Homologous Nitrogen-Doped Hierarchical Carbon Architectures Enabling Compatible Anode and Cathode for Potassium-Ion Hybrid Capacitors.

Abstract

Potassium-ion hybrid capacitors (PIHCs) have been considered as an emerging device to render grid-scale energy storage. Nevertheless, the sluggish kinetics at the anode side and limited capacity output at the cathode side remain daunting challenges for the overall performances of PIHCs. Herein, an exquisite "homologous strategy" to devise multi-dimensional N-doped carbon nanopolyhedron@nanosheet anode and activated N-doped hierarchical carbon cathode targeting high-performance PIHCs is reported. The anode material harnessing a dual-carbon structure and the cathode candidate affording a high specific surface area (2651 m2 g-1 ) act in concert with a concentrated ether-based electrolyte, resulting in an excellent half cell performance. The related storage mechanism is systematically revealed by in situ electrokinetic characterizations. More encouragingly, the thus-derived PIHC full cell demonstrates a favorable energy output (157Wh kg-1 ), showing distinct advantages over the state-of-the-art PIHC counterparts.