A universal strategy for the refined frameworks and improved performance of distinct commercial polyacrylonitriles in sulfur cathodes  

针对不同商业聚丙烯腈的结构与性能的普适性优化研究

作　　者：Yikun Yi Feng Hai Wenting Chen Xin Gao Jingyu Guo Weicheng Xue Mingtao Li 易义坤;海峰;陈文婷;高昕;郭靖宇;薛崴成;李明涛(Shaanxi Key Laboratory of Energy Chemical Process Intensification,School of Chemical Engineering and Technology,Xi’an Jiaotong University,Xi’an,710049,China)

机构地区：[1]Shaanxi Key Laboratory of Energy Chemical Process Intensification,School of Chemical Engineering and Technology,Xi’an Jiaotong University,Xi’an,710049,China

出　　处：《Science China Materials》2024年第9期2915-2924,共10页中国科学（材料科学）（英文版）

基　　金：supported by the National Natural Science Foundation of China(21978231 and 22008193);International Science and Technology Cooperation Program of Shaanxi Province—Key Project(2022KWZ-08);Natural Science Foundation of Jiangsu Province(SBK2020021757)。

摘　　要：Sulfurized polyacrylonitrile(SPAN)with the exceptional stability,safety,low cost,and high capacity have been positioned as a highly promising cathode material for next-generation lithium-ion batteries.However,in the market,polyacrylonitrile(PAN)sourced from different suppliers and available at varying prices exhibits significant variations in physical and chemical properties,resulting in diverse behaviors in Li-SPAN batteries.By studying the mechanism,we found that the PAN copolymerization structure leads to the stacking of chain segments which obstructs the embedding of sulfur and lithium ions.Here,we propose a universal strategy for the refined frameworks by an exogenous additive to modify various PAN raw materials,and the battery capacity and cycling performance are obviously improved.As a result,the copolymerized SPAN with a poor original capacity is nearly doubled to over 500 mAh g^(-1),almost comparable to high-quality yet expensively imported products;for the sample with a high initial capacity but fading in ether-based electrolytes,it can be modified to maintain stability over 400 cycles.This strategy offers an alternative approach for SPAN modification that is characterized by its simplicity and low cost,thereby facilitating the large-scale development of Li-SPAN batteries.硫化聚丙烯腈(SPAN)具有优异的稳定性、安全性、低成本和高容量,被认为是下一代锂离子电池极具潜力的正极材料.然而,在市场上来自不同供应商、价格各异的聚丙烯腈(PAN)在物理和化学性质上存在显著差异,导致其在锂电池体系中的性能表现出较大差距.通过研究其机理,我们发现PAN共聚结构会导致链段堆叠,从而阻碍硫和锂离子的嵌入.在此我们提出了一种通用策略,即通过外源添加剂对不同PAN原料进行改性,优化框架结构,并明显提高电池容量和循环性能.结果显示,原始容量较差的共聚型SPAN的容量几乎提高了一倍,达到500 mAh g^(-1)以上,可与高质量但昂贵的进口产品相媲美;对于初始容量较高但在醚基电解质中严重衰退的产品,改性后可使其在400次循环中保持稳定.这一策略为SPAN改性提供了另一种简单、低成本的途径,可推动锂-硫化聚丙烯腈电池的大规模开发.

关 键 词：copolymerization structure universal strategy exogenous additive SPAN modification 

分 类 号：TM912[电气工程—电力电子与电力传动] TQ325.8[化学工程—合成树脂塑料工业]