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INDUSTRY CLUSTER · New energy & green mobility

Liyang power batteries

Liyang traction-battery production is a problem of variation. Small differences in electrode loading, calendering, burrs, alignment, filling and formation grow into capacity, resistance and temperature spread in series-parallel modules. Jiangsu CATL, SAIC-CATL and Zhuogao occupy different cell, system and separator-material stages; five separate bodies of evidence cannot collapse into one battery pass.

Formation and regional foundations

Provincial administrative, transport and environmental material separately records Liyang High-tech Zone battery firms, industry scale, dangerous-goods shipments and manufacturing space. The cluster is organised through material, cell, system, test and logistics interfaces rather than treating vehicle manufacturing, every local new-energy project or Class 9 port handling permission as battery capacity.

Usable capacity in a series module is often set by the first cell to reach a voltage or temperature limit. Low capacity may originate in coating loading, calendered porosity, slitting burrs, winding alignment, electrolyte wetting or formation temperature, which final capacity alone cannot distinguish. Electrode roll, assembly station, formation channel and module position must connect to one cell identity.

Core geography: A Liyang High-tech Zone manufacturing and logistics area joining battery materials, cells, modules and packs, structural parts, testing and transport interfaces

Six variation-propagation stages in Liyang traction batteries

Whether module temperature spread returns to cells, interconnects, cooling or control limits

Nodes represent data and physical flow rather than fixed supply among firms. Roll, cell and module-position identities remain mapped.

  • Slurry, coating and electrode roll — Solids, viscosity, loading, drying and roll position describe an electrode segment together.
  • Calendering, slitting and clean edges — Density, thickness, porosity, burrs, dust and web tension enter pre-assembly judgement.
  • Winding or stacking and electrolyte filling — Electrode alignment, separator coverage, case cleanliness, vacuum and wetting time remain by cell.
  • Formation channel and capacity grading — Temperature, current, voltage, rests and channel calibration define the initial electrochemical record.
  • Module interconnect, compression and thermal management — Cell position, interconnect resistance, compression, cooling and BMS limits shape pack-level spread.
  • Transport condition and operating history — State of charge, package, temperature, shock and later operation remain separate from factory tests.

01 · A coating stripe may appear after hundreds of cycles

Loading, drying and roll position jointly define the electrode start.

Traction-battery electrodes begin as active material, conductive additive, binder and solvent slurry coated on current collector and dried. Liyang industry material covers battery materials and cells but cannot replace data for one electrode roll. Solids, viscosity, dispersion, coating gap, line speed and oven zones shape loading and residual solvent, while one roll may develop persistent longitudinal or cross-web stripes.

One average measurement at roll head, middle and tail may miss a local deviation from a coating edge or oven-air path. A slightly low-loading area may not dominate initial capacity yet changes local current density, porosity and ageing. Raising line speed for output without adjusting slurry rheology and drying can leave a visually uniform surface while adhesion and residual solvent have changed. An abnormal stripe follows web coordinates into downstream cells.

The coating record retains slurry lot, mixing time, solids and viscosity, filtration, collector roll, head settings, line speed, oven profile and web coordinates. Online and offline measurement first receive measurement-system comparison, with abnormal segments physically marked and isolated. A process change checks cross-web distribution, adhesion, residual solvent and representative-cell cycling as well as average loading, so higher speed does not carry stripes into grouping. First-roll confirmation also samples both web edges.

  • Slurry lot and web coordinates remain connected so average loading does not hide local stripes.

02 · Calender density and porosity cannot collapse into one number

Electrodes of equal thickness can have different transport and rebound.

Calendering compresses a dried electrode to target thickness and density while changing pore networks, particle contact and collector stress. A traction cell balances volumetric energy, ion transport and mechanical stability, and positive and negative electrodes do not share one window. Liyang cell and material firms provide different process capabilities, while a calender result still corresponds to chemistry, roll temperature, line pressure and incoming thickness.

Inferring density from thickness can misclassify a coating issue as calendering if loading or collector thickness already varies. The electrode also rebounds after the rolls, so different sample time and gauge pressure give different thickness. Excess compaction can reduce wetting and rate, while insufficient compaction increases contact and volume variation; roll temperature, deflection and web joints create cross-web density gradients.

The calender baseline records chemistry and coated roll, gap, pressure, temperature, speed, roll surface and environment, with thickness and density measured at fixed time and method. Samples cover head-tail, edge-centre and web-joint regions, adding porosity and adhesion where needed. A material or loading change re-establishes the window and uses wetting and rate performance to verify pore function rather than treating higher density alone as improvement; the first roll after a roll change receives a separate confirmation.

  • Density, thickness, porosity, rebound and temperature are evaluated by web position.

03 · Average size is useless when a slitting burr approaches the separator

Edge defects and metal dust are local safety risks.

Electrode slitting defines width and edge quality, while blade wear, tension, tracking and collector condition create burrs, shedding and wavy edges. A separator divides electrodes, but local metal burrs or particles near it are not explained by average width. Liyang’s battery chain includes separator and cell interfaces, where separator performance and electrode cleanliness meet during assembly rather than remaining separate factory passes.

Inspecting a few edge segments can miss rapid blade deterioration before replacement, while the first segment after replacement may have defects from installation or cleaning. Room-air particle monitoring does not describe deposits on the web or blade area. Extending blade life to reduce stops enlarges the tail of burr height, and later winding compression can turn a small anomaly into separator damage without immediate final-voltage failure.

Slitting records parent roll, strip position, blade identity, accumulated length, tension, speed and extraction state, with edge inspection sampled along length. Blade changes, breaks and joints are marked separately, and metal dust or burr events quarantine a traced preceding interval. Closed movement and clean storage remain before assembly, and mapping from strip to cell identity returns later short or self-discharge events to a blade period. A slit-width change updates the vision region at the same time.

  • Each slit strip retains parent-roll position, blade life and edge inspection.

04 · A half-millimetre stack shift changes edge electrochemical load

Electrode alignment, separator coverage and case cleanliness jointly define assembly risk.

Winding or stacking places positive electrode, negative electrode and separator into a case with designed overlap, where dimensions, tension, location and separator width define edge margin. Different cell formats use winding, stacking or a combination and cannot share one alignment threshold. Liyang firms cover cells and separator materials, while assembly still proves how each material lot and equipment recipe forms a particular cell.

Vision may pass planar edges while missing internal folds, accumulated tension or particles attracted by separator static. If web width and camera coordinates are not updated together after recipe change, equipment produces a stable systematic shift. Particles from the case or tab welding may move after sealing, and average assembly yield does not reveal the machine, shift or web segment where the issue concentrates.

The assembly baseline fixes electrode and separator widths, overlap, tension, vision coordinates, case cleanliness, tab position and recipe revision, with first pieces opened or imaged to confirm internal relationships. Every cell binds positive, negative and separator rolls, machine, time and vision result, stratifying anomalies by equipment and web position. Maintenance, camera calibration or material-dimension change triggers boundary-sample regression rather than using an automatic-running flag as assembly geometry evidence. Alignment imaging retains the original frame without decision overlays.

  • Vision decisions align with cell identity, web lots and equipment recipe.

05 · End of filling is not the moment electrodes are wetted

Vacuum, pores, temperature and rest determine where electrolyte reaches.

Electrolyte must cross winding or stack pores and contact electrodes and separator; accepted fill mass does not establish uniform distribution. Density, electrode area, separator wetting, vacuum, temperature, dosing sequence and rest all change absorption. Liyang’s cluster has cell and material interfaces, while a specific electrolyte formula and filling process remain product evidence rather than an inference from the cluster name.

Cell weighing finds gross underfill but can be obscured by case, stack and weld-mass variation, while several small doses and one fill create different wetting paths. Shorter rest for throughput may preserve initial capacity yet reveal dry regions during rate or cycling. Vacuum leakage, nozzle residue or electrolyte temperature produces machine- and time-specific patterns that disappear in one daily output figure.

The filling record connects electrolyte lot, temperature, moisture, equipment, nozzle, vacuum profile, weight, rest and sealing time, with windows by cell structure. The weighing system uses standards and empty cases, while process samples use imaging, opening or electrochemical response to evaluate wetting. Density, separator, formulation or cycle change triggers renewed absorption and rest confirmation rather than treating one fill mass as universal across formats. Wetting rest starts at completed sealing, not equipment release.

  • Fill mass and wetting time are interpreted against cell structure and prior porosity.

06 · A formation channel can write its error into capacity

Current, temperature, rest and calibration jointly define the first electrochemical record.

Formation uses controlled charge-discharge to establish interfaces and record initial capacity, efficiency and voltage, followed by grading that may add resistance and self-discharge. Channel current-voltage accuracy, temperature, contact resistance, rests and programme revision affect results. Liyang shipment and capacity figures do not describe the grading quality of one lot; each cell remains tied to channel, time and calibration state.

A row of channels with slight current bias creates an equipment pattern in the capacity distribution; grading on the result alone turns measurement error into cell grade. Temperature-zone variation changes interface formation and resistance, while rest changes open-circuit voltage and self-discharge judgement. Changing programmes for utilisation without retaining the revision leaves later cycle variation unable to distinguish upstream cells from first-charge conditions.

The formation system retains channel calibration, contact check, temperature, current-voltage trace, programme checksum and interruption, with standards or cross-channel tests identifying equipment bias. Before grading, distributions are viewed by channel, temperature zone, prior web and assembly time; equipment patterns prompt retest and isolation first. Grouping uses corrected capacity, resistance and self-discharge while returning anomalies upstream so grading does not become permanent concealment. Cells after channel repair are reviewed as a separate distribution.

  • Capacity distribution first removes channel and temperature-zone differences before cell process is judged.

07 · A module turns small resistance differences into a heat map

Interconnect, compression, cooling and BMS further amplify or restrain variation.

Cells enter modules and packs through busbars, welds, compression, structures, cooling and BMS. Liyang entities such as SAIC-CATL represent pack-system interfaces, while Jiangsu CATL represents cell manufacture; their responsibilities do not merge through group or partnership. Similar grouped capacity can still produce different heat and ageing from interconnect resistance, cooling position and compression under one current.

Replacing the hottest cell after detecting module temperature spread may overlook weld resistance, cooling contact or sensor bias. BMS balancing can temporarily align state of charge but cannot repair capacity or resistance causes, and excessive balancing adds heat. Structural tolerance and compression change with cycling, while a short laboratory test may miss long-term swelling. Without mapping cell position and lot, position and lot effects are mixed.

Module assembly records cell identity and position, joining process, weld inspection, compression, thermal material, cooling circuit and sensor calibration. Pack tests compare cell voltage, temperature and spread across ambient, power, state of charge and cooling faults with control software retained. Swaps, thermal imaging and resistance measurement first separate cell from position before grouping, structure or control is changed. Cooling-circuit venting can also change local temperature spread.

  • Pack evaluation separates cell body, interconnect resistance, thermal path and control limits.

08 · Dangerous-goods shipment proves only this condition can be handed over

Package, state of charge and test documents do not equal service life or recycling outcome.

Lithium-battery shipment involves product condition, state of charge, package, marking, test documents and carrier conditions, and Jiangsu transport material identifies the Class 9 dangerous-goods boundary. Port or transport permission allows handling under stated conditions; it does not prove capacity, quality or remaining life. After entering a vehicle, batteries experience temperature, rate, incidents and repair, so factory evidence cannot decide future second-life use.

Checking only outer packaging before shipment can carry internal alarms, insulation faults or damage into logistics. Transport temperature, shock or water exposure changes receipt condition, which quantity-only receipt misses. Grading retired packs by initial capacity without operating history, incidents, repair and current consistency carries unknown risk into a new use, while discarding every retired pack also ignores measurable differences.

A shipment binds battery identity, factory tests, state of charge, insulation, appearance, package and dangerous-goods documents, with necessary temperature and shock recorded and receipt checked by risk. Operators retain faults, repairs, thermal events and use data. At retirement, safe isolation precedes applicable condition and destination assessment. Manufacturer, carrier, user and recycler accept responsibility at handovers rather than one certificate covering the lifecycle. Receipt appearance anomalies are isolated rather than repackaged.

  • Factory, transport, use and retirement retain four different state records.

Sources and reading notes

Cell data is stratified by material lot, electrode position, assembly time, formation channel and test temperature. Module evaluation adds interconnect, compression, cooling and control revision. Transport and recycling describe only permitted and inspected states, without converting shipment quantity into manufacturing capability.

  • Company shipments, project capacity, industry sales and port dangerous-goods handling each retain their own year and object and are not added together.
  • Cell grading manages variation already created; it does not repair coating, slitting, filling or formation causes.
  • Retirement state and recycling responsibility follow operating history and later inspection rather than being declared at factory release.

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Sources

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