A supercapacitor constructed with a partially graphitized porous carbon and its performance over a wide working temperature range

Abstract

A supercapacitor that possesses excellent performance in a wide temperature range is constructed with a partially graphitized porous carbon (PGPC) as the electrode material and tetraethylammonium tetrafluoroborate/propylene carbonate (Et₄NBF₄/PC) as the electrolyte. The PGPC-based electrode shows a very consistent performance in a wide temperature range of −20 to 50 °C. At working temperatures as high as 50 °C and as low as −20 °C, it delivers specific capacitances of ∼148 and ∼135 F g⁻¹, respectively, and the supercapacitors exhibit high energy densities of ∼46 and ∼43 W h kg⁻¹. In particular, the low-temperature capacitive performance and rate capability of PGPC are much better than those of the normally used activated carbon and among the best ones ever-reported for carbon-based supercapacitors. More significantly, the PGPC-based supercapacitor shows excellent cycling performance at all tested working temperatures, with a capacitance retention of ∼98% after 1000 cycles at 5 A g⁻¹ even when the working temperature decreases to −20 °C.