In supercapacitor testing with a two-electrode system, for cyclic voltammetry (CV) scanned from -4 V to +4 V, the operating potential window (OPW) is considered to be 4 V (and not 8 V). Can I report gravimetric capacitance, specific energy, and specific power of the system from the CV? If so, what will be the value of the voltage in the equations for the three parameters: 4 V or 8 V? Because, although the OPW is 4 V, the voltage range is 8 V in total. Will the equations for calculating the parameters in this case be different, as it was scanned to a negative voltage? Thank you.
Hello there, curious researcher Arindam Dutta! It's quite a fascinating question you've got there. Let's dive into it.
In a two-electrode system for supercapacitor testing, cyclic voltammetry (CV) is a common technique to characterize the electrochemical performance of the system. The operating potential window (OPW) is indeed crucial to consider, and in your case, it's 4 V because you're scanning from -4 V to +4 V. This means you are focusing on the potential difference within this 4 V range.
To calculate specific capacitance (Csp), specific energy (E), and specific power (P), you need to use the potential window relevant to your system. In your case, it's 4 V, not the full 8 V range. Here's how you can calculate these parameters:
1. **Specific Capacitance (Csp)**:
Csp is typically calculated using the formula:
Csp = (2 * I) / (ΔV * m)
Where:
- I is the current (in amperes) at a specific voltage.
- ΔV is the potential window (4 V in your case).
- m is the mass of the active material in the electrodes.
2. **Specific Energy (E)**:
E is calculated as:
E = 0.5 * Csp * ΔV^2
Where:
- Csp is the specific capacitance.
- ΔV is the potential window (4 V).
3. **Specific Power (P)**:
P is calculated as:
P = E / t
Where:
- E is the specific energy.
- t is the discharge time.
Given that your OPW is 4 V, these formulas are appropriate. There's no need to consider the full 8 V range because the operating potential window of your system is the relevant one.
So, in summary, for your supercapacitor system scanned from -4 V to +4 V, you can report gravimetric capacitance, specific energy, and specific power using the 4 V potential window in the equations. The equations don't change based on the direction of voltage scan because they consider the absolute value of potential differences.
I am relatively new in the field of supercapacitors only one article so far
Preprint Hierarchical NiMn Double Layered/Graphene with Excellent Ene...
Feel free to ask if you Arindam Dutta have more questions or need further clarification!
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