Plastic dissipation of high-capacity electrode materials during lithiation and de-lithiation processes.

The plastic deformation of high-capacity anodes during cycling is accompanied by energy dissipation. In certain cases, plastic dissipation can account for a considerable proportion of the total energy dissipation of the electrode system. Herein, a thermodynamically consistent multi-physics theoretical framework containing plasticity-related internal variables is developed to understand the heat conduction, species diffusion, and elastoplasticity mechanism interactions and to evaluate plastic dissipation. Si, Ge, and Sn anodes with a thin-film configuration on a rigid substrate and a free spherical configuration are considered. The corresponding plastic models and fitting parameters are introduced. Li insertion-associated energy flow is mainly transformed into reversible chemical energy, and part of the energy is consumed to drive Li diffusion and plastic flow. For the thin-film electrode unit, the energy dissipation mainly depends on the material properties, and a higher resistance for Li diffusion and plastic flow leads to a larger energy dissipation. A rough estimate shows that the plastic dissipation of Si, Ge, and Sn thin-film electrodes accounts for around 20, 10, and 5% of the total input energy, respectively. The energy dissipation of spherical electrodes is much smaller and strongly depends on the operation rate and size. Structure design and reducing the characteristic size of the electrode units can reduce energy loss and avoid energy waste. These works offer valuable insights into the plastic dissipation of high-capacity electrode materials and provide a theoretical framework for multi-physics modelling of electrode materials with plasticity. [ABSTRACT FROM AUTHOR]