Through-Space Charge Modulation Overriding Substituent Effect: Rise of the Redox Potential at 3.35 V in a Lithium-Phenolate Stereoelectronic Isomer

Abstract

Raising the operating potential of the organic positive electrode materials is a crucial challenge if they are to compare with lithium-ion inorganic counterparts. Although many efforts have been directed on tuning through substituent electronic effect, the chemistries than can operate above 3 V vs Li + /Li 0 , and thus be air stable in the Li-reservoir form (alike the conventional inorganic Liion positive electrode materials) remain finger-counted. Herein, we report on a new n-type organic Li-ion positive electrode materialthe tetralithium 2,5dihydroxy-1,4-benzenediacetatewith a remarkably high redox potential of 3.35 V vs Li + /Li attained notably in the solid phase. The origin of the high-energy content in this quinone derivative is found in a stereoelectronic chameleonic effect with an intramolecular conformation change and charge modulation leading to a redox potential increase of 650 mV in the solid state as compared to the same chemistry tested in solution (2.70 V vs Li + /Li). The conformational dependent electroactivity rationale is supported by electrochemical and crystallography analysis, comparative infrared spectroscopy, and DFT calculation. We identify and make a linear correlation between the enolate vibrational modes and the redox potential, with general applicability for possibly other phenolate redox chemistries. Owing to these effects, this lithiated quinone is stable in ambient air and can be processed and handled alike the conventional inorganic Li-ion positive electrode materials. Whereas intrinsic to high voltage operation stability issues remain to be solved for practical implementation, our fundamental in nature and proof-of-concept study highlights the strong amplitude of through-space charge modulation effects in designing new organic Li-ion positive electrode chemistries with practical operating potential. 46For all these reasons, the organic battery field has 47

A high capacity small molecule quinone cathode for rechargeable aqueous zinc-organic batteries

“…The effect of protonation on proton insertion is further extended to the compounds of 2,5-diamino-1,4-benzoquinone (DABQ) 37 , THBQ and 2,5-dihydroxy-1,4-benzenediacetate (DOBDA) 53 . Supplementary Fig.…”

Conjugated sulfonamides as a class of organic lithium-ion positive electrodes

“…The most common approach used in the community rely on comparative experimental -DFT analyses while recent developments start enriching this arsenal. Some of us have proposed models in which the charge perturbation and thus the redox potential correlates with the vibration energy of specific bands 16,17,32 . We have also adopted similar approaches to CSA chemistries and found correlations between the vibration frequency of specific bands and the averaged redox potential at various confidence degrees (refer to Online Supplementary Section 12).…”

“…While the chemical space of air-stable organic Li-ion positive electrode materials was so far limited to Li2(Mg)-p-DHT 16 , Li4-p-DHBDS 14 and Li4-p-DOBDA 17 , the proposed CSA family considerably enriches the landscape (Figs. 5g, Fig.…”

“…7,12,13 The state-of-the-art for organic Li-ion positive electrodes (n-type, Li-containing, air stable) is nearly absent to date. Pioneering developments have been just proposed in 2018, with electron withdrawing substituted quinones 14,15 , through sacrificial metal mediated charge delocalization 16 , or through stereoelectronic chameleonic effect 17 . Whereas these set the foundations for practical organic positive electrodes, the proposed chemistries remain limited in structural and compositional diversity relying on the extensively studied enolate-carbonyl redox chemistry, which intrinsically operates at a low redox potential (Fig.…”

Recent progress in metal–organic framework/graphene-derived materials for energy storage and conversion: design, preparation, and application

“…196,197 In conventional LIBs, graphite is commonly used as the negative and lithiated transition metal oxides (e.g., LiFePO 4 , LiMn 2 O 4 , and Li[Ni x Co y -Mn z ]O 2 ) as the positive electrode materials. 198,199 Although great progress has been achieved, they are still insufficient for the above applications due to the relatively low capacity, as well as low energy and power density. 16 Recently, tremendous efforts have been devoted to fabricating MOF/graphene-derived nanocomposites with sophisticated structures, which are considered to be one of the most promising candidates to improve the LIB performance.…”