Battery Manufacturing Process

electrode · assembly · formation · pack

Every lithium-ion cell passes through the same three stages regardless of format. Drying, dry rooms and formation set a cell plant's energy bill and its yield.

Lithium-ion cell manufacturing in three rows. Electrode: mix, coat, dry, calender, slit. Cell assembly: stack or wind, weld tabs, dry room, electrolyte fill, seal. Finishing: formation, aging, test, module, pack. Drying, the dry room and formation are highlighted as the energy-heavy steps; module and pack assembly is often done at or near the vehicle plant. ELECTRODE: SLURRY TO COATED FOIL Mix Coat Dry Calender Slit CELL ASSEMBLY: ELECTRODES TO SEALED CELL Stack/wind Weld tabs Dry room Fill Seal FINISHING: FIRST CHARGE TO PACK Formation Aging Test Module Pack energy-heavy step cell plant often at or near the vehicle plant
Stages
Electrode, cell, finish
Dry room humidity
<1% RH
Formation plus aging
Days to weeks
Solvent-free route
Dry electrode
Hub
Supply Chain

Finding

Cell cost and yield are decided in the electrode line and in formation, which is why process changes there - dry electrode coating, faster formation - matter more than cell format

Cylindrical, prismatic and pouch cells share one flow: coat cathode slurry on aluminum foil and anode slurry on copper foil, dry and compress the electrodes, assemble them with a separator in a dry room, fill with electrolyte, then charge the cell for the first time (formation) and hold it for days to weeks (aging) to screen out defects. Electrode drying with NMP solvent recovery, dry-room air handling and formation cycling are the largest energy loads in a cell plant.

Chinese makers set the benchmark for speed and scrap rate: CATL, BYD, CALB, EVE and Gotion run lines at a scale and yield that new Western plants have struggled to match - Northvolt's failure to ramp its Skellefteå plant ended in bankruptcy in 2025. Korean and Japanese makers (LG Energy Solution, Samsung SDI, SK On, Panasonic) run most US cell plants. Most coating, calendering, winding and formation equipment comes from Chinese suppliers such as Wuxi Lead, Yinghe and Hymson, alongside Korean and Japanese toolmakers.

Dry electrode coating removes the slurry solvent and the drying oven. Tesla has scaled a dry cathode process for 4680 cells at Giga Texas; LG Energy Solution and others are piloting it. Module and pack assembly is less automated, less energy-intensive and is usually done near the vehicle plant.

Process

Process steps

The 14 steps from slurry to pack. Formation and aging are the longest; electrode coating is the most capital-intensive.

Lithium-ion cell and pack manufacturing steps
StepStageKey inputsOutput
Slurry mixingElectrodeCathode (NMC, LFP) or graphite anode powder, binder, conductive carbon, solventUniform slurry
CoatingElectrodeAluminum foil (cathode), copper foil (anode)Active material on current collector
DryingElectrodeConvection ovens; NMP solvent recovery on the cathode lineSolvent removed
CalenderingElectrodeHeated rollersTarget thickness, density and porosity
SlittingElectrodeElectrode rollsElectrode strips at cell width
Stacking or windingCellAnode, cathode, separatorElectrode stack or jelly roll in a can or pouch
Tab weldingCellLaser or ultrasonic weldersTabs joined to terminals or collector plates
Dry room holdCellAir below 1% relative humidityMoisture-free cell before fill
Electrolyte fillingCellLiPF6 in carbonate solvents (EC, DMC)Wetted electrodes
FormationFinishControlled first charge and dischargeSolid-electrolyte interphase (SEI) on the anode
AgingFinishDays to weeks at controlled temperatureSelf-discharge screening
Cell testingFinishCapacity, voltage, internal resistanceGraded, matched cells
Module assemblyPackCells, busbars, thermal interfaceSeries-parallel blocks; skipped in cell-to-pack designs
Pack assemblyPackModules or cells, BMS, cooling, enclosureFinished EV or BESS pack

Energy

Where the energy goes, and the electrified fix

Energy-heavy steps and electrified alternatives
StepConventionalElectrified or eliminatedStatus
Electrode dryingGas-fired or resistive convection ovens; NMP recoveryDry electrode coating; infrared or laser dryingDry cathode in Tesla 4680 production; others piloting
Dry roomsLarge air-handling and desiccant systemsMini-environments around critical stepsCommon in new Chinese lines
FormationResistive cyclers that burn energy as heatRegenerative bidirectional cyclers; shorter protocolsStandard on new lines
CalenderingHydraulic pressesServo-driven rolls with inline thickness controlStandard
Pack assemblyPneumatic toolsElectric servo robots and torque toolsStandard in gigafactories

EV vs BESS

EV and BESS cells

EV versus stationary storage cells
CategoryEV cellsBESS cells
ChemistryLFP for most volume; NMC and NCA for long rangeLFP almost entirely; sodium-ion entering
FormatCylindrical, prismatic, pouchLarge prismatic (280 to 500+ Ah)
PriorityEnergy density, fast chargingCycle life, cost per kWh, safety
Thermal managementLiquid coolingLiquid cooling in most new containers

Sources

Sources and scope

Scope
Battery Manufacturing Process
Sources
Manufacturer disclosures; equipment supplier literature; Northvolt bankruptcy filings (2025)
Updated
October 2026