Single-Ion Homopolymer Electrolytes with High Transference Number Prepared by Click Chemistry and Photoinduced Metal-Free Atom-Transfer Radical Polymerization

Solvent-free single-ion polymer electrolytes with high conductivity have historically been prepared in the form of block copolymer or polymer blends. In this work, single-ion homopolymer electrolytes consisting of poly(poly(ethylene oxide) methacrylate lithium sulfonyl(trifluoromethylsulfonyl)imide), poly(PEOMA-TFSI–Li+), were prepared for the first time by photoinduced metal-free atom-transfer radical polymerization. The PEO-based macromonomer PEOMA-TFSI–Li+ was synthesized via click chemistry, copper-catalyzed alkyne–azide cycloaddition. Because of the conductive, amorphous PEO phase in which the lithium ions are located, these polymers showed improved ionic conductivity (10–5–10–4 S/cm at 90 °C) and high transference number (0.97–0.99). A continued lithium plating–stripping experiment was performed at current density ≥0.1 mA/cm2 over 300 cycles at 90 °C. The potential dendrite-suppressing capability of the polymer with such high transference number was also estimated by employing a kinetic model using the measured transport and transference properties to study the current density at the dendrite tip. The analysis indicates that the synthesized polymers could have a high propensity to suppress dendrite growth.