Glovebox

All glassware used for the polymerisations was dried overnight at 120 °C prior to use. Potassium tert butoxide (KO^tBu, ≥98%), 1,4,7,10,13,16-hexaoxacyclooctadecane (18-crown-6, ≥99%), 1,2-butylene oxide (BO, 99%), ethyl vinyl ether (EVE, ≥98%), glycidol (96%), calcium hydride (CaH₂, 95%), potassium (K, chunks in mineral oil, 98%) and naphthalene (Naph, 99%) were purchased from Sigma-Aldrich (Switzerland) and used as received. Dry THF was obtained from an inert solvent purification system PureSolv MD 5 (Inert Technology, USA), dry 1,4-dioxane was purchased from Acros Organics (Belgium). The chemicals were stored under argon in a glovebox (MBraun Labstar, Germany). All other solvents used were in HPLC grade and purchased from JT Baker (USA), VWR (Switzerland) or Scharlau (Germany). Deionised water was obtained from a Milli-Q Q-POD device (Merck, Germany). Dulbecco's PBS buffer was purchased from Bioconcept Ltd (Switzerland).
Potassium naphthalenide (KNaph) was prepared by adding potassium (1.19 g, 30.5 mmol, 1 eq.) to a stirred solution of naphthalene (4.11 g, 32.0 mmol, 1.05 eq.) in dry THF (61 mL, 0.5 mol L⁻¹) under argon. EEGE was synthesised following the standard protocol^{49 (link)} from glycidol and EVE and dried over CaH₂. The synthesis protocol and the ¹H-NMR spectrum (Fig. S1) can be found in the ESI.†

All compounds used were dried to avoid HF formation in the electrolyte and were assembled in a glove box under argon (MBraun, Germany) having <0.1 ppm of water and oxygen. Typically, the LiCoO₂ electrode was assembled in a coin cell using lithium metal as anode, a few drops of an ethyl carbonate (EC) and diethylene carbonate (DEC) mixture in a 1:1 volume ratio with 1 M LiPF₆ and 2 wt% of vinylene carbonate as electrolyte with respect to solvents and LiPF₆ as well as a Celgard separator.