Molecular Dynamics Simulation–Based Mean Square Displacement Analyses for Determining Diffusive and Kinematic Parameters of the Vanadium Redox Flow Battery Electrolyte Specimens

On the one hand, vanadium redox flow battery (VRFB) technology is extensively marketed and branded worldwide due to its exceptionally low operational cost, high energy storage, and “all‐vanadium”‐based electrolytes functionalizing state‐of‐the‐art cell architectures, but on the other hand, the complexities and complicated compositions of its bench H 2 SO 4 ‐supported electrolyte matrices comprising the freely movable HSO 4 ─ , H 2 O, and H 3 O + as auxiliary and adjacent state V n+ ‐hydrated moieties as working electrolyte specimens are always taken as potential electrochemical hurdles owing to their crucial roles in “water and electrolyte imbalances.” Toward resolving this diffusion gradient subordinated electrochemical consequences, the genuine determinations of the diffusivity ( D ) rates of the imperative electrolyte specimens and the precise assessments of their impacts on acquiring required level viscosity plus the effective correlations of them with proton hopping kinetics (flipping rates ( κ ) and energy barriers ( E a )) are indispensable. The mathematical function by means of which all the electrochemically dispersed yet diffusive electrolyte specimens can be treated as a “random walk” and related their MD simulation derived initial r (0) and time‐lagged position r ( t ) vectors via the [ | r ( t ) − r (0)| 2 ] vs. t graphical plot of 6 D gradient linear lines is a mean square displacement (MSD). Herein, the (a) MD simulation–based theoretical studies carried out to the real‐world VRFB half‐cells at dissimilar Nafionic water contents ( λ = 3 and 22), (b) MSD analyses conducted for deducing the closely associated dynamical assets, and (c) Grotthuss proton hopping kinematics are reported. Therewith determined average diffusivities are D H3O+ = 4.92 × 10 ─7 cm 2 /s ( λ = 3) and 7.17 × 10 ─6 cm 2 /s ( λ = 22), D H2O = 2.58 × 10 ─6 cm 2 /s ( λ = 3) and 1.01 × 10 ─5 cm 2 /s ( λ = 22), and D Vn+_complex = 6.29 × 10 ─8 cm 2 /s ( λ = 22); κ avg and E a are 0.212 ps ─1 and 0.93 kcal/mol ( λ = 22 and T = 300K), respectively; and dynamic viscosities ( η ) are η H3O+ = 2.94 × 10 ─3 Pa.s and η posolyte = 1.48 × 10 ─3 Pa.s, respectively. The author believes that these datasets are worthy enough to understand the crucial roles of the λ in affecting Nafion’s conductivity channels and VRFB‐cell electrolyte specimens’ kinematic diffusive dynamics and hence pave the ways toward designing/optimizing its futuristic prototype model computationally.