Dioxolane

Sublimed sulfur (≥99.5%), bis(trifluoromethane)sulfonimide lithium salt (LiTFSI), anhydrous lithium nitrate, dioxolane (DOL, 99%) 1,2-dimethoxyethane (anhydrous DME, 99.5%), and analytical grade chemicals such as KMnO₄ were procured from Sigma Aldrich. Polyvinylidene fluoride (PVDF), N-methyl pyrrolidinone (NMP) and Super P were purchased from Alfa Aesar. l-glycine was procured from Fischer Scientific. All chemicals were used as received without further purification.

Solubility tests were conducted by dissolving a few milligrams of Li-BL in N-methyl-2-pyrrolidone (Sigma Aldrich), de-ionized water, a mixture of ethylene carbonate (Sigma Aldrich): dimethyl carbonate (Sigma Aldrich) 1 : 1 v/v, dioxolane (Sigma Aldrich), dimethoxymethane (Sigma Aldrich) and tetraethylene glycol dimethyl ether (Sigma Aldrich). Electrochemical measurements were conducted using CR2032-type coin cells (MTI) with quartz membrane (Whatman) as a separator. The electrolyte was prepared by mixing bis(trifluoromethylsulfonyl) amine lithium salt (Sigma Aldrich) in tetraethylene glycol dimethyl ether (TEGDME). Fabrication of coin cells was conducted in an argon-filled glove box. Cyclic voltammetry and electrochemical impedance spectroscopy were measured with an Autolab PGSTAT 302 N potentiostat. Galvanostatic charge–discharge tests were performed on LAND CT2001A battery tester and on an Arbin Instruments BT-2000 battery cycler.

Chemicals: chloroform-d¹, 99.6% (Deutero GmbH, Kastellaun, Germany); dichlorobenzene, anhydrous, 99% (Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany), secure seal, withdrawn under counter current argon flow; dichloromethane, anhydrous, ≥99.8% (Sigma-Aldrich), secure seal, withdrawn under counter current argon flow; dioxolane, anhydrous, 99.8% (Sigma-Aldrich), secure seal, withdrawn under counter current argon flow; n-pentane, technical, >98% (Haltermann Carless, Hamburg, Germany); sulfur trioxide DMF complex, 97+ % (ACROS Organics, Geel, Belgium); triethylamine, >98% (Fluka Analytical, Merck KGaA, Darmstadt, Germany); trioxane, ≥99% (Sigma-Aldrich). These were used as supplied if not stated otherwise. Polyoxyethylene diols A, B, and C were obtained with nominal weights of 1000, 400 and 200 g/mol, respectively, as PEG 1000, (Fluka, Honeywell Specialty Chemicals Seelze GmbH, Seelze, Germany), PEG 400, (Fluka), and PEG 200 for synthesis (Merck KGaA, Darmstadt, Germany); they were then dried in an oil pump vacuum prior to used. The number average molecular weights were determined with gel permeation chromatography, being 1076, 364 and 136 g/mol, respectively.