{ "node": { "id": "term:coulombic-efficiency", "type": "Term", "label": "Coulombic efficiency", "properties": { "id": "coulombic-efficiency", "name": "Coulombic efficiency", "abbr": "CE", "section": "topic-ratings", "definition": "Charge delivered on discharge divided by charge put in on the previous charge. A healthy lithium-ion cell exceeds 99.9 %; the missing fraction is lithium lost to side reactions, so CE is an early and sensitive aging signal.", "formula": "CE = Q_discharge / Q_charge", "unit": "%", "related": [ "energy-efficiency", "loss-of-lithium-inventory", "sei", "formation" ], "example": { "title": "Compare charge in and charge out", "text": "If a defined test charges 5.00 Ah and subsequently discharges 4.95 Ah over the chosen voltage window, its coulombic efficiency is 99%. This ratio alone does not include voltage-related energy loss." }, "url": "https://lemonergy.com/learn/glossary/coulombic-efficiency/", "mentions": [] } }, "edges": [ { "id": "edge:48", "source": "term:coulombic-efficiency", "target": "workflow:ocv-charge-balance", "type": "usedIn", "properties": { "sourceFile": "wiki-blocks.json" } }, { "id": "edge:972", "source": "term:coulombic-efficiency", "target": "topic:topic-ratings", "type": "belongsTo", "properties": { "sourceFile": "terms.json" } }, { "id": "edge:973", "source": "term:coulombic-efficiency", "target": "term:energy-efficiency", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:974", "source": "term:coulombic-efficiency", "target": "term:loss-of-lithium-inventory", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:975", "source": "term:coulombic-efficiency", "target": "term:sei", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:976", "source": "term:coulombic-efficiency", "target": "term:formation", "type": "relatedTo", "properties": { "sourceFile": "terms.json", "meaning": "Related context; not a causal claim" } }, { "id": "edge:977", "source": "term:coulombic-efficiency", "target": "visual:efficiency", "type": "illustratedBy", "properties": { "sourceFile": "visual-pages.json" } } ], "neighbors": [ { "id": "workflow:ocv-charge-balance", "type": "Workflow", "label": "Connect SOC and voltage", "properties": { "id": "ocv-charge-balance", "title": "Connect SOC and voltage", "kind": "studio", "summary": "The battery integrates charge and combines OCV with resistance.", "steps": [ "Inspect capacity, initial SOC and OCV endpoints.", "Compare OCV with terminal voltage." ], "example": "OCV endpoints of 300 and 420 V give 360 V at 50% SOC. Charging at 10 A through 0.08 Ω adds 0.8 V.", "observe": "At unity coulombic efficiency, 10 A for 1 h adds ten percentage points to 100 Ah.", "limits": "Internal model SOC is not an estimate of an unknown physical battery. OCV is linear and resistance fixed.", "url": "https://design.lemonergy.com/cosim.html?example=charging-home", "label": "Open the Studio example", "evidence": [ "js/charging-control.js", "js/charging-scenarios.js", "docs/CHARGING_BLOCKS_SPEC.md" ] } }, { "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:energy-efficiency", "type": "Term", "label": "Energy efficiency", "properties": { "id": "energy-efficiency", "name": "Energy efficiency", "aka": [ "round-trip efficiency" ], "section": "topic-ratings", "definition": "Energy out divided by energy in over a full cycle. It is lower than coulombic efficiency because the charge voltage sits above the discharge voltage; cells reach 95–98 %, and a full storage system 85–92 % after power electronics and cooling.", "unit": "%", "related": [ "coulombic-efficiency", "voltage-hysteresis", "ir-drop", "stationary-storage", "voltage-efficiency" ], "url": "https://lemonergy.com/learn/glossary/energy-efficiency/", "mentions": [] } }, { "id": "term:loss-of-lithium-inventory", "type": "Term", "label": "Loss of lithium inventory", "properties": { "id": "loss-of-lithium-inventory", "name": "Loss of lithium inventory", "abbr": "LLI", "section": "topic-aging", "definition": "The degradation mode in which cyclable lithium is consumed by side reactions — SEI growth, plating, electrolyte decomposition — and can no longer shuttle between the electrodes. It is the dominant cause of capacity fade in most lithium-ion cells.", "related": [ "sei", "lithium-plating", "capacity-fade", "loss-of-active-material", "coulombic-efficiency" ], "url": "https://lemonergy.com/learn/glossary/loss-of-lithium-inventory/", "mentions": [ "electrolyte", "aging-mechanism", "electrolyte-decomposition" ] } }, { "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: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": "visual:efficiency", "type": "Visual", "label": "Charge efficiency versus energy efficiency", "properties": { "title": "Charge efficiency versus energy efficiency", "summary": "Returning most of the charge does not return the same fraction of energy.", "readout": "99% × 92% = 91.08% energy efficiency.", "formula": "η_energy = η_charge × V̄_discharge / V̄_charge", "note": "Matched cycle and measurement boundaries; auxiliary loads omitted.", "software": { "status": "reference", "label": "Reference concept", "body": "For matching cycle boundaries, energy efficiency = charge efficiency × mean discharge/charge voltage ratio. The core nominal-energy helper does not calculate cycle efficiency.", "href": "../fundamentals/capacity-and-c-rate/" }, "html": "
Recovered energy
Recovered energyEnergy put in (Wh) versus Energy recovered (Wh). Ideal 100%; Selected efficiencies. Interpretation follows the graphs.00252550507575100100Energy put in (Wh)Energy recovered (Wh)
Ideal 100%Selected efficiencies (dashed)
" } } ] }