{ "node": { "id": "term:voltage-window", "type": "Term", "label": "Voltage window", "properties": { "id": "voltage-window", "name": "Voltage window", "aka": [ "operating voltage range" ], "section": "topic-ratings", "definition": "The range between a cell’s lower and upper cutoff voltages, such as 2.5–4.2 V for an NMC/graphite cell. Staying inside it is what keeps the electrodes and electrolyte from degrading quickly.", "unit": "V", "related": [ "cutoff-voltage", "overcharge", "over-discharge", "electrochemical-stability-window" ], "url": "https://lemonergy.com/learn/glossary/voltage-window/", "mentions": [ "graphite", "electrolyte" ] } }, "edges": [ { "id": "edge:925", "source": "term:voltage-window", "target": "topic:topic-ratings", "type": "belongsTo", "properties": { "sourceFile": "terms.json" } }, { "id": "edge:926", "source": "term:voltage-window", "target": "term:cutoff-voltage", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:927", "source": "term:voltage-window", "target": "term:overcharge", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:928", "source": "term:voltage-window", "target": "term:over-discharge", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:929", "source": "term:voltage-window", "target": "term:electrochemical-stability-window", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:mentions/voltage-window/graphite", "source": "term:voltage-window", "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:mentions/voltage-window/electrolyte", "source": "term:voltage-window", "target": "term:electrolyte", "type": "mentions", "properties": { "sourceFile": "terms.json", "method": "build_glossary.mention_index + mentions", "field": "definition", "meaning": "Text mention; not a causal claim" } }, { "id": "edge:932", "source": "term:voltage-window", "target": "visual:voltage", "type": "illustratedBy", "properties": { "sourceFile": "visual-pages.json" } } ], "neighbors": [ { "id": "topic:topic-ratings", "type": "Topic", "label": "Capacity, energy, power and ratings", "properties": { "id": "topic-ratings", "name": "Capacity, energy, power and ratings", "lede": "The numbers that size a cell and let two cells be compared.", "context": "Separate nameplate ratings from test results.", "example": "5 Ah at 3.6 V gives 18 Wh nominally. Integrated measured terminal power may give a different result.", "lesson_url": "https://lemonergy.com/learn/fundamentals/capacity-and-c-rate/", "lesson_label": "Open capacity and C-rate" } }, { "id": "term:cutoff-voltage", "type": "Term", "label": "Cutoff voltage", "properties": { "id": "cutoff-voltage", "name": "Cutoff voltage", "section": "topic-charging", "definition": "The terminal-voltage limit that ends a discharge, or caps a charge — in constant-current, constant-voltage (CC-CV) charging the cell is then held at that voltage until the current falls to a cutoff. A real discharge ends at the lower cutoff, which is why actual runtime can differ from the ideal duration.", "unit": "V", "related": [ "voltage-window", "cc-cv-charging", "ideal-duration", "over-discharge", "overcharge" ], "lesson": "fundamentals/capacity-and-c-rate/#real-cells", "url": "https://lemonergy.com/learn/glossary/cutoff-voltage/", "mentions": [ "service-life" ] } }, { "id": "term:overcharge", "type": "Term", "label": "Overcharge", "properties": { "id": "overcharge", "name": "Overcharge", "section": "topic-charging", "definition": "Charging past the upper cutoff voltage. The positive electrode over-delithiates and releases oxygen, the electrolyte oxidises and lithium plates on the negative, so an unprotected overcharge can end in thermal runaway.", "related": [ "cutoff-voltage", "thermal-runaway", "bms", "overcharge-test", "electrolyte-decomposition" ], "url": "https://lemonergy.com/learn/glossary/overcharge/", "mentions": [ "electrode", "positive-electrode", "electrolyte" ] } }, { "id": "term:over-discharge", "type": "Term", "label": "Over-discharge", "properties": { "id": "over-discharge", "name": "Over-discharge", "aka": [ "deep discharge" ], "section": "topic-charging", "definition": "Discharging below the lower cutoff voltage. Near 1.5 V the copper current collector begins to dissolve, and on the next charge it can redeposit as metal that shorts the cell, so a deeply discharged cell should not simply be recharged.", "related": [ "cutoff-voltage", "copper-dissolution", "internal-short-circuit", "bms", "low-voltage-disconnect" ], "url": "https://lemonergy.com/learn/glossary/over-discharge/", "mentions": [ "current-collector" ] } }, { "id": "term:electrochemical-stability-window", "type": "Term", "label": "Electrochemical stability window", "properties": { "id": "electrochemical-stability-window", "name": "Electrochemical stability window", "section": "topic-electrochemistry", "definition": "The potential range within which an electrolyte is neither reduced nor oxidised. Carbonate electrolytes are only stable from about 1 V to 4.3 V vs Li/Li⁺; graphite operates below that, which is why the SEI, not thermodynamics, keeps the cell alive.", "unit": "V", "related": [ "electrolyte-decomposition", "sei", "voltage-window", "lnmo", "homo-lumo" ], "url": "https://lemonergy.com/learn/glossary/electrochemical-stability-window/", "mentions": [ "graphite", "electrolyte" ] } }, { "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": "term:electrolyte", "type": "Term", "label": "Electrolyte", "properties": { "id": "electrolyte", "name": "Electrolyte", "section": "topic-electrolytes", "definition": "The ion-conducting medium between the electrodes. In a liquid-electrolyte cell it fills the pores of both electrodes and the separator, so it is not a separate structural layer.", "related": [ "lithium-salt", "carbonate-solvent", "electrolyte-additive", "ionic-conductivity", "solid-electrolyte", "ionic-liquid-electrolyte" ], "lesson": "fundamentals/cell-architecture/#electrolyte", "example": { "title": "Ions and electrons", "text": "Electrolyte carries ions between electrodes; the external circuit carries electrons. The two paths serve different roles." }, "url": "https://lemonergy.com/learn/glossary/electrolyte/", "mentions": [ "separator" ] } }, { "id": "visual:voltage", "type": "Visual", "label": "Voltage under load", "properties": { "title": "Voltage under load", "summary": "Discharge current creates an ohmic drop below open-circuit voltage.", "readout": "5 A through 20 mΩ gives 0.1 V ohmic drop.", "formula": "V_terminal = OCV − I_discharge R", "note": "Chosen OCV curve; no chemistry calibration, hysteresis or voltage cutoff.", "software": { "status": "studio", "label": "Voltage relationship in Studio", "body": "The native battery calculates terminal voltage from OCV and resistance. The curve here is an illustrative OCV relationship, not a fitted cell dataset.", "href": "https://design.lemonergy.com/cosim.html?example=charging-home" }, "html": "
Illustrative OCV and loaded voltage
Illustrative OCV and loaded voltageSOC (%) versus Voltage (V). Open circuit; Under load. Interpretation follows the graphs.1.802.42253.05503.67754.3100SOC (%)Voltage (V)
Open circuitUnder load (dashed)
" } } ] }