1
Q
Term
A
Definition
2
Q
Lithium-ion Battery
ion rocking chair
A
Rechargeable battery using lithium ions to store and release energy
3
Q
Anode
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Negative electrode; releases lithium ions during discharge
4
Q
Cathode
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Positive electrode; receives lithium ions during discharge. In a battery, the cathode is usually the positive terminal during discharge and the negative terminal during charging.
5
Q
Electrolyte
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Medium (often lithium salt in solvent) for lithium-ion movement
6
Q
Separator
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Membrane preventing physical contact of anode/cathode while allowing ion flow
7
Q
Cycle Life
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Number of charge/discharge cycles before significant capacity loss
8
Q
Energy Density
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Energy stored per mass or volume (Wh/kg or Wh/L)
9
Q
Gravimetric Energy Density
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Energy per unit weight (Wh/kg)
10
Q
Volumetric Energy Density
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Energy per unit volume (Wh/L)
11
Q
Charge Rate (C-rate)
Current intensity
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Speed of charge/discharge relative to capacity (1C = full charge in 1 hr)
12
Q
State of Charge (SOC)
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Percentage of battery charge compared to total capacity
13
Q
Depth of Discharge (DOD)
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Percentage of battery capacity used
14
Q
Battery Management System (BMS)
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Device monitoring and managing battery safety and performance
15
Q
Overcharge Protection
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Prevents charging beyond safe voltage
16
Q
Over Discharge Protection
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Prevents discharge below safe voltage
17
Q
Thermal Runaway
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Uncontrolled temperature increase, risk of fire/explosion
18
Q
Self-Discharge Rate
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Rate of charge loss when battery not in use
19
Q
Voltage
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Potential difference between battery terminals (V), drives current
20
Q
Watt-hour (Wh)
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Unit of energy; voltage × amp-hours
21
Q
Battery Cell
A
Smallest, self-contained unit of battery with electrodes and electrolyte
22
Q
Battery Pack
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Array of interconnected cells or modules for larger capacity
23
Q
Primary Cell
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Non-rechargeable cell; irreversible chemical process
24
Q
Secondary Cell
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Rechargeable cell; reversible chemical process
25
Battery Module
Replaceable grouping of cells in a pack
26
Calendar Aging
Capacity loss occurring during storage rather than cycling
27
Rated Capacity
Manufacturer-specified total charge (Ah, mAh)
28
Capacity Slippage
Irreversible loss of capacity due to side reactions
29
Electric Charge
Quantity of electrons; 1 coulomb = 1 ampere × 1 second
30
Maximum Charge
Highest charge storable by the cell at any state
31
Charge Profile
Schedule or method for charging, e.g., constant current/voltage
32
Coulombic Efficiency
Ratio of discharge/charge capacity in one cycle
33
Cyclability
Ability of battery to retain capacity over cycles
34
Cycle
Complete run from charge to discharge and back
35
Cyclic Voltammetry
Electrochemical method to study electrode behavior
36
Discharge Curve
Voltage vs. time or capacity during discharge
37
Duty Cycle
Usage pattern of a battery, e.g., percent time in various modes
38
Electric Current
Rate of electron flow, measured in amperes
39
EIS (Electrochemical Impedance Spectroscopy)
Method to study electrical response over frequency
40
Electrode
Conductive material for electron entry/exit
41
Electromotive Force (EMF)
No-load voltage between electrodes
42
End of Life (EOL)
When battery falls below set capacity or power
43
Energy Capacity
Total energy released in discharge (usually in Wh or J)
44
Specific Energy
Energy per unit battery mass (Wh/kg)
45
Faraday Constant
Charge per mole of electrons, ≈ 96,485 C/mol
46
GITT (Galvanostatic Intermittent Titration Technique)
Test method for studying ion diffusion
47
High Precision Coulometry
Highly accurate measurement of coulombic efficiency
48
Hybrid Pulse Power Characterization (HPPC)
Pulse test evaluating power capability over age
49
PITT (Potentiostatic Intermittent Titration)
Method assessing diffusion by holding potential steps
50
Power
Rate of energy transfer (W = J/s)
51
Peak Power
Max short-term power delivered by a battery
52
Specific Power
Power per unit mass (W/kg)
53
Ragone Plot
Graph of specific energy vs. specific power
54
AC Internal Resistance (ACIR)
Resistance via alternating current
55
DC Internal Resistance (DCIR)
Resistance measured via direct current
56
Ohmic Resistance
Simple resistive loss in battery components
57
SEI (Solid Electrolyte Interphase)
Layer forming on anode, crucial for stability
58
State of Health (SOH)
Maximum capacity vs. initial rated capacity (%)
59
Trickle Charge
Low-current charge to keep battery full
60
Nominal Voltage
Standard cell voltage, ~3.6–3.7V for Li-ion
61
Midpoint Voltage (MPV)
Voltage at 50% discharge capacity
62
DoD (Depth of Discharge)
Another term for discharge percentage
63
End-of-Discharge Voltage
Voltage when battery is considered dead
64
Float Charge
Maintaining a battery at full charge by constant voltage
65
Overpotential
Deviation from equilibrium potential due to current flow
66
Ohm’s Law
V = IR; voltage equals current × resistance
67
Electrochemical Window
Voltage range electrolyte remains stable
68
Pulse Discharge
Discharge with brief, high current pulses
69
Float Life
Battery lifespan under continuous float charge
70
Capacity Fade
Observable decline in charge capacity due to degradation
71
BMS Balancing
Equalizing charge across all cells
72
Slurry
Mixture of active material, binder, solvent for electrode coating
73
Binder
Polymer holding electrode material together
74
Additive
Minor component introduced to improve performance/safety
75
Conductive Agent
Material enhancing electron transport in electrode
76
Calendar Life
Lifespan of battery in storage/non-use
77
Electrochemical Stability
Resistance to irreversible breakdown
78
LCO
Lithium cobalt oxide, common cathode
79
NMC
Lithium nickel manganese cobalt oxide, advanced cathode
80
LFP
Lithium iron phosphate, safer cathode option
81
LMO
Lithium manganese oxide, high-power cathode
82
NCA
Lithium nickel cobalt aluminum oxide, high-energy cathode
83
Spinel Structure
Specific crystal structure in some cathodes
84
Prismatic Cell
Rectangular battery cell format
85
Cylindrical Cell
Battery in a round metal can format
86
Pouch Cell
Flexible, flat form-factor battery
87
Specific Capacity
Charge per unit mass (mAh/g)
88
Formation Cycling
Initial cycles to form SEI, stabilize cell
89
Aging Test
Assessing performance loss over time
90
Rate Capability
How fast battery can be safely charged/discharged
91
Dendrite
Lithium metal deposition causing internal shorts
92
Black Mass
Mixture from recycling; contains valuable battery metals
93
Outgassing
Release of gases from battery due to reactions
94
Safe Operating Area
Temperature and voltage range for safe operation
95
PTC (Positive Temperature Coefficient)
Safety device; resistance increases at high temp
96
CID (Current Interrupt Device)
Cuts circuit in abuse/overpressure
97
Float Charging
Maintaining battery at constant voltage after full charge
98
Memory Effect
Loss of capacity when repeatedly partially discharged (rare in Li-ion)
99
Cut-off Voltage
Minimum allowable voltage in discharge
100
Heat Generation
Effects of resistance, leading to energy loss
101
Capacity Retention
Amount of original capacity after certain cycles or conditions
102
Recharge Time
Time needed to fully recharge battery
103
Practical Energy Density
Achievable energy density in real applications
104
Theoretical Energy Density
Calculated maximum possible energy density
105
Battery Chemistry
Specific combination of electrode/electrolyte materials
106
Cathode-Specific
107
Term
Definition
108
Cathode Active Material (CAM)
Primary lithium host for electrochemical reactions in cathode
109
Layered Structure
Crystal arrangement with lithium and transition metal oxide layers (LCO, NMC, NCA)
110
Spinel Structure
3D oxide lattice (LMO) that improves power output and stability
111
Olivine Structure
Robust phosphate crystal structure (LFP) with high thermal and chemical stability
112
Disordered Rocksalt
Novel cathode structure enabling high capacity and improved safety
113
Polyanion Cathode
Contains phosphate, silicate, or sulfate for stability/safety
114
Lithium Content
Amount of lithium stored in cathode structure
115
Stoichiometry
Ratio of atoms in the cathode material critical for performance
116
Cobalt Content
Percentage of cobalt, reduced for cost and environmental reasons
117
Nickel Enrichment
Higher Ni fraction for energy density and cost balance
118
Dopant
Element added to improve performance or conductivity
119
Aluminum Foil
Current collector for cathodes
120
Surface Coating
Particle surface enhancement to improve cycle life and stability
121
Morphology Control
Tuning particle shape/size for diffusion and rate capability
122
Gradient Cathode
Changing composition to balance performance and stability
123
Core-Shell Structure
Different core/shell chemistry for optimized stability and cycling
124
Single-Crystal Cathode
Particles made of one continuous crystal, fracture-resistant
125
Oxygen Vacancy
Missing oxygen atom in lattice affects performance and life
126
Initial Irreversible Capacity Loss
First-cycle loss from side reactions and SEI
127
Voltage Fade
Discharge voltage declines with repeated cycling
128
Phase Transformation
Structure change during cycling causing degradation
129
High-Voltage Cathode
Materials supporting voltages above 4.2V
130
Cathode Manufacturing Cost
Sum of materials, energy, labor, yield, and QC for cathode production
131
Precursor Cost
Price of metal salts and chemicals for cathode synthesis
132
Supply Chain Security
Reliability and risk of raw/processed cathode material sourcing
133
Recycling Content (Cathode)
Recycled metals/oxides used in new cathode production
134
Transition Metal Dissolution
Migration of metal ions (Mn, Ni, Co) into electrolyte, accelerating aging
135
Anode-Specific
136
Term
Definition
137
Anode Active Material
Material hosting lithium ions during charge (graphite, silicon)
138
Graphite (Natural/Synthetic)
Mined vs. heat-processed carbon; different purity, cost, stability
139
Hard Carbon
Amorphous/disordered carbon for specialty batteries
140
Carbon Black
Conductive additive for electron transport
141
Silicon
High-capacity future anode, expansion and cycling challenges
142
Silicon Oxide (SiOx)
Composite balances Si capacity with stability
143
Tin-Based Anode
Uses tin or tin oxides for conversion reactions
144
Lithium Titanate (LTO)
Spinel structure, safe, rapid charge, lower energy
145
Copper Foil
Anode current collector
146
Porosity (Anode)
Fraction of open space for ion diffusion and density
147
Surface Coating (Anode)
Protective or functional films for cycling stability
148
SEI Formation (Anode)
Critical layer for aging, safety, and cycling
149
Lithium Plating (Anode)
Dangerous metallic deposition; forms shorts/dendrites
150
Volume Expansion
Swelling/shrinking during cycling, linked to mechanical aging
151
Morphology Control (Anode)
Engineering grain shape for life and rate capability
152
Composite Structure (Anode)
Multiple active materials for balanced performance and cost
153
Alloying Reaction Anode
Li forms alloys with Si, Sn, boosting capacity, risking stress
154
Advanced Carbon Structures
Nanotubes, graphene, diamond-like coatings for high conductivity
155
Nanowire Anode
1D wires for improved performance and expansion management
156
Current Collector Tab (Anode)
Metal extension for cell connection
157
Recycling Content (Anode)
Recovered carbon/copper/Silicon in new anode construction
158
Battery Degradation & Aging
159
Term
Definition
160
Battery Degradation
Irreversible loss of capacity or rate capability over time
161
Aging Phase
Stages of loss: rapid initial, stable mid, end-of-life decline
162
SEI Layer Growth
Expansion of the protective layer causing capacity loss
163
Irreversible Capacity Loss
Permanent charge loss due to side reactions
164
Internal Resistance Gain
Increase in impedance, limiting power/rate, raising heat
165
Stable Phase
Slowed degradation after SEI stabilizes
166
Linear Loss Phase
Near-linear degradation region
167
End-of-Life
Rapid capacity/power decline before cell failure
168
Available Lithium Loss
Less usable lithium in the cell
169
Ion Transport Resistance
Difficulty moving ions due to buildup/loss of material
170
Temperature-Induced Aging
Faster aging at high operating/storage temperature
171
Storage Degradation
Aging when battery is unused
172
Rapid Charge Strain
Accelerated aging during fast charging
173
High/Low SOC Storage
Degradation from prolonged extremes of charge level
174
SEI Instability
Cracking SEI causes renewed parasitic reactions/loss
175
Li Plating/Dendrites
Formation of branch-like metallic lithium shorts
176
Volume Expansion (Anode)
Physical swelling/shrinking during cycling
177
Mechanical Stress/Fracture
Cracking particles, electrical isolation, capacity loss
178
Binder Degradation
Breakdown of binding polymer, lost contact/conductivity
179
Collector Dissolution
Metal collector degradation, affecting conductivity/safety
180
Collector Precipitation
Redeposition causing safety/shorting risk
181
Electrolyte Breakdown
Chemical decay due to reaction or heat
182
Reduced Fast-Charge Rate
Capacity/conductivity decline slows charging speed
183
Range Loss
Diminished driving distance in EVs
184
Power Limitation
Reduced peak output as resistance rises, active material depletes
185
Efficiency Drop
Increased heat, less usable output
186
Electrode Fatigue
Structural damage accumulation over cycling
187
Nonlinear Aging
Aging occurs in distinct phases, not a simple line
188
High Current Stress
Accelerated aging and SEI/mechanical breakdown
189
Heat-Accelerated Aging
High temperatures magnify all aging factors
190
Advanced Degradation Mechanisms
191
Term
Definition
192
Loss of Lithium Inventory (LLI)
Loss of cyclable lithium from reactions reduces capacity
193
Loss of Active Material (LAM)
Material capable of storing lithium becomes inactive
194
Stoichiometric Drift
Electrode imbalance caused by shifts in lithium ratio
195
Impedance Rise
Increased cell resistance limiting power and charge rate
196
Electrolyte Loss
Consumption or drying out from reactions or evaporation
197
Binder Decomposition
Breakdown of binder polymer, loss of electrode cohesion
198
Separator Pore Blockage
Blocked pathways, reduced ion flow
199
Salt Precipitation
Formation of insoluble salts inhibiting function
200
Electrode Particle Fracture
Cracking particles from stress/cycling
201
Positive SEI (pSEI)/CEI
Passivation film growth on cathode surface, increases resistance
202
Transition Metal Dissolution
Loss of cathode metals into electrolyte, accelerating aging
203
Surface Reconstruction
Particle chemical restructuring after cycling/reactions
204
Path Dependence
Usage history determines which aging dominates
205
Pressure-Induced Degradation
External compression or cell swelling drives failure
206
Dead Lithium Formation
Inactive, metallic lithium clusters or dendrites
207
Pore Drying
Local electrolyte-free regions impede ion flow
208
Coupled Mechanisms
Multiple pathways reinforcing/exacerbating aging
209
Modeling Degradation
Simulation/prediction of aging for life improvement
210
Electrode Pulverization
Physical breakdown after cycling, lost contact/capacity
211
Cation Mixing
Transition metal migration disrupting structure
212
Phase Collapse
Structural breakdown from repeated cycling
213
Oxygen Loss
Escape of oxygen atoms from lattice, weakens safety/performance
214
Gas Evolution
Cell swelling/rupture from breakdown gas formation
215
Hydrofluoric Acid Formation
Corrosive HF formed from side reactions, attacks components
216
Localized Overheating
Small hot spots drive aging, risk thermal runaway
217
Electrode Swelling
Expansion from mechanical stress or growth
218
Cell-to-Cell Variation
Manufacturing variability yields different aging rates
219
Accelerated Testing
Quick laboratory protocols to study failure/aging
220
Life Prediction Models
Mathematical/statistical lifespan estimation tools
221
Residual Lithium
Lithium trapped/inactive at end-of-life
222
Impedance Mode
Aging mechanisms that increase resistance and limit power
223
Li-ion Diffusion Hinderance
Slow movement through electrode/electrolyte
224
CEI Growth
Growth of passivating layer on cathode
225
Electrode Material Loss Mode
Mechanisms reducing available active electrode
226
Energy Throughput
Lifetime total energy processed by the cell
227
State-of-Health Estimation
Measurement/algorithm for gauging cell aging/performance
228
Thermal Gradient Degradation
Differing cell regions age at different rates due to heat
229
Polymer Degradation
Breakdown of separator/binder, reducing life
lithium
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