Conductive Polymers As Hybrid Battery-Capacitor Electrode Materials

摘要

The disruption in next-generation batteries can only be realised by employing both new advanced materials and designs, eventually allowing to holistically achieve new levels of performance, safety and sustainability in a single battery system. To close the gap between high power and energy per unit weight, new materials are needed that can act as a battery and capacitor simultaneously. Conductive polymers, e.g. poly(3,4-ethylenedioxythiophene) (PEDOT), used with ionic liquids or semi-solid ionogels have recently attracted attention as hybrid battery-(pseudo)-capacitor systems, achieving a specific capacity, energy, and power of 40-180 Ah kg~(-1), 50-230 Wh kg~(-1), and 30-140 W kg~(-1) when used as positive electrodes in rechargeable aluminium batteries. In addition, the polymer composites are non-flammable, non-toxic, economically available and recyclable at low-cost. In comparison to other charge storage materials, like graphite, conductive polymers are less limited by their capacity as the electrode architecture can be redesigned from a conventional 2D design to an interconnected 3D electrode-electrolyte network, allowing a higher active surface, shorter charge transfer and ion diffusion paths for fast charging (up to 80C), and controllable electrode shapes/sizes (Figure A). The performance of conductive polymers can be tailored by their synthesis path and conditions. The relationship between electrode fabrication, underlying operating mechanisms, and performance was studied by in operando methods such as electrochemical atomic force microscopy (EC-AFM), and electrochemical microgravimetry (EQCM).