Abstract
Dynamic behaviours of the core-shell structured (CSS) Si nanoparticles during electrochemical cycling were modelled. A core-shell-structured model that contained Si nanoparticles wrapped with amorphous carbon (a-C) was established. The system was charged and discharged under constant voltage with a dynamic loading applied on the surface of the particle. The volume change and associated stress simulated by the model without external loading were compared with the previous work done by other researchers and matched well. Different imposing moments of the external loading were introduced into this model to see the dynamic effects on the cycling behaviour of the Si particles. The present study illustrate the dynamic behaviour under external loading, which would give guidance for the Si based battery design and help to understand the coupling effects of dynamic loading and electrochemical cycling on Si anodes.
Highlights
Silicon is one kind of promising electrode materials for Lithium-ion batteries in the near future because of its high capacity (3579 mAh/g) [1, 2]
It is clear that the contact stress evolves nonlinearly in the first cycle while the stress evolution curve is almost linear in the subsequent cycle
The results show that the core-shell structure could help to reduce the contact stress of the Si particles and is an efficient strategy for stress management
Summary
Silicon is one kind of promising electrode materials for Lithium-ion batteries in the near future because of its high capacity (3579 mAh/g) [1, 2]. The large volume expansion/contraction of Si during lithiation/delithiation cycling has been the main barrier of its broad application [3]. These volume changes would lead to significant contact stress between particles and the stresses could cause fracture of particles or delamination of binder from particles. The fracture and delamination could lead to isolation of active particles the electrical network was damaged This is the main mechanism of the capacity fading in practical silicon based electrodes [4]. Zhao et al [10] studied the fracture and debonding in lithium-ion batteries with electrodes of hollow core-shell nanostructures. Liu et al [11] built up an analytical model on stress-regulated lithiation kinetics and fracture of a similar yolk-shell structure
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