A novel self-thermoregulatory electrode material based on phosphorene-decorated phase-change microcapsules for supercapacitors

Phosphorene is a promising candidate for the pseudocapacitive electrode material, because it offers a huge number of ion-accessible sites for multiphase active materials. A high working temperature is bound to deteriorate the electrochemical behavior of supercapacitors due to exothermic redox reactions during the charge–discharge process. To address this problem in supercapacitors, a self-thermoregulatory electrode material is designed and constructed to enhance the electrical energy-storage performance of supercapacitors for use in a wider temperature range. This electrode material is fabricated by microencapsulating n-docosane phase-change material (PCM) with a SiO2 inner shell and then coating a polyaniline/phosphorene hybrid outer layer as an electrochemical active material. A well-defined core-shell microstructure and expected components of the resultant electrode material are confirmed by morphological observations and structural characterizations. In this electrode material, while the polyaniline/phosphorene hybrid layer performs charge storage/release behaviors according to the faradic mechanism, the PCM core can effectively regulate the microenvironmental temperature for the electrode system in situ through phase transitions, thus improving the rate capability and specific capacitance of the electrode system. Furthermore, the hybridization of polyaniline and phosphorene contributes to the enhancement of capacitive behavior and charge–discharge cycle stability by offering more ion-accessible site in the polyaniline active material. In view of a unique combination of phosphorene and PCM, the novel electrode material developed by this work exhibits a potential application for high-performance supercapacitors suitable for use at high working temperatures.