Molecular-level environments of intercalated chloroaluminate anions in rechargeable aluminum-graphite batteries revealed by solid-state NMR spectroscopy

Xu, Jeffrey H.; Jadhav, Ankur L.; Turney, Damon E.; Messinger, Robert J.

doi:10.1039/d0ta02611e

Cited by 13 publications

(11 citation statements)

References 67 publications

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“…The variable-rate cyclic voltammograms (Figure a) were analyzed to better understand the generation of the electroactive ion AlCl 2 + , which is not native to the electrolyte. , The cyclic voltammogram at 1 mV s –1 (Figure b) was disentangled into Faradaic, diffusion-limited contributions to the current as well as non-diffusion-limited current contributions associated with capacitive and pseudocapacitive charge storage. This deconvolution was performed according to the method described in Text S1 (Supporting Information), first described by Wang et al and comprehensively discussed by Schoetz et al The Faradaic contribution to the current was determined to be 63% within the potential window 0.2–1.8 V. The deconvolution also highlighted that the Faradaic, diffusion-limited electrochemical enolization reactions are each followed by a region of non-diffusion-limited current (Figure b, blue shaded region) that is commensurate with the proposed generation of charge-compensating cations at the electrode surface that subsequently coordinate to INDQ via the reaction scheme: The accumulation of these AlCl 4 – anions generated at the electrode surface is likely the root cause of the observed (pseudo)capacitance.…”

Section: Resultsmentioning

confidence: 99%

Molecular-Scale Elucidation of Ionic Charge Storage Mechanisms in Rechargeable Aluminum–Quinone Batteries

et al. 2022

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Rechargeable aluminum–organic batteries are of great interest as a next-generation energy storage technology because of the earth abundance, high theoretical capacity, and inherent safety of aluminum metal, coupled with the sustainability, availability, and tunabilty of organic molecules. However, the ionic charge storage mechanisms occurring in aluminum–organic batteries are currently not well understood, in part because of the diversity of possible charge-balancing cations, coupled with a wide array of possible binding modes. For the first time, we use multidimensional solid-state NMR spectroscopy in conjunction with electrochemical methods to elucidate experimentally the ionic and electronic charge storage mechanism in an aluminum–organic battery up from the atomic length scale. In doing so, we present indanthrone quinone (INDQ) as a positive electrode material for rechargeable aluminum batteries, capable of reversibly achieving specific capacities of ca. 200 mAh g–1 at 0.12 A g–1 and 100 mAh g–1 at 2.4 A g–1. We demonstrate that INDQ stores charge via reversible electrochemical enolization reactions, which are charge compensated in chloroaluminate ionic liquid electrolytes by cationic chloroaluminous (AlCl2 +) species in tetrahedral geometries. The results are generalizable to the charge storage mechanisms underpinning anthraquinone-based aluminum batteries. Lastly, the solid-state dipolar-mediated NMR experiments used here establish molecular-level interactions between electroactive ions and organic frameworks while filtering mobile electrolyte species, a methodology applicable to many multiphase host–guest systems.

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Section: Resultsmentioning

confidence: 99%

Molecular-Scale Elucidation of Ionic Charge Storage Mechanisms in Rechargeable Aluminum–Quinone Batteries

et al. 2022

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“…These findings are well consistent with the results in the previous literature. [43] Interestingly, additional 27 Al signals at 52 and 59 ppm corresponding to the AlCl 2 + can be observed at the fully discharged electrode of rinsing with ultra-dry acetonitrile. This result indicates that there is a new type of aluminum complex ion generated in the ionic liquid (IL) electrolyte, Al 2 Cl 7 − and AlCl 4 − can be removed by washing with ultra-dry acetonitrile.…”

Section: Energy Storage Mechanism Of H 2 Tppmentioning

confidence: 99%

Stable High‐Capacity Organic Aluminum–Porphyrin Batteries

Han

Song

et al. 2021

Advanced Energy Materials

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electric vehicles, and more. [4,5] Among these rechargeable battery technologies, sodium, [6][7][8] magnesium, [9,10] zinc, [11,12] calcium, [13] and aluminum [14][15][16] ion batteries have drawn unique attention as the candidates of next-generation batteries. In particular, rechargeable aluminum-ion batteries (AIBs) hold impressive advantages, such as wide temperature range, high safety, and low cost. [17][18][19] However, there is still plenty of room for improving the energy density and long-term life cycle of the positive electrode materials in AIBs. Hence, it is significant to design appropriate positive electrode materials to promote the performance of current AIBs. Recently, extensive efforts have been devoted to the development of organic materials owing to their unique structural features, such as chemical diversity and structure designability, which allows for achieving suitable active molecules for targeted electrodes. [20][21][22] In addition, weak intermolecular forces between active ions in the electrolyte and host materials are beneficial to the reversibility and kinetics of electrochemical reactions. [23,24] Moreover, molecular engineering could be employed to manipulate the voltage plateaus, electrical conductivity, and structural stability of organic materials, which enables the organic molecules to serve as a promising candidate material for next-generation electrode materials.At present, organic electrode materials reported in the AIBs mainly refer to the oxygen or nitrogen active sites in the compounds with carbonyl (CO) or in the nitrogen-containing compounds (CN), due to their structural diversity and chemical stability. In addition, this type of organic material is mainly based on coordination chemical reactions. [21,22,[25][26][27][28] Specifically, many studies on the compounds with carbonyl functional group have been reported. For example, Stoddart [25] and his colleagues synthesized a redox-active phenanthraquinone (PQ) macrocyclic compound, and the corresponding insertion mechanism between aluminum complex ions and conjugated carbonyl materials has been studied. Subsequently, they have improved specific capacity, electrical conductivity, and areal loading via blending PQ with graphite flakes. In the study from Lu and coworkers, [26] a polyimide (PI)/metal-organic framework (MOFs) hybrid material was reported. Also, Wang and coworkers [22] employed PI/CNT as the positive material in Al-organic battery. In the Aluminum-ion batteries (AIBs) attract interest for their promising features of superior safety and long-life energy storage. Organic materials with engineered active groups are considered promising for promoting energy storage capabilities. However, the corresponding energy density (both voltage plateau and sufficient active sites required) and stability are still unexpectedly poor. To address these challenges, here π-conjugated organic porphyrin molecules, that is, 5,10,15,20-tetraphenylporphyrin (H 2 TPP) and 5,10,15,20-tetrakis(4carboxyphenyl) porphyrin (H 2 TCPP), are selec...

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“…Solid-state nuclear magnetic resonance (NMR) spectroscopy enables battery researchers to selectively probe the intercalated ions themselves, such as identify unique local electronic and magnetic environments associated with intercalation sites, study their dynamics, and quantify their populations. − Solid-state NMR has been used extensively to study Li-ion intercalation into battery electrodes . However, common multivalent ions such as Mg 2+ , Ca 2+ , and Zn 2+ are challenging to study, as their relevant NMR active nuclei, i.e., 25 Mg, 43 Ca, and 67 Zn, are insensitive because of their low gyromagnetic ratios and natural abundances.…”

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confidence: 99%

Quantitative Molecular-Level Understanding of Electrochemical Aluminum-Ion Intercalation into a Crystalline Battery Electrode

Jadhav

Messinger

2020

ACS Energy Lett.

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Few materials are known to electrochemically intercalate trivalent aluminum cations, a charge storage mechanism central to rechargeable aluminum-ion battery electrodes. Here, using the chevrel phase Mo 6 S 8 as a model crystalline electrode material, we couple electrochemical and solid-state 27 Al NMR methods to understand quantitatively the aluminum-ion intercalation mechanism up from the molecular level. Unlike divalent Mg 2+ cations, trivalent Al 3+ cations intercalate simultaneously, as opposed to sequentially, into two cavities within the chevrel framework during galvanostatic discharge. Minimal Al 3+ cation trapping occurs upon deintercalation (<7%). The simultaneous ion intercalation mechanism, as well as slow solid-state ion diffusion, can both be understood in terms of the high charge density of Al 3+ cations. We also reveal that an amorphous surface layer forms upon aluminum-ion desolvation from molecular chloroaluminate anions in the ionic liquid electrolyte. The results yield quantitative molecular-level understanding of aluminum-ion intercalation in a model crystalline electrode material and establish solid-state 27 Al NMR as a powerful characterization tool for rechargeable aluminum-ion batteries.

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Molecular-level environments of intercalated chloroaluminate anions in rechargeable aluminum-graphite batteries revealed by solid-state NMR spectroscopy

Abstract: Solid-state 27Al MAS NMR spectroscopy and DFT calculations reveal that intercalated AlCl4− anions exhibit a wide range of molecular geometries and environments, establishing that the intercalated graphite electrodes exhibit high extents of disorder.

Cited by 13 publications

References 67 publications

Molecular-Scale Elucidation of Ionic Charge Storage Mechanisms in Rechargeable Aluminum–Quinone Batteries

Molecular-Scale Elucidation of Ionic Charge Storage Mechanisms in Rechargeable Aluminum–Quinone Batteries

Stable High‐Capacity Organic Aluminum–Porphyrin Batteries

Quantitative Molecular-Level Understanding of Electrochemical Aluminum-Ion Intercalation into a Crystalline Battery Electrode

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