Plotpot

Plotpot is a Python module that plots half and full cell potentiostatic data automatically imported with Convpot. It keeps a journal with meta information such as mass of active material, capacity etc. for later use.

Getting Started

Prerequisites

Plotpot is based on the following software:

• Convpot
• NumPy
• Matplotlib

To get the Python environment running under Windows I recommend to use a scientific Python distribution such as Anaconda or Enthought Canopy, which include a precompiled version of NumPy and Matplotlib.

Installing

To install Plotpot follow these steps (tested under Windows 7 64 bit as a normal user):

1. Download and install the latest Convpot package. During installation choose to add Convpot to the PATH of the current user.

2. Download and install Anaconda. Choose the Python 3 64 bit version and install "Just for me".

3. Update Anaconda. Open an "Anaconda Prompt" and type:

   conda update conda
   conda update anaconda
   

4. Create a new virtual Python environment just for running Plotpot:

   conda create -n plotpot-env numpy matplotlib
   activate plotpot-env
   

5. Create a shortcut for plotpot-env on the desktop as described in the wiki.

6. Download and install (or upgrade) Plotpot by typing:

   pip install plotpot --upgrade
   

If all goes well you should be able to type plotpot and get a usage message without errors about missing packages.

Usage

Plotpot currently knows two sub-commands show, merge and journal. A detailed help of the sub-command options are printed with plotpot <sub-command> -h

An example plot generated with plotpot show arbintest.res looks like this:

Select data

By default all available data is plotted. The range can be selected by

• cycle number (--cycles)
• time (in hours) (--time)
• data points (--data)

For example to plot data up to cycle 5:

plotpot show arbintest.res --cycles 5

To plot from cycle 2 to 10:

plotpot show arbintest.res --cycles 2,10

Select plots

Plots are selected with the --plot option, e.g.

plotpot show arbintest.res --cycles 2,10 --plot 8-9,14

It is possible to give a comma separated list of plots and ranges separated with "-". If no plots are selected, the voltage versus specific capacity (1) is plotted by default. Plotpot currently supports the following plot types:

1. Specific capacity
2. Specific capacity (circle plot)
3. Voltage and current
4. Temperature
5. dQ/dV
6. Specific capacity [mAh/g]
7. Volumetric capacity [Ah/L]
8. Specific energy [Wh/kg]
9. Volumetric energy [Wh/L]
10. Specific current density [mA/g]
11. Current density [mA/cm²]
12. C-rate
13. Hysteresis
14. Coulombic efficiency

Smooth dQ/dV plot

Plotpot has the option to smooth the dQ/dV plot by convoluting the raw data with a Hanning window of certain width. The smoothing strength is chosen with the level parameter ranging from 1 to 5, which translates to the widths of the window.

plotpot show arbintest.res --cycle 2,2 --plot 5 --smooth 2

Export data

The raw data, statistics, voltage profile and battery properties are exported with

plotpot show arbintest.res --export

This generates files in csv format for further processing with e.g. Microcal Origin or similar software. Data per cycle is packed into a zip archive and png snapshots of the plots genererated on screen are created.

Merge Files

A battery which consists of many individual data files (which is common for the Gamry instruments) can be merged together to a single data file with the "merge" sub-command.

To process multiple files

plotpot merge gamrytest_1.DTA gamrytest_2.DTA

Alternatively, the files to merge can be given in a text file listed one by line. Lines starting with the "!" character are ignored.

plotpot merge --list gamrytest.txt

The output file name can be changed with the --output option.

The journal

On first execution, a journal file plotpot-journal.dat is created in the directory of the plotpot executable. The folder location can be changed by setting the PLOTPOT_JOURNAL environment variable to a full path as described in the wiki.

The journal file keeps a record of mass, capacity, area, volume and mass loading of the electrode. If plotpot is called with the same data file, you have the possibility to use the previously entered values or enter new ones. The content of the journal is displayed with

plotpot journal

A particular entry can be removed from the journal with:

plotpot journal --delete <row_ID>

The individual raw data files of a merged battery can be shown with

plotpot journal --show <row_ID>

The journal file can be exported to a csv file:

plotpot journal --export

Authors

• Alexander Pohl - Initial work

See also the list of CONTRIBUTORS who participated in this project.

Changelog

All notable changes and releases are documented in the CHANGELOG.

License

This project is licensed under the MIT license - see the LICENSE file for details