Activated carbon prepared from waste tire pyrolysis carbon black via CO 2 /KOH activation used as supercapacitor electrode

As the quantity of waste tires increases, more pyrolysis carbon black (CBp), a type of low value-added carbon black, is being produced. However, the application of CBp has been limited. Therefore, it is necessary to identify and expand applications of CBp. This work focuses on the preparation of activated carbon (AC) from CBp using the physicochemical activation of carbon dioxide (CO 2 ) and potassium hydroxide (KOH). Thereafter, AC is applied to the electrode of the electrical double-layer capacitor (EDLC). The AC prepared by CO 2 /KOH activation exhibited a hierarchical pore structure. The specific surface area increased from 415 to 733 m 2 g −1 , and in combination with low ash content of 1.51%, ensured abundant ion diffusion channels and active sites to store charge. The EDLC comprising the AC (AC-2) electrode prepared by excitation of CO 2 (300 sccm) and KOH had a reasonable gravimetric specific capacitance of 192 F g −1 at 0.5 A g −1 , and exhibited a good rate capability of 73% at 50 A g −1 in a three-electrode system. Moreover, the EDLC device comprising the AC-2 electrode delivered excellent cycling stability (capacitance retention of 106% after 10000 cycles at 2 A g −1 in a two-electrode system). Furthermore, a symmetric supercapacitor based on an AC electrode that exhibits a supreme energy density of 4.7 Wh kg −1 and a maximum power density of 6362.6 W kg −1 is demonstrated.