A New Conducting Copolymer Bearing Electro-Active Nitroxide Groups as Organic Electrode Materials for Batteries

To reduce the amount of conducting additives generally required for polynitroxide-based electrodes, a stable radical (TEMPO) is combined with a conductive copolymer backbone consisting of 2,7-bisthiophene carbazole (2,7-BTC), which is characterized by a high intrinsic electronic conductivity. This work deals with the synthesis of this new polymer functionalized by a redox nitroxide. Fine structural characterization using electron paramagnetic resonance (EPR) techniques established that: 1) the nitroxide radicals are properly attached to the radical chain (continuous wave EPR) and 2) the polymer chain has very rigid conformations leading to a set of well-defined distances between first neighboring pairs of nitroxides (pulsed EPR). The redox group combined with the electroactive polymer showed not only a very high electrochemical reversibility but also a perfect match of redox potentials between the de-/doping reaction of the bisthiophene carbazole backbone and the redox activity of the nitroxide radical. This new organic electrode shows a stable capacity (about 60 mAh g(-1)) and enables a strong reduction in the amount of carbon additive due to the conducting-polymer skeleton.