Modified Stoney Model and Optimization of Electrode Structure Based on Stress Characteristics

Abstract

Stress in electrodes is inherently linked to mechanical failure that leads to degradation of cycle performance. To optimize battery performance, we propose a modified Stoney model to study the deformation and stress of a bilayer electrode. This model couples bending deformation and electrochemical‐dependent elastic modulus of active layer, and we apply the model to systematically analyze how thickness ratio l, modulus ratio m, bending, and electrochemical‐dependent elastic modulus impact stresses across a wide range. Results show that stresses non‐monotonously vary with l and m. Surface stress of active material transforms from a trend of first decrease and then increase to monotonous increase with m, and first increases and then decreases with l. Therefore, Li‐induced softening and stiffening as well as Li‐induced‐increased thickness relieve stresses within a certain range. Based on stress characterization, some electrode structures are suggested to improve battery performance. For a constant elastic modulus of active layer, l and m should be smaller or make stress factor close to 0. And l and m should be selected on the left (right or near) of extreme points for softening (stiffening) of active layer. This work provides a comprehensive stress analysis to guide the optimization of electrode structures.

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