biostudies-literatureUnknown8(12)Goodwin ZAHThe solvation environments of Li⁺ in conventional nonaqueous battery electrolytes, such as LiPF₆ in mixtures of ethylene carbaronate (EC) and ethyl methyl carbonate (EMC), are often used to rationalize transport properties and solid electrolyte interphase (SEI) formation. Solvation environments in the compact electrical double layer (EDL) next to the electrode, also known as the Helmholtz layer, determine (partially) what species can react to form the SEI, with bulk solvation environments often being used as a proxy. Here, we develop and test a theory of cation solvation in the Helmholtz layer of nonaqueous Li-ion battery electrolytes. First, we validate the theory against bulk and diffuse EDL atomistic molecular dynamics (MD) simulations of LiPF₆ EC/EMC miACS applied energy materials8376-8387https://www.ebi.ac.uk/biostudies/studies/S-EPMC12188516biostudies-literatureTheory of Cation Solvation in the Helmholtz Layer of Li-Ion Battery Electrolytes.PMC12188516Wu QGoodwin ZAHQi YBazant MZMarkiewitz DMfalseTheory of Cation Solvation in the Helmholtz Layer of Li-Ion Battery Electrolytes.The solvation environments of Li⁺ in conventional nonaqueous battery electrolytes, such as LiPF₆ in mixtures of ethylene carbaronate (EC) and ethyl methyl carbonate (EMC), are often used to rationalize transport properties and solid electrolyte interphase (SEI) formation. Solvation environments in the compact electrical double layer (EDL) next to the electrode, also known as the Helmholtz layer, determine (partially) what species can react to form the SEI, with bulk solvation environments often being used as a proxy. Here, we develop and test a theory of cation solvation in the Helmholtz layer of nonaqueous Li-ion battery electrolytes. First, we validate the theory against bulk and diffuse EDL atomistic molecular dynamics (MD) simulations of LiPF₆ EC/EMC mi2025-01-01T00:00:00Z2025 Jun2026-06-03T07:35:07.854Z2026-04-26T03:10:00.624ZS-EPMC121885164057537310.1021/acsaem.5c00883