Study on the microcrystalline structure variation of quinoline-based mesophase and its lithium storage mechanism

Abstract

Quinoline-based pitch was synthesized through the induction polymerization of quinoline with Cl-containing aromatic hydrocarbons. Subsequently, intermediate quinoline-based mesophase pitch with varying anisotropic degrees and structures was produced through liquid-phase carbonization. Such quinoline-based mesophase pitch was further prepared as the anode material for lithium-ion batteries after further high temperature treatment. The microstructure and microcrystalline size variation with different anisotropic content, as well as their impact on electrochemical performance were systematically examined. The results indicate that quinoline pitch can effectively form a large molecule mesophase streamlined structure, and the long-range ordered structure formed after carbonization exhibits excellent electrochemical performance, with a stable capacity of 365.4 mAh/g at a current density of 0.5 C. Nitrogen can introduce certain defects in the long-range ordered structure, enhancing the diffusion rate of Li⁺ in the material. Additionally, this work provides a new method for enhancing electrochemical performance by adjusting the texture orientation through quinoline-based pitch liquid-phase carbonization process, as well as a feasible strategy for improving material electrochemical performance through in-situ nitrogen doping by quinoline.