Cyclic Charge-Discharge Setup Parameters

Default button Restores all the parameters on the screen to their default values. Use it to fix typing errors or find out previous values for a parameter you have already retyped. The default values are the values as specified by the Explain™ script. All of the standard scripts perform an automatic restore of the last used values. These are the values first shown to the user. In order to get to the values specified by the script, use the Default button.
Save button

Save the current parameter set on your disk. This is very useful when you are running repetitive tests. Parameter sets are stored in a file with a .SET file-name extension. More than one parameter set can be stored in each file, with the set distinguished by aSet Name. This system is a powerful tool for organizing your experimental setups. For example, each worker in a lab can have his own setup file (JOE.SET, KAREN.SET, etc.). Within her file, Karen can save multiple parameter sets under descriptive Set Names (C1010 Noise, Fast Noise, etc.).

Clicking Save opens a dialog box which requests the name of the file where you wish to save the parameter set, and the Set Name within in the file. Once you are satisfied with the names, clicking the OK button saves the set in the specified file.

Restore button Recovers a parameter set from your disk. This is useful when you are running repetitive tests. Clicking Restore opens a dialog box which requests the name of the file where your parameter set has been saved, and the Set Name within the file. Once you are satisfied with the names, clicking the OK button recalls the set from the specified file.
Pstat Selects the potentiostat/galvanostat/ZRA to perform the experiment. Each labeled radio button corresponds to an installed potentiostat. When you choose a potentiostat, its corresponding radio button is filled in. In a multiple-potentiostat system, you can change the potentiostat selection by clicking on a Pstat’s radio button using the mouse. From the keyboard, tab down until a dotted line appears around one of the Pstat labels, then hit the space bar to select among the potentiostats. Only one potentiostat can be selected at a time, so selecting one potentiostat de-selects another one.
Test Identifier

A string that is used as a name. It is written to the data file, so it can be used to identify the data in database or data manipulation programs.

The Identifier string defaults a name derived from the technique's name. While this makes an acceptable curve label, it does not generate a unique descriptive label for a data set. The Identifier string is limited to 80 characters. It can include almost any normally printable character. Numbers, upper- and lower-case letters, and most normal punctuation characters including spaces are valid.

Notes

Enter several lines of text that describe the experiment. A typical use of Notes is to record the experimental conditions for a data set.

To the right hand side of the notes is a button. This button allows you to open the Experiment Notes dialog box, shown below, which shows more of the notes at one time.

You can edit the notes in either place.

Notes defaults to an empty string. The Notes string is limited to 400 characters. It can include all printable characters including numbers, upper- and lower-case letters, and the most normal punctuation including spaces. tab characters are not allowed in the Notes string. You can divide your Notes into lines using enter.

Base Filename

The pathname of the file in which the output data are written. It can be a simple filename with no path information, where the output file is located in the default data directory. The default data directory is specified in the Gamry.INI file under the [Framework] section with a Key named DataDir. This default pathname can be changed using the Path command under the Options menu. It can also include path information, such as C:\DATA\YOURDATA.DTA. In this example, the data are written to the YOURDATA.DTA file in the DATA directory on drive C.

The default value of the Output Filename parameter is an abbreviation of the technique name with a .DTA filename extension. We recommend that you use a .DTA filename extension for your data filenames. The dat- analysis package assumes that all data files have .DTA extensions.

NOTE: The software does not automatically append the .DTA filename extension. You must add it yourself.

If the script is unable to open the file, an error message box, Unable to Open File, appears. Common causes for this type of problem include:

  • An invalid filename.
  • The file is already open under a different Windows® application.
  • The disk is full.

After you click the OK button in the error box, the script returns to the Setup box where you can enter a new filename.

Save Raw Data

NOTE: The format of these raw data files is identical to that are created by the Electrochemical Energy Charge and Discharge experiments, and use the same analysis routines when opened in the Gamry Echem Analyst™. Determines whether or not raw charge and discharge data files are saved during a cyclic charge-discharge experiment.

If the Yes radio button is selected, individual charge and discharge data files are recorded for the cycles of the cyclic charge-discharge experiment. The files are saved to a subfolder of the current data folder. The subfolder is automatically given the name CHARGE_DISCHARGE. The filenames for the raw data files consist of the word CHARGE or DISCHARGE followed by an underscore and the cycle number in which the data was recorded. For example CHARGE_#21.dta contains data recorded during the charge step of the 21st charge-discharge cycle.

If the Yes radio button is active, the Page 3 window appears.

Capacity Specifies the capacity—the amount of charge needed to charge or discharge a battery—to be recorded. This value is not used during the experimental phase, but rather during the analysis where a percent capacity graph can be displayed. The units for this parameter are ampere-hours (Ah).
Cell Type

An optional parameter only displayed if a Reference 3000 or Interface 5000 is present.

Half Cell radio button

When the cell type is half-cell, the instrument measures the voltage between the working sense lead (blue) and the reference lead (white). This is the normal electrometer. The maximum measurable voltage in half-cell mode varies by instrument. See the manual for your instrument and the specifications for the electrometer.

Full Cell radio button

Full Cell mode is generally used to test a single-cell electrochemical device. The test assumes a two-electrode cell. The positive terminal of the cell is connected to the potentiostat’s working (green) and working sense (blue) leads. The negative terminal of the device is connected to the potentiostat’s counter (red) and reference (white) leads. The Electrochemical Energy software displays an error message if the Working Lead parameter is set to Negative. Connect the potentiostat’s counter sense (orange) lead to the cell cable’s ground (black) lead.

Both radio button

Both mode is only used for the Interface 5000 dual-electrometer mode. It measures the voltage difference between the reference lead (white) and both sense leads (blue and orange).

Working Lead

Specifies how the potentiostat is connected to the electrochemical cell.

When the working lead (green) is connected to the positive electrode (discharge cathode) of the electrochemical cell, select thePositive radio button for this parameter. When the working lead is connected to the negative electrode (discharge anode) of the electrochemical cell, select the Negative radio button for this parameter.

In general, we recommend Positive.

Cable Check checkbox

If you activated this checkbox, the software warns you to confirm that your cable connections are appropriate for the selected Cell Type.

First Step

Decides whether the first step of a cyclic charge-discharge experiment is a charge or discharge step.

Number of Cycles

Controls the number of charge-discharge cycles to be executed. Each cycle consists of one charge step and one discharge step.

Sample Period

The spacing between output data points. The units used for the Sample Period are seconds.

The shortest Sample Period we recommend is 50.0 ms (0.05 s). The longest Sample Period allowed is 715 s (Reference Family). The Number of Points must be less than 262143 (218 – 1).

Voltage Finish

Primarily for the charging of batteries. When the battery has reached a voltage limit, it is held at the voltage limit for the user-specified time, or until the current draw has dropped below a user-specified limit.

The checkbox is used to turn the voltage finish ON and OFF. The first field specifies the lower limit of current, in A, at which the voltage finish terminates. The second field specifies the maximum amount of time the voltage is to be applied if the current limit is never reached.

NOTE: You must specify a Stop At criterion based on a voltage limit in order to use a voltage finish.

Loop End Terminates the repeating experiment when a conditional test becomes true. In a Cyclic Charge-Discharge experiment, a Loop End test is typically used to stop the experiment when the device has lost most of its capacity or fails to charge.
IR Measure checkbox Determines whether or not the instrument performs IR measurements during the experiment. When performing an IR measurement, the flow of current is interrupted and the uncompensated resistance is determined based on the corresponding drop in the voltage measurement. Do not use this measurement with fast sample periods. As a general rule, any sample period faster than 1 second is too fast for IR measurement. The IR value is stored in a Vu column in the raw data file.
Eis Spectrum

With the addition of an Electrochemical Impedance Spectroscopy license, electrochemical impedance measurements can also be integrated into cyclic charge-discharge experiments. This setup parameter indicates if EIS data are to be recorded. If EIS data are recorded, an additional set up page appear, with an EIS Spectrum Parameters area.

AE Channels

An optional parameter that appears only if an instrument with the Auxiliary Electrometers option is present in the system. If you do not have an instrument with an AE option, you do not see this setup parameter. This parameter consists of checkboxes to select which channels are active during the experiment.

Click the All button to select all of the channels.

Click the None button to deselect all of the channels.

In some experiments, there is aSet Limits checkbox. This checkbox opens a secondaryAE Channel Limits window where limits for the individual AE channels can be entered, as seen here:

The checkbox for each AE channel turns the limit-checking on for that channel. The Under (V) parameter tests for voltages less than the entered value. TheOver (V) parameter tests for voltages above the entered value. If the measured value on an AE channel exceeds one of these limits, the experiment skips to the next step, or end if there is no next step.

Discharge Mode

Specifies the mode used during the discharge step of an experiment. The drop-down list specifies the mode. There are five available modes: Constant Current, Constant Load, Constant Power, Capacity * N, and Capacity / N.

The field is for the appropriate value in the units specified by each mode. Capacity * N and Capacity / N use C rate, in units of #N.

Max Discharge Charge Time

Specifies the maximum amount of time to maintain the discharge or current charge. The first field specifies the value. The value entered is based on the following drop-down box. Select the appropriate units of time for the value entered in the field.

Stop At

Allow you to specify various limits to an experiment. The limit, if met, causes the experiment to skip to the next step, or stop if there is no subsequent step.

Most experiments have Stop At 1 and Stop At 2. These parameters are treated equally, and if both are used, they are both tested on every raw data point. If either limit is reached, the experiment skips to the next step or stop. The available stop tests are shown in the drop-down list below.

Different experiments allow different tests, but the principles that govern their behavior are the same. After you choose a limit, the appropriate units for entry of the limit are shown to the side of the limit-value entry box as depicted below.

When a voltage limit is selected, the entry units are Volts. When a temperature limit is selected, the entry units are Celsius.

The available stop tests are:

None

No stop test specified. The experiment runs until the maximum specified time.

Voltage

Voltage < Limit Stop if measured voltage is less than the value entered in V.
Voltage > Limit Stop if the measured voltage is greater than the value entered in V.
|Voltage| < Limit

Stop if the absolute value of the measured voltage is less than the value entered in V.

|Voltage| > Limit Stop if the absolute value of the measured voltage is greater than the value entered in V.
|dV/dT| < Limit Stop if the absolute value of the measured voltage change rate is less than the value entered in V/s.
|dV/dT| > Limit Stop if the absolute value of the measured voltage change rate is greater than the value entered in V/s.

Current

Current < Limit

Stop if measured current is less than the value entered in A.

Current > Limit

Stop if the measured current is greater than the value entered in A.

|Current| < Limit

Stop if the absolute value of the measured current is less than the value entered in A.

|Current| > Limit Stop if the absolute value of the measured current is greater than the value entered in A.
|dI/dT| < Limit

Stop if the absolute value of the measured current rate of change is less than the value entered in A/s.

|dI/dT| > Limit Stop if the absolute value of the measured current rate of change is greater than the value entered in A/s.

Temperature

Temp > Limit Stop if measured temperature is greater than the value entered in °C.
|dTemp/dt| > Limit

Stop if absolute value of measured temperature change is greater than the value entered in °C/min.

Charge and Energy

|Charge| > Limit Stop if absolute value of accumulated charge is greater than the value entered in A-h.
|Energy| > Limit Stop if absolute value of transferred energy is greater than the value entered in J.
Rest Time The charge and discharge Rest Time setup parameters make the system sit idle at the charged or discharged state for the specified time. After the specified time has elapsed, the next step begins.
Charge Mode

Specifies the mode used during the charge step of an experiment.

The dropdown list specifies the mode. There are three available modes: Constant Current, Capacity * N, and Capacity / N.

The field is for the appropriate value in the units specified by each mode. Capacity * N and Capacity / N use C rate, in units of #N.

Save Interval

If the Yes radio button is active for Save Raw Data, the Page 3 window appears. On Page 3, three choices are possible:

  • All radio button saves all the data
  • Skip N radio button saves every N + 1 cycles, skipping over Skip Number N data points. Thus N = 4 saves every fifth data point.
  • After Delta Q radio button saves data after a certain percentage change in charge Q specified in Delta Q Increase and DeltaQ Decrease.
Skip Number

The number of data points to be skipped over during the Save Interval, before saving the raw data point.

The Skip # parameter specifies the frequency at which the raw data files are saved. If this number is zero, files are saved for every charge-discharge cycle. If the Skip # is set to a value greater than zero, n cycles are skipped for each cycle that is saved.

For example if the Skip # is set to 4 as shown above, the 1st cycle is saved, the next four cycles (2, 3, 4 and 5) are skipped, cycle 6 is saved, cycles 7, 8, 9 and 10 are skipped, cycle 11 is saved, and so on.

DeltaQ Increase

DeltaQ Decrease

The percentage change in charge Q that must occur before the system starts recording raw data points, if you have chosen Yes to Save Raw Data.