Advanced core-sheath structured phase-change fiber membrane for in situ thermal regulation in flexible...

Extreme temperature conditions often accelerate the degradation of supercapacitor materials and elevate electrolyte resistance, reducing device longevity and reliability. Efficient temperature regulation is necessary to ensure that supercapacitors can work stably under harsh environmental conditions. To overcome these challenges, we introduce a phase-change fiber film with a core-sheath structure and dual phase-change temperature range fabricated using advanced layer-by-layer coaxial electrospinning. The film was used as a substrate for the in situ polymerization of polyaniline nano-arrays after vacuum coating with a gold layer to create flexible supercapacitors with a PVA/H₂SO₄ gel electrolyte. The unique needle-like polyaniline nano-arrays enhance the surface area and ion transport channels, resulting in a device with an areal capacitance of 521.3 mF cm^-2 at a scan rate of 5 mV s^-1. Our phase change fibers have a high latent heat of 62.4 J g^-1 in the 0-10 °C and 40-50 °C ranges for efficient temperature regulation. The stabilized capacitance and internal resistance over two phase-change regions highlight the robust thermal regulation of the device. This advancement represents a significant leap forward for flexible supercapacitors, offering enhanced thermal management and vast potential for future energy storage applications.