Lemonergy · Core equation

parabolic_film_thickness

Square-root film growth relative to an authored reference thickness.

Implementation ID: parabolic_film_thickness
Reviewed: 2026-10-27

Behavior

Thickness, elapsed time and acceleration factor are nonnegative; reference time is positive. Time units must be consistent. This relation is not an identified SEI, capacity-fade or SOH model.

Interface

Original Lemonergy interface view. Lines identify ports; they are not a completed simulation circuit.

Ports and observed outputs
Name	Direction	Unit	Meaning
`return`	output	same length unit	Scalar float or NumPy array following broadcasting.

Parameters

Defaults are initial model values. Select values for your own model and operating conditions.

Configuration fields
Parameter	Unit	Default	Meaning and limits
reference thickness `reference_thickness`	chosen length unit	Supplied by the user	Nonnegative reference thickness.
elapsed time `elapsed_time`	chosen time unit	Supplied by the user	Nonnegative elapsed time.
reference time `reference_time`	same time unit	1	Positive reference time.
acceleration factor `acceleration_factor`	dimensionless	1	Nonnegative multiplier.

Equations and rules

delta = delta_ref * sqrt((t / t_ref) * A)

Worked example

Explore film growth

At a factor of one, 10 nm at 1 h becomes 20 nm at 4 h and 30 nm at 9 h.

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Use in a workflow

Explore film growth

Lemonergy Core evaluates this relation.

parabolic_film_thickness: Core equation
- Reference thickness
- Elapsed and reference time
- Acceleration factor

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Connected concepts

Limits and interpretation

This does not identify SEI chemistry or fit state of health.

Implementation sources

This reference follows Lemonergy implementation sources. Scientific articles support the linked concepts separately.

Repository: battery-core · Revision: main

src/battery_core/aging.py

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