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

Abstract

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.

Preface—Focus Issue on Battery Safety, Reliability and Mitigation

“…Combining with accurate data analytics and precise model predictions, such quantifications might become possible. Several articles [2][3][4][5][6][7][8][9][10][11][12] in this issue had shown some success, which is encouraging. In one example, 11 using Figure 1.…”

Temperature Dependence in Responses of Lithium-Ion Pouch Cells Under Mechanical Abuse

“…3b. The test approach is in line with the one adopted in one of our previous studies (Pan et al 47 ), so here we do not introduce how to demonstrate the sealing capability of the ziplock bag any more. Besides, it is also necessary to verify whether the ziplock bag for sealing the sample affects measurement of the force imposed on the tensile test sample.…”

“…4 To guarantee authenticity of the component level mechanical test results, oxidation of the active coating materials during the tests has to be avoided as much as possible due to their strong electrochemical activity. 47,48 Special procedures of sample preparation and testing were designed for tensile and compression tests, respectively, by protecting the samples inside an argon atmosphere.…”

The Nail Penetration Behaviour of Carbon Nanotube Composite Electrodes for Energy Storage

“…The electrodes in batteries are not symmetrical and are either made of graphite for the anode or inorganic lithium compounds as cathode material. In both cases they are sponge, foam like materials that contribute very little to the structural properties of the batteries themselves with yield and tensile strengths of < 10 MPa Wang et al (2018), Pan et al (2020). Due to this the cell will fail when either the nail or indentation head has passed through or crushed the first electrode it encounters and punctures the separator allowing current to flow through one electrode to the other.…”