Boosting electrochemical energy storage of carbon fabric supercapacitors through in-situthermal regulation by microencapsulated phase change materials

Thermal management can address the key challenges in the high performance, long lifespan, and safety of supercapacitor devices. Aiming at boosting the electrochemical energy-storage performance of flexible supercapacitors under high ambient temperatures, a novel type of electroactive microencapsulated phase change material (MEPCM) was designed and fabricated with n-docosane as a PCM core, melamine-formaldehyde resin as a polymeric inner shell, and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS)/NiO/MXene composite as an electroactive outer layer. The resultant MEPCM not only shows desired layer-by-layer core-shell microstructure, size-uniform spherical morphology, and electrochemical-featured chemical structures, but also exhibits high phase-change enthalpies of over 138 J g−1. The developed electroactive MEPCM was employed as a thermal self-regulatory electrode material to modify the carbon fabric electrode (CFE) for use in carbon fabric supercapacitors (CFSCs) to enhance their electrochemical energy-storage performance through in-situthermal management. Through a rational integration of n-docosane as a PCM and PEDOT:PSS, NiO nanoparticles, and MXene nanosheets as electroactive materials in the CFE, the developed MEPCM-modified CFE exhibits a good capacitive behavior for electrochemical energy storage. The PCM core within the developed MEPCM can implement reversible phase transitions to generate a heat buffering effect on the MEPCM-modified CFE, thus suppressing the capacitance attenuation of CFSCs and enhancing their electrochemical energy-storage performance under high ambient temperatures. Compared to the conversional CFE without a PCM for thermal management, the developed MEPCM-modified CFE achieved an increase in the specific capacitance by 8.5 % at 45 °C thanks to its in-situthermal management effectiveness, and its capacitance retention after 3000 charge-discharge cycles was also improvement by 11.8 %. Through constructing highly electroactive MEPCM as a thermal self-regulatory smart electrode material, this study provides a novel design idea for boosting the electrochemical energy-storage performance of flexible supercapacitor devices under high ambient temperatures.