吡咯基三嗪聚合框架用于固相转变硫聚物正极性能研究

Performance of Pyrrole-Based Triazine Polymer Frameworks for Solid-Phase Conversion Sulfur Polymer Cathodes

针对锂硫电池存在严重穿梭效应的问题,硫物质的固相转变可有效消除多硫化锂在液相中的溶解扩散。以聚丙烯腈为代表的常规链状聚合物可通过共价结合短链硫实现固相转变,然而往往受到硫含量低、倍率性能差的限制。通过氰基三聚与吡咯自由基聚合构筑了吡咯基三嗪聚合物框架(P-CNPy),其硫含量较高,达到47%。电化学测试结果显示硫聚物正极具有优异的循环稳定性与倍率性能,0.2C循环500次平均容量衰减仅为0.03%,4C时可逆容量仍保留580mA∙h/g。该方法可为高性能二维框架结构硫聚物正极的设计应用提供指导。

Aiming at the serious shuttle effect of lithium-sulfur batteries,solid-phase conversion of sulfur can effectively eliminate the dissolution and diffusion of lithium polysulfide in the liquid phase.Conventional chain polymers represented by polyacrylonitrile can realize solid-phase conversion by covalently combining short-chain sulfur chemically,yet they are often limited by low sulfur contents and poor rate performance.Herein,a higher sulfur content of 47%can be achieved by constructing a pyrrole-based triazine polymer framework(P-CNPy)through the polymerization of cyanotrimerization and pyrrole radicals.The electrochemical testing results show that the sulfur-polymer cathode possesses excellent cycling stability and rate performance,with an average capacity decay of only 0.03%during 500 cycles at 0.2 C,and a reversible capacity of 580 mA∙h/g at 4 C.This method provides a guidance for the design and application of high-performance two-dimensional framework-based sulfur polymer cathodes.