Lithiation-induced stress and damage in electrode materials: Effects of current variations

Abstract

Lithium-ion batteries likely experience different structural evolution during electrochemical charging and discharging under dynamic environments from the corresponding one under “conventional” cycling conditions. In this work, we introduce a time-dependent influx in the analysis of the evolution of stress, strain, mechanical and chemical damages under galvanostatic operation. The time-dependent term is presented in two different forms – one in the form of a set of cosine terms and the other in the form of a Gaussian pulse. For the time-dependent term in the form of a single cosine term, both the angular frequency and amplitude contribute to the evolution of stress, strain, mechanical and chemical damages. The cosine term with a larger amplitude and/or a smaller angular frequency has a larger effect on the structural integrity of the electrode materials in LIBs than the corresponding one with a smaller amplitude and/or a larger angular frequency. For the time-dependent term in the form of a Gaussian pulse, the degradation of LIBs is dependent on the energy coefficient of the Gaussian pulse. Increasing the energy coefficient of the Gaussian pulse leads to the increase of mechanical and chemical damages.