Redox Shuttles with Axisymmetric Scaffold for Overcharge Protection of Lithium‐Ion Batteries |
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| Authors: | Wei Weng Jinhua Huang Ilya A Shkrob Lu Zhang Zhengcheng Zhang |
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| Affiliation: | 1. Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, IL, USA;2. Joint Center for Energy Storage Research, Argonne National Laboratory, Argonne, IL, USA |
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| Abstract: | The derivatives of 1,4‐dimethoxybenzene are thus far the best performing redox shuttle additives for overcharge protection of Li‐ion batteries. The most durable molecules of this kind typically possess two in‐plane methoxy groups that are equivalent by inversion symmetry. However, such geometry leads to a vanishing average dipole moment that causes poor solubility of these molecules in carbonate‐based electrolytes. In this study, a novel redox shuttle additive, 1,2,3,4‐tetrahydro‐6,7‐dimethoxy‐1,1,4,4‐tetramethyl‐naphthalene (TDTN), is introduced. It has been demonstrated that reversible oxidation at 4.05 V versus Li+/Li, high polarity, high solubility (around 0.4 m ), and excellent electrochemical stability (150 overcharge cycles at C/2 rate with 100% overcharge) can all be achieved simultaneously by the imposition of axial symmetry in the corresponding radical cation that is generated by electrochemical oxidation of TDTN in the battery. The intricate interplay between the symmetry and the chemical stability of the radical cation is scrutinized using magnetic resonance spectroscopy and electron structure modeling. |
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| Keywords: | lithium‐ion batteries molecular symmetry overcharge protection redox shuttle additives |
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