Poly(7-oxanorbornenes) carrying 2,2,6,6-tetramethylpiperidine-1-oxy (TEMPO) radicals: Synthesis and charge/discharge properties

TEMPO-containing 7-oxanorbornene monomers 1-4 (TEMPO = 2,2,6,6-tetramethylpiperidine-1-oxy) were synthesized and polymerized via ring-opening metathesis using a ruthenium carbene catalyst. Monomers 1 and 3 gave polymers with number-average weights of 80 100 and 112 200 in 85 and 96% yields, respectively, whereas monomers 2 and 4 did not provide high molecular weight polymers. Poly(1) and poly(3) were soluble in common solvents including CHCl3, CH2Cl2 and THF, while insoluble in hexane, diethyl ether and MeOH. They were thermally stable up to ca. 240 °C according to the TGA measurements in air. The secondary batteries utilizing the present polymers as cathode-active material demonstrated reversible charge/discharge processes, whose discharge capacities were 107 and 92.8 A h/kg, and displayed excellent high-rate charge and discharge properties. These cells demonstrated excellent cycle life, e.g., the discharge capacities of poly(1) and poly(3) showed less than 10% decrements even after 100 cycles.

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