Synthesis of δ-MnO2/C assisted with carbon sheets by directly carbonizing from corn stalk for high-performance supercapacitor

As one kind of agricultural bio-waste, the corn stalk is abundant in the nature. The corn stalk carbon owns inherent sheet-like and porous structure, bestowing favorable condition to load delta-MnO2 nanowalls on it. The corn stalk was directly carbonized at 500 degrees C without being activated by KOH, and the as-prepared carbon (Corn-C) was dispersed in KMnO4 solution and hydrothermal treated at 140 degrees C for 12 h, finally delta-MnO2/C composite was obtained. delta-MnO2/C possesses lower diffusive resistance and faster ion transport than pure delta-MnO2 due to the formation of mesoand macro-porous structure. delta-MnO2/C exhibits high specific capacitance of 520 F g(-1) at the scan rate of 5 mV s(-1) and excellent cycle stability. The capacitance retention is about 80.9% at 5 A g(-1) after charging-discharging for 5000 cycles. (c) 2020 Elsevier B.V. All rights reserved.

Automated summary

Corn stalk carbon was directly carbonized to obtain delta-MnO2/C composite through hydrothermal treatment, which exhibits lower diffusive resistance and faster ion transport. The composite shows high specific capacitance and excellent cycle stability, with a capacitance retention of about 80.9% after 5000 cycles at a scan rate of 5 mV s(-1).