Thermal distribution evolution model of SEI in lithium metal anodes

Abstract

Lithium metal batteries are considered an advantageous choice for high energy density batteries due to their extremely high theoretical specific capacity. However, the interface instability has always been the biggest challenge for the commercial development of lithium metal batteries. The evolution mechanism of the thermal field is a key factor affecting the cyclic life during the evolution of lithium metal interfaces. Herein, the interface evolution mechanism for the impact of thermal distribution on Li dendrites is revealed and quantified by the thermal distribution evolution model of the solid electrolyte interphase (SEI). Three influencing factors are outlined as follows: 1) the ratio of the SEI to electrolyte diffusion capability. 2) The SEI diffusion coefficients for both anionic and cationic species. 3) The anisotropy in the SEI. The results indicate that under the appropriate ratio, the temperature gradient at the tip of lithium dendrites and the SEI-electrolyte interface are lower, which is favorable for a more even distribution of heat within the SEI. Additionally, the diffusion of anions can also influence the temperature gradient during the evolution process of lithium dendrites. Furthermore, introducing anisotropy to the SEI can induce lateral growth of lithium dendrites and reduce the temperature gradient at the tip of the lithium dendrites and the SEI-electrolyte interface. This work provides valuable insights for the interface design of lithium metal batteries.