A high mechanical strength, deformable, fatigue-resistant polyacrylonitrile nanosphere-reinforced gel electrolyte for supercapacitors

There is an urgent need to develop gel electrolytes with excellent mechanical properties, deformability, and fatigue resistance to meet the flexibility requirements of novel supercapacitors. In this paper, polyacrylonitrile nanosphere-nanocomposite (PANNS-NC) hydrogels were synthesized by incorporating polyacrylonitrile nanospheres as reinforcing agents and employing N, N'-Methylenebis(acrylamide) (MBA) and N, N'-hexamethylenebisacrylamide (SMBA) as crosslinkers to achieve both physical and chemical crosslinking. The resulting PANNS-NC hydrogels demonstrated exceptional mechanical properties, including an ultrahigh elongation of 2380% and a remarkable tensile strength of 229.6 kPa. The gel electrolyte prepared from the PANNS-NC exhibited an ultrahigh ionic conductivity of 0.34 S·cm−1 and remarkable fatigue resistance, indicated by the absence of structural damage even after 1000 compression and tension cycles. Furthermore, the assembled supercapacitor demonstrated exceptional cycling stability, with a capacitance retention rate of 93% after 10,000 compression cycles with 50% strain. It maintained a 100% capacitance retention rate after 10,000 cycles with 90° bending. PANNS-NC holds great promise for use as a gel electrolyte material in supercapacitor development. Additionally, its suitability extends beyond supercapacitors, as it represents a novel material option for various other flexible devices.