Recently, for the pursue of high energy density of Li-ion battery system and more lightweight and flexible battery for potential applications in flexible electronic devices such as wearable devices, artificial electronic skins, and distributed sensors, an extensive research effort is underway to produce soft free-standing electrode-active materials without binder and conductive agent for such bendable batteries.[1-3]

We propose here an N-rich pure carbon film synthesized by calcining vapour phase polymerized polypyrrole (PPy) film as an anode for Li-ion battery.[4] The PPy precursor film was synthesized via a simple vapor phase polymerization (VPP) bottom-up assembly method using Fe(III) tosylate oxidant (Figure 1). The obtained PPy film shows smooth surface and continuously cross-linked structure. After carbonized at high temperature at inert atmosphere, a continuously cross-linked carbon film doped with nitrogen can be formed. The carbonization process of PPy film precursor was result in large numbers of uniform mesopores in N-C film, which is expected to provide very regular pore channels for Li⁺ charge transfer and storage. The as-derived free-standing nitrogen-containing carbon film anode exhibits excellent electrochemical performance, especially, at high charge/discharge rate for lithium-ion batteries. The reversible capacities are 908.4, 825.7, 664.0, 531.6, 415.5 and 325.9 mAh g^-1at 1C, 2C, 5C, 10C, 20C and 40C, respectively. The N-C film anode also shows excellent cyclability with high capacity. After 800 cycles, the reversible capacity retains 91.6% of the initial stage. The coulomb efficiency is close to 100%. Such free-standing flexible N-C film anode can be straightforwardly used to fabricate the lithium-ion batteries which are required to deliver high energy and power.

Acknowledgements:

We are grateful for financial support for this work from the National Basic Research Program of China (2014CB239700), the Natural Science Foundation of China (21336003, 21403139, 51472161, 51472160), the Shanghai Pujiang Program (No. 14PJ1407100) and the Science and Technology Commission of Shanghai Municipality (14DZ2250800, 15JC1490800, 12JC1406900, 14520721700). We acknowledge the support of the Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning (TP2014048) and the Hujiang Foundation of China (B14006).

References:

[1] S. Zheng, Y. Chen, Y. Xu, F. Yi, Y. Zhu, Y. Liu, J. Yang, C. Wang, ACS nano, 10995-11003, 7 (2013).

[2] Y. Xu, Q. Liu, Y. Zhu, Y. Liu, A. Langrock, M.R. Zachariah, C. Wang, Nano lett., 470-474, 13 (2013).

[3] T. Yuan, B. Zhao, R. Cai, Y. Zhou, Z. Shao, J. Mater. Chem., 15041-15048, 21 (2011).

[4] T. Yuan, Y-S. He, W. Zhang, Z-F. Ma, Chem. Commun., 112-115, 52 (2016).