Li-ion Cell Forced Internal Short-Circuit Tester

Lithium-ion Battery Forced Internal Short Circuit Testing Equipment China Manufacturer

Li-ion Cell Forced Internal Short-Circuit Tester is used to simulate the short-circuit between positive and negative active material coated area or between positive aluminum foil and negative active materials coated area of cylindrical cells or prismatic cells. The safety of the sample cells is determined by whether they catch fire during the test.

Our forced internal short-circuit tester features a temperature-controlled chamber and a set of press equipment in it.

The chamber enables you to set any desired test temperature from 0 to 100 degrees Celsius. The temperature in the chamber is uniform, and the heating and cooling speed are fast. The moving part of the press equipment with a maximum load of 1000 N can move at a constant speed and be stopped immediately when an internal short-circuit is detected. The position of the pressing jig is allowed to be maintained for a specified time before the pressure relief. The bottom surface of the pressing jig comes with a piece of nitrile rubber for the cylindrical cell test and a piece of acrylic resin attached to the nitrile rubber for the prismatic cell test.

Forced Internal Short Circuit Test on the Prismatic Cell

Test on the prismatic cell

Inside the short-circuit test chamber, we configure a pair of wire clips to connect to the positive and negative poles of the winding core for voltage measurement and thermocouple terminals to attach to the surface of the winding core for temperature measurement.

During the descent of the pressing jig, any of the three conditions of pressure, voltage, and deformation can be used as a single condition for ending the test.

You can also use any combination of these three test conditions as control variables. That is, after setting three or two test conditions at the same time, when any one of the conditions is satisfied, the machine will stop the test.

The entire test is controlled and run automatically by professional software installed on our configured computer. The software supports the input of various parameters, real-time data monitoring, and test results output.

Forced Internal Short Circuit Test on the Cylindrical Cell

Test on the cylindrical cell

If you are looking for a lithium-ion battery external short circuit tester, please go HERE.

Cell Forced Internal Short-Circuit Testing Machine Features

  • The material of the outer box is the cold-rolled steel plate, and the inner box is 304 stainless steel.

  • Equipped with a piece of thickened tempered glass on the door to observe specimens under test.

  • There is an explosion-proof lighting lamp inside the chamber to facilitate the observation.

  • A world-renowned compressor is used to meet various requirements for low temperatures.

  • Adopts a unique balance temperature adjustment method and PID control to achieve high precision and high stability temperature control inside the chamber.

  • Fitted with an touch screen on the front of the chamber to achieve chamber temperature adjustment and control.

  • Adopts servo motor and driver, coupled with the precision load cell to ensure accurate output and feedback of downward pressure.

  • Configured with a separate computer to bring an excellent human-computer interaction experience.

  • Supports the collection and real-time display of test data such as pressure, voltage, deformation, and sample surface temperature.

  • Test conditions for pressure, voltage, or deformation can be freely set. After meeting any set conditions, the pressure is automatically released to terminate the test.

  • Various test data and graphs can be displayed on the monitor in real-time.

  • It has alarm prompt functions, such as when a fault occurs and test is finished.

  • Equipped with overload emergency stop, up and down stroke limit, and other safety devices.

  • AMADE TECH can customize chambers with different sizes and features for users.

FAQ on Forced Internal Short-Circuit

  • The positive electrode material is impure or placed in the air for too long, resulting in incomplete drying. Suppose the metal impurities in the positive electrode material are not cleaned up. In that case, they will pierce the separator or promote the formation of lithium dendrites in the negative electrode, resulting in an internal short-circuit.

  • Short-circuit between copper/aluminum current collectors. Metal foreign objects that are not trimmed during battery processing or use pierce the separators or electrodes. The displacement of the pole piece or tab in the battery package causes contact between the positive and negative current collectors.

  • The quality of the lithium battery separator is not up to standard, and the lithium-ion battery pack is often charged and discharged with a large current during use. The separator cannot withstand the huge flow of lithium ions in a short period of time, resulting in partial or large area damage and severe heating.

  • During the cycle of the lithium-ion battery, due to the low lithium storage capacity of the negative electrode material or the excessive speed of the lithium ions struggling from the positive electrode, too many lithium ions are dissociated on the surface of the negative electrode. Over time, dendritic crystals are formed. When the dendrite grows to a certain length, it is easy to pierce the separator and cause a micro-short circuit of the battery. Too low temperature also contributes to the growth of lithium dendrites, so low temperatures can also cause micro-short circuits in lithium-ion batteries.

  • Many factors cause the internal short-circuit of lithium-ion cells, including the characteristics of the separator, whether the positive and negative materials are qualified, whether the production process and equipment meet the standards, and whether the packaging and transportation methods are qualified, overcharge and over-discharge, and so on. These factors may cause indirect or direct internal short-circuits of lithium-ion cells.
  • In order to grasp in advance whether there will be severe consequences in the event of an internal short circuit, we need a way to create this scene artificially. The cell forced internal short circuit test is to verify whether fire or explosion occurs when an internal short circuit occurs by simulating extreme conditions, thereby identifying the cell’s inherent safety characteristics and the battery system’s safety characteristics. A forced internal short-circuit test is a vital means to check battery material, quality, and safety of finished products.

1  Li-ion Cell Preconditioning

1.1  Prepare 5 pieces of lithium-ion cells per test temperature and charge them at (20±5) degrees Celsius based on the manufacturer’s recommendation, then discharge them at a constant current of 0.2 It A under the same temperature until they reach the voltage specified by the manufacturer is reached.

1.2  Store the specimens at an ambient temperature ranging from (10±2)℃ to (45±2)℃ for 1 hour to 4 hours.

1.3  Charge the specimens at an ambient temperature ranging from (10±2)℃ to (45±2)℃, at the upper limit charging voltage at the constant current specified by the manufacturer. When the upper limit charging voltage is reached, continue charging at constant voltage until the charge current drops to 0,05 It A.

2  Disassembly of charged cells and Insertion of nickel particles in winding cores

The disassembly of the cell and the insertion of nickel particles are the key steps in the preparation of samples for the forced internal short-circuit test, which are technically challenging. In order to ensure the safety of operation, the whole process is required to be carried out in a vacuum glove box. IEC 62133 has a dedicated section detailing how to operate on cylindrical and diamond cells. Please refer to ANNEX A.5 Sample Preparation.

3  Pressing the winding core with nickle particle

3.1  Preset and maintain the temperature inside the chamber to a value ranging from (5±2)℃ to (50±2)℃, then place the aluminum laminated bag with the winding core and nickel particle into the chamber for (45±15) min.

3.2  Take the winding core out of the bag and fix corresponding terminals for voltage and temperature measurements.

3.3  Place the winding core under the press equipment, ensuring that the position of the nickle particle is just under the pressing jig.

3.4  Remove the insulating sheet and close the chamber door.

3.5  Set various test conditions in the control software, including moving speed of the press equipment (0.1 mm / s), target voltage (original voltage – 50mV), pressure retention time (30 s), desired pressure value (800 N for a cylindrical cell or 400 N for a prismatic cell).

3.6  Confirm that the winding core surface temperature is in the range of (10±5)℃ to (45±5)℃, and click the “Start” button to allow the pressing jig to move down until either the voltage drop value or the pressure value comes first, the machine automatically maintains the pressure and then releases the pressure to end the test.

3.7  It should not cause a fire throughout the short circuit. Record the force when an internal short-circuit occurs if there was no fire.

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