Anthraquinone Derivatives in Aqueous Flow Batteries
TL;DR: In this article, the authors investigate four anthraquinone derivatives as negative electrolyte candidates for an aqueous quinone-bromide redox flow battery: AQS-2-sulfonic acid (AQS), 1,8-dihydroxyanthrathraquinones-2,7-disulfonics acid (DHAQDS), alizarin red S (ARS), and 1,4-dioxymethyl sulfonic acid, and DHAQDMS.
Abstract: Anthraquinone derivatives are being considered for large scale energy storage applications because of their chemical tunability and rapid redox kinetics. The authors investigate four anthraquinone derivatives as negative electrolyte candidates for an aqueous quinone-bromide redox flow battery: anthraquinone-2-sulfonic acid (AQS), 1,8-dihydroxyanthraquinone-2,7-disulfonic acid (DHAQDS), alizarin red S (ARS), and 1,4-dihydroxyanthraquinone-2,3-dimethylsulfonic acid (DHAQDMS). The standard reduction potentials are all lower than that of anthraquinone-2,7-disulfonic acid (AQDS), the molecule used in previous quinone-bromide batteries. DHAQDS and ARS undergo irreversible reactions on contact with bromine, which precludes their use against bromine but not necessarily against other electrolytes. DHAQDMS is apparently unreactive with bromine but cannot be reversibly reduced, whereas AQS is stable against bromine and stable upon reduction. The authors demonstrate an AQS-bromide flow cell with higher open circuit potential and peak galvanic power density than the equivalent AQDS-bromide cell. This study demonstrates the use of chemical synthesis to tailor organic molecules for improving flow battery performance.
Citations
More filters
TL;DR: This critical review aims to provide the recent advances in the fabrication of COF thin films not only supported on substrates but also as free-standing nanosheets via both bottom-up and top-down strategies.
Abstract: As a newly emerging class of porous materials, covalent organic frameworks (COFs) have attracted much attention due to their intriguing structural merits (e.g., total organic backbone, tunable porosity and predictable structure). However, the insoluble and unprocessable features of bulk COF powder limit their applications. To overcome these limitations, considerable efforts have been devoted to exploring the fabrication of COF thin films with controllable architectures, which open the door for their novel applications. In this critical review, we aim to provide the recent advances in the fabrication of COF thin films not only supported on substrates but also as free-standing nanosheets via both bottom-up and top-down strategies. The bottom-up strategy involves solvothermal synthesis, interfacial polymerization, room temperature vapor-assisted conversion, and synthesis under continuous flow conditions; whereas, the top-down strategy involves solvent-assisted exfoliation, self-exfoliation, mechanical delamination, and chemical exfoliation. In addition, the applications of COF thin films including energy storage, semiconductor devices, membrane-separation, sensors, and drug delivery are summarized. Finally, to accelerate further research, a personal perspective covering their synthetic strategies, mechanisms and applications is presented.
482 citations
TL;DR: This review provides a comprehensive overview of all reported cell configurations that involve electroactive organic compounds working either in the solid state or in solution for aqueous or nonaqueous electrolytes and highlights the most promising systems based on such various chemistries.
Abstract: As the world moves toward electromobility and a concomitant decarbonization of its electrical supply, modern society is also entering a so-called fourth industrial revolution marked by a boom of electronic devices and digital technologies. Consequently, battery demand has exploded along with the need for ores and metals to fabricate them. Starting from such a critical analysis and integrating robust structural data, this review aims at pointing out there is room to promote organic-based electrochemical energy storage. Combined with recycling solutions, redox-active organic species could decrease the pressure on inorganic compounds and offer valid options in terms of environmental footprint and possible disruptive chemistries to meet the energy storage needs of both today and tomorrow. We review state-of-the-art developments in organic batteries, current challenges, and prospects, and we discuss the fundamental principles that govern the reversible chemistry of organic structures. We provide a comprehensive overview of all reported cell configurations that involve electroactive organic compounds working either in the solid state or in solution for aqueous or nonaqueous electrolytes. These configurations include alkali (Li/Na/K) and multivalent (Mg, Zn)-based electrolytes for conventional "sealed" batteries and redox-flow systems. We also highlight the most promising systems based on such various chemistries relying on appropriate metrics such as operation voltage, specific capacity, specific energy, or cycle life to assess the performances of electrodes.
408 citations
TL;DR: This review presents a systematic molecular engineering scheme for designing organic and organometallic redox species in terms of solubility, redox potential, and molecular size and introduces recent advances covering the reaction mechanisms, specific functionalization methods, and electrochemical performances ofredox species classified by their molecular structures.
Abstract: With high scalability and independent control over energy and power, redox flow batteries (RFBs) stand out as an important large-scale energy storage system. However, the widespread application of conventional RFBs is limited by the uncompetitive performance, as well as the high cost and environmental concerns associated with the use of metal-based redox species. In consideration of advantageous features such as potentially low cost, vast molecular diversity, and highly tailorable properties, organic and organometallic molecules emerge as promising alternative electroactive species for building sustainable RFBs. This review presents a systematic molecular engineering scheme for designing these novel redox species. We provide detailed synthetic strategies for modifying the organic and organometallic redox species in terms of solubility, redox potential, and molecular size. Recent advances are then introduced covering the reaction mechanisms, specific functionalization methods, and electrochemical performances of redox species classified by their molecular structures. Finally, we conclude with an analysis of the current challenges and perspectives on future directions in this emerging research field.
387 citations
TL;DR: In this paper, the recent development of a variety of Redox-Active Organic Materials (ROMs) and associated battery designs in both aqueous and nonaqueous electrolytes are reviewed.
Abstract: Redox flow batteries (RFBs) are propitious stationary energy storage technologies with exceptional scalability and flexibility to improve the stability, efficiency, and sustainability of our power grid. The redox-active materials are the key component for RFBs with which to achieve high energy density and good cyclability. Traditional inorganic-based materials encounter critical technical and economic limitations such as low solubility, inferior electrochemical activity, and high cost. Redox-active organic materials (ROMs) are promising alternative “green” candidates to push the boundaries of energy storage because of the significant advantages of molecular diversity, structural tailorability, and natural abundance. Here, the recent development of a variety of ROMs and associated battery designs in both aqueous and nonaqueous electrolytes are reviewed. The critical challenges and potential research opportunities for developing practically relevant organic flow batteries are discussed.
323 citations
TL;DR: It is found that simple galvanostatic charge-discharge cycling is inadequate for assessing capacity fade when fade rates are low or extremely low and refining methods to include potential holds for accurately assessing molecular lifetimes under such circumstances are recommended.
Abstract: Aqueous organic redox flow batteries (RFBs) could enable widespread integration of renewable energy, but only if costs are sufficiently low. Because the levelized cost of storage for an RFB is a function of electrolyte lifetime, understanding and improving the chemical stability of active reactants in RFBs is a critical research challenge. We review known or hypothesized molecular decomposition mechanisms for all five classes of aqueous redox-active organics and organometallics for which cycling lifetime results have been reported: quinones, viologens, aza-aromatics, iron coordination complexes, and nitroxide radicals. We collect, analyze, and compare capacity fade rates from all aqueous organic electrolytes that have been utilized in the capacity-limiting side of flow or hybrid flow/nonflow cells, noting also their redox potentials and demonstrated concentrations of transferrable electrons. We categorize capacity fade rates as being "high" (>1%/day), "moderate" (0.1-1%/day), "low" (0.02-0.1%/day), and "extremely low" (≤0.02%/day) and discuss the degree to which the fade rates have been linked to decomposition mechanisms. Capacity fade is observed to be time-denominated rather than cycle-denominated, with a temporal rate that can depend on molecular concentrations and electrolyte state of charge through, e.g., bimolecular decomposition mechanisms. We then review measurement methods for capacity fade rate and find that simple galvanostatic charge-discharge cycling is inadequate for assessing capacity fade when fade rates are low or extremely low and recommend refining methods to include potential holds for accurately assessing molecular lifetimes under such circumstances. We consider separately symmetric cell cycling results, the interpretation of which is simplified by the absence of a different counter-electrolyte. We point out the chemistries with low or extremely low established fade rates that also exhibit open circuit potentials of 1.0 V or higher and transferrable electron concentrations of 1.0 M or higher, which are promising performance characteristics for RFB commercialization. We point out important directions for future research.
288 citations
References
More filters
Book•
01 Jan 1973TL;DR: CRC handbook of chemistry and physics, CRC Handbook of Chemistry and Physics, CRC handbook as discussed by the authors, CRC Handbook for Chemistry and Physiology, CRC Handbook for Physics,
Abstract: CRC handbook of chemistry and physics , CRC handbook of chemistry and physics , کتابخانه مرکزی دانشگاه علوم پزشکی تهران
52,268 citations
3,162 citations
1,952 citations
TL;DR: In this article, the components of RFBs with a focus on understanding the underlying physical processes are examined and various transport and kinetic phenomena are discussed along with the most common redox couples.
Abstract: Redox flow batteries (RFBs) are enjoying a renaissance due to their ability to store large amounts of electrical energy relatively cheaply and efficiently. In this review, we examine the components of RFBs with a focus on understanding the underlying physical processes. The various transport and kinetic phenomena are discussed along with the most common redox couples.
1,661 citations
TL;DR: This work describes a class of energy storage materials that exploits the favourable chemical and electrochemical properties of a family of molecules known as quinones, and demonstrates a metal-free flow battery based on the redox chemistry of 9,10-anthraquinone-2,7-disulphonic acid.
Abstract: Flow batteries, in which the electro-active components are held in fluid form external to the battery itself, are attractive as a potential means for regulating the output of intermittent renewable sources of electricity; an aqueous flow battery based on inexpensive commodity chemicals is now reported that also has the virtue of enabling further improvement of battery performance through organic chemical design. Flow batteries differ from the conventional type in that the electro-active components of flow batteries are held in fluid form external to the battery itself, enabling such systems to store arbitrarily large amounts of energy. Flow batteries are therefore attractive as a potential means for regulating the output of intermittent sources of electricity such as wind or solar power. But an important limitation of most such systems is the abundance and cost of the electro-active materials. To overcome this limitation, Brian Huskinson and colleagues have developed an aqueous flow battery on the basis of inexpensive, non-metallic commodity chemicals, with the added advantage of enabling the tuning of key battery properties through chemical design. As the fraction of electricity generation from intermittent renewable sources—such as solar or wind—grows, the ability to store large amounts of electrical energy is of increasing importance. Solid-electrode batteries maintain discharge at peak power for far too short a time to fully regulate wind or solar power output1,2. In contrast, flow batteries can independently scale the power (electrode area) and energy (arbitrarily large storage volume) components of the system by maintaining all of the electro-active species in fluid form3,4,5. Wide-scale utilization of flow batteries is, however, limited by the abundance and cost of these materials, particularly those using redox-active metals and precious-metal electrocatalysts6,7. Here we describe a class of energy storage materials that exploits the favourable chemical and electrochemical properties of a family of molecules known as quinones. The example we demonstrate is a metal-free flow battery based on the redox chemistry of 9,10-anthraquinone-2,7-disulphonic acid (AQDS). AQDS undergoes extremely rapid and reversible two-electron two-proton reduction on a glassy carbon electrode in sulphuric acid. An aqueous flow battery with inexpensive carbon electrodes, combining the quinone/hydroquinone couple with the Br2/Br− redox couple, yields a peak galvanic power density exceeding 0.6 W cm−2 at 1.3 A cm−2. Cycling of this quinone–bromide flow battery showed >99 per cent storage capacity retention per cycle. The organic anthraquinone species can be synthesized from inexpensive commodity chemicals8. This organic approach permits tuning of important properties such as the reduction potential and solubility by adding functional groups: for example, we demonstrate that the addition of two hydroxy groups to AQDS increases the open circuit potential of the cell by 11% and we describe a pathway for further increases in cell voltage. The use of π-aromatic redox-active organic molecules instead of redox-active metals represents a new and promising direction for realizing massive electrical energy storage at greatly reduced cost.
1,194 citations