Molecular dynamics study of propylene carbonate based concentrated electrolyte solutions for lithium ion batteries

Ion Transport in Organic Electrolyte Solutions for Lithium-ion Batteries and Beyond

“…It has been observed from simulations [107,135,136] as well as experiments [99,104] that the increase in the salt concentration beyond 1 M translates into a decrease in diffusion, as can be seen from Figure 8. In particular, the diffusion mechanism of Li + at room temperature was observed to be a mix of vehicular and structural diffusion in the 1-3 M concentration range (Figure 8), exhibiting an increase in the structural diffusive mode in the super-concentrated regime [57,107,127,138].…”

“…In this section, we will focus on the atomistic modeling studies of electrolytes for LIBs. Several computer simulation studies are available in the literature [77,98,99,106,107,[130][131][132][133][134][135][136][137][138][139] that focus on diffusion in such organic liquid solutions. In particular, the DFT calculations and AIMD simulations have been used for simulating the diffusion of Li + within the liquid EC solvent [140].…”

“…Only recently, the self-diffusion of Li + for different electrolyte concentrations was calculated in the range of 298-303 K, using the classical MD simulations, in PC solutions [99,107,136,145], EC solutions [130,131,[136][137][138][139]146], DME solutions [132], DMC solutions [137,139,147,148] or even mixtures of them, such as EC:DMC [137,145,146], PC:DME [145] or ternary (EMC:DMC:EC) mixtures [149]. At low LiPF6 concentration (0.1 M), the EMC-LiPF6 electrolyte was observed to exhibit higher ion dynamics than the DEC-LiPF6 and DMC-LiPF6 electrolytes (DMC-LiPF6 electrolyte exhibited the lowest) [147].…”

“…In another study, it was found that in PC solutions, there are contact ion pairs and multi ion complexes formed at high concentrations, which impact the transport properties (diffusivity and ionic conductivity) [136]. However, it is well-known from several studies that non-polarizable force fields do not reproduce ion transport accurately.…”

“…In particular, they underpredict the dynamic (diffusive) properties since they overestimate the ion-ion correlations [151]. Several atomistic computational studies with non-polarizable force fields have failed to predict ion transport (diffusion) in organic liquid electrolyte solutions (PC [99,134,136] and EC [131,134,137,147,150]).…”