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 cm3 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.