Preparation of porous carbons from corn straw pyrolysis using double activation method in combination of FeCl3 and their electrochemical performance

In the study, an effective method of preparation was applied for the production of electrode materials from corn straw pyrolysis by employing KOH and KMnO4 as activators in combination with FeCl3 as graphitization catalyst. The results showed that the preparation method facilitated the development of the pore structure and improved the electrochemical performance of the materials. When the mass of corn straw, KOH, KMnO4 and FeCl3 was 5 g: 5 g: 5 g: 5 g and the activation temperature was 750 °C, the prepared K5Mn5Fe5–750 indicated the most excellent electrochemical performance and its pore structure was also the best with the specific surface area (SSA) of 1921 m2g−1. The largest specific capacitance was 305.3 F/g at 0.5 A/g for K5Mn5Fe5–750. It still held a 77 % of the specific capacitance retention, suggesting its good rate capability at 10 A/g. The capacitance retention is also still 88.5 % after 10,000 cycles at 10 A/g. The power density of K5Mn5Fe5–750 was 125.06 W kg−1, the energy density was 5.09 Wh kg−1. The study provides a solution with great promise for the carbon materials (CMs) preparation with good electrochemical performance, which is beneficial to the high-value utilization of the biomass materials for the energy storage.