issues. To address these problems, we have developed a novel composite polymer membrane for gel polymer electrolytes (GPEs). This membrane features an internal fibrous framework composed of shape-memory polymers, while surface dielectric layers of PVDF-HFP cross-linked with modified TiO₂ nanoparticles are constructed on both sides of the framework. This configuration modulates the Stern layer potential gradient and diffuse layer ionic distribution through dielectric polarization, thereby suppressing electrolyte decomposition at high voltages, mitigating side reactions and facilitating ionic conduction. The resultant quasi-solid-state supercapacitor demonstrates excellent electrochemical stability at a voltage of 3.5 V, achieving an energy density of 43.87 Wh kg⁻¹, with a high-power density of 22.66 kW kg⁻¹ along with exceptional cyclic stability and mechanical flexibility. The synergistic structural design offers a safe and efficient energy harvesting solution for wearable electronic devices and portable energy storage systems.