No abstract

Ageing in Li-ion batteries is a prime concern, due to the rapid increase of their use as a power source for numerous applications from stationary applications to automotive industries. During a battery lifetime, state of health is deteriorating due to irreversible physical and chemical changes like loss of active Li+ ions, internal resistance rise, solid electrolyte interphase (SEI) growth, electrolyte oxidation and loss of active electrode material. This paper aims to demonstrate the potential of a non-invasive method: Magnetic Field Probing (MFP) for monitoring loss of porosity due to ageing in the battery. A multi-physics model using COMSOL Multiphysics simulation tool evaluates the magnetic field response, battery polarization (ohmic potential drop) and internal resistance (IR) of the Li-ion battery. The electrode porosity variation has a significant influence on the magnetic field response (MFR). The analysis shows that the porosity loss at graphite electrode has a major impact on the battery ageing factors (polarization and internal resistance). Moreover, research work infers that the MFR and IR have higher sensitivity at the anode. Approach: The Li-ion battery works on rock n chair concept. Li-ions travels back and forth between electrodes. The concentration of Li-ion shows the amount of energy the battery contains. During simulation the external magnetic field is applied with Li-ion battery module.Li-ion is a paramagnetic ion that alters the magnetic field. At anode, the change in Li-ions concentration during cycling will certainly change the applied magnetic field.Lithium metal oxide is used as cathode material. During charge-discharge cycle, lithium metal oxide converts to metal oxide. The process changes the phase and valency of metal ions. The phase and valency change of ions affect its magnetic properties and alters the value of applied magnetic field.The model uses LiMn2O4 as the cathode, LiC6 as the anode, and the electrolyte consists of LiPF6 salt in 1:2 EC:DMC solvent. A bidirectional coupling is used between the Li-ion battery an external applied magnetic field. Physics based Li-ion battery model equations and standard Maxwell's and Lorentz force equations are coupled Figure 1