The cylindrical cell has been the workhorse of lithium-ion battery manufacturing since Sony commercialized the 18650 format in 1991. Three decades later, a cylindrical cell production line must contend with a format landscape that has expanded from a single dominant size to three commercially significant form factors: the legacy 18650, the intermediate 21700, and the emerging 46xx large-format family. Each format imposes distinct requirements on winding equipment, canning stations, electrolyte filling systems, and formation protocols—and manufacturers investing in new capacity must decide whether to optimize for one format or build flexibility across multiple sizes.
The stakes of this decision are amplified by the scale of current investment. Global cylindrical cell production capacity exceeded 200 GWh in 2025 and continues to expand, by electric vehicle manufacturers adopting large-format cylindrical cells and by the enduring demand for 18650 and 21700 cells in power tools, e-bikes, and energy storage applications. A production line designed for the wrong format mix—or one that cannot adapt as market demand shifts—represents a capital misallocation measured in hundreds of millions of dollars.
Form Factor Comparison: Dimensions, Energy, and Thermal Behavior
The three cylindrical formats differ fundamentally in geometry, and geometry drives nearly every downstream equipment decision on a cylindrical cell production line.
The 18650 cell, with an 18-millimeter diameter and long history on the cylindrical cell production line and 65-millimeter length, established the manufacturing template that all subsequent cylindrical formats follow. A standard 18650 delivers approximately 3.5 ampere-hours of capacity using NMC or NCA cathode chemistry, translating to roughly 12 to 13 watt-hours per cell. The small diameter provides excellent heat dissipation due to a high surface-area-to-volume ratio, which simplifies thermal management during high-rate discharge but limits total energy per cell. A 60-kilowatt-hour EV battery pack requires approximately 4,500 to 5,000 individual 18650 cells, each with its own welded connections and thermal interface. The cylindrical cell production line for this format is highly mature.
The 21700 format—21 millimeters in diameter, 70 millimeters in length—increases cell volume by roughly 50 percent compared to the 18650, and transitioning a cylindrical cell production line from 18650 to 21700 requires changes while retaining the same can material (nickel-plated steel) and jelly-roll architecture. Typical capacity ranges from 4.5 to 5.5 ampere-hours, delivering approximately 17 to 20 watt-hours per cell. The 21700 reduces the cell count in a 60-kilowatt-hour pack to approximately 3,000 to 3,500 units, cutting the number of welded interconnects by roughly one-third. This reduction in connection points directly improves pack assembly yield and reduces per-kilowatt-hour manufacturing cost, which is why the 21700 became the dominant format for Tesla’s Model 3 and Model Y production.
The 4680 format—46 millimeters in diameter, 80 millimeters in length—represents a discontinuous change for the cylindrical cell production line rather than an incremental scaling. Cell volume increases by a factor of approximately five compared to the 21700, yielding a capacity of roughly 25 to 30 ampere-hours and 90 to 100 watt-hours per cell. At this scale, a 60-kilowatt-hour pack requires only 600 to 700 cells. But the larger diameter creates a thermal management challenge: the heat generated during charge and discharge must travel a much longer radial path to the cell surface, making the 4680 format dependent on novel thermal design features—particularly the tabless electrode architecture—to maintain acceptable temperature uniformity.
Equipment Adaptations Across Formats
A cylindrical cell production line built for 18650 or 21700 cells relies on a well-established equipment sequence: electrode slitting to the required width, winding the anode-separator-cathode sandwich around a central mandrel, inserting the jelly roll into a pre-formed steel can, welding the current-collector tabs to the can (negative) and cap (positive), electrolyte filling under vacuum, crimping or laser-welding the cap assembly, and formation cycling.
The 4680 format disrupts this sequence at multiple points. The most significant change is the tabless electrode design, which replaces the conventional single-tab or multi-tab current collection with a continuous laser-patterned edge along the full length of the electrode foil. Instead of welding discrete nickel or aluminum tabs to the current collector, the tabless design uses the uncoated edge of the foil itself as the current path, laser-cut into a pattern of closely spaced fingers that are folded and welded to the cell terminal. This architecture reduces internal resistance by shortening the electron path length through the electrode from a maximum of approximately half the electrode length (in a single-tab design) to a few centimeters in the tabless configuration.
The winding station on a 4680-capable cylindrical cell production line cylindrical cell production line must handle wider electrodes—the electrode width scales with cell height from approximately 58 millimeters for 18650 to roughly 75 millimeters for 4680—at higher winding tension and with precision alignment of the laser-patterned foil edges. Conventional winding machines designed for discrete tab welding cannot be adapted to tabless processing without replacing the winding head, the tab detection and positioning system, and the tension control architecture. The capital cost of a tabless-capable winding station is approximately 40 to 60 percent higher than a conventional winding station of equivalent throughput.
Can forming and sealing equipment scales with cell diameter. The can for a 4680 cell requires a deep-drawing press with higher tonnage and larger tooling than the can for a 21700 cell, and the can-sealing process—whether by crimping or laser welding—must accommodate a significantly larger cap circumference. Electrolyte filling time increases with cell volume: a 4680 cell may require two to three times the filling and wetting time of a 21700 cell at equivalent vacuum level and electrolyte viscosity, creating a throughput bottleneck that must be addressed through higher parallelization of filling stations.
Single-Line Multi-Format Design: Flexibility vs. Optimization
A dedicated cylindrical cell production line configured for a single format can be optimized for maximum throughput and minimum cost per cell, with every station tuned to one geometry. The winding mandrel diameter, can-handling tooling, electrolyte dosing volume, and formation protocol are all tuned to one cell geometry, and changeover between formats is not required. Single-format lines achieve the highest overall equipment effectiveness and the lowest capital cost per unit of annual capacity.
A multi-format cylindrical cell production line accepts the overhead of changeover in exchange for the ability to serve multiple cell markets from one production asset. Changeover between 18650 and 21700 formats on the same line is relatively straightforward: the winding mandrel, can-handling grippers, and formation contact fixtures are swapped, a process that can be completed in one to two shifts if the line was designed for quick changeover from the start. The electrode slitting width, coating pattern, and separator width are pre-configured for each format, and the coating line upstream must be capable of producing electrode rolls in multiple slit widths.
Incorporating 4680 capability into a multi-format line is substantially more difficult. The tabless winding station, larger can-handling equipment, and extended filling and formation times create a minimum efficient scale for 4680 production that is difficult to reconcile with the lower-throughput 18650 or 21700 operations running on the same line. Most manufacturers that produce 4680 cells do so on dedicated lines, reserving multi-format flexibility for the 18650-21700 pairing.
Cost per Kilowatt-Hour Across Formats
The economic case for each format on a cylindrical cell production line depends on the balance between cell-level manufacturing cost and pack-level integration cost.
At the cell level, larger formats reduce manufacturing cost per kilowatt-hour because the same winding, canning, and filling operations produce more energy storage capacity per unit of equipment time. A winding station producing 30 cells per minute generates approximately 1.8 kilowatt-hours per minute with 18650 cells, 4.5 kilowatt-hours per minute with 21700 cells, and 13.5 kilowatt-hours per minute with 4680 cells—a 7.5-fold throughput advantage for the largest format assuming equal winding speed in cells per minute. The capital cost of the winding station does not scale linearly with throughput, so the capital cost per kilowatt-hour of annual capacity declines as format size increases.
At the pack level, however, the cost advantage of larger formats is partially offset by higher thermal management complexity. The 4680’s larger diameter concentrates heat generation in a smaller number of larger cells, requiring more sophisticated cooling strategies—typically bottom-plate cooling or immersion cooling—compared to the side-cooling approaches that work effectively for 18650 and 21700 packs. [Battery pack teardown analyses](https://www.munrolive.com/) published by engineering consultancies indicate that the pack-level cooling system cost per kilowatt-hour for 4680-based packs is approximately 10 to 15 percent higher than for 21700-based packs of equivalent total energy, due to the higher cooling capacity required per cell.
Choosing a Production Line Strategy
The decision framework for a cylindrical cell production line investment rests on three questions.
First, what is the primary market? Manufacturers serving the EV market with large-format cells should evaluate dedicated 4680 cylindrical cell production line, accepting the higher capital intensity in exchange for the cell-level throughput advantage and the alignment with automotive OEM platform strategies that are increasingly designed around large cylindrical formats. Manufacturers serving diversified markets—power tools, e-bikes, medical devices, and industrial equipment—may find that a multi-format 18650-21700 line offers better capacity utilization across demand cycles.
Second, what is the technology trajectory of the electrode process? The 4680 cylindrical cell production line is closely associated with dry electrode processing, which eliminates the NMP solvent recovery and vacuum drying infrastructure that dominates wet-process electrode manufacturing cost. A production line that pairs tabless winding with dry electrode coating may achieve a step-change reduction in electrode manufacturing cost, but the dry electrode process remains in active development and has not yet been deployed at multi-gigawatt-hour scale across multiple manufacturers. The risk of committing a production line to a format that depends on an emerging electrode technology must be weighed against the cost advantage that technology promises.
Third, what is the realistic time horizon for format evolution? The 18650 has remained in volume production for over three decades. The 21700 has been in production for roughly eight years. The 4680 cylindrical cell production line is in its early years of volume ramp. A production line investment with a 15-year depreciation schedule must consider the possibility that a format introduced after the line is commissioned could capture market share, and that the line’s ability to accommodate new formats through retooling may determine its economic life.
Conclusion
The cylindrical cell production line market is settling into a three-format equilibrium. The 18650 remains relevant for smaller packs and legacy applications. The 21700 occupies the high-volume automotive middle ground. The 4680 targets the frontier of large-format performance, enabled by tabless electrode architecture and, increasingly, dry electrode processing. Each format demands different equipment specifications, different capital intensity, and different production economics.
For manufacturers evaluating new capacity, the central trade-off is between the proven reliability and multi-format flexibility of 18650-21700 lines and the compelling cost-per-kilowatt-hour arithmetic of the 4680 format. There is no universally correct answer—only the answer that aligns the production line design with the manufacturer’s market position, technology roadmap, and risk tolerance.
For cylindrical cell production line solutions covering 18650, 21700, and 46xx large-format cells, with options for single-format optimization or multi-format flexibility, visit TOBGROUP Solutions or explore our completed production line projects.
