Stress Analysis in Spherical Composition-Gradient Electrodes of Lithium-Ion Battery

In recent years, sufficient evidences have accumulated that novel spherical composition-gradient electrode materials exhibit excellent capacity, cyclability and charging rate. To investigate the mechanism of electrochemical performances of composition-gradient electrode, thermodynamic theory and Fick's law of diffusion are employed. The inhomogeneous diffusion coefficient may affect the rate of charge and discharge, and the increasing diffusion coefficient from center to surface along the radial direction may accelerate the rate of charge. The magnitudes of radial stresses and hoop stresses are reduced when the Young's modulus and partial molar volume decrease from center to surface along the radial direction, which means inhomogeneous Young's modulus and partial molar volume can protect the lithium-ion battery from capacity fading and mechanical degradation without sacrificing its capacity. (C) 2014 The Electrochemical Society. All rights reserved.