富硫螺芴桥连氮杂三角烯氧化还原活性聚合物
Sulfur-rich Spirofluorene-Bridged N Heterotriangulene Redox-Active Polymers
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中文总结 AI 辅助
该研究合成了FTN基富硫螺芴桥连氧化还原活性聚合物，揭示硫与三联噻吩连接基对其电化学性能的影响，为有机正极材料设计提供了依据。
中文摘要 AI 辅助
通过亲核芳香取代反应和Stille交叉偶联聚合反应，合成了含有共价连接低聚硫单元的富硫螺芴桥连氮杂三角烯（FTN）聚合物，以及基于三联噻吩的类似物。所得材料为无定形不溶性固体，具有高热稳定性，硫含量高达25 wt%。通过燃烧分析、飞行时间二次离子质谱（ToF-SIMS）、傅里叶变换红外光谱（FT-IR）、X射线光电子能谱（XPS）和固体核磁共振（NMR）进行的结构与组成分析，证实了短低聚硫至二硫键以及明确的三联噻吩单元在对应聚合物中的有效引入。在锂半电池中的电化学表征显示，FTN单元在3.8-4.0 V（相对于Li/Li+）下发生可逆的高电压氧化，同时在1.5-2.5 V（相对于Li/Li+）下伴随基于硫或三联噻吩的低电压氧化还原过程。硫的引入显著提高了理论和初始放电容量（高达129 mA h g-1），但由于硫化物溶解，硫化物转化过程表现出快速衰减和较差的可逆性。相比之下，三联噻吩连接的聚合物仅表现出短暂的低电压活性，而由持久的FTN主链氧化还原事件主导，维持了高库仑效率（约99.7%）。本研究结果强调了不同氧化还原活性连接基如何影响FTN基聚合物的电化学行为，并为具有多氧化还原过程的功能性有机正极材料的设计提供了见解。
英文摘要
Sulfur-rich spirofluorene-bridged N-heterotriangulene (FTN) polymers featuring covalently linked oligosulfide units and a terthiophene-based analogue were synthesized via nucleophilic aromatic substitution and Stille cross-coupling polymerization. The resulting materials are amorphous, insoluble solids with high thermal stability and sulfur contents up to 25 wt%. Structural and compositional analyses by combustion analysis, ToF-SIMS, FT-IR, XPS, and solid-state NMR confirm the efficient incorporation of short oligosulfide to disulfide linkages and well-defined terthiophene units in the respective polymers. Electrochemical characterization in lithium half-cells reveals a reversible, high-voltage oxidation of the FTN unit at 3.8-4.0 V (vs. Li/Li+), accompanied by low-voltage sulfur- or terthiophene-based redox processes between 1.5-2.5 V (vs. Li/Li+). Sulfur incorporation markedly increases the theoretical and initial discharge capacities (up to 129 mA h g-1), while the sulfide conversion processes exhibit rapid fading and poor reversibility due to sulfide dissolution. In contrast, the terthiophene-linked polymer shows only transient low-voltage activity while maintaining high Coulombic efficiencies (ca. 99.7%) governed by the persistent FTN backbone redox event. Our results highlight how different redox-active linkers influence the electrochemical behavior of FTN-based polymers and provide insights into the design of functional organic cathode materials featuring multi-redox processes.
