MnO₂@Corncob Carbon Composite Electrode and All-Solid-State Supercapacitor with Improved Electrochemical Performance.

Area of Science:

• Materials Science
• Electrochemistry
• Renewable Energy

Background:

• Biomass-derived carbon materials offer sustainable alternatives for energy storage applications.
• The electrochemical performance of biomass-derived carbons can be enhanced by incorporating pseudocapacitive materials like manganese dioxide (MnO₂).
• Pore structure significantly influences the interaction between MnO₂ and carbon supports, affecting overall capacitance.

Purpose of the Study:

• To investigate the effect of pore structure (microporous vs. meso/macroporous) of corncob-derived carbon on MnO₂ electrodeposition.
• To fabricate and characterize an asymmetric all-solid-state supercapacitor (ASC) using optimized biomass-derived electrodes.
• To evaluate the electrochemical performance, including specific capacitance, energy density, and cycle life, of the fabricated ASC.

Main Methods:

• Preparation of two types of corncob-derived carbon materials: activated carbon (AC) with micropores and corncob carbon (CC) with mesopores/macropores.
• Anodic electrodeposition of MnO₂ onto both AC and CC electrode materials.
• Fabrication of an asymmetric all-solid-state supercapacitor using AC as the anode, MnO₂-coated CC (MnO₂@CC) as the cathode, and a polyvinyl alcohol (PVA)/LiCl gel electrolyte.

Main Results:

• MnO₂ electrodeposition significantly enhanced the capacitance of the CC electrode (MnO₂@CC) by up to 9 times, reaching 4475 mF cm^-2, while the AC electrode (MnO₂@AC) showed minimal improvement.
• The fabricated ASC device achieved an ultrahigh specific capacitance of 3455.6 mF cm^-2 at 1 mA cm^-2.
• The ASC demonstrated a maximum energy density of 1.56 mW h cm^-2 and an excellent cycle life of 10,000 cycles.

Conclusions:

• The mesoporous/macroporous structure of corncob carbon (CC) is crucial for effective MnO₂ loading and enhanced electrochemical performance in supercapacitors.
• This study highlights the importance of pore structure engineering in biomass-derived electrode materials for supercapacitor applications.
• A green and efficient pathway for fabricating high-performance ASCs from waste biomass has been demonstrated, showing great potential for sustainable energy storage.