{ "node": { "id": "term:aging-model", "type": "Term", "label": "Aging model", "properties": { "id": "aging-model", "name": "Aging model", "aka": [ "degradation model", "lifetime model" ], "section": "topic-transport", "definition": "A model that predicts capacity fade and resistance growth as functions of time, temperature, SOC and throughput. 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A cell that lost 4 % in its first year will lose about 1.7 % more in the second.", "formula": "Q_loss ∝ √t", "related": [ "sei", "calendar-aging", "aging-model" ], "example": { "title": "Compare equal time intervals", "text": "If an illustrative diffusion-limited loss is 1% after 100 h and follows only a square-root law, it is 2% after 400 h. Reaching twice the modeled loss takes four times the elapsed time." }, "url": "https://lemonergy.com/learn/glossary/square-root-of-time/", "mentions": [] } }, { "id": "term:arrhenius", "type": "Term", "label": "Arrhenius law", "properties": { "id": "arrhenius", "name": "Arrhenius law", "section": "topic-aging", "definition": "The rule that a rate constant is proportional to exp(−Ea/RT), so a thermally activated reaction speeds up steeply with temperature. Near room temperature many degradation reactions roughly double their rate for every +10 °C.", "formula": "k = A·exp(−Eₐ/RT)", "related": [ "activation-energy", "calendar-aging", "operating-temperature", "accelerated-aging", "celsius-kelvin" ], "lesson": "fundamentals/battery-aging/#arrhenius", "example": { "title": "Compare reaction-rate factors", "text": "For an illustrative activation energy of 40 kJ/mol, increasing temperature from 25 °C to 35 °C multiplies the modeled rate by about 1.69. Convert both temperatures to kelvin before evaluating the exponential." }, "notes": [ "A reaction-rate factor alone is not a prediction of battery lifetime." ], "url": "https://lemonergy.com/learn/glossary/arrhenius/", "mentions": [] } }, { "id": "term:calendar-aging", "type": "Term", "label": "Calendar aging", "properties": { "id": "calendar-aging", "name": "Calendar aging", "section": "topic-aging", "definition": "Degradation that happens with time even when a cell is not cycled — in storage, for example. It is driven mainly by side reactions such as SEI growth and accelerates with temperature.", "related": [ "cycle-aging", "sei", "arrhenius", "square-root-of-time", "calendar-life" ], "lesson": "fundamentals/battery-aging/#whole-cell", "url": "https://lemonergy.com/learn/glossary/calendar-aging/", "mentions": [] } }, { "id": "term:cycle-aging", "type": "Term", "label": "Cycle aging", "properties": { "id": "cycle-aging", "name": "Cycle aging", "section": "topic-aging", "definition": "Degradation caused by charging and discharging: mechanical strain in the particles, fresh SEI on cracked surfaces and, at high rate or low temperature, lithium plating. It scales with charge throughput and grows with depth of discharge and C-rate.", "related": [ "calendar-aging", "particle-cracking", "lithium-plating", "depth-of-discharge", "equivalent-full-cycle" ], "lesson": "fundamentals/battery-aging/#cracking", "url": "https://lemonergy.com/learn/glossary/cycle-aging/", "mentions": [ "sei", "c-rate", "energy-throughput" ] } }, { "id": "term:remaining-useful-life", "type": "Term", "label": "Remaining useful life", "properties": { "id": "remaining-useful-life", "name": "Remaining useful life", "abbr": "RUL", "section": "topic-state", "definition": "A prediction of how many cycles, or how much time, a battery has left before reaching end of life. It is estimated from the trend of state of health, and is uncertain near a knee point where fade accelerates.", "related": [ "state-of-health", "end-of-life", "knee-point", "cycle-life" ], "url": "https://lemonergy.com/learn/glossary/remaining-useful-life/", "mentions": [] } }, { "id": "term:digital-twin", "type": "Term", "label": "Digital twin", "properties": { "id": "digital-twin", "name": "Digital twin", "section": "topic-transport", "definition": "A model of a specific battery, kept in step with its real counterpart by live data, used to estimate state, predict life and plan operation. The term is used loosely; a model only earns it when it is continuously updated from the asset.", "related": [ "aging-model", "state-of-health", "bms", "remaining-useful-life" ], "url": "https://lemonergy.com/learn/glossary/digital-twin/", "mentions": [] } }, { "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:state-of-charge", "type": "Term", "label": "State of charge", "properties": { "id": "state-of-charge", "name": "State of charge", "abbr": "SOC", "section": "topic-state", "definition": "How full a cell is, as a fraction of its available capacity. State of charge, like temperature, affects how fast a stored cell ages.", "unit": "%", "related": [ "depth-of-discharge", "ocv-soc-curve", "coulomb-counting", "state-of-health", "bms" ], "lesson": "fundamentals/battery-aging/#storage-soc", "example": { "title": "Interpret a charge inventory", "text": "If available capacity is 5 Ah and 3 Ah remains by the chosen estimator, SOC is 60%. A different estimate of available capacity changes this percentage, so compare SOC values only with the capacity convention recorded." }, "url": "https://lemonergy.com/learn/glossary/state-of-charge/", "mentions": [ "usable-capacity" ] } }, { "id": "term:capacity-fade", "type": "Term", "label": "Capacity fade", "properties": { "id": "capacity-fade", "name": "Capacity fade", "section": "topic-aging", "definition": "The loss of charge a cell can store and deliver, for example through lithium locked into the SEI or active material that has cracked out of service.", "related": [ "loss-of-lithium-inventory", "loss-of-active-material", "state-of-health", "knee-point" ], "lesson": "fundamentals/battery-aging/#chain", "url": "https://lemonergy.com/learn/glossary/capacity-fade/", "mentions": [ "active-material", "sei" ] } }, { "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. It costs voltage under load and therefore power, even while the stored charge is still there.", "related": [ "internal-resistance", "sei", "cei", "state-of-power", "state-of-health" ], "lesson": "fundamentals/battery-aging/#crystals", "url": "https://lemonergy.com/learn/glossary/impedance-rise/", "mentions": [ "closed-circuit-voltage" ] } }, { "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)
" } } ] }