Transforming Mesoporous Covalent Organic Polymers into Efficient 18-Electron-Redox Anodes via Redox Site Engineering for Superior Li-Ion Storage

Abstract

Redox-active covalent organic polymers (COPs) have emerged as appealing renewable electrode materials for next-generation Li-ion batteries, but their performance is limited by insufficient redox sites and inadequate Li-ion diffusion. Here, we develop a novel class of mesoporous covalent organic polymer (namely TF-Azo-COP) bearing multiple redox sites and explore its first use as efficient 18-electron-redox anodes for superior Li-ion storage in both coin-type and fiber-type batteries. The newly produced TF-Azo-COP involves three types of active sites including C=N in triazines and imines, N=N in azo, and C₆-ring aromatics to enable 18-Li-ion storage on one repeatable segment, while affording extended π-conjugation for fast electron transfer and a pore size of ~2.5 nm for facilitated ion diffusion with a high coefficient up to ~10⁻¹⁰ cm² s⁻¹—superior to some reported organic electrodes. Meriting from the above, pairing TF-Azo-COP with metal Li endows a coin cell with good cycling stability and a large reversible capacity of 795.4 mAh g⁻¹ at 0.1 A g⁻¹—representing one of the best performances among reported organic electrodes. When coupled with fiber-shaped LiFePO₄ cathodes, the assembled fiber cell delivers an excellent combination of linear capacity (0.23 mAh cm⁻¹), energy density (0.55 mWh cm⁻¹), cycling stability (250 cycles), and good flexibility.

Keywords

covalent organic polymers / fiber batteries / Li-ion batteries / multiple redox chemistry / organic electrode materials

References

[1] Y. Wang, X. Yang, Y. Meng, Z. Wen, R. Han, X. Hu, B. Sun, F. Kang, B. Li, D. Zhou, C. Wang, G. Wang, Chem. Rev. 2024, 124, 3494.

[2] Y. Lu, J. Chen, Nat. Rev. Chem. 2020, 4, 127.

[3] J. Kim, Y. Kim, J. Yoo, G. Kwon, Y. Ko, K. Kang, Nat. Rev. Mater. 2023, 8, 54.

[4] Q. Bai, J. Huang, K. Tang, Y. Zhu, D. Wu, Adv. Mater. 2025, 18, 602.

[5] Y. Lu, Q. Zhang, J. Chen, CCS Chem. 2023, 5, 1491.

[6] C. Peng, G. Ning, J. Su, G. Zhong, W. Tang, B. Tian, C. Su, D. Yu, L. Zu, J. Yang, M. F. Ng, Y. Hu, Y. Yang, M. Armand, K. P. Loh, Nat. Energy 2017, 2, 17074.

[7] Y. Lu, X. Hou, L. Miao, L. Li, R. Shi, L. Liu, J. Chen, Angew. Chem. Int. Ed. 2019, 58, 7020.

[8] Y. Wu, R. Zeng, J. Nan, D. Shu, Y. Qiu, S.-L. Chou, Adv. Energy Mater. 2017, 7, 1700278.

[9] S. Bai, B. Kim, C. Kim, O. Tamwattana, H. Park, J. Kim, D. Lee, K. Kang, Nat. Nanotechnol. 2021, 16, 77.

[10] M. Li, J. Yang, Y. Shi, Z. Chen, P. Bai, H. Su, P. Xiong, M. Cheng, J. Zhao, Y. Xu, Adv. Mater. 2022, 3, 2107226.

[11] H. Yu, C. Li, Y. Lei, Z. Xiang, Next Energy 2023, 1, 100035.

[12] Y. Lin, H. Cui, C. Liu, R. Li, S. Wang, G. Qu, Z. Wei, Y. Yang, Y. Wang, Z. Tang, H. Li, H. Zhang, C. Zhi, H. Lv, Angew. Chem. Int. Ed. 2023, 62, e202218745.

[13] L. Zhong, J. Li, C. Liu, L. Fang, Z. Yuan, D. Yu, X. Chen, Adv. Funct. Mater. 2023, 33, 2215133.

[14] V. Singh, J. Kim, B. Kang, J. Moon, S. Kim, W. Kim, H. Byon, Adv. Energy Mater. 2021, 11, 2003735.

[15] J. Hou, H. Liu, M. Gao, Q. Pan, Y. Zhao, Angew. Chem. Int. Ed. 2023, 134, e202414566.

[16] B. Gui, G. Lin, H. Ding, C. Gao, A. Mal, C. Wang, Acc. Chem. Res. 2020, 53, 2225.

[17] L. Zhong, Y. Zhang, J. Li, L. Fang, C. Liu, X. Wang, Z. Zhang, D. Yu, ACS Nano 2023, 17, 18190.

[18] M. Wu, Y. Zhao, B. Sun, Z. Sun, C. Li, Y. Han, L. Xu, Z. Ge, Y. Ren, M. Zhang, Q. Zhang, Y. Lu, W. Wang, Y. Ma, Y. Chen, Nano Energy 2020, 70, 104498.

[19] R. Shi, L. Liu, Y. Lu, C. Wang, Y. Li, L. Li, Z. Yan, J. Chen, Nat. Commun. 2020, 11, 178.

[20] Y. Su, J. Shang, X. Liu, J. Li, Q. Pan, Y. Tang, Angew. Chem. Int. Ed. 2024, 63, e202403775.

[21] Z. Fang, Y. Li, J. L, C. Shu, L. Zhong, S. Lu, C. Mo, M. Yang, D. Yu, Angew. Chem. Int. Ed. 2022, 60, 17615.

[22] Z. Hu, X. Zhao, Z. Li, S. Li, P. Sun, G. Wang, Q. Zhang, J. Liu, L. Zhang, Adv. Mater. 2021, 33, 2104039.

[23] X. Yang, L. Gong, X. Liu, P. Zhang, B. Li, D. Qi, K. Wang, F. He, J. Jiang, Angew. Chem. Int. Ed. 2022, 134, e202207043.

[24] M. Zhang, Y. Zhao, F. Kang, W. Huang, Q. Zhang, Adv. Funct. Mater. 2025, 35, 2415186.

[25] Q. Liu, X. Su, D. Lei, Y. Qin, J. Wen, F. Guo, Y. A. Wu, Y. Rong, R. Kou, X. Xiao, F. Aguesse, J. Bareño, Y. Ren, W. Lu, Y. Li, Nat. Energy 2018, 3, 936.

[26] T. Zhao, C. Liu, T. Meng, F. Yi, A. Gao, F. Zhang, D. Shu, Y. Tong, Chem. Eng. J. 2023, 466, 143053.

[27] X. Liu, Y. Jin, H. Wang, X. Yang, P. Zhang, K. Wang, J. Jiang, Adv. Mater. 2022, 34, 2203605.

[28] X. Lu, H. Wang, Y. Sun, Y. Xu, W. Sun, Y. Wu, Y. Zhang, C. Yang, Y. Wang, Angew. Chem. Int. Ed. 2024, 136, e202409436.

[29] C. Wu, M. Hu, X. Yan, G. Shan, J. Liu, J. Yang, Energy Storage Mater. 2021, 36, 347.

[30] J. Zhao, W. Zhang, D. Du, Z. Liu, W. Ji, H. Huang, S. Pang, Angew. Chem. Int. Ed. 2025, 64, e202419887.

[31] X. Han, G. Qing, J. Sun, T. Sun, Angew. Chem. Int. Ed. 2012, 51, 5147.

[32] S. Zhao, Z. Bian, Z. Liu, Y. Wang, F. Cui, H. Wang, G. Zhu, Adv. Funct. Mater. 2022, 32, 2204539.

[33] Z. Pan, H. Guo, B. Liu, L. Sun, Y. Chen, H. Zhang, N. Wu, Z. Lu, W. Yang, Microporous Mesoporous Mater. 2022, 340, 112030.

[34] D. Wu, F. Fei, Q. Zhang, X. Wang, Y. Gong, X. Chen, Y. Zheng, B. Tan, C. Xu, H. Xie, W. Fang, Z. Chen, Y. Wang, Sci. Adv. 2022, 8, eabm3381.

RIGHTS & PERMISSIONS

2025 The Author(s). Energy & Environmental Materials published by John Wiley & Sons Australia, Ltd on behalf of Zhengzhou University.