In this work, we developed a family of sulfonimide salts with varied numbers and positions of fluoro (–F), oxy (alkoxy, –OR), and piperidinyl (–Pip) substituents by successive nucleophilic aromatic substitution (SNAr) reaction of fluorinated phenyl sulfonimide. The electrochemical oxidative stability of these sulfonimide salts were assessed by both density functional theory calculations and experimental potentiostatic measurements. Furthermore, we evaluated the chemical stability of the sulfonimide salts in a basic, nucleophilic and radical-rich environment that mimics the oxygen electrode in a typical aprotic Li-O2 battery; the number of –Pip and the type of –OR substituents were found to strongly affect the chemical stability. Interestingly, there appears to be a tradeoff between the chemical and electrochemical oxidative stability. Finally, we investigated the donor ability of the sulfonimide salt anions by computing the Gibbs free energy of Na-sulfonimide ion pair association, ΔGasso, and by 23Na NMR. Ionic conductivities of 1,2-dimethoxyethane (DME) solutions as well as PEO-based electrolytes containing these sulfonimides were measured and found to correlate well with the computed ΔGasso. We believe these new sulfonimide salts with tunable stability and degree of dissociation will find applications in lithium and sodium batteries.

A new family of sulfonimide salts: Structure-property relationships for battery application

256th National Meeting (2018)

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