Nonlinear Aging Characteristics of Lithium-Ion Batteries

Abstract

As the lithium-ion batteries become increasing prevalent in daily-life and industry, such as electric cars, aircrafts and portable devices, monitoring and predicting battery aging becomes critical. Typically, aging occurs due to multiple complex phenomena and reactions that are occurring simultaneously at different places in battery, and the degradation rate varies between different certain stages during a load cycle, depending on electric potential, local concentration, temperature, and also the direction of current. Battery aging is found to be linear in the early stage of cycling, however, highly non-linear at the end with rapid capacity drop. This nonlinear capacity drop phenomenon is called as “knee-point effect” and the cause leading to this is unexplored. In this work, we investigate this effect, by systematically account the mass and charge transport with interfacial reactions and parasitic solid-electrolyte-interface (SEI) and lithium plating forming reactions at the anode electrode surface as a function of porosity, C-rate and depth-of-discharge. Our findings are expected to improve the understanding of battery aging and we expect this fundamental model formulation to be promising for future predictive battery studies and design optimization.