{ "node": { "id": "term:passivation", "type": "Term", "label": "Passivation", "properties": { "id": "passivation", "name": "Passivation", "section": "topic-aging", "definition": "The formation of a surface film that slows further reaction. In lithium-ion cells, the SEI passivates the graphite negative electrode.", "related": [ "sei", "aluminium-foil", "formation" ], "lesson": "fundamentals/battery-aging/#sei", "url": "https://lemonergy.com/learn/glossary/passivation/", "mentions": [ "electrode", "negative-electrode", "graphite" ] } }, "edges": [ { "id": "edge:22", "source": "term:passivation", "target": "workflow:film-growth", "type": "usedIn", "properties": { "sourceFile": "wiki-blocks.json" } }, { "id": "edge:1425", "source": "term:passivation", "target": "topic:topic-aging", "type": "belongsTo", "properties": { "sourceFile": "terms.json" } }, { "id": "edge:1426", "source": "term:passivation", "target": "term:sei", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:1427", "source": "term:passivation", "target": "term:aluminium-foil", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:1428", "source": "term:passivation", "target": "term:formation", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:mentions/passivation/electrode", "source": "term:passivation", "target": "term:electrode", "type": "mentions", "properties": { "sourceFile": "terms.json", "method": "build_glossary.mention_index + mentions", "field": "definition", "meaning": "Text mention; not a causal claim" } }, { "id": "edge:mentions/passivation/negative-electrode", "source": "term:passivation", "target": "term:negative-electrode", "type": "mentions", "properties": { "sourceFile": "terms.json", "method": "build_glossary.mention_index + mentions", "field": "definition", "meaning": "Text mention; not a causal claim" } }, { "id": "edge:mentions/passivation/graphite", "source": "term:passivation", "target": "term:graphite", "type": "mentions", "properties": { "sourceFile": "terms.json", "method": "build_glossary.mention_index + mentions", "field": "definition", "meaning": "Text mention; not a causal claim" } }, { "id": "edge:1432", "source": "term:passivation", "target": "lesson:fundamentals/battery-aging/", "type": "explainedIn", "properties": { "sourceFile": "terms.json", "url": "https://lemonergy.com/learn/fundamentals/battery-aging/#sei" } }, { "id": "edge:1433", "source": "term:passivation", "target": "visual:film", "type": "illustratedBy", "properties": { "sourceFile": "visual-pages.json" } }, { "id": "edge:1434", "source": "term:passivation", "target": "reference:edge-degradation", "type": "cites", "properties": { "sourceFile": "wiki-references.json", "scope": "direct technical reference" } } ], "neighbors": [ { "id": "workflow:film-growth", "type": "Workflow", "label": "Explore film growth", "properties": { "id": "film-growth", "title": "Explore film growth", "kind": "core", "summary": "Lemonergy Core evaluates this relation.", "steps": [ "Open the lesson and inspect the equation.", "Change one input while holding the others fixed." ], "example": "At a factor of one, 10 nm at 1 h becomes 20 nm at 4 h and 30 nm at 9 h.", "observe": "Compare the result with the equation and units.", "limits": "This does not identify SEI chemistry or fit state of health.", "url": "https://lemonergy.com/learn/fundamentals/battery-aging/#sei", "label": "Open the worked lesson", "evidence": [ "src/battery_core/aging.py" ] } }, { "id": "topic:topic-aging", "type": "Topic", "label": "Aging and degradation", "properties": { "id": "topic-aging", "name": "Aging and degradation", "lede": "Why a cell loses capacity and gains resistance, and the mechanisms behind it.", "context": "Separate mechanisms, observations and fitted models.", "example": "Capacity loss and resistance rise can have different causes; a film-growth curve cannot identify both.", "lesson_url": "https://lemonergy.com/learn/fundamentals/battery-aging/", "lesson_label": "Open aging" } }, { "id": "term:sei", "type": "Term", "label": "Solid–electrolyte interphase", "properties": { "id": "sei", "name": "Solid–electrolyte interphase", "abbr": "SEI", "section": "topic-aging", "definition": "A film of electrolyte reaction products on the negative-electrode particles — graphite, and also silicon or lithium metal. It protects the electrode from further reaction but grows slowly for the whole life of the cell, consuming cyclable lithium.", "related": [ "passivation", "formation", "calendar-aging", "loss-of-lithium-inventory", "cei" ], "lesson": "fundamentals/battery-aging/#sei", "url": "https://lemonergy.com/learn/glossary/sei/", "mentions": [ "electrode", "graphite", "electrolyte" ] } }, { "id": "term:aluminium-foil", "type": "Term", "label": "Aluminium foil", "properties": { "id": "aluminium-foil", "name": "Aluminium foil", "section": "topic-components", "definition": "The positive current collector, typically 10–15 µm thick. A thin passive film keeps it stable at the high potential of the positive electrode, where copper would corrode.", "related": [ "current-collector", "copper-foil", "passivation" ], "example": { "title": "Keep normalization consistent", "text": "Active-material capacity can remain unchanged while a heavier foil lowers a finished electrode’s capacity per unit total mass." }, "url": "https://lemonergy.com/learn/glossary/aluminium-foil/", "mentions": [ "electrode", "positive-electrode" ] } }, { "id": "term:formation", "type": "Term", "label": "Formation", "properties": { "id": "formation", "name": "Formation", "section": "topic-manufacturing", "definition": "The first controlled charge and discharge cycles of a newly assembled cell, during which the SEI forms. It is part of cell production, before aging and grading.", "related": [ "sei", "degassing", "aging-step", "first-cycle-loss", "cell-finishing" ], "lesson": "fundamentals/cell-production/#finishing", "example": { "title": "Distinguish first finishing cycles", "text": "Initial controlled cycles are a cell-finishing operation; their purpose and observations differ from later customer charging." }, "url": "https://lemonergy.com/learn/glossary/formation/", "mentions": [ "cell-production" ] } }, { "id": "term:electrode", "type": "Term", "label": "Electrode", "properties": { "id": "electrode", "name": "Electrode", "section": "topic-components", "definition": "A solid conductor where the cell’s reaction happens, in contact with the electrolyte. A lithium-ion cell has a negative electrode and a positive electrode, each a porous coating on a metal foil.", "related": [ "negative-electrode", "positive-electrode", "porous-electrode", "current-collector" ], "lesson": "fundamentals/cell-anatomy/#components", "example": { "title": "Two transport paths", "text": "Electrons need connected solid paths to the collector; ions need electrolyte paths to reaction sites. More of one constituent displaces others at fixed volume." }, "url": "https://lemonergy.com/learn/glossary/electrode/", "mentions": [ "electrolyte", "coating" ] } }, { "id": "term:negative-electrode", "type": "Term", "label": "Negative electrode", "properties": { "id": "negative-electrode", "name": "Negative electrode", "section": "topic-components", "definition": "The electrode at the lower potential, usually graphite on copper foil in a lithium-ion cell. It holds the lithium when the cell is charged and releases it on discharge, and industry calls it the anode.", "related": [ "anode", "graphite", "positive-electrode", "copper-foil" ], "lesson": "fundamentals/cell-anatomy/#anode-cathode", "example": { "title": "Keep the polarity name", "text": "Graphite remains the negative electrode during charge and discharge, while the anode/cathode reaction labels change with operating direction." }, "url": "https://lemonergy.com/learn/glossary/negative-electrode/", "mentions": [ "electrode" ] } }, { "id": "term:graphite", "type": "Term", "label": "Graphite", "properties": { "id": "graphite", "name": "Graphite", "section": "topic-components", "definition": "Layered carbon, the negative active material of nearly all lithium-ion cells. Lithium intercalates between its layers up to LiC₆, a theoretical 372 mAh/g, at a potential about 0.1 V above lithium metal.", "related": [ "anode-active-material", "intercalation", "natural-graphite", "synthetic-graphite", "lithium-plating" ], "lesson": "fundamentals/cell-anatomy/#components", "example": { "title": "Compare matching mass bases", "text": "A graphite value per gram of active material cannot be directly compared with a value including binder, additive and foil." }, "url": "https://lemonergy.com/learn/glossary/graphite/", "mentions": [ "milliampere-hour", "active-material" ] } }, { "id": "lesson:fundamentals/battery-aging/", "type": "Lesson", "label": "Lesson 4 · Battery aging", "properties": { "url": "https://lemonergy.com/learn/fundamentals/battery-aging/" } }, { "id": "visual:film", "type": "Visual", "label": "Diffusion-limited film growth", "properties": { "title": "Diffusion-limited film growth", "summary": "Four times the elapsed time gives twice the film thickness in this model.", "readout": "At four reference time units, thickness is 2× the reference thickness.", "formula": "δ / δ_ref = √[(t / t_ref) A]", "note": "Normalized analytical relation, not a capacity-loss or SOH prediction.", "software": { "status": "implemented", "label": "Implemented in battery-core", "body": "parabolic_film_thickness uses reference thickness × √(relative time × acceleration). Converting film thickness to capacity loss requires a calibrated relationship.", "href": "../fundamentals/battery-aging/" }, "html": "
Relative film growth
Relative film growthTime / reference time versus Thickness / reference thickness. Selected acceleration; Reference conditions. Interpretation follows the graphs.002448612816Time / reference timeThickness / referencethickness
Selected accelerationReference conditions (dashed)
" } }, { "id": "reference:edge-degradation", "type": "Reference", "label": "Lithium ion battery degradation: what you need to know", "properties": { "title": "Lithium ion battery degradation: what you need to know", "publisher": "Physical Chemistry Chemical Physics", "url": "https://doi.org/10.1039/D1CP00359C", "type": "Review article", "scope": "Degradation mechanisms, modes, operational effects and their interactions.", "year": 2021, "accessed": "2026-10-27" } } ] }