Fig. 1

The research subject and corresponding suitable physical models in LIB"

Fig. 2

Significance of SEI in lithium ion battery and its research progress in characterization and modeling"

Fig. 3

Workflows of (a) stand-alone models; (b) multiscale models based on sequential linking (MSMSL); (c) multiscale models based on iterative coupling (MSMIC); and (d) multiscale models based on tight coupling (MSMTC). “PE” refers to “physical equation” (mathematical equation based on a fundamental physics theory which defines the relations between physics quantities of an entity) and “MR” to material relation (materials specific equation providing a value for a parameter in the physics equation)[13]"

Table 1

Main stream MSMs for SEI study[1]"

Fig. 4

Decomposition of EC. Initially one electron is transferred from the surface to (a) Li-EC, causing a (b) Ccarbonyl —Oring bond to break. Subsequently, a second electron is transferred to (c) the EC- radical anion, triggering the breaking of a second Ccarbonyl —Oring bond and (d) generating the C2H4+CO32-pair. The net charges of the EC molecule and the CO32-/ C2H4 products are shown[43]. SEI after 16 ps of simulation using 4 mol/L (e) LiFSI or (f) LiTFSI in DME electrolytes vs. a lithium surface[49]"

Fig. 5

(a) Energy profile for breaking C2H4 from o-EC/Li+, as obtained from QC calculations and gas phase simulations using ReaxFF at 10 K[63]； (b) Schematic of a Li metal electrode dipped in an electrolyte (left) and initial configuration of the cell (right)[64]； (c) Distribution of the SEI components for different electrolytes (left). Atomic configurations from MD simulations; the components of the SEI are identified (right)[64]； (d) Potential energy profile for the reduction of EC/Li+ and the radical termination reactions according to various pathways. ΔER and ΔEB denote the reaction energy and reaction barrier, respectively. Color scheme: cyan, carbon; white, hydrogen; red, oxygen; purple, Li+; large blue sphere, electron[70]"

Fig. 6

(a) Li+ cation diffusion coefficients for ordered and amorphous SEI models consisting of Li2BDC and Li2EDC[54]； (b) Snapshots highlighting the Li+ distribution in ordered Li2BDC and Li2EDC, and amorphous Li2BDC, all at 393 K； Representative Li+-anion coordination in the double layer at (c) negative electrode potentials and (d) positive electrode potentials. Red and blue bars indicate the (x, y) plane of the anode and cathode surfaces, respectively[76]"

Fig. 7

(a) Model system and reaction scheme (cyan, carbon; red, oxygen; white, hydrogen; orange, phosphorus; green, fluorine; blue, lithium) [77]. (b) Schematic representation of the 4 types of events selected to occur in the kMC simulations[79]. (c, d) Effect of SEI solvent activation energy on the total charging time and SEI thickness during a full charging process [80]"

Fig. 8

SEI film thickness under OCV as a function of time for various initial SOC. The simulations assumed an initial SEI thickness of 1 nm[84]"

Fig. 9

Schematic diagram of multi-scale modeling for SEI"