Potentiostatic Intermittent Titration Technique (PITT) Set-up Parameters

To change parameters in a PITT experiment, click the script in the User Defined Sequence column. The Setup Parameters window appears:

Potentiostatic Intermittent Titration Technique Potentiostatic Intermittent Titration Technique (PITT) Set-up Parameters

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.

PITT Setup Parameters Notes

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.

Potentiostatic Intermittent Titration Technique Setup Parameters

  • 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:DATAYOURDATA.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.

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 the Positive 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.

PITT) Set-up Parameters Cable Check

Initial E

  • Voltage at which the first pulse will be applied. Typically 5–20 mV vs Eoc for a Li-ion charge, and 4.2 V.vs Eref for a discharge.

Final E

  • Voltage at which the final pulse will be applied. Typically 4.2 V for Li-ion charge, and 3.0 V vs Eref for a discharge.

Max Current

  • The largest magnitude of current that is allowed to flow during any of the pulse steps.

Step Size

  • The voltage step increment for the pulses. This is always entered as a positive value even for a discharge.

Max On Time

  • Duration for each voltage pulse to be applied.

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).

Stop At On 1, Stop At On 2

  • 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.

PITT Step at

  • Most experiments have Stop At On 1 and Stop At On 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.
  • PITT Voltage LimitDifferent 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.

PITT Limit Value Stop At 1

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

PITT Temp Limit Value Entry

  • 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

  • Duration for each rest section that occurs after a pulse.

Sample Period Rest

  • Rate at which the potentiostat records data during the rest periods.

Stop At Rest

  • Allows you to specify various limits during the rest periods. The limit, if met, causes the experiment to skip to the next step, or stop if there is no subsequent step. See the Stop At On description for more details about the limits.