Multiscale Investigation of the Diffusion Mechanism within the Solid-Electrolyte Interface Layer: Coupling Quantum...

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• The solid-electrolyte interface (SEI) layer is crucial for lithium-ion battery (LIB) lifespan, yet its complex nature leads to significant capacity loss (over 50%) in commercial LIBs.
• Current mathematical models often oversimplify SEI layer behavior by using constant diffusion coefficients, failing to accurately predict capacity fading and SEI growth.
• Understanding diffusion mechanisms within the SEI layer is essential for improving battery longevity and performance.

Purpose of the Study:

• To develop a multiscale approach for investigating diffusion mechanisms within the SEI layer of LIBs.
• To derive equations for evaluating the energy barrier and diffusion coefficient in the inner SEI layer.
• To provide a more accurate basis for mathematical modeling of LIB performance.

Main Methods:

• Employed a multiscale investigation combining quantum mechanics, molecular dynamics, and macroscale mathematical modeling.
• Developed equations to calculate the energy barrier against diffusion and the diffusion coefficient.
• Evaluated these equations as a function of temperature and concentration for different SEI crystal structures.

Main Results:

• Presented novel equations to quantify diffusion barriers and coefficients within the SEI layer.
• Demonstrated the dependence of diffusion parameters on temperature, concentration, and SEI crystal structure.
• Established a foundation for more accurate modeling of SEI layer dynamics.

Conclusions:

• The derived equations offer a more precise method for studying SEI layer diffusion mechanisms in LIBs.
• These equations can be integrated into existing LIB models to enhance predictions of capacity fading and SEI growth.
• This work paves the way for improved design and performance of next-generation lithium-ion batteries.