Synthesis, Characterization, and Charge/Discharge Properties of Polynorbornenes Carrying 2,2,6,6-Tetramethylpiperidine-1-oxy Radicals at High Density

TEMPO-containing norbornene monomers 1 − 8 (TEMPO = 2,2,6,6-tetramethylpiperidine-1-oxy) were synthesized and polymerized via ring-opening metathesis using a ruthenium−carbene catalyst. The TEMPO moiety did not inhibit the polymerization, and the monomers gave corresponding polymers in good to high yields. Poly( 2 ) and poly( 3 ) were soluble in common solvents and possessed high molecular weight, while other polymers were insoluble. The resulting polymers were thermally stable up to ca. 240 °C according to TGA measurements in air. In the case of poly( 1 )−poly( 3 ), the charge/discharge capacities of the polymer-based cells were largely dependent on the spatial arrangement of the two TEMPO moieties on each repeating unit. Quite interestingly, the capacity of the poly( 2 )-based cell reached its theoretical value (109 A h/kg), and a large capacity (>90 A h/kg) was retained even at high current densities up to 6 A/g, indicating the possibility of very fast charging (within 1 min). The cells utilizing the present polymers as cathode-active materials demonstrated excellent cycle life; e.g., the discharge capacities of poly( 2 ) and poly( 3 ) showed no more than 10% decrement even after 400 cycles.