Error capacitor energy storage experiment

Does a capacitor store energy?

Student experiment: Energy stored – two alternatives (20 minutes) Student questions: Calculations on the energy formula (30 minutes) The idea that a capacitor stores energy may have already emerged in previous sections but it can be made clear by using the energy stored in a capacitor to lift a weight attached to a small motor.

Why is it difficult to push charge on to a capacitor?

At first, it is easy to push charge on to the capacitor, as there is no charge there to repel it. As the charge stored increases, there is more repulsion and it is harder (more work must be done) to push the next lot of charge on. Can we make this quantitative? A first try says that the pd was on average V 2, so the energy transferred was Q × V 2.

How are ESR and capacitance C calculated?

ESR and capacitance C were calculated by fits from each EIS spectrum. The potential V was recorded during the charge step. Table 2. Measured parameters of the stack and its single cells. Looking only at the parameters of the stack does not reveal imbalances of single cells.

What is the relationship between voltage and energy stored?

Having seen that the energy depends on the voltage, there are several approaches which lead to the relationship for the energy stored. Start with a reminder of the idea that joules = coulombs × volts. The simplest argument is that with a pd V, a capacitor C will store charge Q, but the energy stored is not Q × V. Why not?

What are the fit-parameters for electrochemical capacitors?

The fit-parameters are typical values for electrochemical capacitors: ESR 100 mΩ Rleakage 100 kΩ Figure 2. Bode plot of Randles model. () magnitude, (+) phase. Above 10 Hz, magnitude and phase approach 100 mΩ and 0° respectively. The ESR dominates this region. Between 100 μHz and 100 mHz, capacitance controls the impedance.

What is a typical EIS spectra of electrochemical capacitors?

The fit-results are ESR 45.5 mΩ ± 0.2 mΩ Rleakage 3.6 kΩ ± 0.4 kΩ This result is typical for EIS spectra of electrochemical capacitors in which electrode porosity leads to very non-uniform access of the electrolyte to the electrode surface, and Faradaic reactions occur.