Effect of State-of-Charge and Air Exposure on Tensile Mechanical Properties of Lithium-Ion Battery Electrodes

The large deformation and failure behaviors of electrodes under various SOC conditions are essential for understanding the battery impact response and reconstructing battery impact scenarios with numerical methods. Depending on the chemical activity, the electrodes may react with oxygen if exposed to air, which leads to change of mechanical properties to some extent. To obtain the real mechanical properties of electrodes as they are sealed inside a battery, an argon-protected testing method was developed to test the electrodes. In this way, we identified the SOC sensitivities of tensile behaviors for the electrodes extracted from a pouch cell for electronic devices. The mechanical properties of anode change with SOC but the cathode does not present apparent difference. By comparing test results of anode and anode current collector under different SOCs, we inferred that anode current collector is responsible for the SOC effect of anode. We further evaluated the influence of oxidation on the tensile behaviors of electrodes at different SOCs after exposing them in the air for different durations. For anodes from charged batteries, we come up with a couple of competing mechanisms to explain the non-monotonic change of mechanical properties along with air exposure.