Battery Chemistry Definitions & Glossary

Battery Chemistry Definitions & Glossary has quite a lot of overlap with the Cell Glossary. Hence apologies for any repeats, although some are required.

Ah – Ampere-hour is the unit of cell capacity.

Anode – the negative or reducing electrode that releases electrons to the external circuit and oxidizes during and electrochemical reaction.

Anode-Cathode – in chemistry, we define Cathode as the electrode where reduction takes place and Anode the electrode where oxidation occurs. Both, during the discharge and recharge electrons move from the Anode to the Cathode. {Anode and Cathode swap places}.

Anode Free – a battery cell where the Anode is formed during the cell formation cycles.

Binder – something that holds the active materials together.

Button Cell

Calendar Ageing – the capacity loss of the battery with time and without cycling.

Calendaring – in the calendaring process the dried anode and cathode are run separately between rollers to compress the active layer. This brings the thickness and porosity to a given dimension.

Capacity – battery capacity is expressed in ampere-hours.

Cathode – the positive electrode, at which electrochemical reduction takes place. As current flows, electrons from the circuit and cations from the electrolytic solution in the device move towards the cathode.

Charge – the process of electrical energy being converted into chemical energy.

Coating – the process of applying the active materials to the backing electrodes.

Coin Cell –

Coulomb – unit of electric charge. One coulomb (1C) equals one ampere-second (1As).

C rate – the Ampere current in charge or discharge divided by the Ah capacity of the cell.

Cycle Ageing – the capacity loss in a battery through charge and discharge repeated cycling.

Cycle Life – the number of charge and discharge cycles that a battery can complete before losing performance.

Discharge – the process of chemical energy being converted into electrical energy.

Dry Room –

Dry Separator – the separator is produced without solvents being used in the process.

EL Cell

Electrode – the electrical part of a cell and consists of a backing metallic sheet with active material printed on the surface.

Electrolyte – the medium that allows ionic transport between the electrodes during charging and discharging of a cell.

Electrolyte Additives – used for a number of functions, including:

  • improved SEI formation
  • reduce irreversible capacity loss and gas generation
  • enhance thermal stability of LiPF6 
  • protect the cathode material from dissolution and overcharge
  • improve the physical properties of the electrolyte

Formation –


Humidity –

Instrumenting Cells – if you are going to instrument a cell you need to be able to do this reliably and robustly. The process flow diagram illustrates the experimental stages employed for cell instrumentation and includes: sensor fabrication, cell modification and sensor insertion. The diagram highlights the different verification stages for assessing LIB performance, operation and ageing.
WMG Smart Cell instrumentation
Battery Capacity versus number of cycles showing the Knee Point

Knee Point – describes a sudden change in the gradient of a cell cycling curve.

Also called [1]:

  • rollover failure
  • nonlinear aging
  • sudden death
  • saturation
  • second-stage degradation
  • two-phase degradation
  • capacity plunge
  • drop-off

LCA – Life Cycle Analysis

LFP – Lithium Iron Phosphate, a lithium ion cathode material with graphite used as the anode. This cell chemistry is typically lower energy density than NMC or NCA, but is also seen as being safer.

LiPF6 – Lithium hexafluorophosphate

Lithium Plating – This is the deposition of metallic lithium on the surface of the graphite anode. This is one of the most significant degradation mechanisms.

LMB – Lithium Metal Battery

LMFP – Lithium manganese iron phosphate.

LMO – Lithium Manganese Oxide

LNMO – Lithium Nickel Manganese Oxide

LRM – Lithium Rich Manganese has a high specific capacity because of both cationic and anionic redox activity

LTMO – Layered Transition Metal Oxide

M3PCATL’s trade name for their own developed variation on LFP.

Na Ion – Sodium Ion battery cell.

NCMA – Nickel Cobalt Manganese Aluminium cathodes are more stable than NMC.

Negative Electrode – the anode.

NMC – Lithium Nickel Manganese Cobalt Oxides are a family of mixed metal oxides of lithium, nickel, manganese and cobalt. Nickel is known for its high specific energy, but poor stability. Manganese has low specific energy but offers the ability to form spinel structures that allow low internal resistance.

typical OCV vs SoC
Open Circuit Voltage (OCV) – is the potential difference between the positive and negative terminals when no current flows and the cell is at rest.

PbA – abbreviation of lead acid battery.

PBA – Prussian Blue Analogues

Positive Electrode – the cathode.

Prelithiation – introduces extra active lithium ions through various lithium sources. These extra lithium ions contribute to the formation of the solid electrolyte interphase (SEI), hence improving the delivered energy density of the cell.

Primary Cell – a cell that can only be discharged once.

Secondary Cell – a rechargeable battery cell.

Self Discharge

Separator – material that separates the anode and cathode electrically whilst allowing ions to pass through.

Solid Electrolyte Interphase – is formed on electrode surfaces from decomposition products of electrolytes. The SEI allows Li+ transport and blocks electrons in order to prevent further electrolyte decomposition and ensure continued electrochemical reactions.

Solid State – anode, cathode and electrolyte are solid.

Third Electrode – electrode used in cells to establish the potential of the anode and cathode independently.

Wet Separator – the separator is produced using solvents.