Effect of Pore Structure on the Low-Temperature Performance of Activated Carbon-Based Supercapacitors

Electrochemical double-layer capacitors (EDLCs) have attracted considerable attention due to their high power density and long cycle life. However, the wide temperature range performance of EDLC, especially the ultralow-temperature performance, cannot meet the increasing market demand. The pore structure of the electrode material activated carbon (AC) is a key factor affecting the performance of EDLC in ultralow-temperature environments. In this work, we screened four ACs with different pore structures for EDLC at low temperatures. MAC-2 exhibits optimal low-temperature electrochemical performance compared to the other materials (YP-50F, CMK-3, and MAC-1), which is attributed to the high effective pore volume (0.778 cm 3 g –1 in the 0.8–4.0 nm range) and the hierarchical pore structure, with the 0.8–2.0 nm pore volume accounting for 76.33% of the micropore volume and the 2.0–4.0 nm pore volume accounting for 35.99% of the mesopore volume. The EDLC based on MAC-2 provides a high specific capacitance of 30.94 F g –1 at 0.5 A g –1 at −60 °C and an excellent capacitance retention rate of 91.3% at −35 °C after 10,000 cycles at 1.0 A g –1 . This screening provides guidance for the design direction of electrode materials for EDLC at low temperatures.