Lithium Battery Nomenclature
Aging
Loss of capacity due, for example, to loss of lithium ions or spallation of anodes. This may be due to use (charging and discharging) and/or open circuit rest (calendar aging)
Anode
The positive electrode. In lithium-ion batteries, these are most often small particles of graphite.
Battery
The complete energy storage unit consisting of several modules
Ability
The amount of charge stored in a battery or cell, usually specified in ampere-hours (Ah). 1 A h = 3600 Coulombs (C)
Cathode
The negative electrode. These typically include lithium transition metal oxides: for example, lithium nickel manganese cobalt oxide (LiNi 0 33 Mn 0 33 Co 0 33 O 2 )
Cell
The smallest unit of a battery
Electrolyte
In electrochemistry, this term can designate either the inorganic salt (ex: LiPF 6) or the salt + organic solvent
End of Life (EoL)
The point at which a battery becomes unsuitable for its current application. For automotive batteries, this is typically 75-80% health
Energy
The energy stored in a battery is specified in Watthours (Wh) or kiloWatthours (kWh): 1 Wh = 1 Amp Volt x 3600 s = 3600 AVs = 3600 Joules
Energy density
Energy per unit volume (litre) of the battery
Galvanic battery
Usually just called a cell. A device which, when charged with electricity, is in a higher state of energy than when discharged. Upon discharge, the stored chemical energy is released as an electric current
OCL cathode
Lithium cobalt oxide, LiCoO 2
LFP cathode
Lithium iron (ferrous) phosphate, LiFePO 4
Cathode LMO
Lithium manganese oxide, e.g. LiMn 2 O 4
Module
Manufacturer-specific term, e.g. set of cells arranged in series and/or in parallel
Cathode NEC
(lithium) Nickel Cobalt Aluminum oxide, e.g. LiNi 0 8 Co 0 15 Al 0 05 O 2
NMC cathode
(lithium) Nickel Manganese Cobalt oxide, e.g. LiNi 0.33 Mn 0.33 Co 0.33 O 2 (NMC 111), LiNi 0 6 Mn 0 2 Co 0 2 O 2 (NMC 622)
Open circuit
The state when a battery or cell is disconnected from an external circuit
Open Circuit Voltage (OCV)
The difference in potential (voltage) across a cell or battery when no current is allowed to flow. This can be correlated with the state of charge (SoC)
Salt
The inorganic compound used to produce ions in the cell. It is typically lithium hexafluorophosphate (LiPF 6 ) which dissociates in the organic solvent to produce lithium cations (positively charged ions, Li + ) and hexafluorophosphate anions (negatively charged ions, PF 6 – )
Separator
A plastic film permeable to lithium ions and hexafluorophosphate which prevents the anode and cathode from touching and causing a short circuit
Solid Electrolyte Interface (SEI)
The protective layer that forms on the anode during the first charge from the reduction of LiPF 6 and solvent which prevents further explosive electrolyte degradation and thermal runaway
Solvant
Mixture of organic carbonates, containing ethylene carbonate, as it is essential for the formation of SEI. Ethylene carbonate is a solid at room temperature and other carbonates are essential to reduce viscosity
Specific energy
Energy per kg of battery
State of Charge (SoC)
The amount of charge stored compared to that equivalent to a full charge, expressed in %
State of Health (SoH)
The amount of charge currently stored when fully charged compared to that stored (when fully charged) at the start of the cell or battery life, expressed as a %