Charged Interface in Battery Breaks Molecular Chiral Symmetry

Molecular events occurring within a few solvent layers at a charged electrode surface govern the rate and reversibility of reactions in electrochemical devices, yet such interfacial mechanism was never sufficiently understood at atomistic-level. Here we report a counter-intuitive discovery that charged interface breaks down the mirror symmetry between R - and S -enantiomers of propylene carbonate (PC), which expresses at graphite surface into distinct interphasial chemistries. Using enantiopure R - and S -PC as a chemically identical model pair against their racemic mixture, we find interphase at graphite diverges sharply at high lithium salt concentration, where R -PC enables reversible graphite lithiation with a LiF-rich interphase, while S -PC exfoliates graphite. Simulations and spectroscopies identify the combination of high salt concentration and charged interface collectively responsible for inducing the collapse of enantiomerism into diastereomerism. This knowledge not only establishes a hitherto-unknown dimension for electrolyte design, but also introduces a new concept of broad implications beyond battery applications.