Lithium-ion Battery Production and Testing

Home Industries & Solutions Manufacturing & Inspection Lithium-ion Battery Production and Testing

Learn how Hioki can help your Li-ion battery inspection/testing in each production process

Li-ion Battery Production Process

  1. Mixing

    Active materials, conductive auxiliary agents, polymer binders, and organic solvents are mixed together to form an electrode slurry.

  2. Coating, Drying, and Calendering

    The electrode slurry is coated to copper and aluminum foil, dried, and calendared.

  3. Slitting

    The electrode sheets are slit to each battery size.

  4. Winding or Stacking

    A separator is inserted between the anode and cathode electrode sheets, and the electrode sheets are wound or stacked together.

  5. Tab Welding

    The tabs of the layered electrode sheets are welded together, and collectors are welded to the tabs.

  6. Terminal Welding

    The covers and collectors are welded together.

  7. Assembly

  8. Case Closing

    The covers and cases are welded together.

  9. Before Filling

  10. Electroyte Filling

    Electrolyte is filled via the electrolyte port.

  11. After Filling

    The electrolyte port is closed.

  12. Pre-charging

    Following electrolyte fill, a charging current is fed to the cells for the first time.

  13. Charging and Discharging

    The cells are repeatedly charged and discharged.

  14. Aging

    The cells are stored for a certain period of time.

  15. Pre-shipment inspection

    Quality is tested prior to shipment.

Li-ion Battery Inspection and Testing Methods

Lithium-ion Battery Insulation Resistance TestingOpen new window

Structurally, it’ s necessary to keep the anode and cathode electrodes, as well as the electrodes and enclosure (case), insulated from each other. Failure to keep those components properly insulated—in other words, insufficient insulation resistance - could lead to a risk of ignition or fire accidents.

This type of testing measures the insulation resistance between battery cells’ anode and cathode electrodes, and between the electrodes and the enclosure.

Lithium-ion Battery Weld Quality TestingOpen new window

If welds connecting tabs, collectors, and other battery components are insufficient, resistance between components will increase significantly, resulting in electrical energy loss and battery overheating. Such heating can reduce the battery’ s service life or cause fire.

This type of testing measures the resistance between welded components.

Charge/Discharge Testing of High-Voltage BatteriesOpen new window

Voltage and temperature are recorded during the charging and discharging test process in order to monitor changes in battery state. Recorded data is then analyzed to detect defects and rank batteries.

This type of testing records fluctuations in battery cells’ voltage and temperature across multiple channels.

Lithium-ion Battery Internal Resistance TestingOpen new window

Although batteries’ internal resistance would ideally be zero, internal resistance exists due to a variety of factors. Internal resistance increases as a battery degrades.

This type of testing measures battery cells’ internal resistance.

Lithium-ion Battery Open-circuit Voltage (OCV) TestingOpen new window

A battery’ s voltage when it is not connected to any load is known as the open-circuit voltage (OCV). OCV values gradually decline due to self-discharge, a characteristic of batteries. When a battery has an internal defect, self-discharge increases, causing the OCV to decrease beyond the defined value.

This type of testing measures battery cells’ open-circuit voltage.

Reducing testing times with multichannel measurementOpen new window

Testing times can be reduced by increasing the number of measurement channels, helping shorten lead times.

The DM7276, BT3562A, and BT4560 support up to 264, 132, and 72 channels, respectively. In addition, the SW1002 can connect to two different instruments, and the switching between them can be done automatically.

Managing Electrode Slurry qualityOpen new window

Electrode slurries consist of active materials, conductive auxiliary agents, polymer binders, and organic solvents. By ensuring these materials are uniformly dispersed, it is possible to produce batteries with favorable characteristics.

This process measures electrode slurries’ impedance. Calculations are then performed using a proprietary algorithm to quantify the slurry’ s mixture conditions based on measured values.

Managing electrode sheet manufacturing qualityOpen new window

To produce electrode sheets with favorable characteristics, manufacturers study materials, composition, and manufacturing conditions based on two indicators: the composite layer resistance and the interface resistance between the composite layer and collector.

The system allows users to visualize those two quantities by measuring the surface of the electrode sheet with a test fixture that consists of an array of test probes and then using proprietary analytical.