Issue 11, 2020

Phenoxazine as a high-voltage p-type redox center for organic battery cathode materials: small structural reorganization for faster charging and narrow operating voltage

Abstract

Although organic p-type cathode materials with high redox potential (>3.5 V vs. Li/Li+) are sustainable alternatives to transition metal oxide cathodes for lithium-ion batteries, only a limited number of these materials have been investigated to date. Therefore, the discovery of new p-type redox centers is essential for further development of successful organic cathodes. Herein, we report phenoxazine (PXZ) as a new p-type redox center for high-voltage cathode materials. Negligible structural reorganization of this PXZ center facilitates a kinetically faster electrochemical pathway, leading to a narrow voltage plateau, full utilization of the capacity, and superior rate capability in a new PXZ-based cathode material, PXZ trimer (3PXZ). The 3PXZ cathode delivered a specific capacity of 112 mA h g−1 at 1C with a high average discharge voltage of 3.7 V vs. Li/Li+ in a Li-organic cell; moreover, even at a high rate of 20C, 73% capacity retention (76 mA h g−1) was achieved. In addition, a 3PXZ composite with mesoporous carbon CMK-3 exhibited a capacity of 100 mA h g−1 with high stability, losing only 0.044% capacity per cycle over 500 cycles at 5C. As 3PXZ outperforms most reported p-type cathodes in terms of both rate capability and stability, we suggest the adoption of the PXZ unit as a novel and promising redox center for high-performance and sustainable energy storage systems.

Graphical abstract: Phenoxazine as a high-voltage p-type redox center for organic battery cathode materials: small structural reorganization for faster charging and narrow operating voltage

Supplementary files

Article information

Article type
Paper
Submitted
31 mars 2020
Accepted
23 juin 2020
First published
23 juin 2020

Energy Environ. Sci., 2020,13, 4142-4156

Phenoxazine as a high-voltage p-type redox center for organic battery cathode materials: small structural reorganization for faster charging and narrow operating voltage

K. Lee, I. E. Serdiuk, G. Kwon, D. J. Min, K. Kang, S. Y. Park and J. E. Kwon, Energy Environ. Sci., 2020, 13, 4142 DOI: 10.1039/D0EE01003K

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