Redox-active covalent organic frameworks (COFs) are considered to be promising cathode materials for various secondary batteries. In particular, the combination of building blocks containing p-type/bipolar-type redox-active centers with p-type/bipolar-type linkages into the COF skeleton is supposed to have advantages in outputting a high redox potential with increased capacities and good cycling stability, which, however, has not been reported, to the best of our knowledge. Herein, a bipolar-type 2D COF, namely TPPDA-CuPor-COF, has been fabricated through the condensation of tetraphenyl-p-phenylenediamine (TPPDA) with copper-5,10,15,20-tetrakis(4-formylphenyl)-porphyrin (Cu-TFPP). In TPPDA-CuPor-COF, the TPPDA moieties enable a p-type doping reaction while the Cu-TFPP moieties are able to act as bipolar-type active centers, favorable for a high redox potential and increased content of redox-active groups. Thus, in combination with the unhindered ion/electron diffusion paths caused by its stable and crystalline porous structure, the TPPDA-CoPor-COF cathode gives a high capacity of 142 mA h g⁻¹ with a high average output voltage of 2.7 V vs. Li/Li⁺ at 60 mA g⁻¹, excellent rate performance, and good cycling stability in LIBs, revealing the promising application of TPPDA-CuPor-COF as a cathode material for secondary batteries. In addition, the bipolar redox mechanism for the TPPDA-CuPor-COF cathode has been demonstrated by density functional theory (DFT) calculations and ex situ X-ray photoelectron spectroscopy (XPS) during its electrochemical process.

中文翻译：

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用于有机高性能锂离子电池正极的具有 p 型和双极型氧化还原活性中心的二维共价有机框架

氧化还原活性共价有机骨架（COFs）被认为是用于各种二次电池的有前途的正极材料。特别是，将含有 p 型/双极型氧化还原活性中心和 p 型/双极型键的结构单元组合到 COF 骨架中，应该具有输出高氧化还原电位、增加容量和良好循环的优势。然而，据我们所知，尚未报告稳定性。在此，通过四苯基-p的缩合制备了双极型二维COF，即TPPDA-CuPor-COF。-苯二胺 (TPPDA) 与铜-5,10,15,20-四(4-甲酰基苯基)-卟啉 (Cu-TFPP)。在 TPPDA-CuPor-COF 中，TPPDA 部分能够进行 p 型掺杂反应，而 Cu-TFPP 部分能够充当双极型活性中心，有利于提高氧化还原电位和增加氧化还原活性基团的含量。因此，结合由其稳定的结晶多孔结构引起的不受阻碍的离子/电子扩散路径，TPPDA-CoPor-COF 正极具有 142 mA hg ^-1的高容量和 2.7 V vs. Li的高平均输出电压/Li ⁺在 60 mA g ^-1、优异的倍率性能和LIBs中良好的循环稳定性，揭示了TPPDA-CuPor-COF作为二次电池正极材料的广阔应用前景。此外，TPPDA-CuPor-COF 阴极的双极氧化还原机制已在其电化学过程中通过密度泛函理论 (DFT) 计算和非原位X 射线光电子能谱 (XPS) 得到证明。