Conjugated Pyridine-Based Polymers Characterized as Conductivity Carrying Components in Anode Materials

Herein, polypyridine (P₂₅Py) is for the first time evaluated as an anode material for organic matter based electric energy storage devices. P₂₅Py is synthesized both chemically and electrochemically and the influence of electrolyte and solvent on the doping behavior of the material is investigated in propylene carbonate and acetonitrile with LiClO₄ and TBAPF₆. A battery consisting of P₂₅Py coupled to a lithium metal disc is assembled and the electrochemical performance and cycling stability of the conjugated polymer is analyzed. In all electrolyte combinations P₂₅Py is conductive and shows reversible redox chemistry between -1.0 and -2.0 V vs ferrocene with capacitive response characteristics. The electrochemical impedance spectroscopy response of the material can be described by a Randles equivalent circuit with a finite length Warburg diffusion element in which the diffusion coefficient of the cations increases with increasing doping level of the polymer. In the battery cell configuration the polymer shows reversible cycling with no capacity fading during the first 100 cycles without conducting additives. P₂₅Py thus provides a promising alternative conducting polymer base for electrical energy storage applications which expands both the potential widow as well as the electrolyte compatibility of the flora of known conducting polymers.