Strain effects on Li+ diffusion in solid electrolyte interphases: A molecular dynamics study

Dilithium ethylene dicarbonate (Li2EDC) and dilithium butylene dicarbonate (Li2BDC) are the common organic compositions of the solid electrolyte interphase (SEI) layers in rechargeable lithium-ion batteries. The Li+ diffusion in the amorphous and ordered phases of Li2EDC and Li2BDC under various strains has been investigated by using molecular dynamics simulations. It is found that different strains lead to diverse changes in Li+ diffusivity. The tensile strain makes the Li+ diffusion coefficients increase in amorphous and ordered Li2EDC or Li2BDC, and the compressive strain makes the Li+ diffusion coefficients decrease in them. The average Li+ coordination number calculation, ion conductivity calculation and the calculation of the residence autocorrelation function in amorphous and ordered Li2EDC or Li2BDC are performed to further analyze the strain effects on Li+ transport in them. The factors influencing Li+ diffusion in amorphous and ordered Li2EDC or Li2BDC under the strain are discussed.