Cycling Stability Issues Faced When Trying To Apply Anodic Films on Copper or Its Alloys as Supercapacitor Electrodes

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Copper oxide/hydroxide nanomaterials are promising for supercapacitors due to high capacitance, low cost, and eco-friendliness.
• Anodization is a favored method for electrode fabrication due to efficiency and control.

Purpose of the Study:

• Investigate the mechanism behind the unusual capacitance increase in copper-based supercapacitor electrodes during cycling.
• Identify strategies to enhance cycling stability by preventing this phenomenon.

Main Methods:

• Fabrication of anodic films on copper and brass substrates.
• Cycling stability tests in concentrated potassium hydroxide (KOH) electrolyte.
• Analysis of the mechanism causing capacitance increase.

Main Results:

• Anodic films on copper and brass showed a persistent increase in capacitance during cycling.
• Secondary growth of new oxides on the underlying metal substrate was identified as the cause.
• Replacing copper substrates with electroplated copper films on graphite eliminated the capacitance increase.

Conclusions:

• The secondary growth of oxides on copper substrates leads to increased capacitance, compromising cycling stability.
• Using alternative substrates like graphite prevents this issue, ensuring stable supercapacitor performance.