A low discharge time during galvanostatic charge-discharge testing could indicate several possible issues. Here are a few factors to consider: 1. Capacitor capacity: The discharge time is directly related to the capacity of the capacitor. If the capacitor has a low capacity, it will discharge quickly. Ensure that the capacitor you are using has an appropriate capacitance value for your application. 2. Internal resistance: High internal resistance within the supercapacitor can lead to a rapid voltage drop during discharge, resulting in a short discharge time. This can be caused by factors such as poor electrode-electrolyte contact or high resistance in the electrolyte. Consider optimizing the electrode and electrolyte materials, as well as the cell design, to minimize internal resistance. 3. Electrode material: The choice of electrode material can significantly impact the discharge time. Electrodes with high surface area and good conductivity can provide better charge storage capacity and slower discharge rates. Consider using electrode materials with optimized properties for your specific application. 4. Electrolyte concentration: The concentration of ions in the electrolyte affects the conductivity and charge storage capacity of the supercapacitor. Ensure that the electrolyte concentration is appropriate for your specific electrode material and design to achieve optimal discharge characteristics. 5. Experimental setup: Check that your experimental setup is accurate and consistent. Make sure the measurements are performed under the same conditions, such as temperature and current density, to obtain reliable results. 6. Supercapacitor aging: Over time, supercapacitors may experience degradation or aging, leading to reduced capacity and shorter discharge times. If your supercapacitor has been in use for an extended period, it might be worth considering replacing it with a new one. By considering these factors and evaluating their potential impact on your supercapacitor's performance, you can identify the root causes of the low discharge time and take appropriate steps to improve it.

Dear Zeynab Molaei ,

if you measure (some diagnostic) EIS[1-3], you might identify this (latent, complex) problem[1].

1. Supercapacitors Investigations Part II: Time Constant (EIS characterization, note-34) https://www.biologic.net/documents/eis-characterization-supercapacitor-application-note-34/

2. Testing Super-Capacitors Part 1: CV, EIS, and Leakage Current https://www.gamry.com/assets/Uploads/Super-capacitors-part-1-rev-2.pdf

3. Supercapacitor and electrochemical techniques: A brief review https://www.sciencedirect.com/science/article/pii/S2211715623001248

@Muhammad_Sajjad

Thank you for your attention, the problem was solved by reducing the mass of the substance to one milligram. Apparently, I covered too much active substance on the nickel foam and used too much glue, which causes internal resistance. Thankful

@loannis-Samaras

Thank you for your attention and guidance

Is 560 F/g a good capacitance,If not what measures should be taken to increase it