Pore engineered carbon nanocages enhancing capacitive performance for supercapacitors at extreme temperatures

Energy storage devices capable of stable operation across extreme temperatures are crucial for applications in harsh environments, whereas achieving consistent performance under such conditions remains a significant challenge. In this work, a wide-temperature-range supercapacitor was constructed using hierarchically porous spherical carbon nanocages (HPC) synthesized by soft template method. The synergistic integration of HPC electrodes with the 3-methoxypropionitrile (MPN) electrolyte enabled the symmetric supercapacitors to operate from −70–100 °C. At −70 °C, the specific capacitance of HPC electrode achieves 130 F g⁻¹, approximately 200 % higher than that of commercial activated carbons. Furthermore, the system exhibits remarkable thermal stability, retaining 70 % of its initial capacitance after 10,000 cycles under a scan rate of 100 mV s⁻¹ at 100°C. Quantitative analysis confirms that the hollow structure with a large mesopore volume (1.8 cm³ g⁻¹) generated efficient ion transport channels at low temperatures. Meanwhile, the abundant micropores (S_BET = 2959 m² g⁻¹) provide substantial adsorption sites for the efficient charge storage.