Cyclic Voltammetry (CV) Data Extraction and Preprocessing

This Workflow processes raw text format (.txt) CV data exported from DIGSIM software. It automatically identifies test parameters, splits continuous test curves into independent cycles, precisely aligns and pairs data according to scan direction (forward/reverse), and exports the results as structured Excel spreadsheets.

This Workflow serves as the data foundation for all subsequent CV analysis processes.

Steps

Select input folder: Use the file picker to select the folder containing the .txt raw data files exported from the electrochemical workstation.
After automatic processing is complete, the output folder will be displayed in the interface and can be opened directly.
An overlay plot of the last-cycle CV curves at each scan rate will also be automatically generated for quick data quality preview.

Data Format

The beginning of the data should look similar to this:

source program: DIGISIM WINDOWS
program version: 3.05
file type: CV

experimental parameters:
Estart (V): 0.430
Eswitch (V): 0.530
Eend (V): 0.430
v (V/s): 1.000e-002
temperature (K): 298.2
Ru (Ohms): 0
Cdl (F): 0
cycles: 3

experimental CV curve:
number of E(V), I(A) couples: 600
0.430, -8.770e-005
0.431, -8.125e-005
0.432, -7.841e-005

Scientific Principles and Processing Logic

CV Scan Segmentation Principle

Cyclic voltammetry characterizes electrochemical behavior by applying a triangular wave potential scan to the working electrode. A complete cycle typically consists of two scan segments:

Forward Scan: Potential increases in the positive direction, corresponding to oxidation reactions.
Reverse Scan: Potential decreases in the negative direction, corresponding to reduction reactions.

Cycle Splitting

Scan direction switching is identified by detecting turning points in the potential sequence. A point is identified as a turning point when the potential $E_i$ satisfies the following conditions:

E_i \approx E_{\text{high}} \;\text{or}\; E_i \approx E_{\text{low}}, \quad (E_i - E_{i-1}) \cdot (E_{i+1} - E_i) \leq 0

Endpoint Completion: Due to hardware sampling frequency limitations, the last recorded data point may not fully reach the set $E_{\text{high}}$ or $E_{\text{low}}$ . The system automatically performs mathematical interpolation to ensure each scan segment lies within the strictly defined potential window $[E_{\text{low}},\, E_{\text{high}}]$ , thereby eliminating systematic errors in subsequent integration calculations caused by inconsistent windows.

Data Alignment and Closure

To ensure curve continuity, the system implements cross-scan alignment:

Ensures that the endpoint of the preceding scan segment coincides with the starting point of the following scan segment in physical space.
In Full Cycles mode, forces data to start and close at the lowest potential, facilitating direct use in plotting or integration calculations.

Output File Structure

The output Excel file (one .xlsx file per original .txt file) contains three sheets:

Metadata

Records the original test conditions of the sample, including:

Parameter	Meaning	Unit
`init_e`	Initial potential	V
`high_e` / `low_e`	Potential window upper/lower limit	V
`scan_rate`	Scan rate	V/s
`sample_interval`	Sampling interval	V

Full_Cycles

Arranges data by complete cycles, where each cycle contains a full forward and reverse scan. Used for plotting multi-cycle overlapping CV curves to observe cycling stability.

Scans_Split

Completely separates forward and reverse scans, formatted as C{n}_forward and C{n}_reverse. This sheet is the core input data for subsequent analysis workflows such as CV: Coulombic Efficiency and Capacitance Calculation, CV/Pseudocapacitance Analysis: b-Value Kinetic Analysis, and CV/Cdl: Double-Layer Capacitance and Electrochemically Active Surface Area Analysis.

FAQ

Scientific notation: The system can automatically recognize current values in scientific notation format such as 1.0e-03.
Incomplete cycles: If a cycle is incomplete (containing only a unidirectional scan), the system will retain and flag that data segment without affecting the normal processing of other cycles.

Cyclic Voltammetry (CV) Data Extraction and Preprocessing CV: Coulombic Efficiency and Capacitance Calculation