Lithium-ion Battery and Recycling Terminology

Anode: Negative (or reducing) electrode gives up electrons to the external circuit and is oxidized during the electrochemical reaction. (discharging)

Battery: Device that converts chemical energy contained in its active materials into electrical energy by means of an electrochemical oxidation-reduction reaction. A battery is composed of one or more cells.

Battery Pack: Interconnected battery modules that have been configured (typically with a BMS, cooling system, and other protections) for a specific energy storage application.

BEV: Battery electric vehicle: a vehicle powered only by a battery powered electric motor.

Black Mass: Mixture of residual cell materials, typically isolated after shredding and sieving.

BMS: Battery management system: electronic circuits designed to monitor the battery pack and keep it within its specified operating conditions and to protect it from abuse during both charging and discharging.

Calcine: Act of heating an inorganic substance to a temperature below its melting point to drive off volatile matter, cause chemical changes, or encourage particle-particle diffusion

Calendar Life: a measure of the ability of a battery to maintain state of charge while at rest and being held at constant voltage. Related: shelf life

Capacity: Quantity of energy a battery can deliver in a single discharge, normally expressed in amp-hours.

Capacity Fade: Gradual decrease in the total quantity of electric charge that is transferred between electrodes of a cell on charge and discharge, caused by chemical and structural changes in active cell components.

Cathode: Positive (or oxidizing) electrode that accepts electrons from the external circuit and is reduced during the electrochemical reaction. (discharging)

Cathode-to-Cathode Recycling: Recovery of cathode material for reuse in a battery (see direct recycling).

Cell: Most basic complete electrochemical unit that provides electrochemical energy by direct conversion of chemical energy. The cell consists of an assembly of electrodes, separators, electrolyte, container, and terminals. (AKA Galvanic cell)

Class 9: Materials that present a hazard during transportation, but do not meet the definition of any other hazard class (lithium-ion batteries are classified as Class 9).

Consumer Electronics: Electronic devices intended for use without training (e.g., cell phone, tablet). Often powered by lithium-ion batteries.

Critical Mineral: (i) a non-fuel mineral or mineral material essential to the economic and national security of the United States, (ii) the supply chain of which is vulnerable to disruption, and (iii) that serves an essential function in the manufacturing of a product, the absence of which would have significant consequences for our economy or our national security. (Executive Order 13817, 12/20/2017)

Crystal structure: A specific packing pattern or arrangement of atoms within a substance that represents the constituents of a crystal.

Charge: Conversion of electric energy, provided in the form of a current, into chemical energy within the battery.

Charging: Process of supplying electrical energy for conversion to stored chemical energy by changing the lithium content within the electroactive materials

Charge Rate (C Rate): The discharge or charge current, in Amperes, as a fraction of the battery capacity in A-h, e.g., a rate of C/2 will charge a cell in 2 h.

Constant-Current Charge (CC): Charging process in which the current applied to the battery is maintained at a constant value.

Constant-Voltage Charge (CV): Charging process in which the voltage applied to a battery/cell is held at a constant value.

Cycle: One sequence of charge and discharge.

Cycle Life: Total number of charge/discharge cycles the cell can sustain before its capacity is significantly reduced or it reaches End-Of-Life conditions. End of life is usually considered to be reached when the battery delivers only 80% of rated ampere- hour capacity.

Cylindrical Cell: Cell in the shape of a cylinder, inside of which the components are wrapped in a spiral.

DDR: Damaged, defective, or recalled batteries.

Depth of Discharge (DOD): Quantity of energy that has been removed from a battery, usually expressed as a percentage of the total capacity, e.g., 50% depth of discharge means that half of the energy in the battery has been used.

Direct (Cathode) Recycling: Recovery, regeneration, and reuse of battery components (cathode material) directly without breaking down the chemical structure.

Discharge: The conversion of the chemical energy of the battery into electric energy.

Disposal: Final disposition of a material for which no use is economical, often in a landfill.

Electrode: The physical component within the cell at which electrochemical processes take place. The anode and cathode are separate electrodes.

Electrolyte: Ionic conductor that provides a medium for transfer of charge inside the cell between anode and cathode while maintaining minimal electronic conductivity.

End-of-Life: Designation of a product that has reached the end of its useful life for its primary application (typically falling below 80% of original discharge capacity for EV batteries).

EV: Electric vehicle. Vehicle that uses one or more electric motors for propulsion.
Energy Density: Volumetric energy storage density of a battery, expressed in Watt-hours per litre (Wh/l).

Formation: In battery manufacturing, the first few cycles using the process of charging and discharging the battery for the purpose of establishing the electrodes working environment (electrolyte wetting, SEI formation, etc.).

Gassing: Evolution of gas from any component within a cell. Cells are typically degassed after formation.

HEV: Hybrid electric vehicle: vehicle with both an internal combustion engine and an electric motor that is powered by regenerative braking and/or a battery pack.

Hydrometallurgy: Process or technique of extracting material at ordinary temperatures by leaching ores (or recovered material) with liquid solvents.

Internal Resistance: Resistance to the flow of an electric current within the cell or battery.

Life Cycle Analysis: Analysis of environmental impacts, cost, and energy use of a product from production process, to use, to disposal or recycling for the purposes of identifying variables that contribute to a battery over its lifetime.

Life Cycle Inventory: Systematic accounting of water, energy, and raw material inputs and outputs for the production, use, and final disposition of a product.

Module: Grouping of interconnected cells in a single mechanical and electrical unit.

Negative: Side of a cell from which electrons flow, through the load, during discharge. (related: anode)

Negative Terminal: Terminal of a battery from which electrons flow in the external circuit when the cell discharges. See cathode.

New Scrap: Scrap generated in manufacturing processes from out of specification products or general manufacturing reject material (also known as home scrap).

Non-aqueous Batteries: Cells that do not contain water, such as those with molten salts or organic electrolytes.

Ohm’s Law: Formula that describes the amount of current flowing through a circuit. Current (in amperes (I)) equals the voltage (V) divided by the resistance (in ohms (R)).

Old Scrap: Material from end-of-life products that can be recovered (also known as post-consumer scrap).

Open Circuit: Condition of a battery which is disconnected from a circuit.

Open-Circuit Voltage: The voltage of a battery when it is not delivering or receiving power.

Oxidation: Chemical reaction that results in the release of electrons by an electrode’s active material (an anode being discharged or a cathode being charged)

PEV: Plug-in electric vehicle: any vehicle that can be recharged from an external source of electricity, such as wall sockets, and the electricity stored in the rechargeable battery packs drives or contributes to drive the wheels.

PHEV: Plug-in hybrid vehicle: a hybrid electric vehicle whose battery can be recharged by plugging it into an external source of electric power, as well by its on-board engine and generator.

Side of a cell to which electrons flow, through the load, during discharge. Related: cathode

Positive Terminal: Terminal of a battery toward which electrons flow through the external circuit when the cell discharges. See anode

Pouch Cell: Cell without rigid packaging, inside of which the components are generally folded repeatedly.

Power Density: Volumetric power density of a battery, expressed in Watts per liter (W/l).

Primary Battery: Single use battery whose electrochemical reaction is not reversible and so cannot be recharged.

Prismatic Cell: Rectangular cell with rigid packaging, inside of which the cell components are folded or wound.

Pyrometallurgy: Process or technique of refining ores (or recovered material) using heat to melt the metallic and burn the non-metallic content.

Rechargeable: Capable of being recharged; refers to secondary cells or batteries that can be used multiple times.

Reduction: Chemical process that results in the acceptance of electrons by an electrode’s active material. (Anode being charged or a cathode being discharged)

Recycle: Convert materials that are no longer functional into usable materials or products. The “RE” terms below are widely used with varying connotations. Terms are not mutually exclusive.

Recycling Preparation and Management: Reducing volume, weight, and cost by separating battery packs into their individual components and neutralizing cells for safe and low-cost shipping.

Refurbish: Repair or freshen a product to meet original specifications, typically done by the original manufacturer. Generally, does not entail major modification.

Rejuvenate: Restore materials or devices to performance similar to their pristine state. Similar to refurbish, but not necessarily done by original manufacturer.

Remanufacture: Return previously sold, worn, or non-functional products to same-as-new condition and performance for original use. Automotive parts are disassembled and re-machined during remanufacture.

Repair: Restore to operational condition.

Repurpose: Reuse a battery pack or components for a new and often less demanding application. Generally, requires reconfiguration and new BMS.

Reserve: That part of the reserve base which could be economically extracted or produced at the time of determination. The term reserves need not signify that extraction facilities are in place and operative. Reserves include only recoverable materials.

Resource: A concentration of naturally occurring solid, liquid, or gaseous material in or on the Earth’s crust in such form and amount that economic extraction of a commodity from the concentration is currently or potentially feasible.

Reuse: Using a product again with or without major modifications. (Generic term)

Reverse Logistics: Process of moving goods from their final destination for the purpose of capturing value or proper disposal.

Second Life: Use of an end-of-life battery for a new purpose.

Secondary Battery: Cell whose electrochemical reaction is reversible and therefore is capable of being charged and discharged more than once. Related: rechargeable battery

Secondary Material: Material that has been previously used and is to be used again.

Self Discharge: Discharge that takes place while the battery is in an open-circuit condition.

Separator: Porous membrane that allows the passage of ions but prevents electrical contact between the anode and the cathode.

Shallow Cycling: Charge and discharge cycles which do not allow the battery to approach its cutoff voltage.

Shelf Life: A period of time (measured from date of manufacture), at a storage temperature of 21 degrees C, after which the cell retains a specified percentage (usually 90%) of its original energy content.

Short Circuit: Condition that occurs when a short electrical path is unintentionally created.

Specific Energy: Gravimetric energy storage density of a battery, expressed in Watt-hours per kilogram (Wh/kg).

Specific Power: Gravimetric power density of a battery expressed in Watts per kilogram (W/kg).

State of Charge (SOC): Percentage of a battery’s total energy capacity that is still available to discharge (use). Comparable to an automobile’s fuel tank, with 0% being empty and 100% being full.

State of Health (SOH): Metric denoting quality of a rechargeable battery’s performance relative to its initial state; typically, the percentage of original capacity that remains usable.

Stationary Storage: Device for storing energy in a fixed location for future use.

Stranded energy: Energy remaining in used batteries that have not been fully discharged.

Tap Density: Density of a naturally-compacted powder used in an electrode.

Terminals: Parts of a battery to which the external electric circuit is connected.

Thermal Runaway: Condition whereby a cell will breakdown or fail through internal heat generation caused by high overcharge or high rate of discharge or other abusive conditions.

Universal Waste: Category of common waste materials designated as “hazardous.”

Upcycle: Recycle to a higher-value use. ReCell is trying to upcycle NMC111 to NMC811.

Voltage, Cutoff (or Final): Voltage at the end of useful discharge.

Voltage, End-Point: Cell voltage below which the connected equipment will not operate or below which operation is not recommended. (AKA cutoff voltage).

Voltage, Nominal: Voltage of a fully charged cell when delivering rated current.