{ "node": { "id": "term:tortuosity", "type": "Term", "label": "Tortuosity", "properties": { "id": "tortuosity", "name": "Tortuosity", "abbr": "τ", "section": "topic-transport", "definition": "How winding the path through a porous layer is, compared with a straight line through it. 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It is fast and well understood, and it produces the round roll of a cylindrical cell or the flattened roll of many prismatic cells.", "related": [ "jelly-roll", "stacking", "cylindrical-cell", "prismatic-cell" ], "lesson": "fundamentals/cell-production/#assembly", "url": "https://lemonergy.com/learn/glossary/winding/", "mentions": [ "electrode", "separator" ] } }, { "id": "lesson:fundamentals/cell-architecture/", "type": "Lesson", "label": "Lesson 1B · Cell architecture", "properties": { "url": "https://lemonergy.com/learn/fundamentals/cell-architecture/" } }, { "id": "visual:porous", "type": "Visual", "label": "Porosity reduces effective transport", "properties": { "title": "Porosity reduces effective transport", "summary": "A Bruggeman relation approximates transport through a porous medium.", "readout": "At 40% porosity, D_eff is 25.298% of bulk diffusivity.", "formula": "D_eff = D εᵇ", "note": "An empirical pore-structure assumption; actual tortuosity must be characterized.", "software": { "status": "reference", "label": "Reference concept", "body": "The flux helper accepts a supplied diffusivity. It does not estimate porosity or tortuosity. The shown D_eff = D εᵇ relationship is an explicit teaching assumption.", "href": "../transport/ficks-first-law/" }, "html": "
Effective diffusivity fraction
Effective diffusivity fractionPorosity ε (fraction) versus D_eff / D (fraction). εᵇ; Straight-pore scaling ε. Interpretation follows the graphs.000.250.250.50.50.750.7511Porosity ε (fraction)D_eff / D (fraction)
εᵇStraight-pore scaling ε (dashed)
" } }, { "id": "reference:doyle-model", "type": "Reference", "label": "Modeling of Galvanostatic Charge and Discharge of the Lithium/Polymer/Insertion Cell", "properties": { "title": "Modeling of Galvanostatic Charge and Discharge of the Lithium/Polymer/Insertion Cell", "publisher": "Journal of The Electrochemical Society", "url": "https://doi.org/10.1149/1.2221597", "type": "Research article", "scope": "Porous-electrode transport and insertion-cell modeling; foundational work rather than a specification for a particular commercial cell.", "year": 1993, "authors": [ "Marc Doyle", "Thomas F. Fuller", "John Newman" ], "accessed": "2026-10-27" } } ] }