Compared with conventional inorganic electrode materials, organic electrode materials have the advantages of flexible molecular structure, low cost, large-scale preparation, and abundant and adjustable active sites. However, poor electrical conductivity, low exposure of active sites and high solubility of small organic molecules in the electrolyte lead to poor cycle stability and rate performance of organic electrode materials.
Prof. Xiaosi Zhou (School of Chemistry and Materials Science, Nanjing Normal University) and Prof. Qichun Zhang (Department of Materials Science and Engineering, City University of Hong Kong) studied the preparation of PDPI/CNTs polyimide composites by a two-step hydrothermal-calcination method using carbon nanotubes (CNTs) as templates. Solid-state NMR, IR, XRD and XPS analyses verified the successful synthesis of the polymers. Ex situ XPS and ex situ infrared spectroscopy illustrated the potassium storage mechanism of PDPI/CNTs, which provides a theoretical basis for the study of their energy storage in potassium ion batteries.
Two sets of universal experiments (PPPI/CNTs and NPPI/CNTs), TOF-SIMS and TEM analysis displayed the degree of polymerization shows a gradual increasing trend with the reaction polymerization time, and the potassium storage properties of the three polyimide materials gradually improve with the increase of the degree of polymerization. However, when the polymerization degree reaches the maximum value, the polymers start to self-stack outside the carbon nanotubes, and the potassium storage properties of the nanocomposites gradually decrease.
In summary, the optimized PDPI/CNTs exhibits long cycle stability (138.5 mAh g−1 after 2000 cycles at 0.5 A g−1). Furthermore, the PDPI/CNTs-10||soft carbon full cell exhibits exhibits superior potassium storage capacity, with a high initial energy density of 154.8 Wh kg−1 at 0.1 A g−1 and a conspicuous energy retention rate of 70.6% after 1000 cycles at 0.5 A g−1. This work sheds light on the advancement of organic cathode materials for K-ion batteries and points out that the reasonable adjustment of the polymerzation degree is the key to obtain high-efficiency K-ion batteries.
See the article:
Modulating polymerization of aromatic polyimides on carbon nanotubes for high-performance organic potassium-ion batteries. Science Bulletin, 2024, 69(21).
https://www.sciencedirect.com/science/article/pii/S2095927324006376
