GB/T 43092-2023Electrochemical performance test of lithium ion battery cathode materials—Test method for high temperature performance (English PDF)

3.1 Charge and discharge

of 6 µm~20 µm.

5.2 Apparatus

5.2.1 Electronic balance: The division value is 0.0001 g.

5.2.2 Mixer.

5.2.3 Small coater or scraper.

5.2.4 High-temperature oven: The temperature control range is from room temperature to 250 °C.

5.2.5 Roller press: It is dedicated to lithium batteries.

5.2.6 Thickness gauge: The measuring range is not less than 2 mm, and the accuracy is 0.001 mm.

5.2.7 Electrode punching machine: The diameter of the punching die is 10 mm~16 mm.

5.2.8 Electronic balance: The division value is 0.00001 g.

5.2.9 Vacuum oven: The temperature control range is from room temperature to 250 °C, and the vacuum degree is not greater than -0.1 MPa.

5.2.10 Glove box: inert gas atmosphere; moisture content and oxygen content are not greater than 0.0001%.

5.2.11 Button battery sealing machine

Assembly shall be carried out in the glove box (5.2.10). Assemble the positive electrode (see 5.3.1), negative electrode (5.1.6), separator (5.1.7), liquid absorbent paper (5.1.8), electrolyte (5.1.9), button battery case and components (5.1.10) together, use the button battery sealing machine (5.2.11) to seal the battery, and use the lithium-ion battery electrochemical performance tester (5.2.12) to carry out the charge and discharge tests.

5.4 Testing of button half cells

5.4.1 High-temperature storage test

5.4.1.1 After the produced battery is left to stand for 6 hours, it is placed in an environment of 25 °C±1 °C. Use the lithium-ion battery electrochemical performance tester (5.2.12) to conduct the first charge and discharge tests by referring to the following process:

a) Constant current charging: current of 0.1 C, constant current charging to the limiting voltage;

b) Constant voltage charging: cut-off current of 0.01 C;

c) Standing: 10 min;

d) Constant current discharge: current of 0.1 C;

e) Standing: 10 min;

f) Constant current charging: current of 1 C, constant current charging to the limiting voltage;

g) Constant voltage charging: cut-off current of 0.01 C;

h) Standing: 10 min;

i) Constant current discharge: current of 1 C, constant current discharge to the cut-off voltage;

j) Standing: 10 min;

k) Repeat 2 times according to f) ~ j);

l) Constant current charging: current of 1 C, constant current charging to the limiting voltage;

m) Constant voltage charging: cut-off current of 0.01 C.

NOTE: Please refer to Table 1 for the limited charge voltage and cut-off discharge voltage of different materials.

5.4.1.2 After the battery has been left at room temperature for 4 hours, use a voltage tester (5.2.13) to test the voltage, and then place it in a high-temperature environment for a certain period of time (It is recommended to be stood at 60 °C for 7 days). After storage, take the battery out, let it stand at room temperature for 4 hours, and then test the battery voltage. The charge and discharge tests can be carried out according to the following process:

a) Constant current discharge: current of 1 C, constant current discharge to the cut-off voltage;

b) Standing: 10 min;

c) Constant current charging: current of 1 C, constant current charging to the limiting voltage;

d) Constant voltage charging: cut-off current of 0.01 C;

e) Standing: 10 min;

f) Constant current discharge: current of 1 C, constant current discharge to the cut-off voltage;

g) Standing: 10 min;

h) Repeat 5 times according to c) ~ g).

NOTE: Please refer to Table 1 for the limited charge voltage and cut-off discharge voltage of different materials.

5.4.2 High-temperature cycle test

The manufactured battery is left to stand for 4 hours in a high-temperature environment (recommended at 45 °C±1 °C), and the charge and discharge tests are performed in the above-mentioned high-temperature environment with reference to the following process:

a) Constant current charging: current of 0.1 C, constant current charging to the limiting voltage;

b) Constant voltage charging: cut-off current of 0.01 C;

c) Standing: 10 min;

d) Constant current discharge: current of 0.1 C, constant current discharge to the cut-off voltage;

e) Standing: 10 min;

6.1.14 High-temperature tape

6.1.15 Termination tape

6.2.23 Electronic solid density meter

6.2.24 Internal resistance tester

6.2.25 Hot pressing formation machine

6.3 Manufacturing steps for soft-packed full batteries

6.3.1 Raw material handling

Use a vacuum oven (6.2.1) to bake the cathode material (6.1.1), and use a high-temperature oven (6.2.3) to bake conductive agent (6.1.2), positive electrode binder (6.1.3), negative electrode material (6.1.7), negative electrode dispersant (6.1.8).

6.3.2 Preparation of positive electrodes

The environmental dew point during the preparation process shall not be greater than - 20 °C. In the formula, the mass fraction of the cathode material is 90%~98%, the mass fraction of the conductive agent is 1%~5%, and the mass fraction of the positive electrode binder is 1%~5%. Weigh the processed cathode material (see 6.3.1), conductive agent (see 6.3.1), positive electrode binder (see 6.3.1), and positive electrode solvent (6.1.4) with an electronic scale (6.2.2); use a vacuum mixer (6.2.4) to prepare a positive electrode slurry with a solid content of 40%~75%, and use a coating machine (6.2.5) to apply the positive electrode slurry to the positive electrode current collector (6.1.5) and dry it. Strictly control the process of homogenization and coating.

The thickness of the electrode coating shall be uniform. Use a slitting machine (6.2.6) to cut the positive electrode, use a roller press (6.2.7) to roll (the compaction density reference range is shown in Table 2), and use a thickness gauge (6.2.8) to test the thickness of the electrode during rolling. Use an electronic balance (6.2.9) to weigh the baked electrode and record it.

6.3.3 Preparation of negative electrodes

The environmental dew point during the preparation process shall not be greater than - 20 °C. In the formula, the mass fraction of negative electrode material (6.1.7) is 95%~97%, the mass fraction of conductive agent (6.1.2) is 0.5%~1%, the mass fraction of negative electrode dispersant (6.1.8) is 1.0%~1.5 %, and the mass fraction of negative electrode binder (6.1.9) is 1.5%~2.5%. Use the negative electrode material, conductive agent, CMC, SBR, and negative electrode solvent (6.1.10) to prepare the negative electrode slurry with a solid content of 40%~60%, and use a coating machine (6.2.5) to apply the negative electrode slurry to the negative electrode current collector (6.1.11) and dry it. Strictly control the process of homogenization and coating. The thickness of the electrode coating shall be uniform. The negative electrodes shall be rolled, cut, baked, and weighed respectively.

6.3.4 Assembly of soft-packed full batteries

The dew point of the battery assembly environment shall not be greater than -20 °C.

Preparation method of wound cells: The positive electrode (see 6.3.2) and the negative electrode (see 6.3.3) are welded with tabs by using the positive electrode ultrasonic welding machine (6.2.10) and the negative electrode ultrasonic welding machine (6.2.11 ) respectively; use a winding machine or laminating machine (6.2.12) to wind the positive electrode (see 6.3.2), separator (6.1.13), and negative electrode (see 6.3.3) into a wound cell. Preparation method of laminated cells: Use a laminating machine (6.2.12) to laminate the positive electrode (see 6.3.2), separator (6.1.13), negative electrode (see 6.3.3), and separator (6.1.13) in sequence, and use the positive electrode ultrasonic welding machine (6.2.10) and the negative electrode ultrasonic welding machine (6.2.11) to weld the tabs then to make the laminated cell.

Use the aluminum plastic film forming machine (6.2.14) to make the aluminum plastic film (6.1.16) into the aluminum plastic case, and use the jellyroll pressing machine (6.2.13) to flatten the wound cell or laminated cell and place it into the aluminum plastic case; after that, use the top-side sealing machine (6.2.15) to seal the top and side edges.

Put the battery into a vacuum oven (6.2.1) to bake (the baking regime is recommended to be 85 °C, 36 h; replace the dry gas every 4 h), use the liquid injector (6.2.17) in the glove box (6.2.16) to inject liquid, use a vacuum standing box (6.2.18) to let it stand, and use a vacuum pre-sealing machine (6.2.19) to pre-seal.

6.3.5 Formation and capacity grading for soft-packed full batteries

6.3.5.1 Clamp the prepared battery with plywood, and use a lithium-ion battery electrochemical performance tester (6.2.20) or a hot-pressing formation machine (6.2.25) to form the battery. The test can be carried out by referring to the following process:

a) Constant current charging: current of 0.05 C, charging for 200 min;

b) Constant current charging: current of 0.1 C, charging for 200 min;

c) Constant current charging: current of 0.2 C, charging to the limiting voltage (recommended limiting voltage is 3.9 V, lithium iron phosphate is 3.4 V);

d) Standing: 10 min.

6.3.5.2 Use a vacuum second sealing machine (6.2.21) to degas air and seal, and use a lithium-ion battery electrochemical performance tester (6.2.20) to conduct charge and discharge tests by referring to the following process:

a) Constant current charging: Constant current charging to the limiting voltage;

e) Standing: 10 min;

f) Repeat 2 times according to a) ~ e);

g) Constant current charging: a constant current of 1 C, charging to the limiting voltage;

h) Constant voltage charging: cut-off current of 0.02 C.

NOTE: The limited charge voltage and cut-off discharge voltage of different materials are shown in Table 2.

b) Standing: 10 min;

e) Standing: 10 min;

g) Standing: 10 min;

NOTE: The limited charge voltage and cut-off discharge voltage of different materials are shown in Table 2. […]