Electrochemical Characterization Dataset for Commercial N21700-BAK-CG50 Battery Cell

Scope This collection contains data records related to the comprehensive laboratory characterization of the commercial 21700 cylindrical battery cell N21700-BAK-CG50 cell with 5.0 Ah nominal capacity manufactured by BAK Battery Co., Ltd. and its electrodes after cell tear-down. The records contain (i) the raw and processed data including electrochemical time-series data and imaging data and (ii) model parameters obtained from processing this raw data and from direct laboratory measurements of geometrical, physical and microstructural properties. Metadata describing measurement conditions (temperature, current rates, SOC range), laboratory equipment, experimental protocols, data processing routines, and parameter extraction methods are included to ensure traceability and reproducibility. The data contained in the records is intended to support model parameterization for the N21700-BAK-CG50 cell and could also be relevant for other Li-ion cells using NCA, graphite and silicon oxide as active materials. The electrochemical data includes quasi-OCV (qOCV) measurements in charge and discharge direction on full cell- and electrode-level rate tests at various C-rates on full cell- and electrode-level EIS measurements at various SOCs on full cell- and electrode-level GITT measurements at electrode-level Imaging data includes Scanning electron microscopy (SEM) images of the electrodes For visualization, exemplary plots of the measurement results are included. The data format complies to the Battery Data Format (.bdf) recommendation suggested by the Battery Data Alliance (https://lfenergy.org/projects/battery-data-alliance/) introducing fixed table schema for time-series battery data. The data is stored in csv format while for model parameterization workflows parquet is used as it is most suitable for efficient storage and processing of large time-series datasets. For inquiries or further assistance, please contact John Mugisa at [e-mail] Battery Cell General Metadata Property Value Name N21700-BAK-CG50 Model CG50 Manufacturer BAK Battery IEC Designation INR21700 Chemistry NCA (Nickel Cobalt Aluminum Oxide) / Graphite-Silicon Oxide Format Cylindrical (21700) Nominal Voltage / V 3.6 V Nominal Capacity / Ah 5 Ah Standard charge voltage 4.2 V Cut-off voltage 2.5 V Cell diameter ~21 mm Cell height ~70 mm Test Equipment Property Value Manufacturer Basytec Model CTS Lab (half-cell) / CTS Standard (full-cell) Impedance: Battery cycler Full Cell Characterization The following dataset contains beginning-of-life (BoL) open-circuit voltage measurements (GITT-OCV and qOCV), rate capability tests and electrochemical impedance spectroscopy (EIS) measurements at defined states of charge on the full cell level. Quasi-Open Circuit Voltage (qOCV) Technical Metadata Parameter Value C-rate 0.04C Voltage range 2.5- 4.2 V Temperature 25 °C Tabular data Filename Description Format Usage N21700-BAK-CG50-DLR-cell46-qOCV.bdf.csv qOCV for cell 46 csv OCV reference; model initialization; cell balancing analysis N21700-BAK-CG50-DLR-cell47-qOCV.bdf.csv qOCV for cell 47 csv Rate Performance Test Data Technical Metadata for rate test Parameter Value Discharge rates 0.2C, 0.5C, 1C, 2C, 3C Charge protocol CC–CV Charge CC rate 0.5C CV voltage 4.2 V CV cutoff C/50 (0.02C) Temperature 25 °C Tabular data Filename Description Format Usage N21700-BAK-CG50-DLR-cell44-ratetest.bdf.csv Rate capability test of full cell at beginning of life (BoL) under controlled current steps csv Rate capability benchmarking; transport/kinetics sensitivity; validation targets for dynamic models Electrochemical Impedance Spectroscopy (EIS) Data Technical Metadata Parameter Value Excitation current 0.2 A Frequency range 0.005 Hz – 50 kHz SOC levels 100, 95, 90, 75, 50, 25, 10, 5, 0 % Temperature 25 °C Impedance Acquisition criteria Cell is charged to 100% followed by impedance recorded at specific SOC points during discharge Tabular EIS data (cell id: 042) Filename Description Format Usage N21700-BAK-CG50-DLR-cell42-EIS-SOC0-discharge.csv EIS spectra at SOC 0% csv Fit ECM parameters; initialize/validate impedance sub models; track baseline resistances vs SOC N21700-BAK-CG50-DLR-cell42-EIS-SOC5-discharge.csv EIS spectra at SOC 5% csv N21700-BAK-CG50-DLR-cell42-EIS-SOC10-discharge.csv EIS spectra at SOC 10% csv N21700-BAK-CG50-DLR-cell42-EIS-SOC25-discharge.csv EIS spectra at SOC 25% csv N21700-BAK-CG50-DLR-cell42-EIS-SOC50-discharge.csv EIS spectra at SOC 50% csv N21700-BAK-CG50-DLR-cell42-EIS-SOC75-discharge.csv EIS spectra at SOC 75% csv N21700-BAK-CG50-DLR-cell42-EIS-SOC90-discharge.csv EIS spectra at SOC 90% csv N21700-BAK-CG50-DLR-cell42-EIS-SOC95- discharge.csv EIS spectra at SOC 95% csv N21700-BAK-CG50-DLR-cell42-EIS-SOC100-discharge.csv EIS spectra at SOC 100% csv Note: CT images will be provided at a later stage. Thermal Parameterization Dataset for N21700-BAK-CG50 Cells This dataset contains full-cell thermal characterization measurements on N21700-BAK-CG50 cells performed for thermal model parameterization. These are discharge tests conducted at 1C and 1.5C under both 30-minute and full-depth-of-discharge (100% DoD) conditions. Three temperature sensors were mounted on the cell surface to monitor spatial thermal gradients. Thermal Measurement Metadata Parameter Value Number of sensors 3 Sensor type Thermocouple Sensor positions See sensor layout sketch Temperature reference Ambient / chamber temperature Tabular data Filename Description Format N21700-BAK-CG50-DLR-052-ThermalDischarge-1C-30min-discharge.csv data for a 1C constant-current discharge over 30 minutes, including time-resolved voltage, current, and multi-sensor temperature measurements csv N21700-BAK-CG50-DLR-052-ThermalDischarge-1C-100DoD-discharge.csv Processed dataset of a 1C constant-current discharge to 100% depth of discharge (DoD), including voltage and three-point temperature sensor data csv N21700-BAK-CG50-DLR-052-ThermalDischarge-1p5C-30min-discharge.csv Processed dataset of a 1.5C constant-current discharge over 30 minutes, including synchronized voltage, current, and multi-sensor temperature measurements csv N21700-BAK-CG50-DLR-052-ThermalDischarge-1p5C-100DoD-discharge.csv Processed dataset of a 1.5C constant-current discharge to 100% depth of discharge (DoD), containing full electrical and thermal measurement data. csv Plot_temperature_time.png Plot of temperature variation as function of time png sketch_sensor_mounting.png Sketch of temperature sensor mounting png N21700-BAK-CG50-Parameterset This collection contains reduced parameterset which includes only the physically relevant parameters required for the grouped DFN model formulation. These are (i) literature-based or experimentally measured parameters that were kept fixed during optimization and (ii) calculated and optimized parameters obtained through inverse modeling. The literature (obtained from DOI 10.1149/1945-7111/ace1a7) or experimentally determined parameters include geometric properties, microstructural descriptors and baseline thermodynamic values that were either measured directly or adopted from validated reference sources. Filename Description Format Usage N21700-BAK-CG50-Parameterset.py collection of parameterset for N21700-BAK-CG50 cell py Fitting of physics based model formulations Cell Level Universal Test Plans This is an exemplary universal testplan provided in two complementary formats: (i) human-readable and executable Python scripts and (ii) machine-readable JSON representations in a standardized “universal cycling language” generated from the Python definitions for qOCV, ratetest and thermal calibration protocols. Filename Description Format N21700-BAK-CG50-DLR-qOCV-cell00-bmgen.py Python-based quasi-OCV protocol for full-cell py N21700-BAK-CG50-DLR-ratetest-cell00-bmgen.py Python-based rate capability protocol py N21700-BAK-CG50-DLR-thermal-model-calibration-cell00-bmgen.py Python-based thermal excitation protocol py N21700-BAK-CG50-DLR-qOCV-cell00-bmgen.json JSON representation of the full-cell quasi-OCV protocol in standardized universal cycling language format. json N21700-BAK-CG50-DLR-ratetest-cell00-bmgen.json JSON representation of the full-cell rate test protocol json N21700-BAK-CG50-DLR-thermal-model-calibration-cell00-bmgen.json JSON representation of the full-cell thermal model calibration protocol json Electrode-Level Characterization The following dataset contains electrode-level electrochemical and physical characterization data and corresponding meta-data obtained from the harvested negative (graphite-silicon oxide) and positive electrode (NCA). The data enables detailed investigation of thermodynamic, kinetic and transport properties at the electrode scale, independent of full-cell interactions as the measurements are performed in three-electrode arrangement with Li reference electrode to isolate individual electrode behavior. The record includes GITT and qOCV measurements, rate capability tests, microscopy images, and derived parameter sets from parameter extraction activities. Note: to avoid misinterpretation when working with half-cell data, we refer to the full cell discharge as negative electrode delithiation and positive electrode lithiation. Charging in the full cell corresponds to negative electrode lithiation and positive electrode delithiation. Anode / Negative Electrode Characterization GITT Measurements - Anode Technical Metadata Field value Technique GITT Current rate 0.1 C Pulse length 10 min Relaxation Voltage-controlled relaxation; duration determined by the voltage criterion defined in the test plan Tabular data Filename Description Format Usage N21700-BAK-CG50-DLR-anode-01-GITT-delithiation.csv Extracted GITT segment - delithiation (discharge in full cell) csv Parameterizing models N21700-BAK-CG50-DLR-anode-01-GITT-delithiation.parquet Structured and compressed dataset in Apache Parquet format, generated after an additional preprocessing step. The file contains merged, cleaned and consistently formatted charge data, optimized for efficient storage, fast loading, and model-based analysis. parquet Parameterizing models N21700-BAK-CG50-DLR-anode-01-GITT-lithiation.csv Extracted GITT segment- lithiation (charge in full cell) csv Parameterizing models N21700-BAK-CG50-DLR-anode-01-GITT-lithiation.parquet Compressed Apache Parquet file containing preprocessed, merged, and formatted lithiation (discharge) data for efficient storage and analysis. parquet Parameterizing models The files listed in the table below are generated as outputs of the DigiBatt automated GITT processing pipeline, using the dataset N21700-BAK-CG50-DLR-anode-01-GITT-lithiation.parquet as an example input. The pipeline processes raw GITT measurements in a structured and reproducible manner, performing OCV extraction, OCV curve fitting, SOC mapping and overpotential calculation. Filename Description Format Usage N21700-BAK-CG50-DLR-anode-GITT-01-lithiation-OCV-extraction.pdf OCV extraction plot pdf QC/validation of extraction N21700-BAK-CG50-DLR-anode-GITT-01-lithiation-OCV-fit-log.json Fit report (Birkl OCV fit) json Record fitted params + metadata N21700-BAK-CG50-DLR-anode-GITT-01-lithiation-OCV-fit-plot.pdf OCV fit plot pdf QC/validation of fit N21700-BAK-CG50-DLR-anode-GITT-01-lithiation-OCV-extraction-negative-soc.json Extraction JSON with electrode SOC mapping json Downstream overpotential extraction N21700-BAK-CG50-DLR-anode-GITT-01-lithiation-ocv-function.py Auto-generated OCV function module py Direct import into models / parameter sets N21700-BAK-CG50-DLR-anode-GITT-01-lithiation-overpotentials.pdf Overpotential plot pdf QC/validation of subtraction N21700-BAK-CG50-DLR-anode-GITT-01-lithiation-overpotentials.parquet Overpotential dataset in parquet parquet fast downstream fitting; archiving Open Circuit Voltage (OCV) Data - Anode Note: For comparison, OCV curves are aquired via both GITT measurements as well as qOCV measurements at low current. Technical Metadata a) Quasi-Open Circuit Voltage (qOCV) Parameter Value C-rate 0.1C Voltage range 0.01–1.4 V Temperature 25 °C b) OCV extracted from GITT measurements Parameter Value C-rate 0.02C Voltage range 0.07–0.7 V Temperature 25 °C Tabular Data Filename Description Format Usage N21700-BAK-CG50-DLR-anode-01-qOCV-GITT-delithiation.bdf.csv OCV curve extracted from GITT measurement during delithiation (charge in full cell) csv Derivation and validation of anode OCP functions; comparison with qOCV-based thermodynamic data N21700-BAK-CG50-DLR-anode-01-qOCV-GITT-lithiation.bdf.csv OCV curve extracted from GITT measurement during lithiation(discharge in full cell) csv Assessment of hysteresis effects and SOC-dependent thermodynamic behavior N21700-BAK-CG50-DLR-anode-01-qOCV-DLR delithiation.bdf.csv qOCV measurement obtained during delithiation (charge in full cell) csv Thermodynamic parameterization of the anode OCP and validation of GITT-based OCV extraction N21700-BAK-CG50-DLR-anode-01-qOCV-lithiation.bdf.csv qOCV measurement obtained during lithiation (discharge in full cell) csv Evaluation of lithiation/delithiation hysteresis and consistency of OCP models Rate Test Data - Anode Note: the rate was varied according to discharge rate tests in full cell, i.e. during negative electrode delithiation and with constant lithiation c-rate. The c-rate is defined by the capacity in the previous delithiation cycle. Technical Metadata Parameter Value Discharge (delithiation) rates 0.1 C, 0.2 C, 0.5 C, 1 C, 2 C, 3 C Charge (lithiation) protocol CC-CV Charge CC rate 0.1 C CV voltage 0.01 V CV cutoff C/50 (0.02 C) Temperature 25 °C Tabular data Filename Description Format Usage N21700-BAK-CG50-DLR-anode-01-ratetest-delithiation.bdf.csv Processed rate-test data exported to tabular format csv Analysis of rate capability, kinetic overpotential, and validation of anode transport and reaction parameters Scanning Electron Microscopy Images (SEM) - Anode Filename Description Format Usage N21700-BAK-CG50-anode-SEM-2000x.tif SEM characterization image of harvested anode surface / cross-section at a magnification of 2000x PNG image (.tif) microstructure reference; qualitative support for diffusion/active area assumptions; documentation Note: More microscopy images will be provided at a later stage. Cathode / Positive Electrode Characterization GITT Measurements - Cathode Technical Metadata Field value Technique Galvanostatic Intermittent Titration Technique (GITT) Current rate 0.1 C Pulse length 10 min Relaxation Voltage-controlled relaxation; duration determined by the voltage criterion defined in the test plan Tabular Data Filename Description Format Usage N21700-BAK-CG50-DLR-cathode-01-GITT-lithiation.csv Tabular export of processed GITT data csv Quick inspection, plotting, and compatibility with generic analysis tools N21700-BAK-CG50-DLR-cathode-01-GITT-lithiation.parquet Cleaned and structured GITT dataset with corrected pulse segmentation parquet Efficient downstream processing, scripting and model parameterization The files listed in the table below are generated as outputs of the DigiBatt automated GITT processing pipeline, using the dataset N21700-BAK-CG50-DLR-cathode-01-GITT-lithiation.parquet as an example input. The pipeline processes raw GITT measurements in a structured and reproducible manner, performing OCV extraction, OCV curve fitting, SOC mapping and overpotential calculation. Filename Description Format Usage N21700-BAK-CG50-DLR-cathode-GITT-01-lithiation-OCV-.pdf Visualization of OCV points extracted from GITT relaxation steps pdf Quality control and visual validation of OCV extraction N21700-BAK-CG50-DLR-cathode-GITT-01-lithiation-OCV.json Detailed log of Birkl-type OCV fitting procedure and optimization results json Reproducibility of OCV fitting and inspection of fit parameters N21700-BAK-CG50-DLR-cathode-GITT-01-lithiation-OCV.pdf Plot showing measured OCV data and fitted OCV curve pdf Visual assessment of OCV fit quality OCV_extraction_with_positive_soc.json OCV dataset augmented with fitted positive-electrode SOC values json Input for electrode balancing and full-cell modeling N21700-BAK-CG50-DLR-cathode-GITT-01-lithiation-OCV.py Auto-generated Python module defining the fitted cathode OCV function and py Direct use in PyBaMM and custom electrochemical models N21700-BAK-CG50-DLR-cathode-GITT-overpotential.pdf Plot of cathode overpotential obtained after OCV subtraction pdf Visualization of kinetic and transport overpotentials N21700-BAK-CG50-DLR-cathode-GITToverpotentials.json Overpotential time series data derived from GITT pulses json Analysis of kinetic behavior and validation of electrode models N21700-BAK-CG50-DLR-cathode-overpotentials.parquet Columnar storage of overpotential data parquet High-performance processing and integration into modeling workflows Open-Circuit-Voltage (OCV) Data - Cathode Note: For comparison, OCV curves are aquired via both GITT measurements as well as qOCV measurements at low current. Technical Metadata for OCV a) Quasi-Open Circuit Voltage (qOCV) Parameter Value C-rate 0.04C Voltage range 3.5–4.3 V Temperature 25 °C b) OCV extracted from GITT measurements Parameter Value C-rate 0.1C Voltage range 3.5–4.2 V Temperature 25 °C Tabular Data Filename Description Format Usage N21700-BAK-CG50-DLR-cathode-01-qOCV-GITT-delithiation.bdf.csv Cathode OCV curve extracted from GITT relaxation steps during delithiation csv Assessment of hysteresis and charge–discharge asymmetry N21700-BAK-CG50-DLR-cathode-01-qOCV-GITT-lithiation.bdf.csv Cathode OCV curve extracted from GITT relaxation steps during lithiation csv Assessment of hysteresis and charge–discharge asymmetry N21700-BAK-CG50-DLR-cathode-01-qOCV-delithiation.bdf.csv Cathode quasi-OCV curve obtained from qOCV measurement during delithiation csv Thermodynamic parameterization and comparison with GITT-based OCV N21700-BAK-CG50-DLR-cathode-01-qOCV-lithiation.bdf.csv Cathode quasi-OCV curve obtained from qOCV measurement during lithiation csv Validation of equilibrium behavior and hysteresis analysis Rate tests of the cathode are missing and will be uploaded at a later stage. Scanning Electron Microscopy (SEM) - Cathode Filename Description Format Usage N21700-BAK-CG50-cathode-SEM-2000x.tif SEM image of harvested cathode surface / cross-section at a magnification of 2000x PNG image (.tif) microstructure reference; qualitative support for diffusion/active area assumptions; documentation Note: More microscopy images will be provided at a later stage. Half cell Universal Test Plans This is an exemplary universal testplan for some half cell measurements provided in two complementary formats: (i) human-readable and executable Python scripts and (ii) machine-readable JSON representations in a standardized “universal cycling language” generated from the Python definitions for qOCV and GITT test protocols. Filename Description Format N21700-BAK-CG50-DLR-GITT-cathode-bmgen.py Python-based definition of the cathode half-cell GITT protocol including intermittent current pulses and relaxation phases for OCV extraction py N21700-BAK-CG50-DLR-qOCV-anode-bmgen.py Python-based quasi-OCV protocol for the anode half-cell including low-rate charge/discharge steps py N21700-BAK-CG50-DLR-qOCV-cathode-bmgen.py Python-based quasi-OCV protocol for the cathode half-cell py N21700-BAK-CG50-DLR-GITT-cathode-bmgen.json JSON representation of the cathode GITT protocol in standardized universal cycling language format json N21700-BAK-CG50-DLR-qOCV-anode-bmgen.json JSON representation of the anode half-cell quasi-OCV protocol json N21700-BAK-CG50-DLR-qOCV-cathode-bmgen.json JSON representation of the cathode half-cell quasi-OCV protocol in machine-readable format. json