The Role of Elasto-Plasticity on Phase Kinetics in Lithiated Silicon Nanowires: Phase Field Simulation

Abstract

Silicon (Si) is a promising anode material for Li-ion batteries, since it absorbs large amounts of Li. In addition to volumetric expansion, huge stresses, and fracture, recent experiments reveal that the kinetics of Li insertion and extraction, which critically control the rates of charging and discharging, are of great importance for the high performance of LIBs. Here, we first propose a phase field model coupled to elasto-plasticity to study the lithiation kinetics in individual Si nanowires. In contrast to other models, the proposed phase field model is thermodynamically consistent, and the corresponding thermodynamic and kinetics parameters can be obtained from the experiments or Density function theory (DFT) calculations. The developed model describes well the experimental known self-limiting lithiation phenomenon, which is attributed to the retardation effect of the lithiation-induced stress. Further, the proposed model has general character and is applicable to any electrode systems.