Key points are not available for this paper at this time.
Although battery electrode models have been developed to study electrochemical processes and mechanical behavior, including mechanical damage, the response of electrode materials to external mechanical loads remains underexplored. This study considers externally applied loads and mechanical damage in two contexts: high loads that may cause mechanical damage, and low-magnitude harmonic loads used to characterize mechanical damage during dynamic mechanical analysis (DMA). This work establishes a multiphysics framework that addresses the previously overlooked role of externally applied loads and allows their effects to be evaluated alongside electrochemical cycling. A three-dimensional model is used to solve for the microscopic field variables for ion transport, electrochemical reactions, deformation, stress, and mechanical damage, including the effects of applied stress. Electrochemistry and mechanics are coupled through a lithium diffusion strain in the redox-active particle and through the influence of damage on mechanical, transport, and kinetic properties. Damage surfaces, illustrating regions of damage-free operation, are shown as functions of C rate, particle size, matrix stiffness, and applied stress, based on a strain energy criterion. Simulations of electrochemical impedance spectroscopy (EIS) and DMA are used to quantify damage in both the particle and matrix. It is shown that EIS can distinguish surface particle damage from bulk particle damage through the frequency-dependent complex impedance, where damage is quantified by fitting the impedance spectra to a Randles circuit. DMA is less successful in measuring particle damage in conventional battery materials because the matrix stiffness is too low. However, DMA is more successful for matrix materials with higher stiffness.
Metlich et al. (Thu,) studied this question.