Coupled effect of SOC and SOH on tensile behaviors of lithium-ion battery electrodes

Abstract

The mechanical properties of the electrodes, such as failure stress and failure strain, are critical to the electrochemical properties as well as the internal short-circuit modes of lithium-ion batteries (LIBs). These properties can be altered by different states of charge (SOC) and state of health (SOH). However, there is a lack of understanding of the coupled effect of SOC and SOH on mechanical properties of electrodes. To address this, uniaxial tensile tests combined with microstructure observation are conducted to investigate the effects of SOC, SOH, and strain rate on the mechanical properties. The results show that the effects of SOC and SOH on the anode are non-monotonic, while the failure stress of the cathode decreases slightly with increasing SOC and SOH. Two competing mechanisms (Li+ intercalation and cycle aging) are proposed to explain the non-monotonic response of anode. Additionally, the coupled effect of SOC and strain rate of anode is also discussed. Finally, the yield stress and failure strain maps of electrodes with various SOC and SOH are drawn to enrich the material basic database. The work provides valuable insights into the evolution of mechanical response of electrodes in different electrochemical states.