Diffusion Induced Damage and Impedance Response in Lithium-Ion Battery Electrodes

Mechanical degradation, owing to intercalation induced stress and fracture, is a key contributor to the electrode performance decay in lithium-ion batteries. Solid state diffusion of lithium ions in the active particles causes concentration gradients, which results in stress generation and formation of microcracks or propagation of preexisting cracks. Formation and propagation of microcracks in turn affects the solid state transport of lithium ions and the interfacial charge transfer resistance. In this work, a systematic investigation of the influence of mechanical degradation on the resistance to diffusion and charge transport is provided. In this regard, a modeling approach combining fracture formation and electrochemical impedance is presented, which predicts the mechanical damage induced impedance response and resistance evolution in the electrode. The impact of particle size, charge/discharge rate and operating temperature on the electrode impedance response is illustrated. (C) 2014 The Electrochemical Society. All rights reserved.