Cooperative Conformational Change of Bio-Inspired Organic Molecule for Ultrafast Lithium-Ion Batteries

Abstract

Biological energy transduction occurs through stepwise redox reactions of various organic molecules, such as adenosine triphosphate, quinone derivatives, nicotinamide and flavin cofactors.1,2 The redox reactions in the biological system have inspired the design of biomimetic materials for renewable energy and environmental science.3-5 Recently, the exploitation of biological redox reactions has provided a new approach to the design of organic electrode materials for rechargeable batteries.6,7 Redox-active bioorganic molecules led to the development of high-performance battery systems owing to their reversible redox activities.8 For examples, quinone and flavin derivatives, in which stable redox states exist during photosynthesis and cellular respiration, showed reversible battery operation at ~2.5 V vs. Li+/Li.9,10 Electron-withdrawing groups (e.g. N and O) in the vicinity of the redox active centers (e.g. C=O and C=N) in quinone and flavin derivatives further elevated the redox potential by attracting the electrons from the electron cloud around the redox active centers. Unfortunately, battery performance of organic-based electrodes is still lacking of energy and power density to be implemented into the practical energy storage system.11 To tackle this issue, the organic molecules with more redox moieties and higher conductivity have been explored.12,13 In addition, to improve the stability of organic molecules as well as inter-charge transfer, nano-dimensional networking between carbon conductor and organic molecules is of great interest so far.14,15 However, the organic-battery performance can be influenced by molecular geometry and molecular orbital structure according to the literature.16,17 Therefore, we envisage the cooperative conformational change of organic molecules during battery operation.Herein, as depicted in Figure 1, we unveiled that the proton-coupled redox reaction of single organic molecule in an aqueous solution can be translated to the lithium-coupled redox reaction of single organic molecule in a lithium-based organic electrolyte by using phenoxazin-3-one (i.e., resorufin) as a new bio-inspired redox-active molecule. In this report, we elaborate the cooperative conformational change of the single molecule during the redox reaction, which ultimately lead to the outstanding battery performance for the first time. Phenoxazin-3-one is selected as the model single organic molecule. Our analyses using operando Raman spectroscopy and DFT calculations confirmed the conformational flexibility in the molecular shape, enabling formation of strong p-p interactions between redox-active organic molecule and carbon. The strong p-p interaction of the single organic molecule with carbon resulted in the excellent battery performance (high discharge capacity, 298 mAhg-1, and outstanding rate capability, 65% retention at 10 C). Our work provides in-depth understanding about cooperative conformational change in the single molecule and its effect on the battery performance. Furthermore, we suggest a phenoxazin-3-one as a new redox-active molecules derived from biochemical redox reaction for energy storage materials in Li-ion rechargeable batteries.(1) B. B. Lowell, B. M. Spiegelman, Nature 2000, 404, 652.(2) H. Wang, Y. Yang, L. Guo, Adv. Energy Mater. 2017, 7, 1700663.(3) L. Que Jr, W. B. Tolman, Nature 2008, 455, 333.(4) U. G. K. Wegst, H. Bai, E. Saiz, A. P. Tomsia, R. O. Nat. Mater. 2014, 14, 23.(5) Y. J. Lee, H. Yi, W.-J. Kim, K. Kang, D. S. Yun, M. S. Strano, G. Ceder, A. M. Belcher, Science 2009, 324, 1051.(6) Y. Ding, Y. Li, G. Yu, Chem 2016, 1, 790.(7) B. Lee, Y. Ko, G. Kwon, S. Lee, K. Ku, J. Kim, K. Kang, Joule 2018, 2, 61.(8) J. Hong, M. Lee, B. Lee, D.-H. Seo, C. B. Park, K. Kang, Nat. Commun. 2014, 5, 5335.(9) M. Lee, J. Hong, D.-H. Seo, D. H. Nam, K. T. Nam, K. Kang, C. B. Park, Angew. Chem. Int. Ed. 2013, 52, 8322.(10) Z. Song, Y. Qian, X. Liu, T. Zhang, Y. Zhu, H. Yu, M. Otani, H. Zhou, Energy Environ. Sci. 2014, 7, 4077.(11) S. Lee, G. Kwon, K. Ku, K. Yoon, S.-K. Jung, H.-D. Lim, K. Kang, Adv. Mater. 2018, 30, 1704682.(12) B. Häupler, A. Wild, U. S. Schubert, Adv. Energy Mater. 2015, 5, 1402034.(13) Q. Zhao, Y. Lu, J. Chen, Adv. Energy Mater. 2017, 7, 1601792.(14) M. Lee, J. Hong, H. Kim, H.-D. Lim, S. B. Cho, K. Kang, C. B. Park, Adv. Mater. 2014, 26, 2558.(15) C. Luo, R. Huang, R. Kevorkyants, M. Pavanello, H. He, C. Wang, Nano Lett. 2014, 14, 1596(16) Y. Morita, S. Nishida, T. Murata, M. Moriguchi, A. Ueda, M. Satoh, K. Arifuku, K. Sato, T. Takui, Nat. Mater. 2011, 10, 947.(17) V. A. Mihali, S. Renault, L. Nyholm, D. Brandell, RSC Adv. 2014, 4, 38004. Figure 1