BioLogic alkalmazások

2015.10.23 20:03
Szuperkondenzátor cellák tanulmányozása

Szuperkondenzátor cellák tanulmányozása.

 

Az alábbi anyagban le van írva a szuperkondenzátor ( szuperkapacitor ) paramétereinek a maghatározása BioLogic potenciosztát alkalmazásával.

 

Supercapacitors investigations
Part I: Charge/discharge cycling

I-Introduction
Among all the system dedicated to energy storage, supercapacitors are one of the most promising especially for powering electronic devices. This application requires indeed an energy storage device able to provide many charge/discharge and short term pulses (A typical shape of current pulses is displayed in Fig. 1). These requirements are in agreement with the intrinsic characteristics of the supercapacitor.

 

Fig. 1: Typical pulse output requirement for a digital communication device from ref [1].

The capacitor is made of one anode and one cathode separated by a dielectric membrane (Fig. 2).
Capacitor is called supercapacitor when the capacitance is higher than 1 F.

      

In this note, charge/discharge behavior of supercapacitor is investigated. Firstly, successive charges/discharges are done with a potential scan. Then, the second part of this note is dealing with discharge at constant power.
N.B.: All settings and raw data files presented hereafter are available in the Data Sample folder of EC-Lab® Software with the following name: technique_supercap.mpr. 

II-Set-up description
Investigations are performed with a VMP3 equipped with a standard board.
Characteristics of supercapacitor are the following:
capacitance: 22 F
maximum operating voltage: 2.3 V
mass of active material: ~10g
Supercapacitor is connected to VMP3 via a standard 2-electrode connection.
III-Charge/discharge cycling
As stated above, one of the most important characteristic of an energy storage device is the ability of the device to be charged and discharged many times without any performance loss.
In this paragraph, charge/discharge characterizations are carried out by potentiodynamic sweep at slow scan rate.
Cycling of the supercapacitor are performed with 41 cycles of Cyclic Voltammetry (CV). at 3 mV/s between 0 and 2.3 V (Fig. 3).

 

                         

 

I vs E and C vs E curves are plotted in Fig. 4. These curves show that current and capacitance are stable over 41 cycles. The cycling doesn't affect the performance of the supercapacitor.
Note C vs. E curve is plotted thank to the graphic customization ability of EC-Lab®,



 

IV-Constant power discharge
Energy storage devices are commonly represented by Ragone plot i.e. E vs. P. This diagram can be plotted from Constant Power Discharge (CPW) data after mathematical treatment.
Setting of the CPW technique applied to the supercapacitor is described in Fig. 5. The following constant power steps are successively applied to the system: 200, 100, 50, 20, 10, 5 and 1 mW.
Plot of Power vs. Energy is shown in Fig. 6

 

                    

 

                     

 

 

 

 

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