Rate-dependent lithiation-induced failure modes of a cylindrical core-shell electrode

Abstract

The cylindrical core-shell electrode is regarded as one of the promising electrodes for lithium-ion batteries (LIBs) due to its high capacity and stable electrochemical performance. However, owning to the intrinsic structural characteristics of the cylindrical core-shell structure, failures, including fracture of the shell, delamination between the core and the shell, and buckling of the structure, have been observed in experiments and may lead to the mechanical degradation of LIBs. To avert such failures, we employ a rate-dependent model to investigate the critical conditions for the occurrence of the failures. The effects of the shell thickness, core radius, ratio of outer radius to inner radius of the core, and charging rate are evaluated. The calculation results reveal that the shell thickness and the core radius can alter the sequence of different failures, while the ratio of outer radius to inner radius of the core does not have much influence on failures, and the charging rate affects the critical state of charge (SOC) for the onset of failures. Moreover, failure diagrams of the core-shell structure for the variations of geometric features are constructed to obtain the overall optimal values of geometric dimensioning for averting failures, which may guide the design of electrodes.

Keywords

• Rate-dependent
• Failure modes
• Core-shell structure
• Viscoplasticity
• Lithium-ion batteries