ChE126 battery separator properties

Public dataset: https://huggingface.co/datasets/archiitecture/che126

Code and research notes: https://github.com/archiitectures/che126_data_science

This senior-year chemical engineering capstone tabulates battery separator porosity, strength, and size, with temperature recorded whenever available. The dry CSV contains 60 FSRI bulk-polyethylene reference observations (30 HDPE and 30 LDPE), including thermal conductivity and heat capacity. These are clearly labeled bulk-sheet references, not battery separator measurements. The electrolyte-soaked wet CSV still contains zero records. No separator porosity, strength, or pore-size values have been inferred from FSRI thermal data.

Separate dry and wet datasets

• dry_separators.csv / dry subset: measurements without battery electrolyte soaking, including explicitly labeled bulk-sheet reference rows. Leave electrolyte and soaking fields blank. Select sample_form != bulk_sheet_reference to exclude these reference observations from separator-specific analysis.
• wet_separators.csv / wet subset: separators measured while soaked in battery electrolyte. Record composition and soaking conditions whenever reported.

Dry/wet here describes the specimen's state during measurement, not whether the separator was manufactured using a dry or wet process. Do not infer state from manufacturing process. Sources with unclear measurement state need clarification before entering either table. If a soaked specimen is dried before testing, put that measurement in dry and describe its history in notes.

Both CSVs share the same 35 columns (the original 27 plus eight thermal/reference fields). Pair dry and wet measurements from the same material or specimen using a stable sample_id; every row has its own record_id. Hugging Face configurations keep the subsets separate. A library's automatically assigned train split is a storage convention, not an agreed evaluation split.

Row and missing-value conventions

One row describes a source-reported observation under a specific measurement condition and direction. Multiple properties may share a row only when source, specimen, temperature, direction, and protocol apply to all those values. Use separate rows for different temperatures, directions, tests, or replicates; leave unrelated property cells blank rather than copying values into new tests.

An empty cell means unreported or not applicable, never zero. Store numeric values without unit strings. porosity_pct uses 0–100 percent, not a 0–1 fraction. Do not guess room temperature. Preserve original values/units, conversion notes, uncertainties, and unusual protocols in notes until dedicated fields are needed. Only enter strength in a canonical column when its definition and unit match; for example, tensile force in N is not tensile stress in MPa.

Column dictionary

Column	Meaning
record_id	Unique observation identifier across both files.
sample_id	Stable specimen/material identifier for linking conditions.
material	Polymer/material composition, such as PE or PP.
separator_type	Construction, multilayer arrangement, or coating.
product_name	Manufacturer/product designation when known.
temperature_C	Temperature during the reported property measurement, °C.
conditioning_temperature_C	Prior heat-treatment temperature, °C, if distinct.
conditioning_duration_h	Duration of that prior heat treatment, hours.
porosity_pct	Reported void fraction, percent; retain method/context.
tensile_strength_MPa	Ultimate tensile stress, MPa; exclude yield stress.
puncture_strength_N	Force at puncture, N; exclude pressure or stress.
thickness_um	Separator thickness, µm, under the recorded condition.
pore_size_um	Reported pore size, µm; identify mean/median/max in notes.
measurement_direction	MD, TD, through-plane, or source-specific direction.
porosity_method	Porosity measurement method and relevant conditions.
strength_method	Strength test method, geometry, rate, and loading details.
size_method	Thickness/pore-size method, load, and size statistic.
electrolyte_composition	Salt, concentration, solvents/ratios, and additives.
soaking_time_h	Electrolyte soaking duration, hours; wet observations only.
soaking_temperature_C	Electrolyte soaking temperature, °C; wet only.
source_id	Stable source identifier, shared by observations from that source.
source_type	Paper, datasheet, patent, simulation, or public_materials_database; identify origin explicitly.
source_url	DOI link or stable source/document URL.
source_locator	Document version and page, table, figure, or simulation run.
value_type	Measured, typical, minimum, maximum, digitized, simulated, or measured_and_calculated; notes identify calculated fields.
replicate_id	Reported replicate identifier; blank for unspecified replicates.
notes	Original units/values, uncertainty, thermal history, and caveats.
sample_form	Explicit specimen category; bulk_sheet_reference for these FSRI observations.
source_condition	Source's original conditioning terminology and its meaning.
reference_thickness_um	Instrument file-header specimen thickness, µm; temperature unspecified. It is not a thermal thickness curve.
thermal_conductivity_W_m_K	Reported HFM Average Cond, W/(m K).
volumetric_heat_capacity_J_m3_K	Measured HFM heat capacity per unit volume, J/(m³ K).
specific_heat_capacity_J_kg_K	Calculated mass-specific heat capacity, J/(kg K); retain conversion in notes.
reference_density_kg_m3	Arithmetic mean of the source's three density replicates used for conversion, kg/m³; not a temperature-dependent density measurement.
thermal_method	Thermal-property apparatus, test, and relevant protocol.

Temperature during measurement, prior thermal conditioning, and soaking temperature are distinct quantities. A datasheet thickness or porosity should not inherit a temperature from an unrelated shrinkage test.

Curation and access

Hugging Face is the preferred home for the growing property tables. The code repository keeps small versioned tables, this dataset card, and acquisition utilities. The FSRI result-table excerpts are pinned to a source commit for reproducibility. Future records must retain provenance and distinguish literature, manufacturer, digitized, and simulation-derived values.

Once these files are published on the Hub, use the dry and wet configuration names with datasets.load_dataset. The wet subset is empty. FSRI bulk-sheet references alone do not establish separator behavior.

No dataset-wide license is declared yet. Source-specific reuse terms must be recorded and reviewed as real records are curated; public hosting does not grant a new license to third-party source documents.

FSRI polyethylene coverage and provenance

Source: UL Research Institutes, Fire Safety Research Institute, Materials and Products (MaP) Database. Website, experimental methods, and repository citation. Source commit: a432697e4b7d40f642b5cc8f384506439ebb32df.

Material	Conductivity observations	Heat-capacity observations	Total
HDPE	18	12	30
LDPE	18	12	30

All numeric rows in the 12 HFM SI result tables are included: conductivity at 15.01 and 45.01 °C, and heat capacity at 10.00, 20.01, 30.01 and 40.01 °C. Reported temperatures are not rounded to nominal setpoints. Each conductivity file has six results, alternating between its two temperatures three times. These repeated setpoints are retained separately and must not be counted as six independent specimen replicates. Each heat-capacity file has four reported results; its five programmed setpoints include an initial step without a reported heat-capacity result, so no fifth value is invented.

Coverage is the HFM thermal-property series. STA/MCC powder decomposition and combustion time series are not imported as separator measurements. Each row links to its exact source file at the pinned commit, records its blob SHA and SI result-table data-row number, and identifies the source replicate.

FSRI calls these samples “Wet” because they were unconditioned with ambient moisture. They are included in our dry table as bulk-sheet references without battery electrolyte, by project decision. The wet CSV is reserved for actual battery-electrolyte-soaked measurements. This does not imply that FSRI performed oven drying on these specimens.

Instrument header thicknesses (3170–3380 µm) are recorded only in reference_thickness_um. The source does not establish a temperature-dependent thickness measurement, so thickness_um stays blank along with separator porosity, strength, and pore size.

The raw heat-capacity unit is J/(m³ K). To provide J/(kg K), divide by the mean of the three source density records: HDPE (974 + 970 + 970) / 3 and LDPE (925 + 930 + 927) / 3 kg/m³. This follows the mean-density normalization in FSRI's HFM processing script. Calculated specific heat is rounded to 0.001 J/(kg K); this rounding does not represent an uncertainty estimate. The original volumetric measurement and density inputs are preserved. value_type=measured_and_calculated identifies these rows. LDPE density file column labels say HDPE_WET despite their LDPE paths; the inconsistency is recorded in affected row notes.

The source excerpts retain complete SI result tables, file-header excerpts, and all six density CSVs. che126_data_science.data_mining.fsri.polyethylene_reference_rows(snapshot) reproduces the reference records without network access or third-party runtime dependencies. Original UTF-16 file blob hashes were verified during acquisition.