Designing π-conjugated polypyrene nanoflowers formed with meso- and microporous nanosheets for high-performance anode of potassium ion batteries

Abstract

Organic compounds possess great potential as electrode materials for environmentally friendly and sustainable batteries due to their abundance, recyclability, and highly tailorable properties. However, commercialization remains difficult due to several intrinsic problems, including high solubility in electrolytes and low conductivity. Aromatic organic compounds used as anode materials in batteries continue to exhibit severe degradation problems, especially with respect to long-term cycling performance. By using direct molecular design, the stability and conductivity of organic compounds can be modified. Here, we report the design and preparation of π-conjugated polypyrene porous nanoflowers, formed with micro- and mesoporous nanosheets, via a facile one-pot polymerization process. The porous structure at the nanoscale was expected to offer large contact area for electrolyte and short ionic immigration distance, facilitating fast ion diffusion kinetics. When evaluated as an anode for potassium ion batteries, the polypyrene demonstrated excellent long-term cycling stability and improved rate capability. This outstanding electrochemical performance is due to the π-conjugated skeleton showing low solubility in conventional electrolytes, highly stable structure, and meso- and microporous structure, which can not only shorten charge transfer paths, but also enhance ion diffusion kinetics. This approach of utilizing π-conjugated polymer with highly stable structure and porous nanostructures is expected to inspire new research on the development of novel organic electrode materials for rechargeable ion batteries.