Amphi-Charge Storable Pyropolymers with Hierarchical Pore Structures for Hybrid Supercapacitors

摘要

Carbon-based materials have attracted much attention as active materials for energy storage, because of their well-known chemistry and low cost as well as highly tunable and versatile redox-activities. Intrinsic defects such as topological defects and edge defects of aromatic hexagonal carbon structures can store charges mainly in an anodic potential section, while extrinsic defects have redox-activities particularly in a cathodic potential region. Therefore, through a sophisticate design of the carbonaceous materials, a desirable electrochemical performance can be achieved. Pyropolymer is a kind of carbon-based materials fabricated by low temperature pyrolysis of a polymer precursor, which has a number of topological defects and redox-active heteroatoms. In this study, hierarchically nanoporous pyropolymers (HN-PPs) including numerous redox-active heteroatoms are fabricated from polyaniline nanotubes by heating with KOH. In the large operating voltage range 1.0-4.8V versus Li+/Li, HN-PPs store amphi-charges by a pseudocapacitive manner of Li-ion (mainly <3.0 V) and electrochemical double layer formation of anion (primarily >3.0 V). Through these surface-driven charge storage behaviors, HN-PPs achieve a significantly high specific capacity of -460 mA h g-1 at 0.5 A g-1, maintaining specific capacities of 140 mA h g-1 at a high specific current of 30 A g-1 and 305 mA h g-1 after 2000 cycles at 3 A g-1. Furthermore, asymmetric energy storage devices based on HN-PPs deliver a high specific energy of 265 W h kg-1 and high specific power of 5081 W kg-1 with long-term cycling performance.