{ "node": { "id": "term:impedance-rise", "type": "Term", "label": "Impedance rise", "properties": { "id": "impedance-rise", "name": "Impedance rise", "aka": [ "resistance growth", "power fade" ], "section": "topic-aging", "definition": "An increase in a cell’s internal resistance as it ages. 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It converts part of the delivered energy into heat, sets the voltage drop under load, and rises as the cell ages; a large automotive cell has about a milliohm, a small cylindrical cell tens.", "unit": "mΩ", "related": [ "ohms-law", "ir-drop", "impedance-rise", "dcir", "area-specific-resistance", "resistance-capacity-product" ], "lesson": "fundamentals/battery-basics/#datasheet", "url": "https://lemonergy.com/learn/glossary/internal-resistance/", "mentions": [ "electrolyte", "cylindrical-cell" ] } }, { "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. 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The BMS recomputes it continuously from SOC, temperature and resistance and sends it to the motor controller.", "unit": "W", "related": [ "power", "state-of-charge", "continuous-current", "derating", "bms", "state-of-function" ], "url": "https://lemonergy.com/learn/glossary/state-of-power/", "mentions": [] } }, { "id": "term:state-of-health", "type": "Term", "label": "State of health", "properties": { "id": "state-of-health", "name": "State of health", "abbr": "SOH", "section": "topic-state", "definition": "A summary of how far a cell has aged, often expressed through remaining capacity or increased resistance compared with when it was new. By convention a cell has reached end of life at 80 % of its rated capacity.", "unit": "%", "related": [ "capacity-fade", "impedance-rise", "end-of-life", "remaining-useful-life", "state-of-charge", "state-of-certified-energy" ], "lesson": "fundamentals/capacity-and-c-rate/#real-cells", "url": "https://lemonergy.com/learn/glossary/state-of-health/", "mentions": [ "nominal-capacity" ] } }, { "id": "term:closed-circuit-voltage", "type": "Term", "label": "Closed-circuit voltage", "properties": { "id": "closed-circuit-voltage", "name": "Closed-circuit voltage", "abbr": "CCV", "aka": [ "loaded voltage", "voltage under load" ], "section": "topic-units", "definition": "The terminal voltage while current flows, lower than the open-circuit voltage by the polarization. It is what the system actually sees, and the difference between the two is a direct measure of the cell’s resistance.", "unit": "V", "related": [ "open-circuit-voltage", "polarization", "ir-drop", "voltage" ], "url": "https://lemonergy.com/learn/glossary/closed-circuit-voltage/", "mentions": [] } }, { "id": "lesson:fundamentals/battery-aging/", "type": "Lesson", "label": "Lesson 4 · Battery aging", "properties": { "url": "https://lemonergy.com/learn/fundamentals/battery-aging/" } }, { "id": "visual:health", "type": "Visual", "label": "Capacity loss and resistance growth", "properties": { "title": "Capacity loss and resistance growth", "summary": "Energy capability and power capability can degrade differently.", "readout": "At the illustrated endpoint: 80% initial capacity and 140% initial resistance.", "formula": "Capacity ratio = Q_now/Q_initial; resistance ratio = R_now/R_initial", "note": "Chosen qualitative trends. The exposure axis is not predicted cycles or years.", "software": { "status": "reference", "label": "Reference concept", "body": "battery-core supplies individual aging relationships, not a calibrated SOH or remaining-life estimator. The selected trends are illustrations and do not predict cycles or years.", "href": "../fundamentals/battery-aging/" }, "html": "
Chosen degradation trends
Chosen degradation trendsRelative life exposure versus Relative to beginning of life (%). Capacity retained; Resistance. Interpretation follows the graphs.50087.50.251250.51630.752001Relative life exposureRelative to beginning oflife (%)
Capacity retainedResistance (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" } } ] }